Examining Multispecies Management to Increase Productivity in an Alaskan Salmon Fishery

Increased recognition of the shortcomings of single-species management has generated interest in expanding fisheries management strategies to account for multiple species, particularly predators or prey of target species. The Chignik River, Alaska, supports a valuable salmon fishery, with fishery management and harvest focusing primarily on sockeye salmon and only incidentally harvesting coho salmon. As such, the commercial fishery structure exerts an asymmetric effect on the ecosystem.  Species interactions within the freshwater rearing lakes may exacerbate the effects of asymmetric harvest, as juvenile coho salmon consume over half of the emerging sockeye fry annually, potentially limiting the productivity of the sockeye populations.  Here, we examine relationships between historical coho salmon escapement and sockeye salmon productivity to the Chignik River system.  We then use a simulation approach to examine the potential effect of a directed coho salmon fishery on future sockeye salmon production. Our results suggest that limiting coho salmon escapement through directed harvest could substantially increase the harvest of sockeye salmon.  The effect of the directed coho salmon harvest on sockeye salmon productivity is highly variable between years, and depends on the target escapement goal set for coho salmon.