Modelling interactions of fish, fishers and consumers: should bycatch be taken into account?

Abstract

Consumers’ preferences coupled with available fishing technology determine fisheries’ harvests and impacts on the ecosystem. In this paper, I investigate the effects of unintended catch, or bycatch, on consumption decisions and harvests. To this end, a multi-species coupled ecosystem economy model including consumer preferences is extended to also include bycatch in harvesting. The resulting equilibria and dynamics of the model are solved analytically. This allows demonstration of the effects of bycatch not only on the ecosystem, which are comparatively well researched, but also on the economic actors harvesting and consuming fish stocks. The main results, besides replicating the finding that bycatch can increase harvesting mortality, are that even strong bycatch may have no effects on stocks and that the harvesting economy may change dramatically depending on bycatch intensity. Therefore, bycatch should indeed be taken into account in the economic modelling of fisheries. Furthermore, understanding the interrelation of bycatch and market forces is essential in designing overarching policy where economic effects, such as changing employment, need to be considered while also ensuring sustainable use of the ecosystem.