Abstract
In mixed fisheries where there is an increased ecological interdependence between two or more target species, the possibilities of fishing these species must be determined jointly, since catches of one species will impact the natural growth not only of that species but of the others, as well. The objective of this paper is to develop a predator-prey model for two major species caught by the EU fishing fleet on European Union fishing grounds. The predator and prey’s population dynamics follow the Lotka-Volterra equation and are assumed to be logic-based, and a lineal interaction between the predator and prey populations is assumed. Optimal single owner multispecies fishery management is analysed, and the applied model is solved, obtaining the equilibrium value of biomasses, catches, and net benefits of the mixed fishery. The results show that the MSY of the predator is higher than that estimated by ICES, while MSY for prey is lower. The sensitivity analysis of the results reveals that the biomass levels of both species decrease as the discount rate increases, while catches increase.
Highlights
The complex series of interactions among a fishery’s different species has led an increasing number of scientists to recommend multispecies approaches to fishery management [1] [2]
The objective of this paper is to develop a predator-prey model for two major species caught by the EU fishing fleet on European Union fishing grounds
Biological interactions among fish stocks can dominate the structuring of marine ecosystems and so can strongly affect the population dynamics
Summary
The complex series of interactions among a fishery’s different species has led an increasing number of scientists to recommend multispecies approaches to fishery management [1] [2]. Development of the current analytical/theoretical framework for proposing management guidelines was based on bioeconomic models that account for the biological and economic aspects, in general, of just a single species, an approach that fails to acknowledge the importance of interactions among the marine community’s various components. It is important to continue developing this approach and urging decision makers to consider it, since catching a greater or lesser number of tonnes of a given species can have serious repercussions for the biomass of other species with which there is a trophic interaction (altering the tonnage would affect, at least some, within-fishery species that were not “targets”) Such catch differences can affect the sustainability of the ecosystem and of the enterprises that depend on it.
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