Assessing the impact of artisanal and recreational fishing and protection on a white seabream ( Diplodus sargus sargus) population in the north-western Mediterranean Sea using a simulation model. Part 1: Parameterization and simulations

Abstract

This study focuses on the parameterization of a model describing the dynamics of an exploited population and aims at improving management practices by simulating various measures. The study species is white seabream, an important resource exploited by the mixed fisheries of the French Catalan coast, where the Cerbère-Banyuls marine reserve was created more than 30 years ago. We used the ISIS-Fish fishery simulation model to evaluate the population's sustainability under the current fishing regime. This simulator combines three sub-models within a single working environment: population dynamics, multi-fleet exploitation and management measures. Knowledge of the white seabream and related fishing activities was compiled from both literature and analyses of existing fisheries data, and is used to parameterize and calibrate the model. Simulation results highlighted that: (i) under current management, the white seabream population biomass has declined to 88% of initial biomass over 20 years; (ii) with various scenarios of recruitment, the population dynamics tends to stabilize over the long term. In a second article ( Hussein et al., 2011), we undertook an analysis of the sensitivity of the model to uncertain parameters and explored scenarios aiming at evaluating the impact of fishing activities and the effects of protection effects on white seabream dynamics.