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Improved production strategies for endangered freshwater species.

Periodic Reporting for period 2 - IMPRESS (Improved production strategies for endangered freshwater species.)

Reporting period: 2017-01-01 to 2018-12-31

The IMPRESS European Training Network has provided a new generation of researchers with the multidisciplinary skills and competences needed to oversee new stocking strategies for Europe’s most important and threatened freshwater fish species (Atlantic salmon, European eel and sturgeons) thus enabling conservation and growth in a sector of significant economic and societal importance. Freshwater fish populations bring many benefits to Europe´s citizens through leisure activities, and enhance rural employment through fishing and tourism.

The main scientific objective of IMPRESS has been to improve the methods for rearing of fish that are intended for stocking into the wild. This has required training for all ESRs in basic fish biology, improved knowledge on the rearing techniques themselves (how to improve the Fitness of Fish intended for life in the wild), and lastly how to improve your understanding of implementation of new insight into practice. For this last point, Our ESRs have undergone intensive training in the social dimensions of healthy river systems, including how this is regarded among the general public and more specifically among key stakeholders such as hatchery workers. The different ESRs within IMPRESS has focussed on one of these three main issues.

The species included in IMPRESS are sentinel species of clean, healthy freshwater ecosystems and of major historical, cultural and economic importance. Over-exploitation and anthropogenic activities have critically endangered wild populations of these fish groups, especially sturgeons. As the main flaw of past stock enhancement is high post-release mortality, the researcher training in IMPRESS has built upon recent scientific advances, especially in fish genomics and enriched hatchery techniques, to develop innovative production regimes resulting in increased survival rates of released fish.

Although making significant progress in both the biology, rearing and the social aspects of all three species in IMPRESS, it is clear that a paradigm shift in stock enhancement strategies is challenging within the time frame of this Project and will require changes at every level of the production cycle, from broodstock management and gamete quality to hatchery design.
Dissemination has been an integral part of IMPRESS with all students participating in different activities, such as Researchers Night, Fish Migration Day, Researcher Grand Prix, Research Fair, visits to local schools and more. The ESRs have produced a common popular science article at the start of the project. Further examples include a children's book in Spanish and English on the life cycle of the eel, construction of a 230 m long Atlantic salmon broadcasted on le Tour de France 2017, and numerous press coverages in local newspapers, radio, and TV.
In terms of research, IMPRESS has provided novel information on the neuroendocrine regulation of reproduction and smoltification in salmon, eel, and sturgeon. Also, big leaps have been taken in gamete quality assessment, storage, and management, especially in eel and sturgeon. To improve production strategies intended for stocking, this project provides results showing the importance of enriched rearing environment for improved fitness in salmon and sturgeon, both in terms of feeding and predator escape. As support for the sturgeon part of the project, we have assembled a draft genome of European sturgeon, and a number of tissue specific transcriptomes that greatly facilitates future molecular studies in their physiology. Regarding socio-economic dimensions we have gathered a lot of data on the general public and their view on various aspects of wild fish populations and river systems, performing comparative studies in several European countries. Furthermore, we show that the mode of communication between scientists, (local) politicians, and important stakeholders such as hatchery workers is key to transfer scientific knowledge into practice.
- Neurokinin B and F that have been shown to stimulate the release and synthesis of Fsh and Lh was herein found to inhibit their synthesis in the eel.
- Gnrh receptor 2b1 in salmon is expressed specifically in Lh-producing cells.
- Unlike in any other known vertebrate - activation of salmon melatonin receptors was shown to increase cAMP intracellular levels.
- IMPRESS has improved Our understanding of the interaction between environmental stimuli and behavioural capacity but more research is needed.
- The endogenous regulation of downstream migration in Atlantic salmon emphasizes the importance of using local strains of fish for restocking purposes.
- The draft genome from the European sturgeon has been assembled, and accompanied by numerous tissue specific transcriptomes.
- IMPRESS has contributed with novel insights showing that the general public in Europe report lack of knowledge about conservation of aquatic biodiversity.
- The resilience against adapting existing rearing technology and posing additional labour-constraints highlights the necessity for close collaboration between scientists and practitioners.
IMPRESS consortium during training school 2 in Valencia
Tour de France - 280 m long salmon made during TS4
IMPRESS ESRs working with salmon
Training school 1 in Leiden, the Netherlands
Training school 2 in Valencia, Spain
IMPRESS ESRs working with eel
IMPRESS ESRs working with sturgeon
IMPRESS group in Chantegues, France, during training school 4
Field work ESR Hannah Harrison and research associate