Virtual population analysis of two snapper species, Lutjanus analis and Lutjanus chrysurus, caught off Pernambuco State, north-eastern Brazil

Abstract

We applied steady-state Virtual Population Analysis - VPA to two stocks of snappers (Lutjanus analis and L. chrysurus) exploited by artisanal hand-line fleets along the Pernambuco State coast (North-eastern Brazil). We show that even short-data series (1 year of sampling) can produce a useful diagnosis of fisheries resources. Both stocks are slightly overexploited by the hand-line fishery and a higher yield-per-recruit would be obtained by a reduction of effort of 16% for L. analis and 43% for L. chrysurus. Given the impracticability of managing the two stocks separately, we propose a 25% decrease of fishing effort for the hand-line fleet. By incorporating the results of VPA into a simulation framework, we can develop a comparison of the likely result of different policy options (effort regulation) based on 3 simple indicators (Spawning stock biomass-per-recruit, biomass-perrecruit and yield-per-recruit). We compare the results of effort reduction with those of effort increase (25%) through simulation analysis. Allowing for the difficulty of testing assumptions introduced in our model (steady-state, Beverton and Holt recruitment model) and using standard fisheries analysis techniques, we show that useful fisheries advice can be produced even in a context of limited data. Providing advice to developing countries coastal fisheries is an urgent issue, given the high dependence of local communities on coastal living resources and the increasing fishing effort applied by a growing population.