Effects of under-estimating landings and discards in state-space production models: the case of Black hake In NW Africa
| Autor: | Soto-Ruiz, M. (María), Fernández-Peralta, L. (Lourdes), Rey-Sanz, J. (Javier), Pennino, M.G. (María Gracia) |
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| Rok vydání: | 2021 |
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| Zdroj: | e-IEO. Repositorio Institucional Digital de Acceso Abierto del Instituto Español de Oceanografía instname |
| Popis: | Among the Surplus Production Models (SPM), state-space models are recent developments to manage data-limited stocks. Nevertheless, as declared catches can be underestimated and discards ignored, the SPM produce biased and uncertain reference points for management. We use a stochastic surplus production model in continuous time (SPiCT) and Just Another Bayesian Biomass Assessment (JABBA) to simulate different scenarios of underreporting for the black hake in North West Africa. We provide replicable stock assessment alternatives for this and other data-limited stocks in this area; we evaluate the effect of the major uncertainties arising from underreporting catches (by-catch and discards) in the parameters of alternative production models and hence, both in the management quantities and in the uncertainty model quantities; and we determine the relative importance of the different underreporting characteristics. Underestimation of catch and discardsand discards caused changes in the contrast of the data. Conclusions were formulated in two directions: for management purposes, the most robust quantity to be used is B/BMSY, meanwhile for data improvement, controlling the more sensitive variables, like F/FMSY, is a better indicator of success than the quality in data is being achieved. We therefore recommend: 1. To avoid at all costs the increase in underreported catches, and 2. To control discards or, at least, maintaining its underreporting at constant levels in the future to provide more stability in the management quantitie |
| Databáze: | OpenAIRE |
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