Skip to main content

Biological optimisation and development of processing methods for turbot farming (TURPRO)

Final Report Summary - TURPRO (Biological optimisation and development of processing methods for turbot farming)

The project TURPRO has, through a series of small- and large-scale experiments, provided the turbot aquaculture industry with a strategy that will significantly improve growth, reduce maturation and elucidate the impact of critical water quality parameters. It is foreseen that this will reduce production cost per kg market sized fish. In addition the current project has investigated new processing methods especially designed for turbot, where the aim was to improve fish yield and flesh quality.

A sustainable production of turbot was dependent on a year-round supply of juveniles reared in intensive land-based systems at high densities. To effectively exploit such systems it is necessary to obtain detailed knowledge on the impact of key rearing factors (temperature, photoperiod and water quality) on growth performance, food conversion efficiency, age at first maturity and fish welfare.

The objectives of the current project have been achieved through a series of small- and large-scale experiments, and the project has provided a scientific rationale for the establishment of effective husbandry strategies to optimise production, minimise maturation and accelerate growth of turbot in high-density land-based rearing systems. The research programme was structured according to four main work packages (WPs), each consisting of a number of tasks. In order to have maximal support of the activities of the small and medium-sized enterprises (SMEs), all SMEs are tightly linked to research and technological development (RTD) working on the same tasks.

WP 1 consisted of studies on optimisation of production characteristics in turbot farming. The work plan included studies on the effect of rearing at 'temperature-steps' on growth performance and feed conversion efficiency (WP1 - Task 1.1) and studies on the effect from rearing fish under extended photoperiods on age of first maturity and inhabitation of precocious maturation (WP1 - Task 1.2).

These studies combined novel experimental approach and physiological techniques and methods applicable for turbot and other demersal aquaculture species. Our aim was to minimise production time of turbot and to find an appropriate temperature and photoperiod regime that will allow the farmer to improve and increase production, and thus exploit far better the resources in question (seawater, space/land, man power, logistics). This aim has been reached within the project period.

WP 2 was divided into three tasks, which were performed in both laboratory and large scale facilities at the SME farms. The work plan included studies on the effects of chronic exposure and periodical peaks of un-ionised ammonia on growth, food conversion efficiency and stress under intensive culture conditions (WP2 - Task 2.1) studies on interactive effects of unionised ammonia and hyperoxia on growth performance in turbot (WP2 - Task 2.2) and an overall evaluation of flow-through vs. recirculation technology in culture of turbot (WP2 - Task 2.3).

In this task species-specific optimal temperatures and light regimes were applied. The findings from these studies have resulted in methods for reducing negative impact of sub-optimal water quality in turbot, thus allowing for increased production with the use of less water.

WP 3 aimed at monitoring flesh quality and flesh yield in turbot culture. Special attention was given to establishing standard methods to verify the effect of new rearing concepts developed in WP 1 and 2 on the end product. Within WP 3 we have identified what is known or expected product quality related issues for farmed turbot by interviewing farmers, customers and retailers and produced a clear sensory profile of farmed turbot which is very useful for further market research.

Several new protocols for slaughter and processing turbot were addressed, and several quality parameters linked to bleeding, gutting, and processing were tested. Overall, farmed turbot as food is a stable product, where the quality is not so much affected by external factors during harvesting and processing.

WP 4 focused on coordination of the overall development of the project. The WP was devoted to:
a) assess the accomplishment of tasks allocated to each participant;
b) discuss the results obtained during different phases of the project;
c) discuss means of recovering the time lost due to technical or other difficulties in order to keep the targeted goals on time;
d) review the milestones for the each phase in order to make any adjustments;
e) submit internal reports that will make the bases of the period reports to be submitted year to the European Commission.

The new rearing regime developed in this project was applicable for all production systems and will make production time reductions feasible in the farms of the participating SMEs. Preliminary investigations have indicated that the temperature-step principle combined with inhabitation of precocious maturation will yield a 20 % to 30 % higher production. Similar figures were seen in the trials of the project. If a 25 % growth increase is gained, a 1 000 t/year producer could increase his output to about 1 250 t/year with the same production facility, or an additional turnover of about EUR 2.8 million per year.

Thus the SMEs' competitiveness was clearly improved by the project if the anticipated growth increase of 20 % to 30 % can be achieved. Reducing the on-growing period will reduce the need for investments for a given production target or increase the production target with a given production facility. Further the feed conversion factor is expected to be reduced by about 10 % to 15 %, which is a very important improvement, as feed costs constitute approximately 15 % to 25 % of the total production costs in turbot production.

Related documents