Integrated modelling of depredation in marine ecosystems (ORCAPRED)


PhD Thesis Lyndsay Clavareau (2018-2021)


What are the conditions required for cohabitation between fishers and marine mammals in ecosystems where they compete for limited resources?


While living resources harvesting negatively impacts targeted populations, its indirect effects the whole of ecosystems can be complex. In particular, human activities can create new feeding opportunities for wild species both on land and at sea. In the marine environment, certain predator species have developed their ability to feed on fisheries catches. This new behaviour, called depredation, is currently triggering serious conflicts between marine predators and fisheries in several regions of the world. Yet, how depredation impact socio-ecosystems stability and fisheries sustainability remains largely unknown. In particular, depredation is little or poorly taken into account in marine ecosystem and/or fish stock assessment models.



Using different modelling approaches, this research project aims at better understanding and predicting how depredation can affect the structure and dynamics of marine socio-ecosystems. Building upon an extensive literature review about marine depredation around the world, a first aspect of this project consists in developing qualitative models. This first approach both conceptualises and explores how depredation can overall impact the structure and dynamics of socio-ecosystems. Using a quantitative approach based on the Ecopath framework, this research also investigates these questions in a specific case study in the Southern Ocean (the Crozet and Kerguelen archipelagos, where yields of the longliners targeting toothfish are negatively impacted by depredation associated with killer whales and sperm whales).



Martin Marzloff (Ifremer/LEBCO), Paul Tixier (Deakin University), Verena Trenkel (Ifremer/EMH)



Lyndsay Clavareau, Jeffrey M. Dambacher, Verena M. Trenkel, Sophie Gourguet, Paul Tixier, Martin P. Marzloff (2023). Exploitation and depredation rates determine viability of depredation-impacted fisheries. Ecological Modelling, 483,110444.

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