Connectivity between two fishing sites can lead to an emergence phenomenon related to Maximum Sustainable Yield

In this study, we examine the effects of connectivity on the total catch of a fishery consisting of two fishing sites when the fish population is a predator of a larger prey–predator system. To this end, we analyze a prey–predator fish community model in a two-site environment and compute catch at Maximum Sustainable Yield (MSY). We exhibit some emergence phenomenon: the total catch can be greater than the sum of the catch at two isolated sites due to connectivity. This result is obtained when the two sites are heterogeneous. We show that the increase in capture at MSY is maximal for a certain value of the carrying capacity of the second site, all other parameters remaining constant, including the carrying capacity of the first site. A stronger phenomenon can also be observed: even if none of the sites is viable for fishing, the entire system can be viable. We then study the effects of the heterogeneity of the sites and illustrate our results through simulations. It is shown that the excess yield at MSY can become very significant when the characteristics of the prey and predator in terms of potential growth are opposite at each site.