Biophysical processes in Barrow Canyon influence fish distribution, age and growth

Elizabeth Logerwell, NOAA/NMFS/Alaska Fisheries Science Center, Resource Assessment and Conservation Engineering Division, Seattle, WA, United States, Kimberly Rand, NOAA Alaska Fisheries Science Center, Seattle, WA, United States, Seth L Danielson, UAF, College of Fisheries and Ocean Sciences, Fairbanks, AK, United States and Leandra Sousa, North Slope Borough, Wildlife Management, Barrow, AK, United States
Abstract:
Barrow Canyon is a dominant feature of the otherwise shallow (30-50 m) northeastern Chukchi Sea shelf. It is oriented parallel to the shore and plunges to depths exceeding 100 m within 20-40 km from shore. Oceanographic conditions and processes in Barrow Canyon are expected to influence the distribution, abundance and ecology of organisms in the area. To examine these expectations, the benthic fish community in and around Barrow Canyon was surveyed with an 83-112 eastern otter trawl. Oceanographic data (salinity, temperature and depth) were collected at all trawl stations. Arctic cod (Boreogadus saida) dominated the catch, followed by sculpins (Cottidae), eelpout (Lycodes spp.) and snailfish (Liparis spp.). Catch of other taxa made up less than 1% of the total catch. Cold and relatively high salinity water was found at depth in Barrow Canyon, with properties consistent with winter water formed on the Chukchi shelf. Waters inshore of the canyon proper (depths < 40 m) were warmer and weakly stratified. Distribution maps of benthic fish indicate spatial partitioning of abundance, age and growth. In particular, Arctic cod were more abundant, and were older and larger (by weight) in the deeper, higher salinity waters of Barrow Canyon. Ten variables were selected for statistical analysis of the relationships between fish density and the environment. GAM analysis confirmed that bottom depth and salinity were significant factors related to Arctic cod density. Zooplankton may have been advected from either the Chukchi or the Beaufort seas and into the canyon. We hypothesize that Arctic cod occupied Barrow Canyon to take advantage of the local abundant, energy-rich prey, resulting in improved growth and survival. Climate-driven changes in atmospheric forcing and resulting alterations to Chukchi shelf flow pathways could have a downstream impact on the productivity of Barrow Canyon and organisms such as Arctic cod that appear to use the canyon for feeding and growth. 
Back to: Biophysical Processes at the Arctic–Sub-Arctic Interface II