Final Report Summary - EFISHENT (Improvement of feeds and feeding efficiency for seabass in cage farms in the Mediterranean.)
Executive Summary:
The main objective of this project was to optimise feed management methods and allow the European sea bass farmer to significantly reduce production FCR and thus feeding costs. At the same time nutritional and technical improvements will allow improvements in fish growth, labour costs reduction and minimise the environmental impacts of fish farming. Currently, one-third of the world’s fish catch is used to produce fishmeal and fish oil, and in 2004, the aquaculture industry used 87% of the world’s fish oil and 53% of the world’s fishmeal. Improved production FCR will reduce the overall demand for raw materials for fish feed production. Sea bass nutritional requirements and feed formulation.
WP 2. The scope of this workpackage was to fine tune the European sea bass diets’ composition in order to achieve cost efficient industrial production. To achieve this goal we need to reach in depth understanding of the qualitative and quantitative needs of this fish species at different life stages, environmental and physiological conditions. In reality feed producers will fabricate fish diets according to raw material quality, availability and price, not necessarily in that order, unless they are in hold of good arguments for acting otherwise. There is a big but not uniform available data on the effects of each commercially used raw material on different fish species performance. However, it was neither in the time frame nor scope of this project to identify specific raw material effects and qualities on European sea bass performance. We therefore needed to use all experience we had, published or not in order to use in this project’s fish experiments commercially relevant feed formulations of highly predictable quality and performance.
The eFISHent partners joined their efforts in the first part of the project to collect all available production and research data regarding nutrition and production technology of European sea bass in order to be able to formulate well balanced feeds for the different experiments and to choose the most appropriate feeding regimes to be followed. A scientific review on the nutritional requirements of European sea bass and an extensive database including commercial sea bass production results was produced and updated throughout the life time of the project. We determined the maintenance energy requirement of E. sea bass at different temperatures and ages. Following, the utilisation efficiency of dietary protein and energy was determined using two methods, of which the metabolic chamber was proven the easiest and most precise. Best European sea bass growth for body weight sizes from 10 to 200 g was obtained with feeds of 45/16 and 60/12 crude protein/lipid. Best feed utilization was observed for the 45/16 diet. Protein utilization efficiency decreased as dietary protein increased indicating higher nitrogen loss to the environment with higher protein diets and vice versa.
The fish whole body composition and immune status of the fish was not influenced by the different experimental treatments. Last we demonstrated that the fish farmer should expect an economic loss from reducing feed cost by using oils (plant or fish oil) in the expense of dietary protein, even at small increment changes. Reduced feed intake rates and growth were observed by slight increases in the dietary lipids and best growth was observed in E. sea bass of 5-25 g body weight receiving daily 8.3 g protein per kg fish body weight.
WP 3. Seasonal feeds and feeding strategies for sea bass.
The purpose of this workpackage was to determine, under laboratory conditions, rational feeding protocols based on the biology and behaviour of Atlantic European Sea bass Dicentrarchus labrax of varying size and under differing environmental conditions. It also included laboratory scale testing of the diets formulated in WP2, and examining the effect of FCR (Feed Conversion Rate) on diet palatability and pellet size. A nutritional study on reducing fish maturation was also performed.
We demonstrated the significant economic benefit potential from using appropriate dietary formulations and oxygenation in cages where E. sea bass is reared at low water oxygen saturation levels. Though higher protein and lower lipid diets proved in several eFISHent trials superior in terms of E. sea bass performance, this result was inverted at low oxygen levels, where fish fed a lower protein and higher fat diet had best FCR and growth.
In the winter period, FCR was improved significantly by fasting E. sea bass every other or every third day with no reduction in growth. Moreover, by using sustainable 0% fish oil diets rich in low n-6 plant oils (such as palm oil, olive oil and salmon by-product oil), gonadal growth and expression of genes coding for maturation hormones was reduced. Both at low and high water temperatures E. sea bass is able to growth with low to very low FCR by use of well balanced and nutritionally complete diets, even when only 10% fish meal is used in the diet. No negative histopathological effects were observed in the fish fed the high plant diets.
The feeding rhythm of fish species is important in aquaculture and the daily feeding rhythm in sea bass was assessed in triplicate using a demand feeding system designed for the project. There were no differences in feeding behaviour throughout the 24 hour day in the 30 days of the experiment. The current study demonstrated that Sea Bass had a feeding rhythm throughout the day, with a maximum of feeding from 04:00 to 05:00 h. Nevertheless this should be tested in sea cages before recommending any preferred feeding regime. Tables showing recommended feed pellet sizes for fish weights and lengths were produced in this study based on a review of the recommendations provided by all the commercial feed manufacturers.
The main findings of the benchmarking study was to show the relationship between water temperature and fish size in relation to feeding efficiency (FCR) and growth performance (SGR). Commercial FCRs are generally higher both in Greece and Turkey during the winter months when water temperatures are low. FCRs also increase as the fish get bigger. The experimental phase of WP4 demonstrated that increasing daily feeding frequency from 1-meal per day to 2-meals per day on commercial farms during winter offers no benefits in terms of FCR and SGR performance. Feeding fish every other during early winter may also be a cost-effective feeding regime for commercial sea bass farmers during early winter. The feasibility study that investigated whether there is a need or current market for linking feeding and oxygenation systems for Mediterranean cage aquaculture suggests farmers in Turkey are currently prioritising updating their feeding systems and will take the step of possibly upgrading their oxygenation systems when they can find a cost-effective and robust solution to dealing with potential oxygenation problems in cage aquaculture.
WP4. The general aim of WP4 was to deliver operational research to help commercial sea bass aquaculturists reduce their on-farm feed conversion ratios (FCRs) and thus improve production efficiency, reduce feed waste and reduce feed costs. Specifically, the WP4 partners aimed to help our commercial SME partner, Özsu Balik Ltd, improve their operational FCR and feeding efficiency. These findings can then be rolled out amongst other sea bass producers in the Mediterranean region. To achieve the aims of improving operational on-farm FCRs, farmers need to i) understand how their feeding practices affect operational FCRs, and ii) identify ways to improve their on-farm feed management. This can be enhanced through improved dissemination of existing knowledge on best practice in feed management, and also via the identification of commercial technologies and feeding strategies that can be customised to each farmer’s specific needs. The initial aim of WP4 was to benchmark feed conversion ratios on commercial farms. Benchmarking is an emerging aquacultural management tool that allows a farmer to compare their farming practices and performance metrics within their company and against others within the same industry (e.g. Soares et al., 2011). Farmers can then identify areas for potential improvement within their current set-up and economic constraints. The experimental aspect of WP4 involved the operational evaluation of different feeding practices such as i) the effects of different daily feeding frequencies, and ii) the effects of different lengths of feeding/re-feeding periods upon the on-farm FCR, growth performance and welfare of European sea bass held at commercial production facilities. A feasibility study was also carried out by Nofima, ANCO, Element, NESNE Electronics, Özsu Balik and Akvaplan-niva on whether there was scope to combine feeding and oxygenation systems for cage aquaculture, to combat potentially low ambient oxygen levels that can occur during the summer months in Mediterranean sea bass farming. To achieve these aims the benchmarking aspect of WP4 and the feasibility of combining oxygenation and feeding systems started at the beginning of the project, and the majority of experimental work commenced during Year 2 of the project.
WP5. Economic and environmental assessment and impact
The overall purpose of the project is to improve the cost effectiveness of bass and bream culture and thereby to also reduce its local and global environmental impact. The purpose of this WP is thus to quantify the potential economic and environmental benefits likely to accrue from the improved feeds and feeding methods developed. In addition it seeks to clarify the decision making process by which aquaculture companies find out about, evaluate and take decision for the purchase of new technology. This will allow companies such as the SME partner FCN to target their sales and marketing of feed control technology more effectively.
Nine farm managers in Greece (3 small, 3 medium and 3 large companies) and 11 farm managers in Turkey (3 small, 3 medium and 3 large companies) have been interviewed to analyse and assess their decision making process and behaviour.
The actual environmental impact was undertaken collecting and analysing data from round the test cages.The MERAMOD model was set up for Ozsu fish farm,made up of three separate cage groups. Bathymetry data for the surrounding area taken from a survey and an electronic chart were combined and contoured. These data along with cage position data were incorporated into MERAMOD grids.
Assessment in the reduction in the wider ecological footprint using LCA Resource use and greenhouse gas emissions by seabass cage culture systems
The aquaculture sector has been receiving a great deal of criticisms on its potential environmental impacts. The potential impacts from aquaculture systems often highlighted are: Impacts on water quality and sediments, GHG emissions, and high resource use (i.e. wild seed, fish in-fish out ration). The Task evaluated the potential impacts associated with inputs and outputs by the culture of seabass in cages at the Ozsu fish farm in Turkey using some of the Life Cycle Analysis (LCA) methodology. Analysis of the cost benefit the implementation of the knowledge was undertaken for the main research findings: Improved feed, (Summer and winter), High fish meal vs low fish meal, Feed with attractants vs no attractants, Use of cameras, Use of cameras with pellet counting software, Use of oxygenation, Feeding strategy ( 1 meal/day vs 2 meals/day, 50% feed, 1 day feed vs 1 day off, 2 days feed vs1 day off), Maturation control,
WP 6. Dissemination and outreach
All RTD partners played an active role in developing the overall dissemination strategy for the eFISHent project. There was close interaction with the work in WP5, which also is a cross-cutting horizontal activity drawing together the technical, economic and social factors relating to the best practices in feeding management of sea bass farming.
WP 7. Operational validation of feeding technologies and feed formulations
This workpackage set out to validate the findings based around the on-farm testing of feed technologies and diets. The validation work will be carried out on the commercial scale farm cages with the SME partner Oszu. All sampling procedures for evaluating production performance (growth, feed delivered, mortality) were carried out in tandem with Operational Welfare Indicators (OWI’s) to assess whether the different feed technologies and diets are beneficial for aquaculture production in a commercial, on-farm environment.
Project Context and Objectives:
Work Package 1 :
Objectives
• To coordinate the overall development of the project, to assess the accomplishment of tasks allocated to each participant, to discuss the results obtained during different phases of the project.
• To submit internal reports that will make the bases of the periodical reports to be submitted once a year to the REA.
• To fix deadlines for submission of manuscripts for publication, and for submission of results for the elaboration of Period Reports.
• Development of an Exploitation plan, exploitation of results, including the implementation of new rearing methods and feed recipes.
• Handling of relevant IPR issues.
Among the management activities were the monitoring of project progress, deliverables and results, ensuring that the milestones for each phase were achieved. It has kept minutes of all the project meetings and circulated these to the EU and project partners. The partners have formally met 5 times (once pre submission) to discuss planning and achievement of progress. Partners have also met informally with RTD partners visiting SME facilities and during conferences and exhibitions.
Task 1.1 Consortium meetings and coordination of the project
Akvaplan-niva has undertaken the coordination of the overall progress of the project. Among the management activities were the monitoring of project progress, deliverables and results, ensuring that the milestones for each phase were achieved. It has kept minutes of all the project meetings and circulated these to the EU and project partners.
The partners have formally met 5 times to discuss planning, achievement of progress and solve any problems.
• 07 June 2010, Brussels, Belgium
• 28 – 30 November 2010, Athens, Greece
• 25 - 27 May, 2011, Bergen, Norway
• 3 - 4 October, 2011, Brussels, Belgium
• 15 - 7 October 2012, in Izmir, Turkey
Minutes of the meetings were prepared and circulated to all partners and EU project officers. The Coordinator made regular follow up activities to the RTDs for the Project deliverables and ensured that milestones have been met. Partners have also met informally between RTDs and SMEs and during conferences and exhibitions and have communicated regularly through SKYPE and email. Coordination was undertaken by an assigned staff at Company headquarters in Tromso.
Partners have also met informally with RTD partners visiting SME facilities and during conferences and exhibitions.
Task 1.2 Exploitation of results
Draft exploitation and dissemination plan was prepared at Month 9 as a deliverable and the final exploitation and dissemination plan was prepared at the end of the project.
Task 1.3 Handling of IPR matters
A brief description of how the IPR matters would be handled was prepared for the Consortium agreement.
Information was given on background and foreground knowledge in the Attachments to the Consortium Agreement.
• Attachment 1. Background Knowledge
• Attachment 2. Foreground knowledge
• Attachment 3. Access to foreground knowledge
Work package 2 : Sea bass nutritional requirements and feed formulation
Objectives
• Survey on the nutritional requirements, the commercial feeding strategies and the available feed technology in sea bass culture and diet formulation for lab and production scale experiments.
• Determination of growth potential and energy composition of sea bass under different commercial production environments.
• Comparison of different methods to measure energy flow in fish and determination of energy flow in sea bass for diets with different energy densities.
• Determination of optimum energy density for growth and feed utilization of sea bass.
• Determination of optimum protein to energy levels, seasonal feeds and feeding strategies for commercial feeding practices.
• Creation of models for the prediction of fish performance and cost efficiency of production of sea bass using different feed formulations at different fish ages and water temperatures.
The scope of this work package was to fine tune the European sea bass diets’ composition in order to achieve cost efficient industrial production. To achieve this goal we need to reach in depth understanding of the qualitative and quantitative needs of this fish species at different life stages, environmental and physiological conditions. In reality feed producers will fabricate fish diets according to raw material quality, availability and price, not necessarily in that order, unless they are in hold of good arguments for acting otherwise. There is a big but not uniform available data on the effects of each commercially used raw material on different fish species performance. However, it was neither in the time frame nor scope of this project to identify specific raw material effects and qualities on European sea bass performance. We therefore needed to use all experience we had, published or not in order to use in this project’s fish experiments commercially relevant feed formulations of highly predictable quality and performance. The eFISHent partners joined their efforts in the first part of the project to collect all available production and research data regarding nutrition and production technology of European sea bass in order to be able to formulate well balanced feeds for the different experiments and to choose the most appropriate feeding regimes to be followed.
WP 3. Seasonal feeds and feeding strategies for sea bass
Objectives
The elucidation of natural feed intake quantities, feeding frequency patterns and pellet size preferences in bass
• To evaluate if specifically designed winter feeds and winter feeding protocols can be used to improve overall cycle FCR
• To evaluate if feed intake and FCR might be improved by adding specific attractants to the winter and summer diets
• To develop new suggested multivariate feeding tables and protocols, also following the results from WP2, for commercial scale validation in WP4
The purpose of this workpackage was to determine, under laboratory conditions, rational feeding protocols based on the biology and behaviour of Atlantic European Sea bass Dicentrarchus labrax of varying size and under differing environmental conditions. It also included laboratory scale testing of the diets formulated in WP2, and examining the effect of FCR (Feed Conversion Rate) on diet palatability and pellet size. A nutritional study on reducing fish maturation was also performed.
Summary of progress and significant results
Work package 4 : Optimising feed management
Objectives
• evaluate and benchmark current feed management protocols in relation to feeding efficiency and growth
• investigate the optimal timing and frequency of feed delivery in relation production performance and welfare, and examine how this changes with time of year and each SME's labour and budget constraints through CBA (cost benefit analysis)
• develop a series of customised feed management strategies for each SME based upon various demand feeding and feed monitoring technologies
Summary of progress and significant results
The primary objectives of eFISHent WP4 was to deliver operational research to help commercial sea bass aquaculturists reduce their on-farm feed conversion ratios (FCRs) and thus improve production efficiency, reduce feed waste and reduce feed costs. Specifically, the WP4 partners aimed to help our commercial SME partner, Özsu Balik Ltd, improve their operational FCR and feeding efficiency. These findings can then be rolled out amongst other sea bass producers in the Mediterranean region.
The main findings of the WP4 benchmarking study was to show the relationship between water temperature and fish size in relation to feeding efficiency (FCR) and growth performance (SGR). Commercial FCRs are generally higher both in Greece and Turkey during the winter months when water temperatures are low. FCRs also increase as the fish get bigger. The experimental phase of WP4 demonstrated that increasing daily feeding frequency from 1-meal per day to 2-meals per day on commercial farms during winter offers no benefits in terms of FCR and SGR performance. Feeding fish every other during early winter may also be a cost-effective feeding regime for commercial sea bass farmers during early winter. The feasibility study that investigated whether there is a need or current market for linking feeding and oxygenation systems for Mediterranean cage aquaculture suggests farmers in Turkey are currently prioritising updating their feeding systems and will take the step of possibly upgrading their oxygenation systems when they can find a cost-effective and robust solution to dealing with potential oxygenation problems in cage aquaculture.
The general aim of WP4 was to deliver operational research to help commercial sea bass aquaculturists reduce their on-farm feed conversion ratios (FCRs) and thus improve production efficiency, reduce feed waste and reduce feed costs. Specifically, the WP4 partners aimed to help our commercial SME partner, Özsu Balik Ltd, improve their operational FCR and feeding efficiency. These findings can then be rolled out amongst other sea bass producers in the Mediterranean region. To achieve the aims of improving operational on-farm FCRs, farmers need to i) understand how their feeding practices affect operational FCRs, and ii) identify ways to improve their on-farm feed management. This can be enhanced through improved dissemination of existing knowledge on best practice in feed management, and also via the identification of commercial technologies and feeding strategies that can be customised to each farmer’s specific needs.
The initial aim of WP4 was to benchmark feed conversion ratios on commercial farms. Benchmarking is an emerging aquacultural management tool that allows a farmer to compare their farming practices and performance metrics within their company and against others within the same industry (e.g. Soares et al., 2011). Farmers can then identify areas for potential improvement within their current set-up and economic constraints.
Workpackage 5 : Economic and environmental assessment and impact
Objectives
· To evaluate the likely local environmental benefits of the improves feeding protocols developed in WP2-4
· To evaluate the wider environmental benefits from improved use of feeds in bream and bass aquaculture
· To evaluate the economic benefits both at farm and industry level
The overall purpose of the project is to improve the cost effectiveness of bass and bream culture and thereby to also reduce its local and global environmental impact. The purpose of this WP is thus to quantify the potential economic and environmental benefits likely to accrue from the improved feeds and feeding methods developed. In addition it seeks to clarify the decision making process by which aquaculture companies find out about, evaluate and take decision for the purchase of new technology. This will allow companies such as the SME partner FCN to target their sales and marketing of feed control technology more effectively.
Nine farm managers in Greece (3 small, 3 medium and 3 large companies) and 11 farm managers in Turkey (3 small, 3 medium and 3 large companies) have been interviewed to analyse and assess their decision making process and behaviour.
Methodology for the assessment in reduction in local environmental impact in the vicinity of individual units and the assessment in the reduction in the wider ecological footprint using LCA was undertaken.
Workpackage 6 :
Dissemination and outreach Objectives
• To enhance the awareness about the eFISHent project in the main production region, carefully identifying the target audience, the dissemination method and the message content and design
• To make available to a wider audience information about the results and the outcome of the eFISHent project with the aim of enhancing the uptake of its results
• To promote and encourage the uptake and use of the results by stakeholders and environmental managers in Europe, and prepare the basis for maximum impacts of the results
• Disseminate the overall feed management recommendations online and via handbooks to the SME's, large enterprise end users and national and international farming bodies and policy makers
• Publication of peer reviewed studies
The work in this work package was led by Akvaplan-niva, with considerable input from the other partners. All RTD partners played an active role in developing the overall dissemination strategy for the eFISHent project. A close interaction is foreseen with the work in WP5, which also is a cross¬cutting horizontal activity drawing together the technical, economic and social factors relating to the best practices in feeding management of sea bass farming. A project web site (www.efishent.eu) was set up at the start of the Project in November 2010 and has been updated regularly.
Work package 7: Operational validation of feeding technologies and feed formulations
Objectives
• validate through on-site testing, the optimised feed management strategies for each SME developed within WP4
• validate the on-site commercial performance of the feed formulations developed by WPs 2 and 3
• validate the design and performance of combined feeding and oxygenation systems as a means of improving overall feed efficiency in sea bass
Summary of progress and significant results
The primary objectives of the eFISHent demonstration WP7 was to carry out on farm operational research to demonstrate the effectiveness of the outputs of the eFISHent project on a commercial farm. These findings can then be rolled out amongst other sea bass producers in the Mediterranean region.
The main findings of the WP7 technology demonstration study was a ca. 11% improvement in spring and early summer commercial FCRs when farmers used underwater cameras to monitor feeding and feed waste in comparison to existing farm regimes that did not use these technologies. A second study was carried out in commercial scale production facilities that combined underwater cameras and species specific seasonal feed formulations developed in eFISHent WP2 and WP3. The combination of improved diet formulation and camera based feed management resulted in a ca. 12% increase in SGR and a ca. 19% improvement in FCR.
WP7 was the validation and demonstration WP, based around the on-farm testing of feed technologies and diets. The validation work was carried out on commercial scale farm cages with the SME partner Özsu Balik. All sampling procedures for evaluating production performance (growth, feed delivered, mortality) were carried out in tandem with Operational Welfare Indicators (OWI’s) to assess whether the different feed technologies and diets are beneficial for aquaculture production and fish welfare in a commercial, on-farm environment
The initial aim of WP7 was to testing of different feed monitoring technologies in relation to production performance and fish welfare. Özsu and the eFISHent RTDs experimentally investigated the effect of using feeding technology that utilises underwater cameras to monitor feed wastage upon the feeding efficiency, welfare and production performance of sea bass against their existing feed practices.
The next aim of WP7 was to demonstrate the effectiveness of combining advanced feeding technology with the species and seasonally specific feed formulations developed in WP2 and WP3 in a production scale environment.
The final aim of the demonstration WP was to test the feasibility of a combined feeding and oxygenation system. If it proves possible to design a combined feeding and oxygenation system, a prototype unit was to be evaluated in full-scale cage trials to be conducted at Özsu.
Project Results:
The main S&T results and foreground
are as follows;
Work package 2 title: Sea bass nutritional requirements and feed formulation
Task 2.1 Survey on the nutritional requirements and the commercial feeding strategies and feed technology employed in sea bass culture:
We determined the maximum expected growth potential of best performing E. sea bass based on a meta-analysis of the reported data in peer reviewed magazines, as a function of total protein intake rates. A linear relation between fish size and optimal dietary protein level exists and thus feed formulations must be optimised based on the protein requirements and feeding rate capacity of fish at different size and environmental conditions.
Weaker correlations were identified on the basis of total energy intake dietary lipid content, unlike statements in several publications where energy is presented as the main regulative factor of this fish species’ performance. European sea bass appears sensitive to high lipid intake and, according to dietary composition, may stop feeding before the necessary amounts of protein for maximal growth is taken up. Moreover, E. sea bass has also quite high glucose intolerance regulating thus to a significant extend feed intake according to the intake levels of digestible carbohydrates. As fish grow bigger they need lower total digestible protein intake but care must be taken in order not to hinder feed intake by excessive digestible carbohydrate and lipid levels before the protein needs for maximal performance are covered.
The best performing fish picked out from the available research literature had rather stable, slightly increasing levels of whole body protein and also quite stable levels of body fat, as shown in the figure below. Fish fed imbalanced diets deposited more fat in the tissues and performed worse in both feed conversion and growth rate.
VA has collected and analysed the recommended feeding tables produced by various manufacturers of commercial sea bass feed in order to:
a) determine the level of variation in the sizes of pellets recommended for feeding to fish of various sizes.
b) determine the variance in suggested feeding rates (as a percentage of body weight per day) for fish of different sizes at different water temperatures. However, as the diets supplied by different manufacturers may vary in digestible energy content, the collated feeding tables are being re-calculated to give the manufacturers recommendations in terms of daily digestible feed energy to be supplied to the fish.
It is hoped that the results of the above analysis will contribute to a better understanding of the reasoning behind current feeding practices on commercial sea bass farms, and the areas in which some research effort should be directed in order to arrive at more precise feeding recommendations in the areas where the manufacturers’ suggestions may differ.
Task 2.2. Survey on industrial sea bass production results
VA has access to historical monthly sea bass production data, covering a period of 5 years, from up to 14 commercial farm sites in the Mediterranean. There was only a very weak negative correlation between farmed fish growth rates and FCR and an equally very weak positive correlation between FCR and farming duration. The commercial data were analysed to validate a practical base line growth model for sea bass reared commercially under true production conditions (submitted deliverable to EU: D.2.4).
As expected the whole body analysis results showed that farmed E. sea bass whole body protein, fat and energy are increasing with fish size, whole body ash content is stable, and whole body moisture is decreasing with fish size.
Another issue taken into account in this project is the presence of at least 2 very different strains of European sea bass with clearly different performance, the Mediterranean and the Atlantic. In Figure 2.4 are presented some commercial results Nofima has access to where it is clear that both feed and mainly sea bass strain is affecting fish performance (Atlantic fish fed high, medium and low energy diets and Mediterranean fish fed high energy diet). As it is believed that most old and current literature data are based on the Mediterranean strain of this fish species which is clearly inferior to the Atlantic, we believe that a whole new data set on the particular potential and requirements of the Atlantic strain must be created.
The results show that the FCR values published in the literature again for the best performing fish in the different experiments. There is a clear trend (blue spots) of increasing FCR by fish size, but then there are some few out layers (purple points), taken from one of the most recent publications, of significantly better/lower FCR that must have been fish of the Atlantic strain, although there was no relevant mention in the article. Such is the experience we have from the industry during the last 7-8 years when well performing Atlantic sea bass caught again the interest of the producers against sea bream.
Task 2.3. Energy flow in sea bass (HCMR, Nofima):
To perform the task the following steps were undertaken:
a) The metabolic body weight was determined. The metabolic rate (basic metabolism) depends largely on the size of the fish and is proportional to the metabolic body weight in the form of a x BW (kg)b. To define the exponent b of the metabolic body weight the relationships between energy and protein loss at starvation for fish at increasing weights were determined. Fish of different sizes were stocked in tanks at different temperatures and fasted. Then, fish protein and energy content were analyzed for the determination of the energy and protein losses and consequently the metabolic weight of the fish.
b) Feed digestibility at different temperatures was determined for fish of different sizes in cylindroconical tanks with faecal traps according to a modification of the Guelph system and Cr2O3 as a marker.
c) Efficiency of energy and protein utilization was determined: To determine the efficiency of energy and protein utilization and hence the losses due to metabolic excretions and heat losses two methods were compared (Figure 2.5). An indirect slaughter method and a direct novel metabolic chamber method were compared as described below:
1) Slaughter method.
The efficiency of energy utilization for maintenance and growth was derived from feeding Atlantic strain European sea bass increasing amounts of dietary energy from starvation up to maximum intake. 6 weeks growth trials were performed using fish of different weights of about 20, 100 and 200g body weight. Samples were taken before each growth trial and all fish were sacrificed at the end of each trial. Energy, protein and lipid gains in fish were determined and daily retention of energy, protein and lipid was related to mean weight of fish.
2) Metabolic chamber/ respirometer.
The energy expenditure was estimated from the gaseous exchange and the release of N-compounds. The energy flow processes for sea bass was estimated using a special open circuit balance respirometer designed to ensure minimal disturbance of the fish, constant, acceptable water quality and constant temperatures (± 0.5oC) in the range from 15 to 25°C. Respired gases both in water and in air were monitored for several days at constant water and air flows.
Metabolic rate
The equations for the maintenance protein and energy losses and utilization rates for European sea bass at 3 water temperatures: 15, 20 and 25oC were determined and presented below using 2 methods for comparison: the slaughter method and the metabolic chamber.
The feed intake, ammonia excretion and oxygen consumption were temperature dependent. There were no statistically significant differences between diets with different protein and lipid/carbohydrate levels. The metabolic losses were not correlated with the dietary macronutrient composition, but only with temperature. Overall, the metabolic chamber proved to be a must faster and reliable method to estimate energy and protein efficiency of feeds.
Task 2.4. Optimum dietary DP/DE determination:
In the present set of works optimal dietary protein and energy levels for fish of different sizes and at different water temperatures were determined. Based on the results from the previous 2 tasks (2.2 & 2.3) 3 x 3 diets with different DE/DP ratios were formulated and tested on E. sea bass of different body weights reared at different temperatures, for growth, FCR, flesh quality and health. The experiments took place in triplicate tanks for fish from 10 to 200g. Body composition was analyzed at the end of the trials. Flesh quality was evaluated by analyzing the fillet for gross composition and organoleptic characteristics. Health was evaluated by the evaluation of non-specific immune indices of the fish. Complement activity and respiratory burst values were used as immune indicator parameters.
Three diets were formulated and produced by Nofima AS each one at 3 particle sizes: 2.2mm 3.5mm and 5mm for the growing size of fish and the whole feeding trial duration. The formulation and proximate composition analysis results for each one of the three particle sizes of the experimental diets that were produced at Nofima AS are described Table 2.2.
Best European sea bass growth for body weight sizes from 10 to 200 g was obtained with feeds of 45/16 and 60/12 total protein/lipid. Best feed utilization was observed for the 45/16 diet, protein utilization efficiency decreased as dietary protein increased indicating higher nitrogen loss to the environment with higher protein diets and vice versa. No statistical significant differences were observed on fish body composition or in the immune responses of the fish fed the different experimental diets.
The results of the present group of works and the indications for the determined best performing feed formulations were communicated to the partner fish farming SME OZSU and a feed producing SME Raanan Fish feed for the production of the experimental diets for the demonstration activities of the project.
Task 2.5. Modelling of cost efficiency of small gradual DP/DE changes:
Four diets were formulated to contain the same amount of fish meal and variable amount of plant proteins and fish oil, and were balanced with respect to limiting essential amino acids and total soluble phosphorus (Table 2.3). DP/DE diets 1 to 3 contained, as intended, decreasing levels of digestible protein to digestible energy ratio (DP/DE), with low increment changes among them. All experimental diets had similar but higher DP/DE ratio than the suggested optimal by Peres and Oliva Teles (1999).
The protein digestibility in mink (TPD) was high and similar among the diets (90-91 % of total protein) and related to the choice of the protein ingredients/meal in the feed formulation. The results show that a dietary mix with higher fraction of marine proteins (diet 4) does not have significantly higher true protein digestibility (TPD) compared to a dietary mix with increased fraction of plant protein of high nutritional quality for fish (diet 1) (Figures 1a & 1b). This result is in accordance to previous eFISHent project results in European sea bass, showing that at both high and low water temperatures fish performance was equally good using either high or low fish meal diets (Deliverable 3.10).
Sea bass juveniles of ca. 6.5 g mean weight were fed the experimental diets during 90 days in triplicate tanks in the recirculation unit of VA at a (Photo 1) temperature of 17.8±0.6oC.
The trial results showed increased feed intake rates and growth in fish fed the diet with the highest DP/DE (diet 1) (P<0.05). However, though not significantly, feed utilisation was highest in the fish fed the lowest DP/DE diet (diet 4). Fish growth followed feed intake rates, correlating significantly in a linear way, mostly explained by intake of protein energy and less by intake of the non-protein energy fraction of the diets. The FCR was similar for the different diets increasing in the tanks that exhibited the highest feed intake rates. The main factor that explains the observed differences in fish growth was thus feed intake.
We see that, under the experimental conditions, an economic loss for the fish farmer is expected from reducing feed cost by using oils (plant or fish oil) in the expense of dietary protein. This is due to the higher fish biomass produced in the same period of time using the higher protein/lower fat diet 1 due to higher feed intake rates. These results are in accordance to previously reported studies in European sea bass where no protein sparing by dietary lipids occurred beyond 12 % dietary lipid levels (Peres and Oliva-Teles, 1999; Boujard et al., 2004).
Reduced feed intake rates by increasing lipids in the diet were observed also in the present experiment, as also described in the review (D2.3). Using higher lipid and energy dense diets, fish receive higher amounts of energy from a given feed amount and stop eating faster when their energy levels in the body stores reaches a certain limit. The mean daily protein feed intakes per kg fish body weight in our study were DP/DE1: 8.3; DP/DE2: 7.9 and DP/DE3 & DP/DE4: 7.7. Based on recalculated values from several studies in E. sea bass (D2.3) the optimal daily protein intake levels for best growth for fish below 50 g body weight range from 8.2 to 12.6 g kg-1 body weight d-1. Thus, according to the meta-analysis of nutritional studies in E. sea bass, only in treatment DP/DE1 of our present study did the fish receive optimal levels of dietary protein for best growth. It seems then, that even a small deviation from the optimal can induce a significant effect in fish performance. At even smaller increment increases in total lipid, as among diets 2, 3 and 4, we see that there may be an economic benefit for the feed producer from protein sparing by use of plant oils, which is not likely to lead to significantly reduced fish performance.
Work package 3 title: Seasonal feeds and feeding strategies for sea bass
We demonstrated the significant economic benefit potential from using appropriate dietary formulations and oxygenation in cages where E. sea bass is reared at low water oxygen saturation levels. Though higher protein and lower lipid diets proved in several eFISHent trials superior in terms of E. sea bass performance, this result was inverted at low oxygen levels, where fish fed a lower protein and higher fat diet had best FCR and growth.
In the winter period, FCR was improved significantly by fasting E. sea bass every other or every third day with no reduction in growth. Moreover, by using sustainable 0% fish oil diets rich in low n-6 plant oils (such as palm oil, olive oil and salmon by-product oil), gonadal growth and expression of genes coding for maturation hormones was reduced.
Both at low and high water temperatures E. sea bass is able to growth with low to very low FCR by use of well balanced and nutritionally complete diets, even when only 10% fish meal is used in the diet. No negative histopathological effects were observed in the fish fed the high plant diets.
Task 3.1 Evaluating the effect of dissolved oxygen levels and sea bass performance (RMC, Nofima)
During the months of July and October the water oxygen levels measured during 3 years in a sheltered Mediterranean seabass and seabream farm were between 5.5 ppm and 4.5 ppm.
According to the results of our trial the extrapolated loss in body gain due to reduced oxygen levels in the water during the period July-August in a commercial sea bass farm would be 13% using the high protein diet and 9.5% using the high lipid diet. All sea bass stocked around the year pass 2 summers in the cages and on average grow 180 g during the low oxygen summer periods (July-October) out of total 350 g (market size). This means that, in sheltered fish farms, about 50% of fish biomass growth takes place during periods of potentially suboptimal sea oxygen levels. Thus a sea bass farm of total production 1,000 tons per year by applying water oxygenation in the cages up to just above 6ppm during the months of July-October, would have a total benefit in surplus biomass production of 47-69 tons per year, accounting for a value of 251,400-366,800€ (ex-farm sea bass price 5.3€/kg). About a fifth of this value (or less) would be cost of extra feed consumed by the faster growing fish. Nevertheless, feed costs would all together be unchanged as, should aeration be employed to increase oxygen levels in the sea, all summer growth (not only the extra gain) would be more efficient in terms of feed utilization.
In the demonstration activities D4.14 and D7.24 was shown that even in a non-sheltered farm, where oxygen levels do not drop dramatically during the summer (measured by an RBR Dissolved Oxygen Logger DO-1060, RBR Europe Ltd, Stadhampton, UK, supplied by the SME Element), it is feasible to raise dissolved oxygen levels in the sea using oxygenation equipment, already available in most farms (currently used during sampling, vaccination, medical treatment etc). Should a farmer wish to employ an automated system of aeration connected to an oxygen meter which would operate during the night with no extra labor costs involved, an investment on relevant hardware is to be made.
A recent report (Treasurer, 2010) on use of oxygenation systems (Crampton et al., 2005) in sea cages with Atlantic salmon during low oxygen periods of 5 months shows weight increase of the fish reared in cages with oxygenation of 2106 g compared to 1860 g in fish reared without additional oxygen. The additional cost of the oxygen in this period was 40,000 NOK per cage and the additional income was 104,000 NOK giving a net income of 64,000 NOK per cage. These results are equivalent to the predicted ones in our study with E. sea bass (about 20% improved growth). As the oxygenation costs accounted for 40% of the total added incomes, accordingly, a E. sea bass farmer operating cage farms in areas with low oxygen levels in periods of the year, can achieve additional incomes of up to 145,000-220,000€ per 1000 tons fish produced by the use of modern automated cage oxygenation systems.
Task 3.2 Testing the effect of low temperature fasting and/or food restriction on overall cycle FCR (VA, Nofima)
The work activities of this task include two feeding trials: 1) an experiment with different feeding regimes at low water temperature, and 2) an experiment with immature fish at low water temperature to assess the potential to delay of maturation by means of nutrition. In experiment 1 the fish were offered one meal daily and were given either access to an unlimited amount of feed every other day, or for 2 days followed by one day with no feed, or were given a restricted amount of feed daily. In experiment 2 the fish were fed diets with higher or lower energy content and either high or low levels of marine long chain n-3 fatty acids.
Experiment 1: Feeding frequencies
Ad libidum feeding, and fasting E. sea bass every other or every third day gave significantly higher fish growth performance compared to feeding daily feed amounts equivalent to 50% of saturation (Figure 3.6). However, as total feed intake was lower in the fasting regimes (every other or third day) so was FCR (1.4 versus 2.0 in ad libidum treatment).
Experiment 2: Maturation delay
Nofima AS produced four feeds at Nofima’s Feed Technology Centre (Bergen, Norway) with fish meal, horse beans, corn gluten and soy protein concentrate as the main protein sources. The 4 isoproteic diets were produced to either have a high (HF; 180 g kg-1) or low (LF; 21 g kg-1) fat content, and either with marine fish oil (M) or plant oils (olive oil, palm oil) and salmon oil which resembles the composition of a 50% fish oil, 50% rape seed oil (P), as oil source.
Summarising the results from Task 3.2 trials; E. sea bass has the ability through dietary manipulation to reduce FCR, improve or maintain similar growth rates, reduce liver weight and potentially reduce or delay gonadal growth, by 1) reducing total dietary lipid and LC n-3 content and by 2) fasting every other or third day in the winter season.
Task 3.3. Laboratory determination of daily and seasonal voluntary feed intake by using demand feeders:
Demand feeding systems allow fish to dictate the timing and size of their daily ration and can integrate any appetite variability into feed management. These appetite-based demand feeders, such as i) self-feeders, where fish bite or pull a trigger to receive food (Alanärä, 1992a) or ii) interactive feedback systems using camera based pellet detection (Ang and Petrell, 1997) or an infra-red pellet sensor (Blyth et al., 1993) to monitor food wastage, can supply fish with a responsive ration and can feed the majority of fish to satiation. Previous studies have shown that demand feeding can improve FCR in sea bass (Azzaydi et al., 1999; Paspatis et al., 1999) and other species (Noble et al., 2007b; Noble et al., 2008) in comparison to existing farm practices. However, the commercial feasibility of scaling up these studies to the average sea bass farm was not investigated in detail until a previous CRAFT FAIR Project CT-98-9201 entitled "Cost-effective and environmentally-friendly feed management strategies for Mediterranean cage aquaculture" which found farmers could achieve FCR’s of around 1:1 when utilizing demand feeding technology. However, many aquaculture ventures within the Mediterranean have neither utilized nor adopted these systems, as numerous farms still report FCRs of up to 2.2:1. This proposal intends to build upon and expand this original project and provide farmers with customized demand feeding solutions and feed management strategies to increase their uptake and retention within the sea bass aquaculture industry
Experiment
The experiment was carried out at the Viking fish Farms Ltd. (Acharacle, UK). The sea bass were maintained into 3 cylindrical tanks of a 1600 l capacity in an open flow system with an average temperature of 14.43ºC and oxygen saturation above 70%. During the experimental period the fish were exposed to 10:14 LD photoperiod.
Sea bass were obtained from Selonda UK in April 2011. The trial involved a total of 180 fish. After a mixing period of two hours in a big tank (3000 l) the fish were divided into 3 groups of 60 sea bass and placed into 3 tanks of 1600 l. At the start of the experiment the fish had an average body weight of 54.61±1.12 g and an average body length of 163.42±1.53 mm. The fish were fed with commercial pellets- meeting the nutrient and energy requirements of sea bass (INICIO Plus 1.9mm for Sea bass, BIOMAR Ltd, contained 50% protein, 18% lipid, and 16.8% nitrogen free extract). Prior to experimental sampling fish were feed deprived for 24 h. During the self-feeder acclimatation period (day 0) fish were trained to use the demand feeder for 20 days. The trigger was activated randomly during the day by hand and pellets felt to the tank, to show the fish how to use the trigger. At the same time some pellets were distributed by hand close to the trigger to show the fish how to obtain the feed. The fish were measured (weight and length) at the beginning and at the end of the experiment, using 2 mg of 2-phenoxyethanol as anaesthetic. After the acclimation period (20 days), sea bass were fed only using the demand-feeder, connected to a computer that continuously recorded the number of trigger bites by sea bass. The feed was weighed weekly, to evaluate the total feed eaten per week. The trial was carried out for 30 days. At the end of the trial, all sea bass were measured (weight and length).
Self-feeding system
Each tank was equipped with a self-feeding system (Image 5). The self-feeder consists of a motor which is set to turn 1 rotation whenever a trigger is pulled by a fish. The motor drives an auger drill bit which passes through a box of food, dispensing food as it turns. The whole device is contained in a plastic tub which acts as a barrier against moisture and splashing. The trigger was at approximately 4 cm below the water surface during the trial.
Both the feeders and the triggers of the feeding system were powered by a remote 12VDC transformer. The control electronics consisted of a purpose designed circuit board with a 7 channel IC Darlington driver, with each of six input channels connected to each of the three feeder triggers, and the output for each respective channel connecting the negative terminal of each 12V feeder motor to ground. Each trigger input line contained a 33μF capacitor and a 240K variable resistor.
The actuations of the trigger were recorded on a PC in a nearby office. This had an ADC-11 analogue-digital converter (Pico Technologies, UK) connected to its parallel port. Each of six input channels on the ADC was connected via a shielded multicore cable to each of the three trigger circuits, via a resistor ladder which reduced the 12VDC trigger voltage to the 1.5VDC maximum. This output from the trigger circuit was taken prior to a diode in the capacitor circuit to give an instantaneous voltage on the ADC input pin when the trigger was activated.
A specific programme was written in Visual Basic To handle the signals from the ADC, and this programme then embedded as a Macro in an Excel spreadsheet. Essentially, via a loop, every 50 milliseconds this programme “looked for” a voltage on the input channel to which each trigger circuit was connected. When an input was detected the programme sent the value to the Excel spreadsheet which logged it, and the date and time to the nearest second that was received. Initially, due to the sensitivity of the ADC, some problems were encountered with noise on the cable between the trigger control box and the PC which was only partially resolved by using a shielded coaxial cable between the two units. Hence the programme was re-written to record only digital signals exceeding 2000 units which effectively screened out the low voltage noise on the cabling. Also, as it was observed that the fish tended to “hang” on the trigger, when a trigger signal was recorded, the programme was designed to ignore that trigger in the loop until the voltage had dropped back to background levels. This thus ensured that an activation of the trigger was recorded as one single activation however long the fish actually hung onto the trigger.
Discussion
The study of the feeding rhythms of fish species is important in aquaculture, as it provides knowledge of when the fish are more capable to consume more food (Azzaydi et al. 1999). Then, the fish farmers can use the information to improve productivity in two ways, increasing the feeding during certain hours when the fish are more active and capable to feed more, and second to decrease the food waste in those hours that the fish are not really appetant. All this information can be incorporated as a feed management strategy for the farmer. Different studies from other authors in European sea bass show that the fish have an evidence of a seasonal phase where the fish is diurnal feeding during the summer and in winter this changes to nocturnal (Sánchez-Vázquez et al. 1998). In other studies with Oncothynchus masou masou, exhibit a diurnal feeding rhythm during the light phase (Flood et al. 2011).
In the current study, three tanks with self-feeders were used to study the feeding behaviour in the European Sea bass in Ardtoe Marine Laboratory, UK. The self-feeders were tested in 3 replicates, where the fish had a period of acclimatation of 20 days with the self-feeders. After that a trial was conducted for a period of 30 days, the data showed no differences in feeding behaviour during the 24 hours in the 30 days, when the fish pulled the trigger during all the 24 hours to obtain the food. After 19:00 h it seemed that the fish actuated the trigger less frequently, demonstrating a decrease in feeding behaviour at that time, when the fish seemed less active in finding food. Similar results were found by Sánchez-Vázquez et al. 1998 in sea cages at 14ºC, where there was a decrease in feeding behaviour after 20:00 h.
Therefore, the current study demonstrates that the European Sea Bass has a feeding rhythm throughout the day, with a maximum of feeding during 04:00 to 05:00 h. Although this study suggests that European Sea bass have a daily and constant feeding rhythm during the entire day when the temperature is 14 ºC, this should nevertheless be tested in sea cages before recommending any preferred feeding regime.
Task 3.4. Feed size preferences, diet preference and feed attractants (VA, Nofima, RMC
Feed size preference (VA)
The results of the pellet size preference trials were in month 7 of the EU efishent project. In reality there was little chance that this was ever going to be possible. The work needed to be done when the water was warmer in autumn 2010, but as the project did not officially start until the 1st December 2010, and no advance funding was received to enable VA to buy the fish until March, we missed the window, and will thus do the trial in summer 2011. However, in month 7 we have analysed data comparing the feed pellet size versus fish mass recommended by four major sea bass feed manufacturers.
Sea bass qualitative pellet size preference
In this situation Sea bass may typically feed on the larger pellet first because it’s bigger and thus easier to see. The result may have been different if Sea bass had not been starved for 24 h and/or they were fed in darkness. A Sea bass of ~43 g cannot fit a 6.5 mm pellet into its mouth.
Diet preference & feeding & immune system stimulation by the use of marine hydrolysates
Diets were tested in E. sea bass reared both at low (14oC ARDTOE) and high water temperatures (24oC Raanan Fish Feed). Growth, feed efficiency and histopathology results are discussed.
Fish growth was as expected significantly lower at low sea temperatures and FCR higher than at high water temperatures. Nevertheless, FCR levels were below 2 at low temperatures and below 1 at high water temperatures. Moreover, fish fed the low fish meal diet grew equally well as the high fish meal diet and thus there was no additional positive effect of on growth from the addition of the marine hydrolysates. At low water temperatures there was a positive effect in feed intake for fish fed the low fish meal diet supplemented with the krill or herring stickwater but as growth was not improved, especially for the krill treatment, FCR increased.
No disease incidences or mortality differences were observed among the fish fed the different experimental diets. The histopathology examination of fish from both experiments show that the overall morphology of the intestines was normal. In a few samples, mild thickening of a few intestinal folds per section was noted. This was characterized by hyperplasia of the lamina propria and sub epithelial oedema. No sloughing of the epithelium was observed.
Liver samples were examined only from the second experiment (high water temperature). The overall histological picture of all samples indicated mild to moderate fatty infiltration of the hepatocytes. Although no clear difference in the level of fatty infiltration between all group of fish was noted, the fatty infiltration in the samples from the fish that were fed with Diet HFM appeared more prominent, while the samples from the group HSW exhibited milder infiltration. In all cases, the mild infiltration of the hepatocytes was characterized by slightly swollen hepatocytes within which ‘blank’ spaces (existence of fatty droplets) existed. This resulted in extensive discoloration of the cells. No peripheral displacement of their nuclei was observed though. In moderate fatty infiltration, the enlargement of the hepatocytes was more pronounced and in this case many nuclei were pushed towards the cell membranes.
Work package 4 title: Optimising feed management
Task 4.1. Comparing and benchmarking existing feeding practices (VA, Nofima, NESNE Electronics, HCMR, SMEs)
Task 4.1 formed the basis of eFISHent deliverable 4.13 “Review and benchmark the current feeding practices of existing European sea bass producers in relation to key production performance indicators such as feeding efficiency and growth”. To achieve this aim the deliverable was split into two sections according to Task 4.1 of the eFISHent WP4 DoW and involved:
i) benchmarking current feed conversion ratio’s (FCR’s) and growth performance for each farm/company/region for specific months and fish sizes
ii) benchmarking each company’s current feed management practices and feed technologies.
Task 4.1i FCR data was then used to evaluate the eFISHent SME farm (Özsu’s) production performance in relation to time of year, fish size and feed management practices. To benchmark potential FCR performance in relation to fish size and time of year, three commercial databases were made available to WP4 by the eFISHent partner and SMEs. These included:
a) a database collated by HCMR as part of the eFISHent project that covers 21 Greek farms across various regions for each farms entire production cycle
b) a very large historical sea bass production database of a Mediterranean fish farming group which is available to Viking Fish Farms
c) historical production data from the eFISHent farming SME, Özsu Balik Ltd on their production data using their 2006-2009 year classes of bass
Benchmarking procedures: Benchmark charts were developed where
i) FCR and SGR performance were compared between farms and regions in the Mediterranean
ii) the effect of season and time of year upon FCR and SGR was investigated
iii) the effect of fish size upon FCR during the production cycle
The first outputs of this task showed that FCR and SGR performance can vary between both farms and regions:
Özsu Balik production FCRs compare very favourably with other farms from the HCMR dataset and there was also a seasonal effect upon FCRs within each production cycle, with poorer FCRs during winter months (see Fig. 4.6 for the benchmarking of FCR performance of the VFF dataset, and Fig. 4.7 for benchmarking of Özsu Balik data in relation to time of year)
The final aim of task 4.1i was to benchmark FCR with fish size. This data is shown in Fig 4.8 and shows a clear relationship between fish size and increasing FCR.
Task 4.1ii Benchmarking each company’s current feed management practices and feed technologies. The eFISHent WP4 partners were tasked with collating data from numerous Mediterranean sea bass farms to assess:
i) average daily ration in relation to time of year and/or fish size
ii) frequency of daily meals in relation to time of year and/or fish size
iii) choice of feeding method for each farm in relation to fish size
In summary, daily ration recommendations vary for both time of year and fish size, as do feeding frequencies.
When a review of scientific literature was carried out to benchmark FCRs under controlled scientific conditions in relation to feeding practices: free access to self-feeding systems in tanks can give FCRs ranging from 1.1. to 2.57 and self-feeder usage in sea cages can deliver FCRs of 1.35 to 2.45. 1-meal feeding frequencies can generate FCRs ranging from 1.43 to 2.1. 2-meal feeding frequencies can generate FCRs ranging from 1.2 to 2.65. 3-meal feeding frequencies can generate FCRs ranging from 1.05 to 3.52 but if these 3-meal regimes are further manipulated in smaller fish e.g. by subjecting fish to 4 days full ration, 1 day satiation, FCRs can be reduced. But there is such as range of conditions and varying treatments between these studies, that they should be merely used as a guideline of what FCRs can be achieved when subjecting different sized fish to different feeding regimes at different times of the year.
Task 4.2. Developing optimised feed management strategies (NM, NESNE, Akvaplan-niva, Özsu) Task 4.2 formed the basis of eFISHent deliverable 4.14 “Determine feeding efficiency and monitor the growth and welfare of European sea bass” has been split into two sections according to Task 4.2 of the eFISHent WP4 DoW and involves:
Task 4.2.1) experimentally evaluating the effects of different feeding frequencies upon the feeding efficiency, growth performance, mortality and welfare of cage-held sea bass in relation to a number of additional economic indicators such as labour and feed monitoring costs.
Task 4.2.2) experimentally evaluating the effects of different fasting and re-feeding periods upon the feeding efficiency, growth performance, mortality and welfare of cage-held sea bass.
Task 4.2.1 Summary of progress and significant results
Two feeding frequencies were set-up for the duration of the study. Three cages (hereafter termed the 1-meal regime) were hand fed to perceived satiation at 0900 h each day. Three further cages (hereafter termed the 2-meal regime) were hand fed to perceived satiation at 0900 h and 1600 h each day for the duration of the study. During hand-feeding a surface feeding response was used to determine satiation. Fish were fed commercial diets in relation to fish size: a 4mm extruded pellet (OptiBass, Skretting Ltd) until 17th December and from the 18th December a 4mm extruded pellet (Hendrix-Skretting Power Excel) until the end of the experiment.
There was no significant difference between initial fish weight (P = 0.236) condition factor (P = 0.452) or size heterogeneity between regimes (P = 0.532) at the start of the study (see Table 4.11 for further information).
There were also no significant differences between regimes in terms of final fish weight (P = 0.730) condition factor (P = 0.227) or size heterogeneity between regimes (P = 0.629) at the end of the study as well. This was also the case for SGR (P = 0.606) FCR (P = 0.550) and mortality (P = 0.779) for the duration of the study. This suggests there were no discernable productivity or welfare benefits of increasing feeding frequency from 1-meal to 2-meals per day during early winter at large scale production facilities. In addition, FCRs were generally low for this time of year < 1.38. There was however a significant difference in the amount of time spent feeding the fish in relation to feeding regime (see Fig. 4.12). When fish were fed to a 2-meal regime the farm staff spent a significantly greater length of time feeding the fish than when fish were fed once per day (P = 0.003) but this extra effort did not lead to any significant differences in growth or FCR between feeding regimes.
In summary, increasing daily feeding frequency from 1- meal to 2-meals per day at low temperatures (15-17 o C) from December to February does not result in any significant performance benefits in terms of FCR or growth performance. In addition, a 1-meal regime does not have any detrimental impacts upon mortality or fish condition, two commonly used operational welfare indicators. Operational recommendations for sea bass farm SMEs would be to feed their fish once a day to perceived satiation, and an analysis of the costs and benefits of doing this is presented in D5.18.
Task 4.2.2 Summary of progress and significant results
• Control regime: the control cage could not be fed daily and a total of 15 days out of the 42 that were planned were lost to stormy weather. The experiment was then extended to 55 days to account for this loss. In total 19 feeding days of the 55 total were lost and this high number of lost feeding days meant that the fish in the control feed regime were not fed on ca. 35% of the days that they should have been.
• 1 day satiation, 1 day starvation regime: the cage that was subject to 1 day satiation feeding, 1 day no feeding regime lost 4 feeding days because of the storms (14%).
• 21 day starvation, 33 days re-feeding regime: the cage that was originally subjected to 21 days starvation followed by 21 days re-feeding, was changed to a 21 day starvation, 33 days re-feeding but still lost 14 days feeding during the re-feeding period (42%).
The high amount of lost feed days did affect the results of the study and the results should be interpreted with this in mind. There were no marked differences between initial fish weight, condition factor, or size heterogeneity between regimes at the start of the study.
There were differences between regimes in terms of final fish weight. All fish lost weight during the course of the study. The greatest weight loss was in the 21 day starvation/33 days re-feeding regime (ca. 4% weight loss). The least weight loss was observed in the 1 day satiation feeding, 1 day no feeding regime (<1%).
Due to weight loss in each treatment, no FCR figures are reported, and instead the amount of feed fed for the duration of the study is presented.
There was markedly less feed delivered to the 1 day on/1 day off cage compared to the control feeding regime, but interestingly this was one of the best performing cages for the majority of the performance data (growth, condition factor, size heterogeneity, mortality). In addition, another cage that performed well (the cage that was starved for 21 days being re-fed for 33 days) used 55% less feed than the control regime and 23% less feed than the 1 day starvation, 1 day feeding regime, yet only lost ca. 4% of the fish’s body weight.
In terms of GSI there was high variability in GSI values within each cage, irrespective of the choice of feed regime and the data should be interpreted with caution. Interestingly, the greatest increase in GSI and also the greatest increase in GSI variability was in the 1 day starvation, 1 day re-feeding regime. The 21 days starvation, 33 days re-feeding regime showed a slight decrease in GSI by the end of the study, suggesting the maturation investment of these fish was halted. But once again, due to high variability within replicates and also the problems the farm faced in terms of feeding days lost to poor weather conditions, the farmer should interpret this data with caution when making decisions on the choice of feeding regime. However, this data shows some promise and warrants further investigation under controlled conditions.
Task 4.3. Feeding and Oxygenation
The results show that there was daily variability in mean oxygen levels within a day, generally lower during the 4 hour period before lunch and also after midnight. However, this low period did not equate to a risk for the fish and was still >70% DO saturation. In summary, it appears the eFISHent farm SME has neither the biological or economic need to invest in potential aquaculture technology that can automatically adjust feed delivery in relation to oxygen levels. In addition, they currently have no plans to purchase an additional oxygen sensor for their camera-based feeding system. If situation were ever to occur when the farm need to enhance low levels of ambient DO, Özsu Balik would most likely enhance DO manually using an oxygen or aeration system. However, would it be feasible to deploy this technology on other Turkish farms?
NESNE Electronics have gathered information from other Turkish se bass producers during i) the questionnaire phase of WP5 and also ii) during their dissemination and outreach activities with local farmers. During these discussions a number of key factors emerged on whether there is a current (or future) market for systems that automatically link feeding delivery and supplementary oxygenation systems for cage producers.
• Small- to medium sized SMEs are relatively low tech and employ feeding practices that predominantly use feed feed-canons or pneumatic feed delivery systems to feed their fish. The majority of these farmers currently do not yet use underwater camera’s to improve their feed monitoring and enhance the feeding practices, so this would be their first priority if they had the opportunity to invest in new feeding equipment. They therefore believe linking feed technology and oxygenation delivery is too large a technological step and their efforts would be better directed at upgrading their current feeding technologies. This priority is because they see the immediate benefits of using sub-surface camera based feeding systems; they can monitor feeding and appetite levels to improve FCR (see deliverable 7.22 and 7.23) and can also monitor the e.g. cleanliness of the net.
• The economic situation facing a number of small to medium bass producers means they do not have the cash flow available for big investments, and must prioritise their needs accordingly. Larger Turkish producers do have the means to invest in larger scale feeding systems e.g. feed barges that can feed multiple cages, with each cage having a sub-surface camera for monitoring feeding and feed wastage. However, even when deploying this large scale investment, where one of the large farms has invested in 16 underwater cameras, only one of these integrates an underwater camera and oxygen sensor. The farmer uses the DO levels it gets from this cage this cage to monitor and associate changes in DO in relation to the other cages on the farm. If this monitoring system proves to be robust and effective, they may invest in further integrated oxygen sensor and camera systems at a later date, and if the need arises. Furthermore, if this monitoring system is a demonstrably robust, cost-effective and reliable tool for monitoring DO levels within a cage, the medium sized and smaller SMEs may see the value of this technology and invest in it further down the line.
Work package 5 title: Economic and environmental assessment and impact
Task 5.1. Studying the decision making process for the adoption of new technology
Nine farm managers in Greece (3 small, 3 medium and 3 large companies) and 11 farm managers in Turkey (3 small, 3 medium and 3 large companies) have been interviewed to analyse and assess their decision making process and behaviour.
Large and medium companies have one more level of management composed of CEO, Board and General Manager over their financial, purchasing, production and exporting managers.
Owners of small companies have more direct line over their managers and farm workers. Some of the smaller companies are family-operated.
Main findings from the questionnaire
• Position of Manager. Farm owners act as managers of small farms. For all sizes, the position of manager is simply the general manager. The purchasing chief is also the farm manager of one large farm.
• Administration in the farm. Only two farms have the general manager or owner administrator located in the farm.
• Who takes decision. Medium and large farms have decisions taken by group agreement, mostly a combination of farm owner and general farm manager. Only 2 small companies have one person (farmer owner/CEO) making decisions.
• Decision taken at farm or central office level. For large farms farm level decisions must get approval from the administration. For medium farms, farm level decisions must get approval from the farm manager and administration. Small farms have the owner/CEO take decisions at the farm level.
• Decision taken alone or with others. Decisions are not made alone but with farm workers, administrative department, owner, upper management and engineering/maintenance departments.
• Budget level that the decision maker is allowed to take personal decision. The decision maker for small farms is allowed to take personal decision of over 10,000 Euros, while most decision makers of medium farms are allowed only 1- 5,000 Euros. Only one medium farm is allowed over 10,000 Euros. Farm owners & finance departments has the highest allowable budget of over 10,000 Euros.
• Criteria to purchase equipment decision. Main criteria include improvement of economics and productivity.
• Decision made on an economic or scientific basis. Small companies decide on an economic basis; medium and large companies decide on economic and scientific basis.
• Most important economic decision criteria. Cost is the most important economic criteria for small companies. Large and medium consider payback period in addition to cost criteria.
• Production criteria. Top criteria are making work easier and faster. In addition small companies look for equipment that needs less skilled staff, while medium sized companies look for equipment that is easy to use.
• Basis for buying new equipment. Cost reduction is the main basis for buying new equipment. In addition large and medium companies look for the ability of new equipment to solve their current problem and with high quality production. One medium company wait for expansion of its capacity and look for new equipment that reduce production cost and with a high quality.
• What convinces that price is worth it. Payback period, productivity, availability of service and spare parts, price and quality and easy to use are the convincing points for buying equipment.
• How do they find out about new technology. Salesmen and word of mouth are not effective sources of information about new technology. Trade shows, magazines and internet are the main sources for large and medium companies, followed by neighbours and competitors using it.
• Subscription to magazines. Only medium and large/medium companies subscribe to magazines Eurofish and Fishfarming International.
• Subscription to academic journals. Only medium and large/medium companies subscribe to academic journals
• Subscription to industry magazines. Companies subscribe more to industry magazines than journals.
• Attendance at meetings and workshops. Companies encourage attending meetings. Most will attend the European Aquaculture Society Rhodos conference exhibition In August 2011.
• Large size aquaculture company. The recommended marketing strategy for large aquaculture companies are that the technology providers should exhibit and have local agency with spare parts and servicing.
• Medium size aquaculture company. The recommended marketing strategy for medium aquaculture companies are to advertise in trade magazines, publish scientific results and exhibit locally.
• Small size aquaculture company. The recommended marketing strategy for small aquaculture companies are to demonstrate the equipment in farming areas and exhibit locally.
Task 5.2. Assessment in reduction in local environmental impact in the vicinity of individual units
Survey data collection
• Sediment trap collection 24 hours
• Bathymetry around test cages
• GPS reading of cages and sample sites
• Current speed and direction, oxygen levels – 4 days
• Salinity, temperature and oxygen profile through water column around cages
• Sediment samples 0, 10, 30 and 100 m from cages
• Oxygen level inside cage 3 days
Measurement of water circulation/current speed/degree of flushing
Water exchange is one of the most important factors influencing environmental impacts and production carrying capacities. In this regard, current speed, direction and dispersion were measured and used to provide an indication of water exchange and mixing at the cages.
Current dispersion is a measure of the mixing of the water column, and provides an indication of the degree in which nutrients derived from a fish farm are diluted in the receiving water body.
Current dispersion measurement using Drogues
The drogues released at 2 meters depth travelled total of 238 meters in 94 minutes (4 cm/second). The drogues released at 10 meters deep travelled421.6 meters in 94 minutes (7 cm/second). This is not a typical result with the deeper current being faster than the surface current.
The wind direction was from the north estimated at a Beaufort strength of 6 - Strong breeze (10.8-13.6 m/s)
The drogues released at 2 meters depth travelled total of 1,360 meters in 60 minutes (18.8 cm/second). The drogues released at 6 meters deep travelled 596 meters in 60 minutes (8.3 cm/second). Typically surface currents are faster than deeper currents due to wind direction.
Current through a cage
Data was collected of the current speed through a net cage with fish and compared with current speed outside the cage. This was undertaken using a drogue released inside the cage at a depth of 2 meters below water surface. The cage held the trial fish in a net with a mesh size of 6 mm.
The results were that the current speed inside the net was 6.7 cm/s compared to the current speed outside the net at 18.8 cm/s. This showed that the current speed inside cage is approximately 1/3 of current speed outside cage.
Sediment quality below the cages
The organic loading of the sediments takes place over time, and can therefore be used as a long term indicator of impacts. Benthic sediment samples were collected close to the cages and at a reference site. Samples were collected using either a van Veen grab (hard sediments) or a corer (soft sediments).
Sediment samples were characterized according to the following criteria:
• sediment type - shell hash, gravel, sand, or mud (silt and/or clay);
• surface colour and colour change with depth - as a possible indicator an anoxic states;
• smell - sulphide (the odour of H2S or rotten eggs), oily (the odour of petroleum tar), or humid (a musty, organic odour). Typically, un-impacted sediments have no particular odour.
• general sediment colour - black, green, brown, red, yellow etc.
The sediment samples were sieved in water until all the fine material has passed through the sieve, and only the particulate matter remained. These particles were then carefully transferred to a plastic sample jar. All the material that was retained on the sieves and transferred to the sample jar were fixed and stained. A small amount of clean water was added to the sample, followed by formalin as a fixative and Bengal rose as a stain.
1 Modelling the effect of lower FCR on impact to the sediment
Comparison of all scenarios – Severity and extent of footprint
The most important effect of lowering FCR through more efficient husbandry practice and diet is the reduction in the area of severe impact.
Conclusions
This MERAMOD modelling study draws the following conclusions:
• all of the cage groups have adequate spacing between them, so that no overlap of deposition footprints were predicted
• all cage groups are situated in quite deep waters, which aids dispersion of wastes; similarly, advection of wastes by the measured current was also quite high, although the current record was relatively short
• the area occupied by the deposition footprint in all increased production scenarios was less than the mooring area; group 2 had the largest extent of deposition footprint; the model predictions implied that the total deposition footprint area was acceptable for all scenarios in relation to the mooring area
• the increased production scenarios for groups 2 and 3 resulted in a predicted severe impact area of around 5 % of the total footprint; no severe impact was predicted for group 1 for increased production
• however, the predicted areas of severe impact were reduced significantly in the increased production scenarios, when lower FCRs of 1.8 and 1.6:1 were used to represent more efficient diets and practices; this was particularly the case for group 3
• the severe impact predicted for cage group 3 scenarios, were a result of a few cages with high feed input (and biomass); this suggests that a more even distribution of feed input across the whole cage group, or moving around high biomass cages within the group, would limit severe impact in a particular location
• The MERAMOD model predictions also suggest that when increasing production, adding larger and well-spaced cages (rather than adding another row of cages) results in better dispersion of wastes.
Task 5.3. – Assessment in the reduction in the wider ecological footprint using LCA
Resource use and greenhouse gas emissions by seabass cage culture systems
1. Global warming and eutrophication potential
Global Warming Potential Impact assessment results
The calculated Global Warming Potential (GWP) values for the seabass cage production is 1,810.62 kg CO2e/t fish. The majority of the GWP impact is from the manufacture and use of compound feeds primarily from the fish meal, krill meal and wheat products as well as the energy used to manufacture the pellets. Whereas the impact from energy use (electricity and diesel) for other uses is relatively low as water does not need to be pumped through the cage system.
The reduction of GWP impact from the reduction of food conversion rate is significant primarily due to the fact that the feed contributes such a high level to the GWP.
The reduction in GWP due to the improved FCR is 29.9%.
Eutrophication Potential Impact assessment results
The calculated Eutrophication Potential (EP) is 7.78 kg PO43- equivalents. Again the predominant impact is from compound feed but also with significant impact from nutrient output (phosphorous and Nitrogen) in terms of dissolved nutrient excreted from the gills and particulate nutrients in the faeces.
The reduction of EP impact from the reduction of food conversion rate is significant primarily due to the fact that the feed contributes such a high level to the GWP.
The reduction in EP due to the improved FCR is 31.2%.
Comparison with other aquaculture production systems
he level of GHG seabass at 2,048 kg CO2e/t fish is relatively low compared to other semi-intensive and intensive land based and sea based systems including the production of Norwegian salmon in cages.
1.1 Conclusions
The GHG emissions from seabass production are mainly from the use of compound feed. The improved feed quality and feeding management gives a significant reduction in GWP impact and the potential impacts associated with feed ingredients especially fish meal and wheat flour should be taken into account at the feed mill.
The EP impact from seabass production is mainly from the use of compound feed and the release of nutrients. Again, the improved feed quality and feeding management gives a significant reduction in EP impact and the potential impacts could be reduced further with the use of highly digestible ingredients or diets with lower Phosphorous and Nitrogen levels.
2 Analysis of feed resource use
2.1 Fish-in Fish-out Ratio (FIFO)
The estimated FIFO ratios for the case study culture systems used the following formula;
Level of fishmeal in the diet + level of fish oil in the diet
------------------------------------------------------------------------- x FCR
Yield of fish meal from wild fish+ yield of fish oil from wild fish
The FIFA ration for seabass cultured on BioMar feed with a food conversion rate of 2.03:1 is calculated as follows
33.7 + 8
---------- x 2.03 = 3.18
22.5 + 5
The FIFO reduces to 2.43 when FCTR is improved to 1.6:1.
The production of seabass in Turkey is a net user of fish with a FIFO greater than 1. However the improvement of FCR takes the production from a high level of fish use to a moderate level of fish use. However further effort should be made to make seabass production a net producer of fish by substituting fish meal and fish oil with vegetable sourced ingredients.
2.2 Analysis of land or sea area resource use
In cage culture, the sea is used to culture the fish. There are a number of ways to measure the space utilisation
• the physical space or volume that the nets occupy
• the site licence area
• the sea bed are that is utilised by the moorings and anchors.
The land and sea utilisation is therefore calculated to be 442.7 m2/tonne production.
Analysis of energy resource use
In seabass production the highest use of electricity is for the production of feed, production of fry and servicing of the cages by boat with a total of 8,588 MJ per tonne of seabass produced.
Resource use and Global Warming Potential mitigation strategies
The case study data suggest that a moderate degree of Food Conversion Rate can dramatically improve efficiency with regards to GWP and EP.
The GHG emissions from seabass cage culture are mainly from the use of compound feed and production of fry. Thus, the feeding management and the optimal operation of the hatchery must be given the attention in order to reduce the GHG emissions. More importantly, the potential impacts associated with feed ingredients especially fish meal, fish oil and wheat flour should be taken into account at the feed mill.
Task 5.4 – Analysis of the cost benefit of the results of the implementation of the knowledge:
Productivity benefits
For the scope of the eFISHent fish feeding trials optimised diets were formulated for European sea bass of body weight from 5 g to 300g reared in experimental tanks or sea cages, at temperatures from under 10oC and up to 25oC, and oxygen levels of 3.5 ppm to 6.5ppm. Both relevant eFISHent partner SMEs, one fish farmer and one feed producer, have had early access to the best performing and sustainable feed formulations used in the eFISHent trials with documented good fish growth results and remarkably low FCR.
• Improved food Conversion Rate
The obtained FCR values were ranged from 0.84 to 1.9. The highest FCR values were obtained in some winter trials, which were nevertheless always below 2.0. Optimum combined growth and FCR (1.18) results were achieved feeding E. sea bass juveniles with a diet containing 50.5% protein and 16.6% lipid (D2.7) and larger fish with a diet containing 45% protein and 16% lipids (D2.6).
The D2.6 results were confirmed in D3.8 obtaining FCR as low as 1.16 using a 47% protein and 16% lipid diet at high water oxygen levels. However, at low oxygen saturation levels optimal results were obtained using a lower protein (44%) and higher lipid diet (22%). These results provide documentation that allow the farmer and feed producer to cooperate and opt for either using 1) oxygenation in the cages, and obtain optimal production results, or 2) more cost efficient dietary formulations for periods of lower water oxygen levels.
In terms of feed formulation, equally good performances of reared E. sea bass were achieved, both in low and high water temperatures, with diets containing from as low as 10% (D3.10) and up to 35% fish meal in the diet and 0% (D3.9) to 100% fish oil (as % of added oil in the diet; 0% fish oil diet contained some salmon by product oil in addition to plant oils to cover the LC n-3 HUFA requirement of E. sea bass). All experimental diets were optimised and balanced in terms of indispensable amino acids, available phosphorus, LC n-3 HUFA and choline. The plant raw materials used were of documented nutritional value for this fish species (D2.3) and their inclusion level in the diet was chosen taking into account their content in anti-nutritional factors and potential negative interactions.
• Reduced feed cost
Modelling of cost efficiency of small gradual DP/DE changes
The balance between dietary protein and digestible energy is both important for optimal fish growth and nutrient utilisation efficiency (Company et al., 1999) and has practical consequences in feed formulation and cost. The effects on fish growth and FCR as a consequence of major changes in the macronutrient composition of the diets, in the dietary raw materials used, in the water and oxygen levels, and in the applied feeding regimes, are addressed in separate sections of the project. When the main feed specification values for optimal fish performance are determined, still the feed producers face the continuous challenge of formulating the desired feeds in the most cost efficient way according to the day-to-day availability and price of the different raw materials. Moreover, the raw material quality varies from batch to batch leading to small variations in feed quality throughout the year. The effects of small changes in feed composition or formulation around the optimal specifications are not known. This fact creates an almost impossible situation during the price negotiation of the feeds between feed and fish producers.
• Improved feeding strategy
These robust, operational results can then be used by Özsu Balik to compare the performance of their existing current best feeding practices against feeding technologies that incorporate underwater cameras for monitoring changes in fish appetite and satiation during feeding. It will help Özsu Balik and the other eFISHent partners assess the costs and benefits of utilizing emerging feeding technologies in relation to the key performance indicators, growth and FCR.
Summer feeding frequency
Feeding frequency is one important consideration as it can affect feed intake, growth, survival and fish quality as well as environmental impact. Feeding at the optimum frequency can result in savings in feed cost.
The objectives of the feeding frequency study was to evaluate the effects of different feeding frequencies upon the feeding efficiency, growth performance, mortality and welfare of cage-held sea bass in relation to a number of additional economic indicators such as labour and feed monitoring costs.
Use of camera monitoring systems
An underwater camera system was purchased and tested on the test and commercial cages. The camera delivers a high picture quality and has high light sensitivity. This means it can be used in cages without extra light. The camera has been designed for permanent installation. The camera remains in the cage and connected to the feeding boat by cable at the time of feeding the fish in the cage. The camera cables are plugged into an external socket on the boat's wheel house, and are controlled internally with a control console (KB-6000) and monitor. The camera hangs from cables on the cage.
Winter Feeding regimes-fasting/reduced rations
Feed quality and feeding management in commercial farms is a big challenge, but they are also the foundation for achieving improved feeding efficiency and growth throughout the season. The winter season is particularly challenging due to the low temperature, and overfeeding as a result of low feed intake are an common no beneficial cost during the winter season.
• Cage oxygenation system equipment setup and protocol
Fish with low oxygen levels are less capable of metabolizing higher protein levels in their feed, and thus perform less compared to fish that are fed less protein rich diets. The present results on E. sea bass confirm the previously published findings of Fu et al. (2005) and can help the fish farmers and feed producers to formulate efficient summer diets which can achieve optimal fish performance at suboptimal water oxygen levels.
This study demonstrates the potential benefit (in terms of increased biomass production) that a farmer can achieve by improving the water oxygen saturation levels in the sea cages when those drop at very low levels. The balance between the aeration costs and biomass gain is yet to be estimated in large scale.
• Reduced maturation
There is a significant problem in reaching marketable size of reared E. sea bass before the fish enters puberty and genetic maturation during the winter months. In intensive culture condition up to 20-30% of the male population could be precociously mature, following a 20-40% reduction in growth compared to non-precocious male. Age and size at puberty are modulated by genetics and environmental factors, controlled by activation of the brain-pituitary-gonad (BPG) axis, in addition to a range of internal and external factors such as growth, adiposity, feed intake, photoperiod, temperature and social factors. In the wild, the sea bass spawns during the winter months at low temperature (12-14oC) and during short and/or increasing day-lengths. Growth condition and feed availability are improved in farmed species compared with wild, hence both age and size at puberty and maturation are reduced. As slow growing populations (colder regions) experience more winter seasons than fast growing, it is particularly important to improve management control of feed composition and feed intake in these groups. Growth and puberty have previously been shown to be related to feed intake and feed formulation/composition.
Conclusions
The cost benefit analysis shows a range of benefits (additional profit) to the farmer from highly beneficial to no additional benefit.
The seabass farmer gains the highest benefits by using a camera and feed control system in the feed boat. The cost of the investment is paid back within approximately one month. This is followed by the use of oxygenation systems at farm sites which have low dissolved oxygen levels (this does not apply to the farm managed by Ozsu). There are some additional benefits from the use of specialised feed to reduce maturation during the second winter, the feeding strategy of feeding every other day during winter and the substitution of plant protein and oils. There is no significant benefit from feeding only once per day during summer.
Workpackage 6. Dissemination and outreach. Task 6.1: Establishment and maintenance of public web site
A project web site (www.efishent.eu) was set up at the start of the Project in November 2010 and has been updated regularly throughout the project. The project was operational until the end of the project. The website will be maintained by Akvaplan-niva for at least 2 years after the end of the project.
Task 6.2: Publications
A number of articles, posters, handouts and publications were prepared and published
• AquaNor project handout detailing objective and proposed research (APN)
• Fish farmer article (Viking)
• Izmir Offshore conference poster (APN)
• Izmir Offshore conference paper (APN)
• International Innovation article (APN)
• Pan European Article (APN)
• EAS 2011 conference in Rhodes, Greece entitled “Presentation of ‘eFISHent’ FP7 EU Project for the benefit of the SMEs: Improvement of feeds and feeding efficiency for seabass in cage farms in the Mediterranean & a review of the current status of Knowledge on nutrition and feeding of European Seabass (Dicentrarchus labrax)”.
The report was sent to a carefully selected and highly targeted audience of 52,000 key researchers, policy makers, government and decision makers across both the private & public sectors across all member states in the European Union and INCO countries. The report is also available online indefinitely, with each electronic publication optimized for search engines including Yahoo and Google to make sure your project article has the highest possible impact. Please see below for the full breakdown of readership.
The report is received by a wide range of policy makers including
• European Commission
• DG and Head of Unit
• International NGOs (ICES, ICCAT, EFARO, NAFO, WAS, WWF, CI, AFS etc)
• Fisheries Councils
• National Research Councils
• University and Academic Agencies
• Fisheries Legislation
• Ministry of Science, Technology and Innovation
• Ministry of Agriculture and Fisheries
• Agribusiness Agencies and Groups
• Fisheries Agencies
• Food Standards Agencies
• Agriculture and Aquaculture NGOs and International Agencies
• Policy Formulation
• Fisheries Authorities
• Universities
• Public research centers / institutes
• Public authorities
• University Libraries
• European institutions (European Commission, European Parliament, Joint Research Centre)
• EU programmes' National Contact Points (NCPs)
The report is received by a wide range of stakeholders makers including
• Aquaculture
• Commercial Fishing
• Aquaculture policy
• Marine and Costal Fisheries
• Freshwater Fisheries
• Conservation
• Hatcheries
• Breeding
• Retailers
• Suppliers
• Transport
• Consultants
The magazine is publically available through as many mediums and platforms as possible, with the publication also send as a newsletter to those who would rather receive the electronic copy rather than physical. This attracts over 10,000 unique visits a month to the www.research-europe.com website with 65% to the International Innovation newsletter reaching a global audience covering Latin and South America, Africa, Asia Pacific and the Middle East.
Pan European Network magazine Science and Technology is devoted to providing the relevant and up to date information for the use of not only the European Commission, but all government agencies and departments across the continent of Europe. www/paneuropeannetworks.com.
Manuscripts in preparation for publishing in peer reviewed magazines:
• Katerina Kousoulaki & Sissel Albrektsen, 2013. Review of the nutritional requirements and growth potential of European sea bass (suggested review accepted by Aquaculture Nutrition), Manuscript.
• André Bogevik, Jolanda Arjona, Jim Treasurer, Tim Atack, Raja Rathore, Ivar Rønnestad & Katerina Kousoulaki, 2013. Modulation of precocious genetic maturation in male E. sea bass by marine or plant dietary oils, Manuscript.
• Jolanda Arjona, Jim Treasurer, Tim Atack, Tal Prag, Eran Hadas & Katerina Kousoulaki, 2013. Interaction of dietary protein, lipids and dissolved oxygen levels in E. sea bass on-growing performance, Manuscript.
• Katerina Kousoulaki, Jolanda Arjona, Tim Atack, Jim Treasurer, 2013. Modeling of cost efficiency of small gradual dietary DP/DE changes in E. sea bass on-growing performance, Manuscript.
• Jolanda Arjona, Tim Atack, Jim Treasurer, Katerina Kousoulaki, 2013. Winter feeding of E. sea bass with low fish meal diets supplemented with marine hydrolysate attractants, Manuscript.
Task 6.3: Participation in Conferences, Workshops and Events
• Akvaplan-niva participated at AquaNor 2011 exhibition, Trondheim, Norway and distributed a fact sheet about the project to visitors to the stand. Partners FNCm NM, Ozsu and NESNE also attended the conference
• Participation in the AQUA NOR FORUM organised by the European Aquaculture Society (EAS) at the AQUANOR Exhibition and conference held August 17-18, 2011 in Trondheim Spektrum, Norway
• Participation EAS 2011, Rhodes, Greece by Partners HCMR, NM, VA, Ozsu and NESNE. Presented paper entitled “Presentation of ‘eFISHent’
• Participated in the Offshore conference June 2012 – Izmir (see below).
• Will participate at AquaNor 2013 exhibition, Trondheim, Norway and will distribute a fact sheet with a summary of final project results.
Task 6.4: Regional conferences/seminar
The Coordinator participated in the Offshore Mariculture 2012 conference held in Izmir between 17 and 19 October 2012.Offshore 2012 was an international two-day conference, with technical visit day, on the offshore fish farming business. It was aimed at growing offshore fish farming businesses the conference explored the progress and prospects for offshore aquaculture in European and international waters.
The coordinator presented information about the project in the form of a presentation, poster and handout.
Attendees at the Conference included both experienced and aspiring investors and entrepreneurs; fish farm owners, managers and operators; makers and distributors of net pens and mesh materials; feedstuff suppliers and feed manufacturers; and researchers into new species, new farm technologies, genetics, and fish health. Over 25 nationalities were represented at the Conference, including attendees from Chile, Canada, Saudi Arabia, Oman, Germany, Spain, Portugal, Italy, Norway, UK, USA, Australia, Israel and the Lebanon
Work package 7 title: Operational validation of feeding technologies and feed formulations
Task 7.1. Testing of different feed monitoring technologies in relation to production performance and fish welfare.
Two feeding regimes were set-up for the duration of the study. Three cages (hereafter termed the camera regime) were canon fed once a day to satiation at 1500 h in combination with underwater cameras that monitored pellet wastage. Three further cages (hereafter termed the no-camera regime) were canon fed once a day to perceived satiation at 1500 h each day based upon feed tables and surface indicators of satiation for the duration of the study. The feed silos, canon feed delivery system and camera monitoring system were mounted on a boat that fed each cage sequentially.
Fish were fed a commercial diet in relation to fish size (4mm extruded pellet, Hendrix-Skretting Power Excel) until the end of the experiment. The same growth and production performance parameters were used in deliverable 7.22 as those used in deliverable 4.14. Differences in levels of fin erosion, fin splitting or fin haemorhagging between treatments were tested for using a G- test. A significance level of P < 0.05 was used for all statistical analysis.
There was no significant difference between initial fish weight (P = 0.834) condition factor (P = 0.202) or size heterogeneity between regimes (P = 0.078) at the start of the study.
There were also no significant differences between regimes in terms of final fish weight (P = 0.978) condition factor ( P = 0.892) or size heterogeneity between regimes (P = 0.244) at the end of the study as well. This was also the case for mortality (P = 0.691) SGR (P = 0.882) and FCR (P = 0.806) for the duration of the study. However, although non-significant, there was ca. 10.7% reduction in FCR by feeding the fish using a camera based feeding regime at the worst time of year in terms of FCR performance (FCRs were on average 2.6 vs 2.9 for the camera vs no-camera regime respectively). In terms of other productivity indicators, there were no discernable biological productivity risks or benefits of using camera’s to control feed delivery to the fish. In terms of variability in daily feed amounts, there was no significant difference between the regimes and very little in terms of absolute amounts of feed delivered for the duration of the study (see Fig. 7.5 P = 0.967).
There was also no significant difference in the amount of time spent feeding the fish in relation to feeding regime (P = 0.783) suggesting that the factors within each meal (e.g. changes in feed rate in relation to pellet wastage) were more important than absolute times spent feeding for (non-significantly) improving FCR.
In terms of fin injuries, there was no significant difference between regimes with regard to fin erosion, fin splitting or fin haemorrhaging at the end of the study (see Figs. 7.7-7.9 P > 0.05 for all tests). This shows that feeding using a camera based feeding strategy offers little in terms of welfare benefits at this time of year, and also shows that the current feeding regimes do not pose a significant risk for increasing the prevalence of fin injuries. There was no clear pattern in which fins were affected by fin erosion, but the caudal and anal fins were most affected by fin splitting and haemorrhaging, respectively.
In summary, using a camera to feed fish to satiation in late winter and spring does not improve growth performance or size heterogeneity. It also does not improve welfare, by either significantly reducing the frequency of fin injuries, reducing mortality or improving fish condition. It does however improve FCR and feeding efficiency by ca. 11% in comparison to feeding the fish without a camera, and although this result was non-significant, it can have a marked effect upon the economic performance of the farm (as summarized in deliverable 5.18).
Task 7.2 Testing species and seasonally specific feed formulations
Two feeding regimes were set-up for the duration of the study. Three cages (hereafter termed the camera + optimized diet regime) were canon fed the eFISHent summer diet (6mm pellets, produced in the BioMar Hellenique AS factory in Volos, Greece based on the eFISHent Nofima AS formulation: Table 7.10) once a day to satiation in combination with underwater cameras that monitored pellet wastage. Three further cages (hereafter termed the control regime) were canon fed once a day to perceived satiation based upon feed tables and surface indicators of satiation and using the farms existing feed diet (6mm extruded pellet, OptiBass, Skretting Ltd). The eFISHent diet constituents were 40% crude protein, 23% crude fat, 6.1% ash, 10% starch, 1.9% fibers and 10% water.
The same growth and production performance parameters were used in 7.2 as in Task 7.1. There was no significant difference between initial fish weight (P = 0.913) condition factor (P = 0.551) or size heterogeneity between regimes (P = 0.338) at the start of the study.
There were also no significant differences between regimes in terms of final fish weight (P = 0.170) condition factor (P = 0.184) or size heterogeneity between regimes (P = 0.883) at the end of the study as well. This was also the case for mortality (P = 0.752) SGR (P = 0.058) and FCR (P = 0.064) for the duration of the study. However, due to low replication, the statistical power for all tests was < 55%, which may have accounted for the non-significant trend for higher SGR and lower FCR in fish fed to the camera + optimized diet regime. There was ca. 12% increase in SGR and ca. 19% decrease in FCR by feeding the fish using a camera + optimized diet regime during the summer and early autumn (FCRs were on average 1.65 vs 2.04 for the camera + optimized diet vs control regime respectively).
In terms of variability in daily feed amounts, there was no significant difference between the regimes, although fish fed using cameras + optimized diet were fed on average ca 200kg less fed per cage than their corresponding controls for the duration of the study (P = 0.333).
In terms of fin injuries, there was no significant difference between regimes with regard to fin erosion, fin splitting or fin haemorrhaging at the end of the study, with the exception of fin splitting to the caudal fin (which was significantly greater in fish under the control regime, P = 0.034 see Figs. 7.13-7.15 P > 0.05 for all other tests). This shows that the camera + optimized diet regime can reduce the prevalence of caudal fin splitting, but no other forms of fin damage in the current study. The anterior dorsal fins were most affected by fin erosion, irrespective of feeding regime, and the caudal fin was most affected by both fin splitting and haemorrhaging.
In summary, using a camera + optimized diet to feed fish to satiation in summer and early autumn has a non-significant trend for improving SGR and FCR in cage held sea bass. In terms of welfare, it does not have an effect on fin erosion or fin haemorrhaging, but does significantly reduce the prevalence of caudal fin splitting. It also does not affect either condition factor or mortality. FCR was improved by ca. 19% and SGR was improved by ca. 12% in comparison to feeding using existing diets and feed practices, and although this result was non-significant (due to low statistical power), it does have a marked effect upon the economic performance of the farm, (see D5.18).
Task 7.3. Testing of a combined feeding and oxygenation system
As part of this deliverable the eFISHent partners Nofima AS, Element AS, Özsu Balik Ltd, NESNE Electronics and Akvaplan-niva investigated i) the feasibility of raising oxygen levels within commercial sea cages using oxygen delivery systems during the summer, and ii) the cost effectiveness of raising oxygen levels within a cage.
Two different oxygen sensors were used to monitor oxygen levels within the cage. A YSI hand-held oxygen meter (YSI 550A dissolved oxygen meter, YSI Inc., Yellow Springs, USA) was used to record changes in oxygen at a depth of 1m within the centre of the cage. An additional RBR oxygen data logger (RBR Dissolved Oxygen Logger DO-1060, RBR Europe Ltd, Stadhampton, UK) was also deployed at 3m depth within the centre of the cage.
Here is the raw data from each day on how the oxygen delivery system affected oxygen levels at both 1 and 3m depth for each given day.
These data show there was high variability in oxygen raising efficacy between days and between depths. For example, there was a peak in oxygen levels at 3m during the latter stages of oxygen delivery on the 17th July, but this peak was not apparent at 1m depth. And on the 18th and 19th July, there was little in the way of elevated oxygen during oxygenation at 3m depth (no data was recorded at 1m depth due to problems with the data logger). This can be seen clearer when the data is manipulated to include the mean oxygen levels i) before oxygenation ii) during oxygenation and iii) after oxygenation for each day.
The results show how variable the efficacy of attempting to raise oxygenation in sea cages facilities can be when using an array of standard ceramic stones and an oxygen bottle. On the first day of the study, oxygenation lifted ambient oxygen levels from ca. 6.75 mg/l to ca. 7.5 mg/l (although highly variable during oxygenation), and levels were then relatively constant at 7 mg/l for the 30 minutes following oxygenation at 3m. However, on the second and third study day there was little, if any effect of oxygen delivery upon ambient levels, even though the bottle was delivering oxygen at a rate of ca. 50 L/min. There was no data recorded at 1m depth due to technical problems with the data logger. Cost benefit analysis for the use of oxygen is given in WP 5.
In terms of the efficacy of raising ambient oxygen levels during the summer months using an oxygen bottle attached to standards ceramic air stone array: results were highly variable between days. For example, on the first day of the study, oxygenation managed to raise ambient oxygen levels by ca. 0.75 mg/l to 7.5mg/l during oxygen delivery. These levels also remained at ca. 7.0 mg/l during the 30 minutes following oxygenation, suggesting there may be some potential to using this low cost set-up as an emergency aeration system when oxygen levels are low. However, on the two subsequent days of the trial, oxygenation had very little effect upon ambient oxygen levels at 3m. This high variability may have been due to changes in water state and current between days (Tor H. Evensen, pers. obs., although we do not have any quantified data on water currents to support this).
In terms of cost-effectiveness of using this array: many sea bass farmers already have all this equipment for use during e.g. fish sampling or disease treatment, so the farmer would incur little in the way of extra costs in equipment. In summary, these results suggest that ambient oxygen levels can be increased on a marine cage commercial sea bass farm using a low costs system consisting of an oxygen bottle linked to an array of standard ceramic air stones. However, results were highly variable and the system did not elevate ambient oxygen levels during all the trials. The cost effectiveness of such as system is questionable (as its efficacy, see Deliverable 5.18) and the eFISHent partners would recommend that farmers investigate the potential of other oxygen delivery systems or micro-nano bubble diffusers for attempting to increase ambient oxygen levels under commercial farming conditions.
Potential Impact:
Benefits
Efficient use of natural resources:
By reducing the FCR of sea bass farms the project will reduce the industry’s overall demand for fish feed, thereby reducing the quantities of natural resources that have to be exploited to meet that demand. One of the major ingredients in feed for carnivorous fish, such as sea bass, is fish meal. The level of fishmeal used in commercial marine finfish diets varies, but taking an average of 40 %, and an average FCR in the bas production industry of 2:1, then 0.8 kgs of fishmeal are used to produce 1 kg of bass. According to the Federation of European Aquaculture Producers the present (2008) production of sea bass in the Mediterranean is 102,765 tonnes per annum, which means that some 82,000 tonnes of fishmeal are used by the industry. Therefore reducing FCR by, say, 20% (from 2:1 to 1.6:1) would save 16,400 tonnes of fishmeal. With today’s (December 2009) price of fishmeal being around €1000 per tonne, the saving in fishmeal cost alone would be €16.4 million
Reduction of pollution to the environment:
Optimal feeding practices promoted by the eFISHent results will contribute to the reduction of pollution to the environment:
• Through the use of immune-stimulating substances the amount of pharmaceuticals used in sea bass farming that have a toxic effect on the environment can be reduced considerably.
• Reduction of nitrogen and phosphorous load on the wider environment by the reduction in production FCR.
Whether a nutrient becomes a pollutant in an aquatic system, is a function of whether it is a limiting nutrient in a given environment and the magnitude of its concentration. In the Mediterranean phosphorus is the limiting nutrient so its addition will dictate the amount of primary production. In the Atlantic, nitrogen is the limiting nutrient (Howarth and Marino, 2005), so its addition will do likewise. Increased primary production (particularly algae) that occur in high nutrient waters will reduce water clarity (and consequently sunlight availably in the water column to other organisms), and can strip oxygen from the water column when the organisms die, sink and decompose. These effects are conditions of eutrophicaton. Since nitrogen and phosphorus are released from fish cages, there is always the potential for fish culture to promote eutrophic conditions; either by supplying a readily available nutrient source directly to phytoplankton; or oxygen removal, accompanied by nutrient releases, via the decomposition of waste solids.
Reduction of feed loss and improvements in nutrient conversion efficiency will reduce (improve) economic FCR. Mortalities and escapes may reduce the production of harvestable biomass; causing an increase (worsen) in FCR. FCR is also affected by fish size, water temperature and fish health. Assuming similar fish sizes are produced from year to year; improvements in global economic FCR of Seabass production, will contribute to an overall increase in industry efficiency converting nutrients from fish feed to harvestable biomass. Regardless of whether lost nutrients are partitioned as faeces, waste feed; or sequestered in escaped or deceased fish.
Organic material (fecal water and uneaten feed) that is deposited on the seabed is decomposed by bacteria that use oxygen. With high organic nutrient loading, the oxygen level in the surrounding waters and sediment falls affecting local biodiversity. If the assimilative capacity of the seabed is overburdened, when the oxygen has been used up and because toxic hydrogen sulphide is formed in the bottom sediments and the sediments are unable to support any animal life. Any adverse impacts due to eutrophication and sediment impact at a farm location are reversible. Locations to which large quantities of organic material were previously added and had highly anaerobic sediments but these can recover towards the natural state after the nutrient loading is reduced.
Global impacts
Any improvements in feed efficiency will not only have local environmental benefits, but also global effects through a reduction in the use of raw materials and energy for fish feed production, reduced feed transportation costs, reduced carbon footprint etc.
In terms of the preservation of natural resources, it takes roughly 4.7 kg of so called “trash” fish, to make 1 kg of fishmeal, so the above example of a 20% reduction in FCR would reduce the demand for whole trash fish by 77,000 tonnes per annum, thereby taking pressure of stocks and helping to preserve the sustainability of the international fishmeal industry.
Economic impacts
The economic benefits of the project results due to improved feed and reduced FCR are as follows :-
• a reduction in direct feeding cost
• a reduction in feed transportation cost
• a reduction if feed storage and on-site handling cost
• reduced on-cage feed storage capacity
The economic benefits of the project results due to improved feeding strategy as as follows;
• A reduction in labour costs for feeding
• A reduction in boat operational costs (diesel, maintenance and depreciation)
Productivity impacts
The productivity benefits of the project results due to faster fish growth are as follows :-
• a reduction in fish production cycle time, thereby decreasing production cost per kilo
• an increase in productivity per unit cage volume
• the option to grow fish to a larger premium price size in the same time
• ability to sell fish early at premium prices when other producers do not have stock at the market size.
Productivity benefits
For the scope of the eFISHent fish feeding trials optimised diets were formulated for European sea bass of body weight from 5 g to 300g reared in experimental tanks or sea cages, at temperatures from under 10oC and up to 25oC, and oxygen levels of 3.5 ppm to 6.5ppm. Both relevant eFISHent partner SMEs, one fish farmer and one feed producer, have had early access to the best performing and sustainable feed formulations used in the eFISHent trials with documented good fish growth results and remarkably low FCR.
• Improved food Conversion Rate
The obtained FCR values were ranged from 0.84 to 1.9. The highest FCR values were obtained in some winter trials, which were nevertheless always below 2.0. Optimum combined growth and FCR (1.18) results were achieved feeding E. sea bass juveniles with a diet containing 50.5% protein and 16.6% lipid (D2.7) and larger fish with a diet containing 45% protein and 16% lipids (D2.6).
The D2.6 results were confirmed in D3.8 obtaining FCR as low as 1.16 using a 47% protein and 16% lipid diet at high water oxygen levels. However, at low oxygen saturation levels optimal results were obtained using a lower protein (44%) and higher lipid diet (22%). These results provide documentation that allow the farmer and feed producer to cooperate and opt for either using 1) oxygenation in the cages, and obtain optimal production results, or 2) more cost efficient dietary formulations for periods of lower water oxygen levels.
In terms of feed formulation, equally good performances of reared E. sea bass were achieved, both in low and high water temperatures, with diets containing from as low as 10% (D3.10) and up to 35% fish meal in the diet and 0% (D3.9) to 100% fish oil (as % of added oil in the diet; 0% fish oil diet contained some salmon by product oil in addition to plant oils to cover the LC n-3 HUFA requirement of E. sea bass). All experimental diets were optimised and balanced in terms of indispensable amino acids, available phosphorus, LC n-3 HUFA and choline. The plant raw materials used were of documented nutritional value for this fish species (D2.3) and their inclusion level in the diet was chosen taking into account their content in anti-nutritional factors and potential negative interactions.
• Reduced feed cost
Modelling of cost efficiency of small gradual DP/DE changes
The balance between dietary protein and digestible energy is both important for optimal fish growth and nutrient utilisation efficiency (Company et al., 1999) and has practical consequences in feed formulation and cost. The effects on fish growth and FCR as a consequence of major changes in the macronutrient composition of the diets, in the dietary raw materials used, in the water and oxygen levels, and in the applied feeding regimes, are addressed in separate sections of the project. When the main feed specification values for optimal fish performance are determined, still the feed producers face the continuous challenge of formulating the desired feeds in the most cost efficient way according to the day-to-day availability and price of the different raw materials. Moreover, the raw material quality varies from batch to batch leading to small variations in feed quality throughout the year. The effects of small changes in feed composition or formulation around the optimal specifications are not known. This fact creates an almost impossible situation during the price negotiation of the feeds between feed and fish producers.
• Improved feeding strategy
These robust, operational results can then be used by Özsu Balik to compare the performance of their existing current best feeding practices against feeding technologies that incorporate underwater cameras for monitoring changes in fish appetite and satiation during feeding. It will help Özsu Balik and the other eFISHent partners assess the costs and benefits of utilizing emerging feeding technologies in relation to the key performance indicators, growth and FCR.
Summer feeding frequency
Feeding frequency is one important consideration as it can affect feed intake, growth, survival and fish quality as well as environmental impact. Feeding at the optimum frequency can result in savings in feed cost.
The objectives of the feeding frequency study was to evaluate the effects of different feeding frequencies upon the feeding efficiency, growth performance, mortality and welfare of cage-held sea bass in relation to a number of additional economic indicators such as labour and feed monitoring costs.
Use of camera monitoring systems
An underwater camera system was purchased and tested on the test and commercial cages. The camera delivers a high picture quality and has high light sensitivity. This means it can be used in cages without extra light. The camera has been designed for permanent installation. The camera remains in the cage and connected to the feeding boat by cable at the time of feeding the fish in the cage. The camera cables are plugged into an external socket on the boat's wheel house, and are controlled internally with a control console (KB-6000) and monitor. The camera hangs from cables on the cage.
Winter Feeding regimes-fasting/reduced rations
Feed quality and feeding management in commercial farms is a big challenge, but they are also the foundation for achieving improved feeding efficiency and growth throughout the season. The winter season is particularly challenging due to the low temperature, and overfeeding as a result of low feed intake are an common no beneficial cost during the winter season.
• Cage oxygenation system equipment setup and protocol
Fish with low oxygen levels are less capable of metabolizing higher protein levels in their feed, and thus perform less compared to fish that are fed less protein rich diets. The present results on E. sea bass confirm the previously published findings of Fu et al. (2005) and can help the fish farmers and feed producers to formulate efficient summer diets which can achieve optimal fish performance at suboptimal water oxygen levels.
This study demonstrates the potential benefit (in terms of increased biomass production) that a farmer can achieve by improving the water oxygen saturation levels in the sea cages when those drop at very low levels. The balance between the aeration costs and biomass gain is yet to be estimated in large scale.
• Reduced maturation
There is a significant problem in reaching marketable size of reared E. sea bass before the fish enters puberty and genetic maturation during the winter months. In intensive culture condition up to 20-30% of the male population could be precociously mature, following a 20-40% reduction in growth compared to non-precocious male. Age and size at puberty are modulated by genetics and environmental factors, controlled by activation of the brain-pituitary-gonad (BPG) axis, in addition to a range of internal and external factors such as growth, adiposity, feed intake, photoperiod, temperature and social factors. In the wild, the sea bass spawns during the winter months at low temperature (12-14oC) and during short and/or increasing day-lengths. Growth condition and feed availability are improved in farmed species compared with wild, hence both age and size at puberty and maturation are reduced. As slow growing populations (colder regions) experience more winter seasons than fast growing, it is particularly important to improve management control of feed composition and feed intake in these groups. Growth and puberty have previously been shown to be related to feed intake and feed formulation/composition.
Fish welfare and fish quality benefits
The improved fish welfare and fish quality benefits of the project results are as follows :-
• potentially greater consumer demand for the product reducing sales and marketing costs
• reduced risk of losses due to disease/aggression etc
• an improvement in product quality and thus better prices
List of Websites:
www.efishent.eu
Scientific representative of the project's coordinator
Name: Patrick White
Title: Senior Aquaculture Consultant
Organisation: Akvaplan-niva, Tromso, Norway
Tel: 0033 475768014
E-mail: Patrick.white@akvaplan.niva.no
The main objective of this project was to optimise feed management methods and allow the European sea bass farmer to significantly reduce production FCR and thus feeding costs. At the same time nutritional and technical improvements will allow improvements in fish growth, labour costs reduction and minimise the environmental impacts of fish farming. Currently, one-third of the world’s fish catch is used to produce fishmeal and fish oil, and in 2004, the aquaculture industry used 87% of the world’s fish oil and 53% of the world’s fishmeal. Improved production FCR will reduce the overall demand for raw materials for fish feed production. Sea bass nutritional requirements and feed formulation.
WP 2. The scope of this workpackage was to fine tune the European sea bass diets’ composition in order to achieve cost efficient industrial production. To achieve this goal we need to reach in depth understanding of the qualitative and quantitative needs of this fish species at different life stages, environmental and physiological conditions. In reality feed producers will fabricate fish diets according to raw material quality, availability and price, not necessarily in that order, unless they are in hold of good arguments for acting otherwise. There is a big but not uniform available data on the effects of each commercially used raw material on different fish species performance. However, it was neither in the time frame nor scope of this project to identify specific raw material effects and qualities on European sea bass performance. We therefore needed to use all experience we had, published or not in order to use in this project’s fish experiments commercially relevant feed formulations of highly predictable quality and performance.
The eFISHent partners joined their efforts in the first part of the project to collect all available production and research data regarding nutrition and production technology of European sea bass in order to be able to formulate well balanced feeds for the different experiments and to choose the most appropriate feeding regimes to be followed. A scientific review on the nutritional requirements of European sea bass and an extensive database including commercial sea bass production results was produced and updated throughout the life time of the project. We determined the maintenance energy requirement of E. sea bass at different temperatures and ages. Following, the utilisation efficiency of dietary protein and energy was determined using two methods, of which the metabolic chamber was proven the easiest and most precise. Best European sea bass growth for body weight sizes from 10 to 200 g was obtained with feeds of 45/16 and 60/12 crude protein/lipid. Best feed utilization was observed for the 45/16 diet. Protein utilization efficiency decreased as dietary protein increased indicating higher nitrogen loss to the environment with higher protein diets and vice versa.
The fish whole body composition and immune status of the fish was not influenced by the different experimental treatments. Last we demonstrated that the fish farmer should expect an economic loss from reducing feed cost by using oils (plant or fish oil) in the expense of dietary protein, even at small increment changes. Reduced feed intake rates and growth were observed by slight increases in the dietary lipids and best growth was observed in E. sea bass of 5-25 g body weight receiving daily 8.3 g protein per kg fish body weight.
WP 3. Seasonal feeds and feeding strategies for sea bass.
The purpose of this workpackage was to determine, under laboratory conditions, rational feeding protocols based on the biology and behaviour of Atlantic European Sea bass Dicentrarchus labrax of varying size and under differing environmental conditions. It also included laboratory scale testing of the diets formulated in WP2, and examining the effect of FCR (Feed Conversion Rate) on diet palatability and pellet size. A nutritional study on reducing fish maturation was also performed.
We demonstrated the significant economic benefit potential from using appropriate dietary formulations and oxygenation in cages where E. sea bass is reared at low water oxygen saturation levels. Though higher protein and lower lipid diets proved in several eFISHent trials superior in terms of E. sea bass performance, this result was inverted at low oxygen levels, where fish fed a lower protein and higher fat diet had best FCR and growth.
In the winter period, FCR was improved significantly by fasting E. sea bass every other or every third day with no reduction in growth. Moreover, by using sustainable 0% fish oil diets rich in low n-6 plant oils (such as palm oil, olive oil and salmon by-product oil), gonadal growth and expression of genes coding for maturation hormones was reduced. Both at low and high water temperatures E. sea bass is able to growth with low to very low FCR by use of well balanced and nutritionally complete diets, even when only 10% fish meal is used in the diet. No negative histopathological effects were observed in the fish fed the high plant diets.
The feeding rhythm of fish species is important in aquaculture and the daily feeding rhythm in sea bass was assessed in triplicate using a demand feeding system designed for the project. There were no differences in feeding behaviour throughout the 24 hour day in the 30 days of the experiment. The current study demonstrated that Sea Bass had a feeding rhythm throughout the day, with a maximum of feeding from 04:00 to 05:00 h. Nevertheless this should be tested in sea cages before recommending any preferred feeding regime. Tables showing recommended feed pellet sizes for fish weights and lengths were produced in this study based on a review of the recommendations provided by all the commercial feed manufacturers.
The main findings of the benchmarking study was to show the relationship between water temperature and fish size in relation to feeding efficiency (FCR) and growth performance (SGR). Commercial FCRs are generally higher both in Greece and Turkey during the winter months when water temperatures are low. FCRs also increase as the fish get bigger. The experimental phase of WP4 demonstrated that increasing daily feeding frequency from 1-meal per day to 2-meals per day on commercial farms during winter offers no benefits in terms of FCR and SGR performance. Feeding fish every other during early winter may also be a cost-effective feeding regime for commercial sea bass farmers during early winter. The feasibility study that investigated whether there is a need or current market for linking feeding and oxygenation systems for Mediterranean cage aquaculture suggests farmers in Turkey are currently prioritising updating their feeding systems and will take the step of possibly upgrading their oxygenation systems when they can find a cost-effective and robust solution to dealing with potential oxygenation problems in cage aquaculture.
WP4. The general aim of WP4 was to deliver operational research to help commercial sea bass aquaculturists reduce their on-farm feed conversion ratios (FCRs) and thus improve production efficiency, reduce feed waste and reduce feed costs. Specifically, the WP4 partners aimed to help our commercial SME partner, Özsu Balik Ltd, improve their operational FCR and feeding efficiency. These findings can then be rolled out amongst other sea bass producers in the Mediterranean region. To achieve the aims of improving operational on-farm FCRs, farmers need to i) understand how their feeding practices affect operational FCRs, and ii) identify ways to improve their on-farm feed management. This can be enhanced through improved dissemination of existing knowledge on best practice in feed management, and also via the identification of commercial technologies and feeding strategies that can be customised to each farmer’s specific needs. The initial aim of WP4 was to benchmark feed conversion ratios on commercial farms. Benchmarking is an emerging aquacultural management tool that allows a farmer to compare their farming practices and performance metrics within their company and against others within the same industry (e.g. Soares et al., 2011). Farmers can then identify areas for potential improvement within their current set-up and economic constraints. The experimental aspect of WP4 involved the operational evaluation of different feeding practices such as i) the effects of different daily feeding frequencies, and ii) the effects of different lengths of feeding/re-feeding periods upon the on-farm FCR, growth performance and welfare of European sea bass held at commercial production facilities. A feasibility study was also carried out by Nofima, ANCO, Element, NESNE Electronics, Özsu Balik and Akvaplan-niva on whether there was scope to combine feeding and oxygenation systems for cage aquaculture, to combat potentially low ambient oxygen levels that can occur during the summer months in Mediterranean sea bass farming. To achieve these aims the benchmarking aspect of WP4 and the feasibility of combining oxygenation and feeding systems started at the beginning of the project, and the majority of experimental work commenced during Year 2 of the project.
WP5. Economic and environmental assessment and impact
The overall purpose of the project is to improve the cost effectiveness of bass and bream culture and thereby to also reduce its local and global environmental impact. The purpose of this WP is thus to quantify the potential economic and environmental benefits likely to accrue from the improved feeds and feeding methods developed. In addition it seeks to clarify the decision making process by which aquaculture companies find out about, evaluate and take decision for the purchase of new technology. This will allow companies such as the SME partner FCN to target their sales and marketing of feed control technology more effectively.
Nine farm managers in Greece (3 small, 3 medium and 3 large companies) and 11 farm managers in Turkey (3 small, 3 medium and 3 large companies) have been interviewed to analyse and assess their decision making process and behaviour.
The actual environmental impact was undertaken collecting and analysing data from round the test cages.The MERAMOD model was set up for Ozsu fish farm,made up of three separate cage groups. Bathymetry data for the surrounding area taken from a survey and an electronic chart were combined and contoured. These data along with cage position data were incorporated into MERAMOD grids.
Assessment in the reduction in the wider ecological footprint using LCA Resource use and greenhouse gas emissions by seabass cage culture systems
The aquaculture sector has been receiving a great deal of criticisms on its potential environmental impacts. The potential impacts from aquaculture systems often highlighted are: Impacts on water quality and sediments, GHG emissions, and high resource use (i.e. wild seed, fish in-fish out ration). The Task evaluated the potential impacts associated with inputs and outputs by the culture of seabass in cages at the Ozsu fish farm in Turkey using some of the Life Cycle Analysis (LCA) methodology. Analysis of the cost benefit the implementation of the knowledge was undertaken for the main research findings: Improved feed, (Summer and winter), High fish meal vs low fish meal, Feed with attractants vs no attractants, Use of cameras, Use of cameras with pellet counting software, Use of oxygenation, Feeding strategy ( 1 meal/day vs 2 meals/day, 50% feed, 1 day feed vs 1 day off, 2 days feed vs1 day off), Maturation control,
WP 6. Dissemination and outreach
All RTD partners played an active role in developing the overall dissemination strategy for the eFISHent project. There was close interaction with the work in WP5, which also is a cross-cutting horizontal activity drawing together the technical, economic and social factors relating to the best practices in feeding management of sea bass farming.
WP 7. Operational validation of feeding technologies and feed formulations
This workpackage set out to validate the findings based around the on-farm testing of feed technologies and diets. The validation work will be carried out on the commercial scale farm cages with the SME partner Oszu. All sampling procedures for evaluating production performance (growth, feed delivered, mortality) were carried out in tandem with Operational Welfare Indicators (OWI’s) to assess whether the different feed technologies and diets are beneficial for aquaculture production in a commercial, on-farm environment.
Project Context and Objectives:
Work Package 1 :
Objectives
• To coordinate the overall development of the project, to assess the accomplishment of tasks allocated to each participant, to discuss the results obtained during different phases of the project.
• To submit internal reports that will make the bases of the periodical reports to be submitted once a year to the REA.
• To fix deadlines for submission of manuscripts for publication, and for submission of results for the elaboration of Period Reports.
• Development of an Exploitation plan, exploitation of results, including the implementation of new rearing methods and feed recipes.
• Handling of relevant IPR issues.
Among the management activities were the monitoring of project progress, deliverables and results, ensuring that the milestones for each phase were achieved. It has kept minutes of all the project meetings and circulated these to the EU and project partners. The partners have formally met 5 times (once pre submission) to discuss planning and achievement of progress. Partners have also met informally with RTD partners visiting SME facilities and during conferences and exhibitions.
Task 1.1 Consortium meetings and coordination of the project
Akvaplan-niva has undertaken the coordination of the overall progress of the project. Among the management activities were the monitoring of project progress, deliverables and results, ensuring that the milestones for each phase were achieved. It has kept minutes of all the project meetings and circulated these to the EU and project partners.
The partners have formally met 5 times to discuss planning, achievement of progress and solve any problems.
• 07 June 2010, Brussels, Belgium
• 28 – 30 November 2010, Athens, Greece
• 25 - 27 May, 2011, Bergen, Norway
• 3 - 4 October, 2011, Brussels, Belgium
• 15 - 7 October 2012, in Izmir, Turkey
Minutes of the meetings were prepared and circulated to all partners and EU project officers. The Coordinator made regular follow up activities to the RTDs for the Project deliverables and ensured that milestones have been met. Partners have also met informally between RTDs and SMEs and during conferences and exhibitions and have communicated regularly through SKYPE and email. Coordination was undertaken by an assigned staff at Company headquarters in Tromso.
Partners have also met informally with RTD partners visiting SME facilities and during conferences and exhibitions.
Task 1.2 Exploitation of results
Draft exploitation and dissemination plan was prepared at Month 9 as a deliverable and the final exploitation and dissemination plan was prepared at the end of the project.
Task 1.3 Handling of IPR matters
A brief description of how the IPR matters would be handled was prepared for the Consortium agreement.
Information was given on background and foreground knowledge in the Attachments to the Consortium Agreement.
• Attachment 1. Background Knowledge
• Attachment 2. Foreground knowledge
• Attachment 3. Access to foreground knowledge
Work package 2 : Sea bass nutritional requirements and feed formulation
Objectives
• Survey on the nutritional requirements, the commercial feeding strategies and the available feed technology in sea bass culture and diet formulation for lab and production scale experiments.
• Determination of growth potential and energy composition of sea bass under different commercial production environments.
• Comparison of different methods to measure energy flow in fish and determination of energy flow in sea bass for diets with different energy densities.
• Determination of optimum energy density for growth and feed utilization of sea bass.
• Determination of optimum protein to energy levels, seasonal feeds and feeding strategies for commercial feeding practices.
• Creation of models for the prediction of fish performance and cost efficiency of production of sea bass using different feed formulations at different fish ages and water temperatures.
The scope of this work package was to fine tune the European sea bass diets’ composition in order to achieve cost efficient industrial production. To achieve this goal we need to reach in depth understanding of the qualitative and quantitative needs of this fish species at different life stages, environmental and physiological conditions. In reality feed producers will fabricate fish diets according to raw material quality, availability and price, not necessarily in that order, unless they are in hold of good arguments for acting otherwise. There is a big but not uniform available data on the effects of each commercially used raw material on different fish species performance. However, it was neither in the time frame nor scope of this project to identify specific raw material effects and qualities on European sea bass performance. We therefore needed to use all experience we had, published or not in order to use in this project’s fish experiments commercially relevant feed formulations of highly predictable quality and performance. The eFISHent partners joined their efforts in the first part of the project to collect all available production and research data regarding nutrition and production technology of European sea bass in order to be able to formulate well balanced feeds for the different experiments and to choose the most appropriate feeding regimes to be followed.
WP 3. Seasonal feeds and feeding strategies for sea bass
Objectives
The elucidation of natural feed intake quantities, feeding frequency patterns and pellet size preferences in bass
• To evaluate if specifically designed winter feeds and winter feeding protocols can be used to improve overall cycle FCR
• To evaluate if feed intake and FCR might be improved by adding specific attractants to the winter and summer diets
• To develop new suggested multivariate feeding tables and protocols, also following the results from WP2, for commercial scale validation in WP4
The purpose of this workpackage was to determine, under laboratory conditions, rational feeding protocols based on the biology and behaviour of Atlantic European Sea bass Dicentrarchus labrax of varying size and under differing environmental conditions. It also included laboratory scale testing of the diets formulated in WP2, and examining the effect of FCR (Feed Conversion Rate) on diet palatability and pellet size. A nutritional study on reducing fish maturation was also performed.
Summary of progress and significant results
Work package 4 : Optimising feed management
Objectives
• evaluate and benchmark current feed management protocols in relation to feeding efficiency and growth
• investigate the optimal timing and frequency of feed delivery in relation production performance and welfare, and examine how this changes with time of year and each SME's labour and budget constraints through CBA (cost benefit analysis)
• develop a series of customised feed management strategies for each SME based upon various demand feeding and feed monitoring technologies
Summary of progress and significant results
The primary objectives of eFISHent WP4 was to deliver operational research to help commercial sea bass aquaculturists reduce their on-farm feed conversion ratios (FCRs) and thus improve production efficiency, reduce feed waste and reduce feed costs. Specifically, the WP4 partners aimed to help our commercial SME partner, Özsu Balik Ltd, improve their operational FCR and feeding efficiency. These findings can then be rolled out amongst other sea bass producers in the Mediterranean region.
The main findings of the WP4 benchmarking study was to show the relationship between water temperature and fish size in relation to feeding efficiency (FCR) and growth performance (SGR). Commercial FCRs are generally higher both in Greece and Turkey during the winter months when water temperatures are low. FCRs also increase as the fish get bigger. The experimental phase of WP4 demonstrated that increasing daily feeding frequency from 1-meal per day to 2-meals per day on commercial farms during winter offers no benefits in terms of FCR and SGR performance. Feeding fish every other during early winter may also be a cost-effective feeding regime for commercial sea bass farmers during early winter. The feasibility study that investigated whether there is a need or current market for linking feeding and oxygenation systems for Mediterranean cage aquaculture suggests farmers in Turkey are currently prioritising updating their feeding systems and will take the step of possibly upgrading their oxygenation systems when they can find a cost-effective and robust solution to dealing with potential oxygenation problems in cage aquaculture.
The general aim of WP4 was to deliver operational research to help commercial sea bass aquaculturists reduce their on-farm feed conversion ratios (FCRs) and thus improve production efficiency, reduce feed waste and reduce feed costs. Specifically, the WP4 partners aimed to help our commercial SME partner, Özsu Balik Ltd, improve their operational FCR and feeding efficiency. These findings can then be rolled out amongst other sea bass producers in the Mediterranean region. To achieve the aims of improving operational on-farm FCRs, farmers need to i) understand how their feeding practices affect operational FCRs, and ii) identify ways to improve their on-farm feed management. This can be enhanced through improved dissemination of existing knowledge on best practice in feed management, and also via the identification of commercial technologies and feeding strategies that can be customised to each farmer’s specific needs.
The initial aim of WP4 was to benchmark feed conversion ratios on commercial farms. Benchmarking is an emerging aquacultural management tool that allows a farmer to compare their farming practices and performance metrics within their company and against others within the same industry (e.g. Soares et al., 2011). Farmers can then identify areas for potential improvement within their current set-up and economic constraints.
Workpackage 5 : Economic and environmental assessment and impact
Objectives
· To evaluate the likely local environmental benefits of the improves feeding protocols developed in WP2-4
· To evaluate the wider environmental benefits from improved use of feeds in bream and bass aquaculture
· To evaluate the economic benefits both at farm and industry level
The overall purpose of the project is to improve the cost effectiveness of bass and bream culture and thereby to also reduce its local and global environmental impact. The purpose of this WP is thus to quantify the potential economic and environmental benefits likely to accrue from the improved feeds and feeding methods developed. In addition it seeks to clarify the decision making process by which aquaculture companies find out about, evaluate and take decision for the purchase of new technology. This will allow companies such as the SME partner FCN to target their sales and marketing of feed control technology more effectively.
Nine farm managers in Greece (3 small, 3 medium and 3 large companies) and 11 farm managers in Turkey (3 small, 3 medium and 3 large companies) have been interviewed to analyse and assess their decision making process and behaviour.
Methodology for the assessment in reduction in local environmental impact in the vicinity of individual units and the assessment in the reduction in the wider ecological footprint using LCA was undertaken.
Workpackage 6 :
Dissemination and outreach Objectives
• To enhance the awareness about the eFISHent project in the main production region, carefully identifying the target audience, the dissemination method and the message content and design
• To make available to a wider audience information about the results and the outcome of the eFISHent project with the aim of enhancing the uptake of its results
• To promote and encourage the uptake and use of the results by stakeholders and environmental managers in Europe, and prepare the basis for maximum impacts of the results
• Disseminate the overall feed management recommendations online and via handbooks to the SME's, large enterprise end users and national and international farming bodies and policy makers
• Publication of peer reviewed studies
The work in this work package was led by Akvaplan-niva, with considerable input from the other partners. All RTD partners played an active role in developing the overall dissemination strategy for the eFISHent project. A close interaction is foreseen with the work in WP5, which also is a cross¬cutting horizontal activity drawing together the technical, economic and social factors relating to the best practices in feeding management of sea bass farming. A project web site (www.efishent.eu) was set up at the start of the Project in November 2010 and has been updated regularly.
Work package 7: Operational validation of feeding technologies and feed formulations
Objectives
• validate through on-site testing, the optimised feed management strategies for each SME developed within WP4
• validate the on-site commercial performance of the feed formulations developed by WPs 2 and 3
• validate the design and performance of combined feeding and oxygenation systems as a means of improving overall feed efficiency in sea bass
Summary of progress and significant results
The primary objectives of the eFISHent demonstration WP7 was to carry out on farm operational research to demonstrate the effectiveness of the outputs of the eFISHent project on a commercial farm. These findings can then be rolled out amongst other sea bass producers in the Mediterranean region.
The main findings of the WP7 technology demonstration study was a ca. 11% improvement in spring and early summer commercial FCRs when farmers used underwater cameras to monitor feeding and feed waste in comparison to existing farm regimes that did not use these technologies. A second study was carried out in commercial scale production facilities that combined underwater cameras and species specific seasonal feed formulations developed in eFISHent WP2 and WP3. The combination of improved diet formulation and camera based feed management resulted in a ca. 12% increase in SGR and a ca. 19% improvement in FCR.
WP7 was the validation and demonstration WP, based around the on-farm testing of feed technologies and diets. The validation work was carried out on commercial scale farm cages with the SME partner Özsu Balik. All sampling procedures for evaluating production performance (growth, feed delivered, mortality) were carried out in tandem with Operational Welfare Indicators (OWI’s) to assess whether the different feed technologies and diets are beneficial for aquaculture production and fish welfare in a commercial, on-farm environment
The initial aim of WP7 was to testing of different feed monitoring technologies in relation to production performance and fish welfare. Özsu and the eFISHent RTDs experimentally investigated the effect of using feeding technology that utilises underwater cameras to monitor feed wastage upon the feeding efficiency, welfare and production performance of sea bass against their existing feed practices.
The next aim of WP7 was to demonstrate the effectiveness of combining advanced feeding technology with the species and seasonally specific feed formulations developed in WP2 and WP3 in a production scale environment.
The final aim of the demonstration WP was to test the feasibility of a combined feeding and oxygenation system. If it proves possible to design a combined feeding and oxygenation system, a prototype unit was to be evaluated in full-scale cage trials to be conducted at Özsu.
Project Results:
The main S&T results and foreground
are as follows;
Work package 2 title: Sea bass nutritional requirements and feed formulation
Task 2.1 Survey on the nutritional requirements and the commercial feeding strategies and feed technology employed in sea bass culture:
We determined the maximum expected growth potential of best performing E. sea bass based on a meta-analysis of the reported data in peer reviewed magazines, as a function of total protein intake rates. A linear relation between fish size and optimal dietary protein level exists and thus feed formulations must be optimised based on the protein requirements and feeding rate capacity of fish at different size and environmental conditions.
Weaker correlations were identified on the basis of total energy intake dietary lipid content, unlike statements in several publications where energy is presented as the main regulative factor of this fish species’ performance. European sea bass appears sensitive to high lipid intake and, according to dietary composition, may stop feeding before the necessary amounts of protein for maximal growth is taken up. Moreover, E. sea bass has also quite high glucose intolerance regulating thus to a significant extend feed intake according to the intake levels of digestible carbohydrates. As fish grow bigger they need lower total digestible protein intake but care must be taken in order not to hinder feed intake by excessive digestible carbohydrate and lipid levels before the protein needs for maximal performance are covered.
The best performing fish picked out from the available research literature had rather stable, slightly increasing levels of whole body protein and also quite stable levels of body fat, as shown in the figure below. Fish fed imbalanced diets deposited more fat in the tissues and performed worse in both feed conversion and growth rate.
VA has collected and analysed the recommended feeding tables produced by various manufacturers of commercial sea bass feed in order to:
a) determine the level of variation in the sizes of pellets recommended for feeding to fish of various sizes.
b) determine the variance in suggested feeding rates (as a percentage of body weight per day) for fish of different sizes at different water temperatures. However, as the diets supplied by different manufacturers may vary in digestible energy content, the collated feeding tables are being re-calculated to give the manufacturers recommendations in terms of daily digestible feed energy to be supplied to the fish.
It is hoped that the results of the above analysis will contribute to a better understanding of the reasoning behind current feeding practices on commercial sea bass farms, and the areas in which some research effort should be directed in order to arrive at more precise feeding recommendations in the areas where the manufacturers’ suggestions may differ.
Task 2.2. Survey on industrial sea bass production results
VA has access to historical monthly sea bass production data, covering a period of 5 years, from up to 14 commercial farm sites in the Mediterranean. There was only a very weak negative correlation between farmed fish growth rates and FCR and an equally very weak positive correlation between FCR and farming duration. The commercial data were analysed to validate a practical base line growth model for sea bass reared commercially under true production conditions (submitted deliverable to EU: D.2.4).
As expected the whole body analysis results showed that farmed E. sea bass whole body protein, fat and energy are increasing with fish size, whole body ash content is stable, and whole body moisture is decreasing with fish size.
Another issue taken into account in this project is the presence of at least 2 very different strains of European sea bass with clearly different performance, the Mediterranean and the Atlantic. In Figure 2.4 are presented some commercial results Nofima has access to where it is clear that both feed and mainly sea bass strain is affecting fish performance (Atlantic fish fed high, medium and low energy diets and Mediterranean fish fed high energy diet). As it is believed that most old and current literature data are based on the Mediterranean strain of this fish species which is clearly inferior to the Atlantic, we believe that a whole new data set on the particular potential and requirements of the Atlantic strain must be created.
The results show that the FCR values published in the literature again for the best performing fish in the different experiments. There is a clear trend (blue spots) of increasing FCR by fish size, but then there are some few out layers (purple points), taken from one of the most recent publications, of significantly better/lower FCR that must have been fish of the Atlantic strain, although there was no relevant mention in the article. Such is the experience we have from the industry during the last 7-8 years when well performing Atlantic sea bass caught again the interest of the producers against sea bream.
Task 2.3. Energy flow in sea bass (HCMR, Nofima):
To perform the task the following steps were undertaken:
a) The metabolic body weight was determined. The metabolic rate (basic metabolism) depends largely on the size of the fish and is proportional to the metabolic body weight in the form of a x BW (kg)b. To define the exponent b of the metabolic body weight the relationships between energy and protein loss at starvation for fish at increasing weights were determined. Fish of different sizes were stocked in tanks at different temperatures and fasted. Then, fish protein and energy content were analyzed for the determination of the energy and protein losses and consequently the metabolic weight of the fish.
b) Feed digestibility at different temperatures was determined for fish of different sizes in cylindroconical tanks with faecal traps according to a modification of the Guelph system and Cr2O3 as a marker.
c) Efficiency of energy and protein utilization was determined: To determine the efficiency of energy and protein utilization and hence the losses due to metabolic excretions and heat losses two methods were compared (Figure 2.5). An indirect slaughter method and a direct novel metabolic chamber method were compared as described below:
1) Slaughter method.
The efficiency of energy utilization for maintenance and growth was derived from feeding Atlantic strain European sea bass increasing amounts of dietary energy from starvation up to maximum intake. 6 weeks growth trials were performed using fish of different weights of about 20, 100 and 200g body weight. Samples were taken before each growth trial and all fish were sacrificed at the end of each trial. Energy, protein and lipid gains in fish were determined and daily retention of energy, protein and lipid was related to mean weight of fish.
2) Metabolic chamber/ respirometer.
The energy expenditure was estimated from the gaseous exchange and the release of N-compounds. The energy flow processes for sea bass was estimated using a special open circuit balance respirometer designed to ensure minimal disturbance of the fish, constant, acceptable water quality and constant temperatures (± 0.5oC) in the range from 15 to 25°C. Respired gases both in water and in air were monitored for several days at constant water and air flows.
Metabolic rate
The equations for the maintenance protein and energy losses and utilization rates for European sea bass at 3 water temperatures: 15, 20 and 25oC were determined and presented below using 2 methods for comparison: the slaughter method and the metabolic chamber.
The feed intake, ammonia excretion and oxygen consumption were temperature dependent. There were no statistically significant differences between diets with different protein and lipid/carbohydrate levels. The metabolic losses were not correlated with the dietary macronutrient composition, but only with temperature. Overall, the metabolic chamber proved to be a must faster and reliable method to estimate energy and protein efficiency of feeds.
Task 2.4. Optimum dietary DP/DE determination:
In the present set of works optimal dietary protein and energy levels for fish of different sizes and at different water temperatures were determined. Based on the results from the previous 2 tasks (2.2 & 2.3) 3 x 3 diets with different DE/DP ratios were formulated and tested on E. sea bass of different body weights reared at different temperatures, for growth, FCR, flesh quality and health. The experiments took place in triplicate tanks for fish from 10 to 200g. Body composition was analyzed at the end of the trials. Flesh quality was evaluated by analyzing the fillet for gross composition and organoleptic characteristics. Health was evaluated by the evaluation of non-specific immune indices of the fish. Complement activity and respiratory burst values were used as immune indicator parameters.
Three diets were formulated and produced by Nofima AS each one at 3 particle sizes: 2.2mm 3.5mm and 5mm for the growing size of fish and the whole feeding trial duration. The formulation and proximate composition analysis results for each one of the three particle sizes of the experimental diets that were produced at Nofima AS are described Table 2.2.
Best European sea bass growth for body weight sizes from 10 to 200 g was obtained with feeds of 45/16 and 60/12 total protein/lipid. Best feed utilization was observed for the 45/16 diet, protein utilization efficiency decreased as dietary protein increased indicating higher nitrogen loss to the environment with higher protein diets and vice versa. No statistical significant differences were observed on fish body composition or in the immune responses of the fish fed the different experimental diets.
The results of the present group of works and the indications for the determined best performing feed formulations were communicated to the partner fish farming SME OZSU and a feed producing SME Raanan Fish feed for the production of the experimental diets for the demonstration activities of the project.
Task 2.5. Modelling of cost efficiency of small gradual DP/DE changes:
Four diets were formulated to contain the same amount of fish meal and variable amount of plant proteins and fish oil, and were balanced with respect to limiting essential amino acids and total soluble phosphorus (Table 2.3). DP/DE diets 1 to 3 contained, as intended, decreasing levels of digestible protein to digestible energy ratio (DP/DE), with low increment changes among them. All experimental diets had similar but higher DP/DE ratio than the suggested optimal by Peres and Oliva Teles (1999).
The protein digestibility in mink (TPD) was high and similar among the diets (90-91 % of total protein) and related to the choice of the protein ingredients/meal in the feed formulation. The results show that a dietary mix with higher fraction of marine proteins (diet 4) does not have significantly higher true protein digestibility (TPD) compared to a dietary mix with increased fraction of plant protein of high nutritional quality for fish (diet 1) (Figures 1a & 1b). This result is in accordance to previous eFISHent project results in European sea bass, showing that at both high and low water temperatures fish performance was equally good using either high or low fish meal diets (Deliverable 3.10).
Sea bass juveniles of ca. 6.5 g mean weight were fed the experimental diets during 90 days in triplicate tanks in the recirculation unit of VA at a (Photo 1) temperature of 17.8±0.6oC.
The trial results showed increased feed intake rates and growth in fish fed the diet with the highest DP/DE (diet 1) (P<0.05). However, though not significantly, feed utilisation was highest in the fish fed the lowest DP/DE diet (diet 4). Fish growth followed feed intake rates, correlating significantly in a linear way, mostly explained by intake of protein energy and less by intake of the non-protein energy fraction of the diets. The FCR was similar for the different diets increasing in the tanks that exhibited the highest feed intake rates. The main factor that explains the observed differences in fish growth was thus feed intake.
We see that, under the experimental conditions, an economic loss for the fish farmer is expected from reducing feed cost by using oils (plant or fish oil) in the expense of dietary protein. This is due to the higher fish biomass produced in the same period of time using the higher protein/lower fat diet 1 due to higher feed intake rates. These results are in accordance to previously reported studies in European sea bass where no protein sparing by dietary lipids occurred beyond 12 % dietary lipid levels (Peres and Oliva-Teles, 1999; Boujard et al., 2004).
Reduced feed intake rates by increasing lipids in the diet were observed also in the present experiment, as also described in the review (D2.3). Using higher lipid and energy dense diets, fish receive higher amounts of energy from a given feed amount and stop eating faster when their energy levels in the body stores reaches a certain limit. The mean daily protein feed intakes per kg fish body weight in our study were DP/DE1: 8.3; DP/DE2: 7.9 and DP/DE3 & DP/DE4: 7.7. Based on recalculated values from several studies in E. sea bass (D2.3) the optimal daily protein intake levels for best growth for fish below 50 g body weight range from 8.2 to 12.6 g kg-1 body weight d-1. Thus, according to the meta-analysis of nutritional studies in E. sea bass, only in treatment DP/DE1 of our present study did the fish receive optimal levels of dietary protein for best growth. It seems then, that even a small deviation from the optimal can induce a significant effect in fish performance. At even smaller increment increases in total lipid, as among diets 2, 3 and 4, we see that there may be an economic benefit for the feed producer from protein sparing by use of plant oils, which is not likely to lead to significantly reduced fish performance.
Work package 3 title: Seasonal feeds and feeding strategies for sea bass
We demonstrated the significant economic benefit potential from using appropriate dietary formulations and oxygenation in cages where E. sea bass is reared at low water oxygen saturation levels. Though higher protein and lower lipid diets proved in several eFISHent trials superior in terms of E. sea bass performance, this result was inverted at low oxygen levels, where fish fed a lower protein and higher fat diet had best FCR and growth.
In the winter period, FCR was improved significantly by fasting E. sea bass every other or every third day with no reduction in growth. Moreover, by using sustainable 0% fish oil diets rich in low n-6 plant oils (such as palm oil, olive oil and salmon by-product oil), gonadal growth and expression of genes coding for maturation hormones was reduced.
Both at low and high water temperatures E. sea bass is able to growth with low to very low FCR by use of well balanced and nutritionally complete diets, even when only 10% fish meal is used in the diet. No negative histopathological effects were observed in the fish fed the high plant diets.
Task 3.1 Evaluating the effect of dissolved oxygen levels and sea bass performance (RMC, Nofima)
During the months of July and October the water oxygen levels measured during 3 years in a sheltered Mediterranean seabass and seabream farm were between 5.5 ppm and 4.5 ppm.
According to the results of our trial the extrapolated loss in body gain due to reduced oxygen levels in the water during the period July-August in a commercial sea bass farm would be 13% using the high protein diet and 9.5% using the high lipid diet. All sea bass stocked around the year pass 2 summers in the cages and on average grow 180 g during the low oxygen summer periods (July-October) out of total 350 g (market size). This means that, in sheltered fish farms, about 50% of fish biomass growth takes place during periods of potentially suboptimal sea oxygen levels. Thus a sea bass farm of total production 1,000 tons per year by applying water oxygenation in the cages up to just above 6ppm during the months of July-October, would have a total benefit in surplus biomass production of 47-69 tons per year, accounting for a value of 251,400-366,800€ (ex-farm sea bass price 5.3€/kg). About a fifth of this value (or less) would be cost of extra feed consumed by the faster growing fish. Nevertheless, feed costs would all together be unchanged as, should aeration be employed to increase oxygen levels in the sea, all summer growth (not only the extra gain) would be more efficient in terms of feed utilization.
In the demonstration activities D4.14 and D7.24 was shown that even in a non-sheltered farm, where oxygen levels do not drop dramatically during the summer (measured by an RBR Dissolved Oxygen Logger DO-1060, RBR Europe Ltd, Stadhampton, UK, supplied by the SME Element), it is feasible to raise dissolved oxygen levels in the sea using oxygenation equipment, already available in most farms (currently used during sampling, vaccination, medical treatment etc). Should a farmer wish to employ an automated system of aeration connected to an oxygen meter which would operate during the night with no extra labor costs involved, an investment on relevant hardware is to be made.
A recent report (Treasurer, 2010) on use of oxygenation systems (Crampton et al., 2005) in sea cages with Atlantic salmon during low oxygen periods of 5 months shows weight increase of the fish reared in cages with oxygenation of 2106 g compared to 1860 g in fish reared without additional oxygen. The additional cost of the oxygen in this period was 40,000 NOK per cage and the additional income was 104,000 NOK giving a net income of 64,000 NOK per cage. These results are equivalent to the predicted ones in our study with E. sea bass (about 20% improved growth). As the oxygenation costs accounted for 40% of the total added incomes, accordingly, a E. sea bass farmer operating cage farms in areas with low oxygen levels in periods of the year, can achieve additional incomes of up to 145,000-220,000€ per 1000 tons fish produced by the use of modern automated cage oxygenation systems.
Task 3.2 Testing the effect of low temperature fasting and/or food restriction on overall cycle FCR (VA, Nofima)
The work activities of this task include two feeding trials: 1) an experiment with different feeding regimes at low water temperature, and 2) an experiment with immature fish at low water temperature to assess the potential to delay of maturation by means of nutrition. In experiment 1 the fish were offered one meal daily and were given either access to an unlimited amount of feed every other day, or for 2 days followed by one day with no feed, or were given a restricted amount of feed daily. In experiment 2 the fish were fed diets with higher or lower energy content and either high or low levels of marine long chain n-3 fatty acids.
Experiment 1: Feeding frequencies
Ad libidum feeding, and fasting E. sea bass every other or every third day gave significantly higher fish growth performance compared to feeding daily feed amounts equivalent to 50% of saturation (Figure 3.6). However, as total feed intake was lower in the fasting regimes (every other or third day) so was FCR (1.4 versus 2.0 in ad libidum treatment).
Experiment 2: Maturation delay
Nofima AS produced four feeds at Nofima’s Feed Technology Centre (Bergen, Norway) with fish meal, horse beans, corn gluten and soy protein concentrate as the main protein sources. The 4 isoproteic diets were produced to either have a high (HF; 180 g kg-1) or low (LF; 21 g kg-1) fat content, and either with marine fish oil (M) or plant oils (olive oil, palm oil) and salmon oil which resembles the composition of a 50% fish oil, 50% rape seed oil (P), as oil source.
Summarising the results from Task 3.2 trials; E. sea bass has the ability through dietary manipulation to reduce FCR, improve or maintain similar growth rates, reduce liver weight and potentially reduce or delay gonadal growth, by 1) reducing total dietary lipid and LC n-3 content and by 2) fasting every other or third day in the winter season.
Task 3.3. Laboratory determination of daily and seasonal voluntary feed intake by using demand feeders:
Demand feeding systems allow fish to dictate the timing and size of their daily ration and can integrate any appetite variability into feed management. These appetite-based demand feeders, such as i) self-feeders, where fish bite or pull a trigger to receive food (Alanärä, 1992a) or ii) interactive feedback systems using camera based pellet detection (Ang and Petrell, 1997) or an infra-red pellet sensor (Blyth et al., 1993) to monitor food wastage, can supply fish with a responsive ration and can feed the majority of fish to satiation. Previous studies have shown that demand feeding can improve FCR in sea bass (Azzaydi et al., 1999; Paspatis et al., 1999) and other species (Noble et al., 2007b; Noble et al., 2008) in comparison to existing farm practices. However, the commercial feasibility of scaling up these studies to the average sea bass farm was not investigated in detail until a previous CRAFT FAIR Project CT-98-9201 entitled "Cost-effective and environmentally-friendly feed management strategies for Mediterranean cage aquaculture" which found farmers could achieve FCR’s of around 1:1 when utilizing demand feeding technology. However, many aquaculture ventures within the Mediterranean have neither utilized nor adopted these systems, as numerous farms still report FCRs of up to 2.2:1. This proposal intends to build upon and expand this original project and provide farmers with customized demand feeding solutions and feed management strategies to increase their uptake and retention within the sea bass aquaculture industry
Experiment
The experiment was carried out at the Viking fish Farms Ltd. (Acharacle, UK). The sea bass were maintained into 3 cylindrical tanks of a 1600 l capacity in an open flow system with an average temperature of 14.43ºC and oxygen saturation above 70%. During the experimental period the fish were exposed to 10:14 LD photoperiod.
Sea bass were obtained from Selonda UK in April 2011. The trial involved a total of 180 fish. After a mixing period of two hours in a big tank (3000 l) the fish were divided into 3 groups of 60 sea bass and placed into 3 tanks of 1600 l. At the start of the experiment the fish had an average body weight of 54.61±1.12 g and an average body length of 163.42±1.53 mm. The fish were fed with commercial pellets- meeting the nutrient and energy requirements of sea bass (INICIO Plus 1.9mm for Sea bass, BIOMAR Ltd, contained 50% protein, 18% lipid, and 16.8% nitrogen free extract). Prior to experimental sampling fish were feed deprived for 24 h. During the self-feeder acclimatation period (day 0) fish were trained to use the demand feeder for 20 days. The trigger was activated randomly during the day by hand and pellets felt to the tank, to show the fish how to use the trigger. At the same time some pellets were distributed by hand close to the trigger to show the fish how to obtain the feed. The fish were measured (weight and length) at the beginning and at the end of the experiment, using 2 mg of 2-phenoxyethanol as anaesthetic. After the acclimation period (20 days), sea bass were fed only using the demand-feeder, connected to a computer that continuously recorded the number of trigger bites by sea bass. The feed was weighed weekly, to evaluate the total feed eaten per week. The trial was carried out for 30 days. At the end of the trial, all sea bass were measured (weight and length).
Self-feeding system
Each tank was equipped with a self-feeding system (Image 5). The self-feeder consists of a motor which is set to turn 1 rotation whenever a trigger is pulled by a fish. The motor drives an auger drill bit which passes through a box of food, dispensing food as it turns. The whole device is contained in a plastic tub which acts as a barrier against moisture and splashing. The trigger was at approximately 4 cm below the water surface during the trial.
Both the feeders and the triggers of the feeding system were powered by a remote 12VDC transformer. The control electronics consisted of a purpose designed circuit board with a 7 channel IC Darlington driver, with each of six input channels connected to each of the three feeder triggers, and the output for each respective channel connecting the negative terminal of each 12V feeder motor to ground. Each trigger input line contained a 33μF capacitor and a 240K variable resistor.
The actuations of the trigger were recorded on a PC in a nearby office. This had an ADC-11 analogue-digital converter (Pico Technologies, UK) connected to its parallel port. Each of six input channels on the ADC was connected via a shielded multicore cable to each of the three trigger circuits, via a resistor ladder which reduced the 12VDC trigger voltage to the 1.5VDC maximum. This output from the trigger circuit was taken prior to a diode in the capacitor circuit to give an instantaneous voltage on the ADC input pin when the trigger was activated.
A specific programme was written in Visual Basic To handle the signals from the ADC, and this programme then embedded as a Macro in an Excel spreadsheet. Essentially, via a loop, every 50 milliseconds this programme “looked for” a voltage on the input channel to which each trigger circuit was connected. When an input was detected the programme sent the value to the Excel spreadsheet which logged it, and the date and time to the nearest second that was received. Initially, due to the sensitivity of the ADC, some problems were encountered with noise on the cable between the trigger control box and the PC which was only partially resolved by using a shielded coaxial cable between the two units. Hence the programme was re-written to record only digital signals exceeding 2000 units which effectively screened out the low voltage noise on the cabling. Also, as it was observed that the fish tended to “hang” on the trigger, when a trigger signal was recorded, the programme was designed to ignore that trigger in the loop until the voltage had dropped back to background levels. This thus ensured that an activation of the trigger was recorded as one single activation however long the fish actually hung onto the trigger.
Discussion
The study of the feeding rhythms of fish species is important in aquaculture, as it provides knowledge of when the fish are more capable to consume more food (Azzaydi et al. 1999). Then, the fish farmers can use the information to improve productivity in two ways, increasing the feeding during certain hours when the fish are more active and capable to feed more, and second to decrease the food waste in those hours that the fish are not really appetant. All this information can be incorporated as a feed management strategy for the farmer. Different studies from other authors in European sea bass show that the fish have an evidence of a seasonal phase where the fish is diurnal feeding during the summer and in winter this changes to nocturnal (Sánchez-Vázquez et al. 1998). In other studies with Oncothynchus masou masou, exhibit a diurnal feeding rhythm during the light phase (Flood et al. 2011).
In the current study, three tanks with self-feeders were used to study the feeding behaviour in the European Sea bass in Ardtoe Marine Laboratory, UK. The self-feeders were tested in 3 replicates, where the fish had a period of acclimatation of 20 days with the self-feeders. After that a trial was conducted for a period of 30 days, the data showed no differences in feeding behaviour during the 24 hours in the 30 days, when the fish pulled the trigger during all the 24 hours to obtain the food. After 19:00 h it seemed that the fish actuated the trigger less frequently, demonstrating a decrease in feeding behaviour at that time, when the fish seemed less active in finding food. Similar results were found by Sánchez-Vázquez et al. 1998 in sea cages at 14ºC, where there was a decrease in feeding behaviour after 20:00 h.
Therefore, the current study demonstrates that the European Sea Bass has a feeding rhythm throughout the day, with a maximum of feeding during 04:00 to 05:00 h. Although this study suggests that European Sea bass have a daily and constant feeding rhythm during the entire day when the temperature is 14 ºC, this should nevertheless be tested in sea cages before recommending any preferred feeding regime.
Task 3.4. Feed size preferences, diet preference and feed attractants (VA, Nofima, RMC
Feed size preference (VA)
The results of the pellet size preference trials were in month 7 of the EU efishent project. In reality there was little chance that this was ever going to be possible. The work needed to be done when the water was warmer in autumn 2010, but as the project did not officially start until the 1st December 2010, and no advance funding was received to enable VA to buy the fish until March, we missed the window, and will thus do the trial in summer 2011. However, in month 7 we have analysed data comparing the feed pellet size versus fish mass recommended by four major sea bass feed manufacturers.
Sea bass qualitative pellet size preference
In this situation Sea bass may typically feed on the larger pellet first because it’s bigger and thus easier to see. The result may have been different if Sea bass had not been starved for 24 h and/or they were fed in darkness. A Sea bass of ~43 g cannot fit a 6.5 mm pellet into its mouth.
Diet preference & feeding & immune system stimulation by the use of marine hydrolysates
Diets were tested in E. sea bass reared both at low (14oC ARDTOE) and high water temperatures (24oC Raanan Fish Feed). Growth, feed efficiency and histopathology results are discussed.
Fish growth was as expected significantly lower at low sea temperatures and FCR higher than at high water temperatures. Nevertheless, FCR levels were below 2 at low temperatures and below 1 at high water temperatures. Moreover, fish fed the low fish meal diet grew equally well as the high fish meal diet and thus there was no additional positive effect of on growth from the addition of the marine hydrolysates. At low water temperatures there was a positive effect in feed intake for fish fed the low fish meal diet supplemented with the krill or herring stickwater but as growth was not improved, especially for the krill treatment, FCR increased.
No disease incidences or mortality differences were observed among the fish fed the different experimental diets. The histopathology examination of fish from both experiments show that the overall morphology of the intestines was normal. In a few samples, mild thickening of a few intestinal folds per section was noted. This was characterized by hyperplasia of the lamina propria and sub epithelial oedema. No sloughing of the epithelium was observed.
Liver samples were examined only from the second experiment (high water temperature). The overall histological picture of all samples indicated mild to moderate fatty infiltration of the hepatocytes. Although no clear difference in the level of fatty infiltration between all group of fish was noted, the fatty infiltration in the samples from the fish that were fed with Diet HFM appeared more prominent, while the samples from the group HSW exhibited milder infiltration. In all cases, the mild infiltration of the hepatocytes was characterized by slightly swollen hepatocytes within which ‘blank’ spaces (existence of fatty droplets) existed. This resulted in extensive discoloration of the cells. No peripheral displacement of their nuclei was observed though. In moderate fatty infiltration, the enlargement of the hepatocytes was more pronounced and in this case many nuclei were pushed towards the cell membranes.
Work package 4 title: Optimising feed management
Task 4.1. Comparing and benchmarking existing feeding practices (VA, Nofima, NESNE Electronics, HCMR, SMEs)
Task 4.1 formed the basis of eFISHent deliverable 4.13 “Review and benchmark the current feeding practices of existing European sea bass producers in relation to key production performance indicators such as feeding efficiency and growth”. To achieve this aim the deliverable was split into two sections according to Task 4.1 of the eFISHent WP4 DoW and involved:
i) benchmarking current feed conversion ratio’s (FCR’s) and growth performance for each farm/company/region for specific months and fish sizes
ii) benchmarking each company’s current feed management practices and feed technologies.
Task 4.1i FCR data was then used to evaluate the eFISHent SME farm (Özsu’s) production performance in relation to time of year, fish size and feed management practices. To benchmark potential FCR performance in relation to fish size and time of year, three commercial databases were made available to WP4 by the eFISHent partner and SMEs. These included:
a) a database collated by HCMR as part of the eFISHent project that covers 21 Greek farms across various regions for each farms entire production cycle
b) a very large historical sea bass production database of a Mediterranean fish farming group which is available to Viking Fish Farms
c) historical production data from the eFISHent farming SME, Özsu Balik Ltd on their production data using their 2006-2009 year classes of bass
Benchmarking procedures: Benchmark charts were developed where
i) FCR and SGR performance were compared between farms and regions in the Mediterranean
ii) the effect of season and time of year upon FCR and SGR was investigated
iii) the effect of fish size upon FCR during the production cycle
The first outputs of this task showed that FCR and SGR performance can vary between both farms and regions:
Özsu Balik production FCRs compare very favourably with other farms from the HCMR dataset and there was also a seasonal effect upon FCRs within each production cycle, with poorer FCRs during winter months (see Fig. 4.6 for the benchmarking of FCR performance of the VFF dataset, and Fig. 4.7 for benchmarking of Özsu Balik data in relation to time of year)
The final aim of task 4.1i was to benchmark FCR with fish size. This data is shown in Fig 4.8 and shows a clear relationship between fish size and increasing FCR.
Task 4.1ii Benchmarking each company’s current feed management practices and feed technologies. The eFISHent WP4 partners were tasked with collating data from numerous Mediterranean sea bass farms to assess:
i) average daily ration in relation to time of year and/or fish size
ii) frequency of daily meals in relation to time of year and/or fish size
iii) choice of feeding method for each farm in relation to fish size
In summary, daily ration recommendations vary for both time of year and fish size, as do feeding frequencies.
When a review of scientific literature was carried out to benchmark FCRs under controlled scientific conditions in relation to feeding practices: free access to self-feeding systems in tanks can give FCRs ranging from 1.1. to 2.57 and self-feeder usage in sea cages can deliver FCRs of 1.35 to 2.45. 1-meal feeding frequencies can generate FCRs ranging from 1.43 to 2.1. 2-meal feeding frequencies can generate FCRs ranging from 1.2 to 2.65. 3-meal feeding frequencies can generate FCRs ranging from 1.05 to 3.52 but if these 3-meal regimes are further manipulated in smaller fish e.g. by subjecting fish to 4 days full ration, 1 day satiation, FCRs can be reduced. But there is such as range of conditions and varying treatments between these studies, that they should be merely used as a guideline of what FCRs can be achieved when subjecting different sized fish to different feeding regimes at different times of the year.
Task 4.2. Developing optimised feed management strategies (NM, NESNE, Akvaplan-niva, Özsu) Task 4.2 formed the basis of eFISHent deliverable 4.14 “Determine feeding efficiency and monitor the growth and welfare of European sea bass” has been split into two sections according to Task 4.2 of the eFISHent WP4 DoW and involves:
Task 4.2.1) experimentally evaluating the effects of different feeding frequencies upon the feeding efficiency, growth performance, mortality and welfare of cage-held sea bass in relation to a number of additional economic indicators such as labour and feed monitoring costs.
Task 4.2.2) experimentally evaluating the effects of different fasting and re-feeding periods upon the feeding efficiency, growth performance, mortality and welfare of cage-held sea bass.
Task 4.2.1 Summary of progress and significant results
Two feeding frequencies were set-up for the duration of the study. Three cages (hereafter termed the 1-meal regime) were hand fed to perceived satiation at 0900 h each day. Three further cages (hereafter termed the 2-meal regime) were hand fed to perceived satiation at 0900 h and 1600 h each day for the duration of the study. During hand-feeding a surface feeding response was used to determine satiation. Fish were fed commercial diets in relation to fish size: a 4mm extruded pellet (OptiBass, Skretting Ltd) until 17th December and from the 18th December a 4mm extruded pellet (Hendrix-Skretting Power Excel) until the end of the experiment.
There was no significant difference between initial fish weight (P = 0.236) condition factor (P = 0.452) or size heterogeneity between regimes (P = 0.532) at the start of the study (see Table 4.11 for further information).
There were also no significant differences between regimes in terms of final fish weight (P = 0.730) condition factor (P = 0.227) or size heterogeneity between regimes (P = 0.629) at the end of the study as well. This was also the case for SGR (P = 0.606) FCR (P = 0.550) and mortality (P = 0.779) for the duration of the study. This suggests there were no discernable productivity or welfare benefits of increasing feeding frequency from 1-meal to 2-meals per day during early winter at large scale production facilities. In addition, FCRs were generally low for this time of year < 1.38. There was however a significant difference in the amount of time spent feeding the fish in relation to feeding regime (see Fig. 4.12). When fish were fed to a 2-meal regime the farm staff spent a significantly greater length of time feeding the fish than when fish were fed once per day (P = 0.003) but this extra effort did not lead to any significant differences in growth or FCR between feeding regimes.
In summary, increasing daily feeding frequency from 1- meal to 2-meals per day at low temperatures (15-17 o C) from December to February does not result in any significant performance benefits in terms of FCR or growth performance. In addition, a 1-meal regime does not have any detrimental impacts upon mortality or fish condition, two commonly used operational welfare indicators. Operational recommendations for sea bass farm SMEs would be to feed their fish once a day to perceived satiation, and an analysis of the costs and benefits of doing this is presented in D5.18.
Task 4.2.2 Summary of progress and significant results
• Control regime: the control cage could not be fed daily and a total of 15 days out of the 42 that were planned were lost to stormy weather. The experiment was then extended to 55 days to account for this loss. In total 19 feeding days of the 55 total were lost and this high number of lost feeding days meant that the fish in the control feed regime were not fed on ca. 35% of the days that they should have been.
• 1 day satiation, 1 day starvation regime: the cage that was subject to 1 day satiation feeding, 1 day no feeding regime lost 4 feeding days because of the storms (14%).
• 21 day starvation, 33 days re-feeding regime: the cage that was originally subjected to 21 days starvation followed by 21 days re-feeding, was changed to a 21 day starvation, 33 days re-feeding but still lost 14 days feeding during the re-feeding period (42%).
The high amount of lost feed days did affect the results of the study and the results should be interpreted with this in mind. There were no marked differences between initial fish weight, condition factor, or size heterogeneity between regimes at the start of the study.
There were differences between regimes in terms of final fish weight. All fish lost weight during the course of the study. The greatest weight loss was in the 21 day starvation/33 days re-feeding regime (ca. 4% weight loss). The least weight loss was observed in the 1 day satiation feeding, 1 day no feeding regime (<1%).
Due to weight loss in each treatment, no FCR figures are reported, and instead the amount of feed fed for the duration of the study is presented.
There was markedly less feed delivered to the 1 day on/1 day off cage compared to the control feeding regime, but interestingly this was one of the best performing cages for the majority of the performance data (growth, condition factor, size heterogeneity, mortality). In addition, another cage that performed well (the cage that was starved for 21 days being re-fed for 33 days) used 55% less feed than the control regime and 23% less feed than the 1 day starvation, 1 day feeding regime, yet only lost ca. 4% of the fish’s body weight.
In terms of GSI there was high variability in GSI values within each cage, irrespective of the choice of feed regime and the data should be interpreted with caution. Interestingly, the greatest increase in GSI and also the greatest increase in GSI variability was in the 1 day starvation, 1 day re-feeding regime. The 21 days starvation, 33 days re-feeding regime showed a slight decrease in GSI by the end of the study, suggesting the maturation investment of these fish was halted. But once again, due to high variability within replicates and also the problems the farm faced in terms of feeding days lost to poor weather conditions, the farmer should interpret this data with caution when making decisions on the choice of feeding regime. However, this data shows some promise and warrants further investigation under controlled conditions.
Task 4.3. Feeding and Oxygenation
The results show that there was daily variability in mean oxygen levels within a day, generally lower during the 4 hour period before lunch and also after midnight. However, this low period did not equate to a risk for the fish and was still >70% DO saturation. In summary, it appears the eFISHent farm SME has neither the biological or economic need to invest in potential aquaculture technology that can automatically adjust feed delivery in relation to oxygen levels. In addition, they currently have no plans to purchase an additional oxygen sensor for their camera-based feeding system. If situation were ever to occur when the farm need to enhance low levels of ambient DO, Özsu Balik would most likely enhance DO manually using an oxygen or aeration system. However, would it be feasible to deploy this technology on other Turkish farms?
NESNE Electronics have gathered information from other Turkish se bass producers during i) the questionnaire phase of WP5 and also ii) during their dissemination and outreach activities with local farmers. During these discussions a number of key factors emerged on whether there is a current (or future) market for systems that automatically link feeding delivery and supplementary oxygenation systems for cage producers.
• Small- to medium sized SMEs are relatively low tech and employ feeding practices that predominantly use feed feed-canons or pneumatic feed delivery systems to feed their fish. The majority of these farmers currently do not yet use underwater camera’s to improve their feed monitoring and enhance the feeding practices, so this would be their first priority if they had the opportunity to invest in new feeding equipment. They therefore believe linking feed technology and oxygenation delivery is too large a technological step and their efforts would be better directed at upgrading their current feeding technologies. This priority is because they see the immediate benefits of using sub-surface camera based feeding systems; they can monitor feeding and appetite levels to improve FCR (see deliverable 7.22 and 7.23) and can also monitor the e.g. cleanliness of the net.
• The economic situation facing a number of small to medium bass producers means they do not have the cash flow available for big investments, and must prioritise their needs accordingly. Larger Turkish producers do have the means to invest in larger scale feeding systems e.g. feed barges that can feed multiple cages, with each cage having a sub-surface camera for monitoring feeding and feed wastage. However, even when deploying this large scale investment, where one of the large farms has invested in 16 underwater cameras, only one of these integrates an underwater camera and oxygen sensor. The farmer uses the DO levels it gets from this cage this cage to monitor and associate changes in DO in relation to the other cages on the farm. If this monitoring system proves to be robust and effective, they may invest in further integrated oxygen sensor and camera systems at a later date, and if the need arises. Furthermore, if this monitoring system is a demonstrably robust, cost-effective and reliable tool for monitoring DO levels within a cage, the medium sized and smaller SMEs may see the value of this technology and invest in it further down the line.
Work package 5 title: Economic and environmental assessment and impact
Task 5.1. Studying the decision making process for the adoption of new technology
Nine farm managers in Greece (3 small, 3 medium and 3 large companies) and 11 farm managers in Turkey (3 small, 3 medium and 3 large companies) have been interviewed to analyse and assess their decision making process and behaviour.
Large and medium companies have one more level of management composed of CEO, Board and General Manager over their financial, purchasing, production and exporting managers.
Owners of small companies have more direct line over their managers and farm workers. Some of the smaller companies are family-operated.
Main findings from the questionnaire
• Position of Manager. Farm owners act as managers of small farms. For all sizes, the position of manager is simply the general manager. The purchasing chief is also the farm manager of one large farm.
• Administration in the farm. Only two farms have the general manager or owner administrator located in the farm.
• Who takes decision. Medium and large farms have decisions taken by group agreement, mostly a combination of farm owner and general farm manager. Only 2 small companies have one person (farmer owner/CEO) making decisions.
• Decision taken at farm or central office level. For large farms farm level decisions must get approval from the administration. For medium farms, farm level decisions must get approval from the farm manager and administration. Small farms have the owner/CEO take decisions at the farm level.
• Decision taken alone or with others. Decisions are not made alone but with farm workers, administrative department, owner, upper management and engineering/maintenance departments.
• Budget level that the decision maker is allowed to take personal decision. The decision maker for small farms is allowed to take personal decision of over 10,000 Euros, while most decision makers of medium farms are allowed only 1- 5,000 Euros. Only one medium farm is allowed over 10,000 Euros. Farm owners & finance departments has the highest allowable budget of over 10,000 Euros.
• Criteria to purchase equipment decision. Main criteria include improvement of economics and productivity.
• Decision made on an economic or scientific basis. Small companies decide on an economic basis; medium and large companies decide on economic and scientific basis.
• Most important economic decision criteria. Cost is the most important economic criteria for small companies. Large and medium consider payback period in addition to cost criteria.
• Production criteria. Top criteria are making work easier and faster. In addition small companies look for equipment that needs less skilled staff, while medium sized companies look for equipment that is easy to use.
• Basis for buying new equipment. Cost reduction is the main basis for buying new equipment. In addition large and medium companies look for the ability of new equipment to solve their current problem and with high quality production. One medium company wait for expansion of its capacity and look for new equipment that reduce production cost and with a high quality.
• What convinces that price is worth it. Payback period, productivity, availability of service and spare parts, price and quality and easy to use are the convincing points for buying equipment.
• How do they find out about new technology. Salesmen and word of mouth are not effective sources of information about new technology. Trade shows, magazines and internet are the main sources for large and medium companies, followed by neighbours and competitors using it.
• Subscription to magazines. Only medium and large/medium companies subscribe to magazines Eurofish and Fishfarming International.
• Subscription to academic journals. Only medium and large/medium companies subscribe to academic journals
• Subscription to industry magazines. Companies subscribe more to industry magazines than journals.
• Attendance at meetings and workshops. Companies encourage attending meetings. Most will attend the European Aquaculture Society Rhodos conference exhibition In August 2011.
• Large size aquaculture company. The recommended marketing strategy for large aquaculture companies are that the technology providers should exhibit and have local agency with spare parts and servicing.
• Medium size aquaculture company. The recommended marketing strategy for medium aquaculture companies are to advertise in trade magazines, publish scientific results and exhibit locally.
• Small size aquaculture company. The recommended marketing strategy for small aquaculture companies are to demonstrate the equipment in farming areas and exhibit locally.
Task 5.2. Assessment in reduction in local environmental impact in the vicinity of individual units
Survey data collection
• Sediment trap collection 24 hours
• Bathymetry around test cages
• GPS reading of cages and sample sites
• Current speed and direction, oxygen levels – 4 days
• Salinity, temperature and oxygen profile through water column around cages
• Sediment samples 0, 10, 30 and 100 m from cages
• Oxygen level inside cage 3 days
Measurement of water circulation/current speed/degree of flushing
Water exchange is one of the most important factors influencing environmental impacts and production carrying capacities. In this regard, current speed, direction and dispersion were measured and used to provide an indication of water exchange and mixing at the cages.
Current dispersion is a measure of the mixing of the water column, and provides an indication of the degree in which nutrients derived from a fish farm are diluted in the receiving water body.
Current dispersion measurement using Drogues
The drogues released at 2 meters depth travelled total of 238 meters in 94 minutes (4 cm/second). The drogues released at 10 meters deep travelled421.6 meters in 94 minutes (7 cm/second). This is not a typical result with the deeper current being faster than the surface current.
The wind direction was from the north estimated at a Beaufort strength of 6 - Strong breeze (10.8-13.6 m/s)
The drogues released at 2 meters depth travelled total of 1,360 meters in 60 minutes (18.8 cm/second). The drogues released at 6 meters deep travelled 596 meters in 60 minutes (8.3 cm/second). Typically surface currents are faster than deeper currents due to wind direction.
Current through a cage
Data was collected of the current speed through a net cage with fish and compared with current speed outside the cage. This was undertaken using a drogue released inside the cage at a depth of 2 meters below water surface. The cage held the trial fish in a net with a mesh size of 6 mm.
The results were that the current speed inside the net was 6.7 cm/s compared to the current speed outside the net at 18.8 cm/s. This showed that the current speed inside cage is approximately 1/3 of current speed outside cage.
Sediment quality below the cages
The organic loading of the sediments takes place over time, and can therefore be used as a long term indicator of impacts. Benthic sediment samples were collected close to the cages and at a reference site. Samples were collected using either a van Veen grab (hard sediments) or a corer (soft sediments).
Sediment samples were characterized according to the following criteria:
• sediment type - shell hash, gravel, sand, or mud (silt and/or clay);
• surface colour and colour change with depth - as a possible indicator an anoxic states;
• smell - sulphide (the odour of H2S or rotten eggs), oily (the odour of petroleum tar), or humid (a musty, organic odour). Typically, un-impacted sediments have no particular odour.
• general sediment colour - black, green, brown, red, yellow etc.
The sediment samples were sieved in water until all the fine material has passed through the sieve, and only the particulate matter remained. These particles were then carefully transferred to a plastic sample jar. All the material that was retained on the sieves and transferred to the sample jar were fixed and stained. A small amount of clean water was added to the sample, followed by formalin as a fixative and Bengal rose as a stain.
1 Modelling the effect of lower FCR on impact to the sediment
Comparison of all scenarios – Severity and extent of footprint
The most important effect of lowering FCR through more efficient husbandry practice and diet is the reduction in the area of severe impact.
Conclusions
This MERAMOD modelling study draws the following conclusions:
• all of the cage groups have adequate spacing between them, so that no overlap of deposition footprints were predicted
• all cage groups are situated in quite deep waters, which aids dispersion of wastes; similarly, advection of wastes by the measured current was also quite high, although the current record was relatively short
• the area occupied by the deposition footprint in all increased production scenarios was less than the mooring area; group 2 had the largest extent of deposition footprint; the model predictions implied that the total deposition footprint area was acceptable for all scenarios in relation to the mooring area
• the increased production scenarios for groups 2 and 3 resulted in a predicted severe impact area of around 5 % of the total footprint; no severe impact was predicted for group 1 for increased production
• however, the predicted areas of severe impact were reduced significantly in the increased production scenarios, when lower FCRs of 1.8 and 1.6:1 were used to represent more efficient diets and practices; this was particularly the case for group 3
• the severe impact predicted for cage group 3 scenarios, were a result of a few cages with high feed input (and biomass); this suggests that a more even distribution of feed input across the whole cage group, or moving around high biomass cages within the group, would limit severe impact in a particular location
• The MERAMOD model predictions also suggest that when increasing production, adding larger and well-spaced cages (rather than adding another row of cages) results in better dispersion of wastes.
Task 5.3. – Assessment in the reduction in the wider ecological footprint using LCA
Resource use and greenhouse gas emissions by seabass cage culture systems
1. Global warming and eutrophication potential
Global Warming Potential Impact assessment results
The calculated Global Warming Potential (GWP) values for the seabass cage production is 1,810.62 kg CO2e/t fish. The majority of the GWP impact is from the manufacture and use of compound feeds primarily from the fish meal, krill meal and wheat products as well as the energy used to manufacture the pellets. Whereas the impact from energy use (electricity and diesel) for other uses is relatively low as water does not need to be pumped through the cage system.
The reduction of GWP impact from the reduction of food conversion rate is significant primarily due to the fact that the feed contributes such a high level to the GWP.
The reduction in GWP due to the improved FCR is 29.9%.
Eutrophication Potential Impact assessment results
The calculated Eutrophication Potential (EP) is 7.78 kg PO43- equivalents. Again the predominant impact is from compound feed but also with significant impact from nutrient output (phosphorous and Nitrogen) in terms of dissolved nutrient excreted from the gills and particulate nutrients in the faeces.
The reduction of EP impact from the reduction of food conversion rate is significant primarily due to the fact that the feed contributes such a high level to the GWP.
The reduction in EP due to the improved FCR is 31.2%.
Comparison with other aquaculture production systems
he level of GHG seabass at 2,048 kg CO2e/t fish is relatively low compared to other semi-intensive and intensive land based and sea based systems including the production of Norwegian salmon in cages.
1.1 Conclusions
The GHG emissions from seabass production are mainly from the use of compound feed. The improved feed quality and feeding management gives a significant reduction in GWP impact and the potential impacts associated with feed ingredients especially fish meal and wheat flour should be taken into account at the feed mill.
The EP impact from seabass production is mainly from the use of compound feed and the release of nutrients. Again, the improved feed quality and feeding management gives a significant reduction in EP impact and the potential impacts could be reduced further with the use of highly digestible ingredients or diets with lower Phosphorous and Nitrogen levels.
2 Analysis of feed resource use
2.1 Fish-in Fish-out Ratio (FIFO)
The estimated FIFO ratios for the case study culture systems used the following formula;
Level of fishmeal in the diet + level of fish oil in the diet
------------------------------------------------------------------------- x FCR
Yield of fish meal from wild fish+ yield of fish oil from wild fish
The FIFA ration for seabass cultured on BioMar feed with a food conversion rate of 2.03:1 is calculated as follows
33.7 + 8
---------- x 2.03 = 3.18
22.5 + 5
The FIFO reduces to 2.43 when FCTR is improved to 1.6:1.
The production of seabass in Turkey is a net user of fish with a FIFO greater than 1. However the improvement of FCR takes the production from a high level of fish use to a moderate level of fish use. However further effort should be made to make seabass production a net producer of fish by substituting fish meal and fish oil with vegetable sourced ingredients.
2.2 Analysis of land or sea area resource use
In cage culture, the sea is used to culture the fish. There are a number of ways to measure the space utilisation
• the physical space or volume that the nets occupy
• the site licence area
• the sea bed are that is utilised by the moorings and anchors.
The land and sea utilisation is therefore calculated to be 442.7 m2/tonne production.
Analysis of energy resource use
In seabass production the highest use of electricity is for the production of feed, production of fry and servicing of the cages by boat with a total of 8,588 MJ per tonne of seabass produced.
Resource use and Global Warming Potential mitigation strategies
The case study data suggest that a moderate degree of Food Conversion Rate can dramatically improve efficiency with regards to GWP and EP.
The GHG emissions from seabass cage culture are mainly from the use of compound feed and production of fry. Thus, the feeding management and the optimal operation of the hatchery must be given the attention in order to reduce the GHG emissions. More importantly, the potential impacts associated with feed ingredients especially fish meal, fish oil and wheat flour should be taken into account at the feed mill.
Task 5.4 – Analysis of the cost benefit of the results of the implementation of the knowledge:
Productivity benefits
For the scope of the eFISHent fish feeding trials optimised diets were formulated for European sea bass of body weight from 5 g to 300g reared in experimental tanks or sea cages, at temperatures from under 10oC and up to 25oC, and oxygen levels of 3.5 ppm to 6.5ppm. Both relevant eFISHent partner SMEs, one fish farmer and one feed producer, have had early access to the best performing and sustainable feed formulations used in the eFISHent trials with documented good fish growth results and remarkably low FCR.
• Improved food Conversion Rate
The obtained FCR values were ranged from 0.84 to 1.9. The highest FCR values were obtained in some winter trials, which were nevertheless always below 2.0. Optimum combined growth and FCR (1.18) results were achieved feeding E. sea bass juveniles with a diet containing 50.5% protein and 16.6% lipid (D2.7) and larger fish with a diet containing 45% protein and 16% lipids (D2.6).
The D2.6 results were confirmed in D3.8 obtaining FCR as low as 1.16 using a 47% protein and 16% lipid diet at high water oxygen levels. However, at low oxygen saturation levels optimal results were obtained using a lower protein (44%) and higher lipid diet (22%). These results provide documentation that allow the farmer and feed producer to cooperate and opt for either using 1) oxygenation in the cages, and obtain optimal production results, or 2) more cost efficient dietary formulations for periods of lower water oxygen levels.
In terms of feed formulation, equally good performances of reared E. sea bass were achieved, both in low and high water temperatures, with diets containing from as low as 10% (D3.10) and up to 35% fish meal in the diet and 0% (D3.9) to 100% fish oil (as % of added oil in the diet; 0% fish oil diet contained some salmon by product oil in addition to plant oils to cover the LC n-3 HUFA requirement of E. sea bass). All experimental diets were optimised and balanced in terms of indispensable amino acids, available phosphorus, LC n-3 HUFA and choline. The plant raw materials used were of documented nutritional value for this fish species (D2.3) and their inclusion level in the diet was chosen taking into account their content in anti-nutritional factors and potential negative interactions.
• Reduced feed cost
Modelling of cost efficiency of small gradual DP/DE changes
The balance between dietary protein and digestible energy is both important for optimal fish growth and nutrient utilisation efficiency (Company et al., 1999) and has practical consequences in feed formulation and cost. The effects on fish growth and FCR as a consequence of major changes in the macronutrient composition of the diets, in the dietary raw materials used, in the water and oxygen levels, and in the applied feeding regimes, are addressed in separate sections of the project. When the main feed specification values for optimal fish performance are determined, still the feed producers face the continuous challenge of formulating the desired feeds in the most cost efficient way according to the day-to-day availability and price of the different raw materials. Moreover, the raw material quality varies from batch to batch leading to small variations in feed quality throughout the year. The effects of small changes in feed composition or formulation around the optimal specifications are not known. This fact creates an almost impossible situation during the price negotiation of the feeds between feed and fish producers.
• Improved feeding strategy
These robust, operational results can then be used by Özsu Balik to compare the performance of their existing current best feeding practices against feeding technologies that incorporate underwater cameras for monitoring changes in fish appetite and satiation during feeding. It will help Özsu Balik and the other eFISHent partners assess the costs and benefits of utilizing emerging feeding technologies in relation to the key performance indicators, growth and FCR.
Summer feeding frequency
Feeding frequency is one important consideration as it can affect feed intake, growth, survival and fish quality as well as environmental impact. Feeding at the optimum frequency can result in savings in feed cost.
The objectives of the feeding frequency study was to evaluate the effects of different feeding frequencies upon the feeding efficiency, growth performance, mortality and welfare of cage-held sea bass in relation to a number of additional economic indicators such as labour and feed monitoring costs.
Use of camera monitoring systems
An underwater camera system was purchased and tested on the test and commercial cages. The camera delivers a high picture quality and has high light sensitivity. This means it can be used in cages without extra light. The camera has been designed for permanent installation. The camera remains in the cage and connected to the feeding boat by cable at the time of feeding the fish in the cage. The camera cables are plugged into an external socket on the boat's wheel house, and are controlled internally with a control console (KB-6000) and monitor. The camera hangs from cables on the cage.
Winter Feeding regimes-fasting/reduced rations
Feed quality and feeding management in commercial farms is a big challenge, but they are also the foundation for achieving improved feeding efficiency and growth throughout the season. The winter season is particularly challenging due to the low temperature, and overfeeding as a result of low feed intake are an common no beneficial cost during the winter season.
• Cage oxygenation system equipment setup and protocol
Fish with low oxygen levels are less capable of metabolizing higher protein levels in their feed, and thus perform less compared to fish that are fed less protein rich diets. The present results on E. sea bass confirm the previously published findings of Fu et al. (2005) and can help the fish farmers and feed producers to formulate efficient summer diets which can achieve optimal fish performance at suboptimal water oxygen levels.
This study demonstrates the potential benefit (in terms of increased biomass production) that a farmer can achieve by improving the water oxygen saturation levels in the sea cages when those drop at very low levels. The balance between the aeration costs and biomass gain is yet to be estimated in large scale.
• Reduced maturation
There is a significant problem in reaching marketable size of reared E. sea bass before the fish enters puberty and genetic maturation during the winter months. In intensive culture condition up to 20-30% of the male population could be precociously mature, following a 20-40% reduction in growth compared to non-precocious male. Age and size at puberty are modulated by genetics and environmental factors, controlled by activation of the brain-pituitary-gonad (BPG) axis, in addition to a range of internal and external factors such as growth, adiposity, feed intake, photoperiod, temperature and social factors. In the wild, the sea bass spawns during the winter months at low temperature (12-14oC) and during short and/or increasing day-lengths. Growth condition and feed availability are improved in farmed species compared with wild, hence both age and size at puberty and maturation are reduced. As slow growing populations (colder regions) experience more winter seasons than fast growing, it is particularly important to improve management control of feed composition and feed intake in these groups. Growth and puberty have previously been shown to be related to feed intake and feed formulation/composition.
Conclusions
The cost benefit analysis shows a range of benefits (additional profit) to the farmer from highly beneficial to no additional benefit.
The seabass farmer gains the highest benefits by using a camera and feed control system in the feed boat. The cost of the investment is paid back within approximately one month. This is followed by the use of oxygenation systems at farm sites which have low dissolved oxygen levels (this does not apply to the farm managed by Ozsu). There are some additional benefits from the use of specialised feed to reduce maturation during the second winter, the feeding strategy of feeding every other day during winter and the substitution of plant protein and oils. There is no significant benefit from feeding only once per day during summer.
Workpackage 6. Dissemination and outreach. Task 6.1: Establishment and maintenance of public web site
A project web site (www.efishent.eu) was set up at the start of the Project in November 2010 and has been updated regularly throughout the project. The project was operational until the end of the project. The website will be maintained by Akvaplan-niva for at least 2 years after the end of the project.
Task 6.2: Publications
A number of articles, posters, handouts and publications were prepared and published
• AquaNor project handout detailing objective and proposed research (APN)
• Fish farmer article (Viking)
• Izmir Offshore conference poster (APN)
• Izmir Offshore conference paper (APN)
• International Innovation article (APN)
• Pan European Article (APN)
• EAS 2011 conference in Rhodes, Greece entitled “Presentation of ‘eFISHent’ FP7 EU Project for the benefit of the SMEs: Improvement of feeds and feeding efficiency for seabass in cage farms in the Mediterranean & a review of the current status of Knowledge on nutrition and feeding of European Seabass (Dicentrarchus labrax)”.
The report was sent to a carefully selected and highly targeted audience of 52,000 key researchers, policy makers, government and decision makers across both the private & public sectors across all member states in the European Union and INCO countries. The report is also available online indefinitely, with each electronic publication optimized for search engines including Yahoo and Google to make sure your project article has the highest possible impact. Please see below for the full breakdown of readership.
The report is received by a wide range of policy makers including
• European Commission
• DG and Head of Unit
• International NGOs (ICES, ICCAT, EFARO, NAFO, WAS, WWF, CI, AFS etc)
• Fisheries Councils
• National Research Councils
• University and Academic Agencies
• Fisheries Legislation
• Ministry of Science, Technology and Innovation
• Ministry of Agriculture and Fisheries
• Agribusiness Agencies and Groups
• Fisheries Agencies
• Food Standards Agencies
• Agriculture and Aquaculture NGOs and International Agencies
• Policy Formulation
• Fisheries Authorities
• Universities
• Public research centers / institutes
• Public authorities
• University Libraries
• European institutions (European Commission, European Parliament, Joint Research Centre)
• EU programmes' National Contact Points (NCPs)
The report is received by a wide range of stakeholders makers including
• Aquaculture
• Commercial Fishing
• Aquaculture policy
• Marine and Costal Fisheries
• Freshwater Fisheries
• Conservation
• Hatcheries
• Breeding
• Retailers
• Suppliers
• Transport
• Consultants
The magazine is publically available through as many mediums and platforms as possible, with the publication also send as a newsletter to those who would rather receive the electronic copy rather than physical. This attracts over 10,000 unique visits a month to the www.research-europe.com website with 65% to the International Innovation newsletter reaching a global audience covering Latin and South America, Africa, Asia Pacific and the Middle East.
Pan European Network magazine Science and Technology is devoted to providing the relevant and up to date information for the use of not only the European Commission, but all government agencies and departments across the continent of Europe. www/paneuropeannetworks.com.
Manuscripts in preparation for publishing in peer reviewed magazines:
• Katerina Kousoulaki & Sissel Albrektsen, 2013. Review of the nutritional requirements and growth potential of European sea bass (suggested review accepted by Aquaculture Nutrition), Manuscript.
• André Bogevik, Jolanda Arjona, Jim Treasurer, Tim Atack, Raja Rathore, Ivar Rønnestad & Katerina Kousoulaki, 2013. Modulation of precocious genetic maturation in male E. sea bass by marine or plant dietary oils, Manuscript.
• Jolanda Arjona, Jim Treasurer, Tim Atack, Tal Prag, Eran Hadas & Katerina Kousoulaki, 2013. Interaction of dietary protein, lipids and dissolved oxygen levels in E. sea bass on-growing performance, Manuscript.
• Katerina Kousoulaki, Jolanda Arjona, Tim Atack, Jim Treasurer, 2013. Modeling of cost efficiency of small gradual dietary DP/DE changes in E. sea bass on-growing performance, Manuscript.
• Jolanda Arjona, Tim Atack, Jim Treasurer, Katerina Kousoulaki, 2013. Winter feeding of E. sea bass with low fish meal diets supplemented with marine hydrolysate attractants, Manuscript.
Task 6.3: Participation in Conferences, Workshops and Events
• Akvaplan-niva participated at AquaNor 2011 exhibition, Trondheim, Norway and distributed a fact sheet about the project to visitors to the stand. Partners FNCm NM, Ozsu and NESNE also attended the conference
• Participation in the AQUA NOR FORUM organised by the European Aquaculture Society (EAS) at the AQUANOR Exhibition and conference held August 17-18, 2011 in Trondheim Spektrum, Norway
• Participation EAS 2011, Rhodes, Greece by Partners HCMR, NM, VA, Ozsu and NESNE. Presented paper entitled “Presentation of ‘eFISHent’
• Participated in the Offshore conference June 2012 – Izmir (see below).
• Will participate at AquaNor 2013 exhibition, Trondheim, Norway and will distribute a fact sheet with a summary of final project results.
Task 6.4: Regional conferences/seminar
The Coordinator participated in the Offshore Mariculture 2012 conference held in Izmir between 17 and 19 October 2012.Offshore 2012 was an international two-day conference, with technical visit day, on the offshore fish farming business. It was aimed at growing offshore fish farming businesses the conference explored the progress and prospects for offshore aquaculture in European and international waters.
The coordinator presented information about the project in the form of a presentation, poster and handout.
Attendees at the Conference included both experienced and aspiring investors and entrepreneurs; fish farm owners, managers and operators; makers and distributors of net pens and mesh materials; feedstuff suppliers and feed manufacturers; and researchers into new species, new farm technologies, genetics, and fish health. Over 25 nationalities were represented at the Conference, including attendees from Chile, Canada, Saudi Arabia, Oman, Germany, Spain, Portugal, Italy, Norway, UK, USA, Australia, Israel and the Lebanon
Work package 7 title: Operational validation of feeding technologies and feed formulations
Task 7.1. Testing of different feed monitoring technologies in relation to production performance and fish welfare.
Two feeding regimes were set-up for the duration of the study. Three cages (hereafter termed the camera regime) were canon fed once a day to satiation at 1500 h in combination with underwater cameras that monitored pellet wastage. Three further cages (hereafter termed the no-camera regime) were canon fed once a day to perceived satiation at 1500 h each day based upon feed tables and surface indicators of satiation for the duration of the study. The feed silos, canon feed delivery system and camera monitoring system were mounted on a boat that fed each cage sequentially.
Fish were fed a commercial diet in relation to fish size (4mm extruded pellet, Hendrix-Skretting Power Excel) until the end of the experiment. The same growth and production performance parameters were used in deliverable 7.22 as those used in deliverable 4.14. Differences in levels of fin erosion, fin splitting or fin haemorhagging between treatments were tested for using a G- test. A significance level of P < 0.05 was used for all statistical analysis.
There was no significant difference between initial fish weight (P = 0.834) condition factor (P = 0.202) or size heterogeneity between regimes (P = 0.078) at the start of the study.
There were also no significant differences between regimes in terms of final fish weight (P = 0.978) condition factor ( P = 0.892) or size heterogeneity between regimes (P = 0.244) at the end of the study as well. This was also the case for mortality (P = 0.691) SGR (P = 0.882) and FCR (P = 0.806) for the duration of the study. However, although non-significant, there was ca. 10.7% reduction in FCR by feeding the fish using a camera based feeding regime at the worst time of year in terms of FCR performance (FCRs were on average 2.6 vs 2.9 for the camera vs no-camera regime respectively). In terms of other productivity indicators, there were no discernable biological productivity risks or benefits of using camera’s to control feed delivery to the fish. In terms of variability in daily feed amounts, there was no significant difference between the regimes and very little in terms of absolute amounts of feed delivered for the duration of the study (see Fig. 7.5 P = 0.967).
There was also no significant difference in the amount of time spent feeding the fish in relation to feeding regime (P = 0.783) suggesting that the factors within each meal (e.g. changes in feed rate in relation to pellet wastage) were more important than absolute times spent feeding for (non-significantly) improving FCR.
In terms of fin injuries, there was no significant difference between regimes with regard to fin erosion, fin splitting or fin haemorrhaging at the end of the study (see Figs. 7.7-7.9 P > 0.05 for all tests). This shows that feeding using a camera based feeding strategy offers little in terms of welfare benefits at this time of year, and also shows that the current feeding regimes do not pose a significant risk for increasing the prevalence of fin injuries. There was no clear pattern in which fins were affected by fin erosion, but the caudal and anal fins were most affected by fin splitting and haemorrhaging, respectively.
In summary, using a camera to feed fish to satiation in late winter and spring does not improve growth performance or size heterogeneity. It also does not improve welfare, by either significantly reducing the frequency of fin injuries, reducing mortality or improving fish condition. It does however improve FCR and feeding efficiency by ca. 11% in comparison to feeding the fish without a camera, and although this result was non-significant, it can have a marked effect upon the economic performance of the farm (as summarized in deliverable 5.18).
Task 7.2 Testing species and seasonally specific feed formulations
Two feeding regimes were set-up for the duration of the study. Three cages (hereafter termed the camera + optimized diet regime) were canon fed the eFISHent summer diet (6mm pellets, produced in the BioMar Hellenique AS factory in Volos, Greece based on the eFISHent Nofima AS formulation: Table 7.10) once a day to satiation in combination with underwater cameras that monitored pellet wastage. Three further cages (hereafter termed the control regime) were canon fed once a day to perceived satiation based upon feed tables and surface indicators of satiation and using the farms existing feed diet (6mm extruded pellet, OptiBass, Skretting Ltd). The eFISHent diet constituents were 40% crude protein, 23% crude fat, 6.1% ash, 10% starch, 1.9% fibers and 10% water.
The same growth and production performance parameters were used in 7.2 as in Task 7.1. There was no significant difference between initial fish weight (P = 0.913) condition factor (P = 0.551) or size heterogeneity between regimes (P = 0.338) at the start of the study.
There were also no significant differences between regimes in terms of final fish weight (P = 0.170) condition factor (P = 0.184) or size heterogeneity between regimes (P = 0.883) at the end of the study as well. This was also the case for mortality (P = 0.752) SGR (P = 0.058) and FCR (P = 0.064) for the duration of the study. However, due to low replication, the statistical power for all tests was < 55%, which may have accounted for the non-significant trend for higher SGR and lower FCR in fish fed to the camera + optimized diet regime. There was ca. 12% increase in SGR and ca. 19% decrease in FCR by feeding the fish using a camera + optimized diet regime during the summer and early autumn (FCRs were on average 1.65 vs 2.04 for the camera + optimized diet vs control regime respectively).
In terms of variability in daily feed amounts, there was no significant difference between the regimes, although fish fed using cameras + optimized diet were fed on average ca 200kg less fed per cage than their corresponding controls for the duration of the study (P = 0.333).
In terms of fin injuries, there was no significant difference between regimes with regard to fin erosion, fin splitting or fin haemorrhaging at the end of the study, with the exception of fin splitting to the caudal fin (which was significantly greater in fish under the control regime, P = 0.034 see Figs. 7.13-7.15 P > 0.05 for all other tests). This shows that the camera + optimized diet regime can reduce the prevalence of caudal fin splitting, but no other forms of fin damage in the current study. The anterior dorsal fins were most affected by fin erosion, irrespective of feeding regime, and the caudal fin was most affected by both fin splitting and haemorrhaging.
In summary, using a camera + optimized diet to feed fish to satiation in summer and early autumn has a non-significant trend for improving SGR and FCR in cage held sea bass. In terms of welfare, it does not have an effect on fin erosion or fin haemorrhaging, but does significantly reduce the prevalence of caudal fin splitting. It also does not affect either condition factor or mortality. FCR was improved by ca. 19% and SGR was improved by ca. 12% in comparison to feeding using existing diets and feed practices, and although this result was non-significant (due to low statistical power), it does have a marked effect upon the economic performance of the farm, (see D5.18).
Task 7.3. Testing of a combined feeding and oxygenation system
As part of this deliverable the eFISHent partners Nofima AS, Element AS, Özsu Balik Ltd, NESNE Electronics and Akvaplan-niva investigated i) the feasibility of raising oxygen levels within commercial sea cages using oxygen delivery systems during the summer, and ii) the cost effectiveness of raising oxygen levels within a cage.
Two different oxygen sensors were used to monitor oxygen levels within the cage. A YSI hand-held oxygen meter (YSI 550A dissolved oxygen meter, YSI Inc., Yellow Springs, USA) was used to record changes in oxygen at a depth of 1m within the centre of the cage. An additional RBR oxygen data logger (RBR Dissolved Oxygen Logger DO-1060, RBR Europe Ltd, Stadhampton, UK) was also deployed at 3m depth within the centre of the cage.
Here is the raw data from each day on how the oxygen delivery system affected oxygen levels at both 1 and 3m depth for each given day.
These data show there was high variability in oxygen raising efficacy between days and between depths. For example, there was a peak in oxygen levels at 3m during the latter stages of oxygen delivery on the 17th July, but this peak was not apparent at 1m depth. And on the 18th and 19th July, there was little in the way of elevated oxygen during oxygenation at 3m depth (no data was recorded at 1m depth due to problems with the data logger). This can be seen clearer when the data is manipulated to include the mean oxygen levels i) before oxygenation ii) during oxygenation and iii) after oxygenation for each day.
The results show how variable the efficacy of attempting to raise oxygenation in sea cages facilities can be when using an array of standard ceramic stones and an oxygen bottle. On the first day of the study, oxygenation lifted ambient oxygen levels from ca. 6.75 mg/l to ca. 7.5 mg/l (although highly variable during oxygenation), and levels were then relatively constant at 7 mg/l for the 30 minutes following oxygenation at 3m. However, on the second and third study day there was little, if any effect of oxygen delivery upon ambient levels, even though the bottle was delivering oxygen at a rate of ca. 50 L/min. There was no data recorded at 1m depth due to technical problems with the data logger. Cost benefit analysis for the use of oxygen is given in WP 5.
In terms of the efficacy of raising ambient oxygen levels during the summer months using an oxygen bottle attached to standards ceramic air stone array: results were highly variable between days. For example, on the first day of the study, oxygenation managed to raise ambient oxygen levels by ca. 0.75 mg/l to 7.5mg/l during oxygen delivery. These levels also remained at ca. 7.0 mg/l during the 30 minutes following oxygenation, suggesting there may be some potential to using this low cost set-up as an emergency aeration system when oxygen levels are low. However, on the two subsequent days of the trial, oxygenation had very little effect upon ambient oxygen levels at 3m. This high variability may have been due to changes in water state and current between days (Tor H. Evensen, pers. obs., although we do not have any quantified data on water currents to support this).
In terms of cost-effectiveness of using this array: many sea bass farmers already have all this equipment for use during e.g. fish sampling or disease treatment, so the farmer would incur little in the way of extra costs in equipment. In summary, these results suggest that ambient oxygen levels can be increased on a marine cage commercial sea bass farm using a low costs system consisting of an oxygen bottle linked to an array of standard ceramic air stones. However, results were highly variable and the system did not elevate ambient oxygen levels during all the trials. The cost effectiveness of such as system is questionable (as its efficacy, see Deliverable 5.18) and the eFISHent partners would recommend that farmers investigate the potential of other oxygen delivery systems or micro-nano bubble diffusers for attempting to increase ambient oxygen levels under commercial farming conditions.
Potential Impact:
Benefits
Efficient use of natural resources:
By reducing the FCR of sea bass farms the project will reduce the industry’s overall demand for fish feed, thereby reducing the quantities of natural resources that have to be exploited to meet that demand. One of the major ingredients in feed for carnivorous fish, such as sea bass, is fish meal. The level of fishmeal used in commercial marine finfish diets varies, but taking an average of 40 %, and an average FCR in the bas production industry of 2:1, then 0.8 kgs of fishmeal are used to produce 1 kg of bass. According to the Federation of European Aquaculture Producers the present (2008) production of sea bass in the Mediterranean is 102,765 tonnes per annum, which means that some 82,000 tonnes of fishmeal are used by the industry. Therefore reducing FCR by, say, 20% (from 2:1 to 1.6:1) would save 16,400 tonnes of fishmeal. With today’s (December 2009) price of fishmeal being around €1000 per tonne, the saving in fishmeal cost alone would be €16.4 million
Reduction of pollution to the environment:
Optimal feeding practices promoted by the eFISHent results will contribute to the reduction of pollution to the environment:
• Through the use of immune-stimulating substances the amount of pharmaceuticals used in sea bass farming that have a toxic effect on the environment can be reduced considerably.
• Reduction of nitrogen and phosphorous load on the wider environment by the reduction in production FCR.
Whether a nutrient becomes a pollutant in an aquatic system, is a function of whether it is a limiting nutrient in a given environment and the magnitude of its concentration. In the Mediterranean phosphorus is the limiting nutrient so its addition will dictate the amount of primary production. In the Atlantic, nitrogen is the limiting nutrient (Howarth and Marino, 2005), so its addition will do likewise. Increased primary production (particularly algae) that occur in high nutrient waters will reduce water clarity (and consequently sunlight availably in the water column to other organisms), and can strip oxygen from the water column when the organisms die, sink and decompose. These effects are conditions of eutrophicaton. Since nitrogen and phosphorus are released from fish cages, there is always the potential for fish culture to promote eutrophic conditions; either by supplying a readily available nutrient source directly to phytoplankton; or oxygen removal, accompanied by nutrient releases, via the decomposition of waste solids.
Reduction of feed loss and improvements in nutrient conversion efficiency will reduce (improve) economic FCR. Mortalities and escapes may reduce the production of harvestable biomass; causing an increase (worsen) in FCR. FCR is also affected by fish size, water temperature and fish health. Assuming similar fish sizes are produced from year to year; improvements in global economic FCR of Seabass production, will contribute to an overall increase in industry efficiency converting nutrients from fish feed to harvestable biomass. Regardless of whether lost nutrients are partitioned as faeces, waste feed; or sequestered in escaped or deceased fish.
Organic material (fecal water and uneaten feed) that is deposited on the seabed is decomposed by bacteria that use oxygen. With high organic nutrient loading, the oxygen level in the surrounding waters and sediment falls affecting local biodiversity. If the assimilative capacity of the seabed is overburdened, when the oxygen has been used up and because toxic hydrogen sulphide is formed in the bottom sediments and the sediments are unable to support any animal life. Any adverse impacts due to eutrophication and sediment impact at a farm location are reversible. Locations to which large quantities of organic material were previously added and had highly anaerobic sediments but these can recover towards the natural state after the nutrient loading is reduced.
Global impacts
Any improvements in feed efficiency will not only have local environmental benefits, but also global effects through a reduction in the use of raw materials and energy for fish feed production, reduced feed transportation costs, reduced carbon footprint etc.
In terms of the preservation of natural resources, it takes roughly 4.7 kg of so called “trash” fish, to make 1 kg of fishmeal, so the above example of a 20% reduction in FCR would reduce the demand for whole trash fish by 77,000 tonnes per annum, thereby taking pressure of stocks and helping to preserve the sustainability of the international fishmeal industry.
Economic impacts
The economic benefits of the project results due to improved feed and reduced FCR are as follows :-
• a reduction in direct feeding cost
• a reduction in feed transportation cost
• a reduction if feed storage and on-site handling cost
• reduced on-cage feed storage capacity
The economic benefits of the project results due to improved feeding strategy as as follows;
• A reduction in labour costs for feeding
• A reduction in boat operational costs (diesel, maintenance and depreciation)
Productivity impacts
The productivity benefits of the project results due to faster fish growth are as follows :-
• a reduction in fish production cycle time, thereby decreasing production cost per kilo
• an increase in productivity per unit cage volume
• the option to grow fish to a larger premium price size in the same time
• ability to sell fish early at premium prices when other producers do not have stock at the market size.
Productivity benefits
For the scope of the eFISHent fish feeding trials optimised diets were formulated for European sea bass of body weight from 5 g to 300g reared in experimental tanks or sea cages, at temperatures from under 10oC and up to 25oC, and oxygen levels of 3.5 ppm to 6.5ppm. Both relevant eFISHent partner SMEs, one fish farmer and one feed producer, have had early access to the best performing and sustainable feed formulations used in the eFISHent trials with documented good fish growth results and remarkably low FCR.
• Improved food Conversion Rate
The obtained FCR values were ranged from 0.84 to 1.9. The highest FCR values were obtained in some winter trials, which were nevertheless always below 2.0. Optimum combined growth and FCR (1.18) results were achieved feeding E. sea bass juveniles with a diet containing 50.5% protein and 16.6% lipid (D2.7) and larger fish with a diet containing 45% protein and 16% lipids (D2.6).
The D2.6 results were confirmed in D3.8 obtaining FCR as low as 1.16 using a 47% protein and 16% lipid diet at high water oxygen levels. However, at low oxygen saturation levels optimal results were obtained using a lower protein (44%) and higher lipid diet (22%). These results provide documentation that allow the farmer and feed producer to cooperate and opt for either using 1) oxygenation in the cages, and obtain optimal production results, or 2) more cost efficient dietary formulations for periods of lower water oxygen levels.
In terms of feed formulation, equally good performances of reared E. sea bass were achieved, both in low and high water temperatures, with diets containing from as low as 10% (D3.10) and up to 35% fish meal in the diet and 0% (D3.9) to 100% fish oil (as % of added oil in the diet; 0% fish oil diet contained some salmon by product oil in addition to plant oils to cover the LC n-3 HUFA requirement of E. sea bass). All experimental diets were optimised and balanced in terms of indispensable amino acids, available phosphorus, LC n-3 HUFA and choline. The plant raw materials used were of documented nutritional value for this fish species (D2.3) and their inclusion level in the diet was chosen taking into account their content in anti-nutritional factors and potential negative interactions.
• Reduced feed cost
Modelling of cost efficiency of small gradual DP/DE changes
The balance between dietary protein and digestible energy is both important for optimal fish growth and nutrient utilisation efficiency (Company et al., 1999) and has practical consequences in feed formulation and cost. The effects on fish growth and FCR as a consequence of major changes in the macronutrient composition of the diets, in the dietary raw materials used, in the water and oxygen levels, and in the applied feeding regimes, are addressed in separate sections of the project. When the main feed specification values for optimal fish performance are determined, still the feed producers face the continuous challenge of formulating the desired feeds in the most cost efficient way according to the day-to-day availability and price of the different raw materials. Moreover, the raw material quality varies from batch to batch leading to small variations in feed quality throughout the year. The effects of small changes in feed composition or formulation around the optimal specifications are not known. This fact creates an almost impossible situation during the price negotiation of the feeds between feed and fish producers.
• Improved feeding strategy
These robust, operational results can then be used by Özsu Balik to compare the performance of their existing current best feeding practices against feeding technologies that incorporate underwater cameras for monitoring changes in fish appetite and satiation during feeding. It will help Özsu Balik and the other eFISHent partners assess the costs and benefits of utilizing emerging feeding technologies in relation to the key performance indicators, growth and FCR.
Summer feeding frequency
Feeding frequency is one important consideration as it can affect feed intake, growth, survival and fish quality as well as environmental impact. Feeding at the optimum frequency can result in savings in feed cost.
The objectives of the feeding frequency study was to evaluate the effects of different feeding frequencies upon the feeding efficiency, growth performance, mortality and welfare of cage-held sea bass in relation to a number of additional economic indicators such as labour and feed monitoring costs.
Use of camera monitoring systems
An underwater camera system was purchased and tested on the test and commercial cages. The camera delivers a high picture quality and has high light sensitivity. This means it can be used in cages without extra light. The camera has been designed for permanent installation. The camera remains in the cage and connected to the feeding boat by cable at the time of feeding the fish in the cage. The camera cables are plugged into an external socket on the boat's wheel house, and are controlled internally with a control console (KB-6000) and monitor. The camera hangs from cables on the cage.
Winter Feeding regimes-fasting/reduced rations
Feed quality and feeding management in commercial farms is a big challenge, but they are also the foundation for achieving improved feeding efficiency and growth throughout the season. The winter season is particularly challenging due to the low temperature, and overfeeding as a result of low feed intake are an common no beneficial cost during the winter season.
• Cage oxygenation system equipment setup and protocol
Fish with low oxygen levels are less capable of metabolizing higher protein levels in their feed, and thus perform less compared to fish that are fed less protein rich diets. The present results on E. sea bass confirm the previously published findings of Fu et al. (2005) and can help the fish farmers and feed producers to formulate efficient summer diets which can achieve optimal fish performance at suboptimal water oxygen levels.
This study demonstrates the potential benefit (in terms of increased biomass production) that a farmer can achieve by improving the water oxygen saturation levels in the sea cages when those drop at very low levels. The balance between the aeration costs and biomass gain is yet to be estimated in large scale.
• Reduced maturation
There is a significant problem in reaching marketable size of reared E. sea bass before the fish enters puberty and genetic maturation during the winter months. In intensive culture condition up to 20-30% of the male population could be precociously mature, following a 20-40% reduction in growth compared to non-precocious male. Age and size at puberty are modulated by genetics and environmental factors, controlled by activation of the brain-pituitary-gonad (BPG) axis, in addition to a range of internal and external factors such as growth, adiposity, feed intake, photoperiod, temperature and social factors. In the wild, the sea bass spawns during the winter months at low temperature (12-14oC) and during short and/or increasing day-lengths. Growth condition and feed availability are improved in farmed species compared with wild, hence both age and size at puberty and maturation are reduced. As slow growing populations (colder regions) experience more winter seasons than fast growing, it is particularly important to improve management control of feed composition and feed intake in these groups. Growth and puberty have previously been shown to be related to feed intake and feed formulation/composition.
Fish welfare and fish quality benefits
The improved fish welfare and fish quality benefits of the project results are as follows :-
• potentially greater consumer demand for the product reducing sales and marketing costs
• reduced risk of losses due to disease/aggression etc
• an improvement in product quality and thus better prices
List of Websites:
www.efishent.eu
Scientific representative of the project's coordinator
Name: Patrick White
Title: Senior Aquaculture Consultant
Organisation: Akvaplan-niva, Tromso, Norway
Tel: 0033 475768014
E-mail: Patrick.white@akvaplan.niva.no
