Under the Sea: Incorporating Climate Change and Bycatch Considerations into Fishery Management Strategy

Abstract

Marine fishes are responding to ocean warming; they are shifting poleward and into deeper waters. Shifts in fishes’ spatial distributions due to climate change may cause increased or unprecedented interactions between species. The particular interactions that concern this paper are between target and bycatch commercial species. The overarching questions this paper asks are: 1. How does climate change affect the geographic range, interaction, and co-occurrence between fish species and will these new interactions affect bycatch numbers? 2. How can fishery management strategies incorporate bycatch considerations in the context of climate change? I hypothesized that there will be an increase in overlap between bycatch and target fish species in response to climate change. To test this hypothesis, I used AquaMaps model data of the most landed target fish in the North Pacific and endangered bycatch fish in the region to determine species co-occurrence between the present (2000-2010) and the future (2090-2099) and the magnitude and direction of the change. I then looked at the shifts in center of biomass to determine whether keystone species existed that would potentially drive major changes in overlap. The findings from the data analysis do not support this hypothesis, showing that the overlap in 5 out of 336 species interactions are predicted to change more than ten percent in the future, with 2 of those 5 expected to experience an increase in overlap. There were no keystone species of note responsible for major changes in species’ spatial overlaps. The fisheries considered in the analysis are the most important in the Pacific Northwest, indicating that even a change in just 2 target and non-target interactions may pose serious consequences to fisheries. Fishery management strategies should incorporate climate change and bycatch species considerations together for the most sustainable fishery management. The best fishery management strategy uses a combination of the Ecosystem Approach to Fishery Management (EAFM) to set goals, Dynamic Ocean Management (DOM) for day-to-day operations, and a mix of Individual Fishing Quotas (IFQs), Marine Protected Areas (MPAs), harvest control rules, and seasonal closures to implement EAFM goals.