Research Article

Long-term fishing impact on the Senegalese coastal demersal resources: diagnosing from stock assessment models

¹ CRODT, ISRA-Sénégal, Pôle de Recherche de l'ISRA/Hann, 2241 Dakar, Sénégal
² Université Cheikh Anta DIOP, Faculté des Sciences et Techniques, Département de Biologie animale, 5005 Dakar, Senegal
³ Institut Mauritanien de Recherches Océanographiques et des Pêches (IMROP), 22 Nouadhibou, Mauritanie
⁴ Institut de Recherche pour le Développement (IRD), Unité MARBEC, Université de Montpellier, Place E. Bataillon, 34095 Montpellier cedex 5, France
⁵ Université Bretagne Loire, Agrocampus Ouest, UMR985 Ecology and Ecosystems Health, 65 rue de Saint Brieuc, CS 84215, 35042 Rennes cedex, France

^* Corresponding author: kamarel2@hotmail.com

Guest Editor: Jörn Schmidt

Received: 1 March 2017
Accepted: 24 November 2017

Abstract

For the first time in Senegal, assessments based on both stochastic and deterministic production models were used to draw a global diagnosis of the fishing impact on coastal demersal stocks. Based one national fisheries databases and scientific trawl surveys data: (i) trends in landings since 1971 were examined, (ii) abundance indices of 10 stocks were estimated using linear models fitted to surveys data and commercial catch per unit efforts, and (iii) stock assessments were carried out using pseudo-equilibrium Fox and Pella-Tomlinson models and a Biomass dynamic production model fitted in a Bayesian framework to abundance indices. Most stocks have seen their abundance sharply declining over time. All stocks combined, results of stock assessments suggest a 63% reduction compared to virgin state. Three fifth of demersal stocks are overexploited and excess in fishing effort was estimated until 75% for the worst case. We conclude by suggesting that the fishing of such species must be regulated and an ecosystem approach to fisheries management should be implemented in order to monitor the whole ecosystem.