Gulf of Alaska | Fishes and Fish Habitats MASTER’S POSTER PRESENTATION Temperature-driven shifts in Gulf of Alaska foods webs: Insights from network models and applications to management Presenter: Catalina Burch , catburch@uw.edu Anne Beaudreau , annebeau@uw.edu, University of Washington Bridget Ferriss , bridget.ferriss@noaa.gov, NOAA Alaska Fisheries Science Center Kerim Aydin , Kerim.Aydin@noaa.gov Kirstin Holsman , kirstin.holsman@noaa.gov Jon Reum , jonathan.reum@noaa.gov Recent marine heatwaves (MHW) have caused significant, basin-wide changes in the Gulf of Alaska (GOA) ecosystem. Understanding past variation in GOA food web structure in relation to temperature may provide insight into ecosystem resiliency under novel climate regimes. In this study, we use groundfish diet data, collected by NOAA, to examine shifts in diets of key predators and changes in food web network structure in response to altered temperature regimes. We hypothesized that the MHW had a destabilizing effect on the ecosystem, due to shortages or surpluses within the food web that occurred at a faster rate than the adaptive capacity of organisms. As a first step to this research, we developed quantitative diet summaries for four major groundfish species that are targeted in commercial fisheries: Pacific cod, walleye pollock, Pacific halibut, and arrowtooth flounder. We evaluated size-based and annual variation in diet compositions, focusing on temporal shifts in occurrence and weight of important forage species. Ongoing analyses are focused on testing for MHW effects on groundfish diet metrics and structural characteristics of food web networks for the western and eastern GOA, before, during, and after the 2014-2016 MHW. This project will directly address information needs for ecosystem-based management, by providing a synthesis of groundfish diet data for ecosystem status reports. Additionally, we are communicating our findings to a broader audience by designing an educational web tool in collaboration with middle and high school science teachers in Juneau, Alaska. We hope to use network modeling to connect students with their local environments and challenge them to think about reciprocal relationships within natural systems.
Alaska Marine Science Symposium 2023 192
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