Results of 2013 Chukchi Sea Acoustic/Trawl Survey

We conducted acoustic-trawl (AT) surveys of the Alaska northern Bering and Chukchi Seas during ice-free periods with a focus on Arctic cod (Boreogadus saida), a key species in Arctic ecosystems. The mixed species assemblages in the study area required a refinement of standard AT survey methods used in Alaska. These surveys indicate that midwater fishes are dominated by age-0 Arctic and saffron cod (Eleginus gracilis), capelin (Mallotus villosus), and Pacific herring (Clupea pallasii). Age-0 Arctic cod were distributed north of 70 °N, age-0 saffron cod were abundant in coastal areas between 66.5-69.5 °N, and Pacific herring were distributed south of 67 °N. Abundances of Arctic cod, saffron cod, herring and capelin all increased by more than factor of 2 in 2013 compared to 2012. Sizeable populations of age-0 Arctic cod were observed in the northern Chukchi Sea, which suggests that this area is an important nursery ground. However, relatively few larger Arctic cod were observed in this and other surveys of the area, which suggests that either overwinter mortality of age-0 Arctic cod is high, and/or these fish are not retained on the Chukchi shelf.