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Master Thesis

Development and comparison of tools to support the assessment of glass eels catch opportunities

Abstract : Following the decline in glass eel recruitment since the 70s and the implementation of the Eel Regulation in 2007, France implemented a Management Plan in 2008 aiming to reduce glass eel fishing mortality by 60%. Thus, a Scientific Council developed recruitment prediction models to support the establishment of catch quotas. However, since 2015, the management target is no longer achieved, raising questions about models’ performance, and about assumptions on past and future recruitment trends. In this context, this study aims to address the limitations of the two current models by (1) proposing alternative models and (2) proposing new criteria to compare models’ performance. Thus, a model based on a spike and slab prior and one on a random slope were proposed to overcome too strong assumptions on recruitment trends, and they were fitted to the WGEEL abundance index from 1980 to 2019. To compare models, recruitment prediction error based on cross-validation as well as criteria quantifying conservation and fishery risks are studied. These indicators are measured in both retrospective and prospective exercises. The random slope model proves to be a good compromise, providing a limited recruitment prediction error and not favouring a single criterion among the exploitation and conservation criteria. In the future, it would be worthwhile exploring the impact of glass eel catches on escapement, which is the Regulation Management target.
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Master Thesis
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https://dumas.ccsd.cnrs.fr/dumas-03562603
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Submitted on : Wednesday, February 9, 2022 - 10:10:36 AM
Last modification on : Wednesday, April 6, 2022 - 4:08:08 PM
Long-term archiving on: : Tuesday, May 10, 2022 - 6:26:42 PM

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  • HAL Id : dumas-03562603, version 1

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Mathilde Benezech. Development and comparison of tools to support the assessment of glass eels catch opportunities. Life Sciences [q-bio]. 2021. ⟨dumas-03562603⟩

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