Optimal biodiversity erosion in multispecies fisheries

As marine ecosystems are under pressure worldwide, many scientists and stakeholders advocate the use of ecosystem-based approaches for fishery management. In particular, management policies are expected to account for the multispecies nature of fisheries. However, numerous fisheries management plans remain based on single-species concepts such as Maximum Sustainable Yield (MSY) and Maximum Economic Yield (MEY), that respectively aim at maximizing catches and profits of single species or stocks. In this study, we assess the sustainability and profitability of multispecies MSY and MEY in a mixed fishery with technical interactions. First, we analytically show that multispecies MSY and MEY can induce overharvesting and extinction of species with low productivity and low monetary value. Second, we identify and discuss incentives on effort costs and landing prices, as well as technical regulations, that promote biodiversity conservation and more globally sustainability. Finally, a numerical example based on the coastal fishery in French Guiana illustrates the analytical findings.