An analytical solution to ecosystem-based F(MSY) using trophic transfer efficiency of prey consumption to predator biological production

A theoretical basis for Ecosystem-based Fisheries Management (EBFM) was derived for pelagic fish by applying marine ecology theory of analytical relationships of predator-prey biological production transfers between trophic levels to FAO guidelines for an ecosystem approach to fisheries. The aim is to describe a simple method for data-limited fisheries to estimate ecosystem-based F(MSY) and how EBFM modellers could mimic the way natural fish communities function for maintaining ecological processes of biological production, biomass and ecosystem stability. Ecosystem stability (ES) F(MSY) were estimated by proportion of biological production allocated to predators, giving (ES)F(MSY) of 0.23 for small pelagic and 0.27 for pelagic finfish, prioritising ecosystem over economics. To maintain both stability and biomass (SB) a full pelagic EBFM (SB)F(MSY) of about 0.08 was obtained for both small pelagic and pelagic finfish, having mostly ecosystem considerations. As the F(MSY) are single-species averages of catchable species targeted in a specific trophic level, multispecies fishing mortalities were proportioned by the biological production of each species in the trophic level. This way catches for each species are consistent with the average ecosystem F(MSY) for a trophic level. The theoretical estimates gave similar results to other fisheries for sustainable fish catches that maintain the fishery ecosystem processes. They were also tested using six tropical Ecopath Models and showed the effects of imposing commercial fishing mortalities on predominantly EBFM conditions. The ecosystem stability (ES)F(MSY) is suggested to be investigated for sustainable fish catches and the full EBFM (SB)F(MSY) for protected areas or recovery of heavily depleted stocks.