All Climate Events

Tuesday, October 26, 2021. 3:30 PM. Webinar: Climate-driven changes in abundance, distribution, and composition of the pelagic fish community in the Chukchi Sea. Catie Tobin, NOAA; Robert Levine, University of Washington. Sponsored by NOAA. Register here.

Abstract: Acoustic-trawl (AT) surveys of the Chukchi Sea during summers 2012 and 2013 determined that pelagic fishes were dominated by age-0 Arctic cod (Boreogadus saida), with few adults present in the region. This suggests that either survivorship of age-0 fish is very low or that they emigrate to other areas as they grow. To evaluate the role of the region as a nursery for these age-0 fish, we conducted AT surveys in 2017 and 2019 and repeat acoustic surveys from autonomous surface vehicles in 2018. Throughout this period, bottom-moored echo sounders continuously measured fish abundance and movement at several locations. These observations indicate that the abundance and species composition of midwater fishes on the Chukchi Sea shelf is highly variable over seasonal and interannual time scales. Seasonally, abundance was very low in winter, increased in May, and reached peak abundance in late summer. In all years, the highest abundance in summer was observed in the northern Chukchi. The distribution of age-0 gadids is predominantly driven by transport, and an increase in age-0 pollock abundance in 2017 and 2019 suggests that environmental conditions now enable species from the south to colonize the Chukchi Sea, at least on a seasonal basis.

Bio(s): Robert Levine is a PhD Candidate in the School of Oceanography at the University of Washington. His research uses acoustic methods to investigate the changing pelagic fish community of the Alaska Arctic over large spatial and temporal scales, with a focus on the role of transport in shaping species distributions. His PhD work is being done in collaboration with the NOAA Alaska Fisheries Science Center as part of the North Pacific Research Board's Arctic Integrated Ecosystem Research Program. Previously, Robert worked as a contractor for the Midwater Assessment and Conservation Engineering program at AFSC where he began working with the autonomous acoustic systems he utilizes in his current research.

Slides / Recording: Slides and recording will likely be shared with all who register for the webinar.