Effects of under-estimating discards in production models: improving the assessment of Merluccius spp. In NW Africa

Autor: Soto-Ruiz, M. (María), Fernández-Peralta, L. (Lourdes), Rey-Sanz, J. (Javier), Liébana-López, M. (María), Pennino, M.G. (María Gracia), Salmerón, F. (Francisca)
Přispěvatelé: Kell, Laurie
Rok vydání: 2020
Předmět:
Zdroj: e-IEO. Repositorio Institucional Digital de Acceso Abierto del Instituto Español de Oceanografía
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Popis: The participants at WKLIFE IX made the following suggestions to help in developing improved assessment methodologies and species identification through simulation techniques. How to improve the assessment of Merluccius spp: Using SPiCT as the assessment method to develop an OM (Fischer et al., submitted) to pose alternative hypotheses about the nature of discarding (e.g. percentage of misreporting in hake discards) and then simulate datasets to evaluate the impact on estimates of stock status and reference points (e.g. Omori et al., 2016). Quality of observer data required: how good are the observer data to apply to the whole fleet for separating retained and discarded catches and for separating species Merluccius senegalensis and Merluccius polli in catches of the whole fleet? First, explore existing data to identify potential covariates related to species and fishing effort distribution (e.g. Okamoto, to appear). Develop a two species OM (hake - discards and Merlucciuspolli-Meluccius senegalensis) using FLife developed under the MyDas project to explore robustness of current production models assessment approach (e.g. Kell et al., 2009). Growth: It is not possible currently to provide growth curves by species as more otolith readings are needed to evidence different life strategies. Meanwhile, the first step is to try to estimate a robust model VBGM and provide age-length keys for Merluccius spp. Then separate data by ages to help conduct age-based assessments and develop length based indicators
Databáze: OpenAIRE
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