SHELFZ – Nearshore and Offshore Characterization of Arctic Cod and Sculpin Habitats and its Association with Ontogenetic Diet Shifts in the Chukchi Sea

Leandra Sousa, North Slope Borough, Wildlife Management, Barrow, AK, United States, Alexei I Pinchuk, University of Alaska Southeast, Juneau, AK, United States, Elizabeth Logerwell, NOAA/NMFS/Alaska Fisheries Science Center, Resource Assessment and Conservation Engineering Division, Seattle, WA, United States, Seth L Danielson, UAF, College of Fisheries and Ocean Sciences, Fairbanks, AK, United States, JJ Vollenweider, NMFS/NOAA, Alaska Fisheries Science Center, Juneau, AK, United States, Ron Heintz, NOAA NMFS, Alaska Fisheries Science Center, Juneau, AK, United States, Sandra L Parker-Stetter, Northwest Fisheries Science Center, NOAA, Seattle, WA, United States and John K Horne, University of Washington, School of Aquatic and Fishery Sciences, Seattle, WA, United States
Abstract:
Connectivity between the nearshore and offshore Arctic habitats and their role in fish ecology are of critical importance to better understand the Arctic marine environment. Because the nearshore region is inaccessible to most research vessels, there exists a limited understanding of fish and zooplankton ecology in the transition area between nearshore and offshore habitats. The Shelf Habitat and EcoLogy of Fish and Zooplankton (SHELFZ) project collected concurrent data on fish, zooplankton, fisheries acoustics, and water mass properties in the nearshore (< 20 m) and offshore (> 20 m) habitats of the Chukchi Sea in the vicinity of Barrow Canyon. We hypothesize: 1) the nearshore environment may serve as nursery grounds for juvenile Arctic cod and sculpins, and that adults are most abundant in the offshore environment; 2) Juvenile and Adult Arctic cod will have different diets because juveniles and adults occupy pelagic and epibenthic realms, respectively, whereas adult and juvenile sculpins will have similar diet composition because both occupy the epibenthic habitat; 3) Prey type and availability are associated with water mass properties in and around Barrow Canyon. Age-0 Arctic cod and juvenile sculpins dominated the catch in the nearshore midwater and bottom trawls, respectively. Sculpin and Arctic cod adults were most abundant in offshore bottom trawls. Pelagic, small copepods and larvaceans were the most numerous prey in juvenile Arctic cod stomachs while a mix of epibenthic (fish, shrimp, Gammaridea) and pelagic (Calanus spp. larvaceans and Chaetognatha) prey comprised adult Arctic cod diet. Polychaeta, amphipods and shrimp were the most frequent prey in sculpin diets. Calanus spp. and Chaetognatha dominated the zooplankton biomass in the study area and were associated with cool and intermediate salinity water above the pycnocline. Our results indicate that Arctic cod diet and distribution reveal an important connection between nearshore and offshore habitats.
Back to: Biophysical Processes at the Arctic–Sub-Arctic Interface II