Double Doctorate Degree presented by Laure Pecquerie 23 rd January 200 8

1. Bioenergetic modelling of growth, development and reproduction of a small pelagic fish:the Bay of Biscay anchovy Double Doctorate Degree presented by Laure Pecquerie 23rdJanuary 2008 • General and scientific contexts • Objectives • Main results • Conclusion and perspectives

2. Maximum of 85 000 t in 1966 but highly variable • Population at a critical level since the recent years Catches (in tons) The Bay of Biscay anchovy • Spanish and french fisheries • 6th fish species in value in 2003 in France  Closure of the fishery since 2005 CONTEXT OBJECTIVES MAIN RESULTS CONCLUSION

3. Statistical study in the Bay of Biscay (Allain et al. 2003) Temperature, currents, … ENVIRONMENT = Growth, development and survival Fluctuations of 1 year-old anchovy Scientific context • Can we predict the fluctuations of the population (1 year-old fish in particular = 70 % of the catches)? • Small pelagic fish are highly dependent on environmental conditions (fast growth, high reproduction rate, short life span) • Larval stage = most critical periodWhich environmental conditions allow survival ? CONTEXT OBJECTIVES MAIN RESULTS CONCLUSION

4. What is the impact of environment (food and temperature) on the life cycle of an individual (growth, reproduction and survival) ? Reserves for reproduction Growth Dynamic Energy Budget (DEB) theory(Kooijman 2000) Objectives of the study Deterministic approach ENVIRONMENT > 20 spawnings Growth, development and survival CONTEXT OBJECTIVES MAIN RESULTS CONCLUSION

5. Fish metabolism (growth + maintenance) • Number of rings  age • Radius  fish growth Environment Objectives of the study • What is the impact of environment (food and temperature) on the life cycle of an individual (growth, reproduction and survival) ? • What is the impact of environment (food and temperature) on the life cycle of an individual (growth, reproduction and survival)? • What is the influence of fish metabolism and environmental conditions on otolith formation (growth and opacity)? We cannot rear anchovies  But information from otolith collected during IFREMER surveys in spring (2000-2005) •  We built an individual model: • that simulates fish growth, development and reproduction, • and otolith growth and opacity, • according to realistic temperature and food conditions for the Bay of Biscay, • in the context of the DEB theory CONTEXT OBJECTIVES MAIN RESULTS CONCLUSION

6. Fast juvenile growth Length (cm) Hyp.: higher temperature in surface in summer and autumn Development Hyp.: lower food conditions in winter Shorter spawning season in spring puberty Reproduction metamorphosis Higher temperature in surface in late spawning season • Hyp.: Higher larval mortality first feeding Environmental effect on anchovy life cycle  We can reproduce main features of anchovy life cycle  We can formulate environmental scenarios and evaluate their impact on growth, reproduction and survival CONTEXT OBJECTIVES MAIN RESULTS CONCLUSION

7. Otolith growth and opacity Data Length DEB model Simulation Otolith modelling : individual history Environment CONTEXT OBJECTIVES MAIN RESULTS CONCLUSION

8. Length DEB model Otolith modelling : individual history Otolith growth and opacity  We can reproduce main observations on otolith growth and opacity with simple mechanisms Environment CONTEXT OBJECTIVES MAIN RESULTS CONCLUSION

9. DEB model Reconstruction of length + Assimilated food Food history reconstruction from otolith We can theoretically reconstruct both growth and assimilated food from temperature and otolith data • extraction of new information from data difficult to obtain • new information = food in natural conditions, at the individual scale CONTEXT OBJECTIVES MAIN RESULTS CONCLUSION

10. Conclusion and perspectives Perspectives • Anchovy : data collection requires time and money for surveys at sea ; these results can guide data collection • Generic model other fish species (sardine, hake, …) • Otolith model: numerous applications • bivalve shell, paleontology • coupled to isotopes data to reconstruct temperature, water, and food conditions • Conclusions • First application of DEB theory to a small pelagic species • Extension of the theory to the larval stage and to the otolith • Tool to test assumptions and to reconstruct individual life history CONTEXT OBJECTIVES MAIN RESULTS CONCLUSION

11. Acknowledgements Bas Kooijman, Pierre Petitgas, Cédric Bacher, Didier Gascuel, Alain Ménésguen, Martin Huret, Patrick Grellier, Marianne Alunno-Bruscia, Véronique Loizeau, Stéphane Pouvreau, Jacques Massé, Jéremy Lobry, Ronan Fablet, Muriel Mambrini, Jean-Christophe Poggiale, Henk van der Veer, Tiago Domingos, Alain Franc, Olivier Maury, Jaap van der Meer The department EMH (Ifremer Nantes), the department DYNECO (Ifremer Brest) Agrocampus Rennes and the Theoretical Biology department (Vrije Universiteit Amsterdam) The crews of the R/V Thalassa The Local Comities of La Turballe and Saint-Gilles-Croix-De-Vie, Hilaire Drouineau, Youen Vermard, Sigrid Lehuta,Yves Reecht, Xavier Bodiguel, Jonathan Flye Sainte Marie,Nathalie Bodin, François Coutard, Jan and Anke Baas, Truus Meijer My family, my friends, Sylvain and the lambdas !