Results of 2017 Chukchi Sea Acoustic/Trawl Survey

We conducted acoustic-trawl (AT) surveys of the US continental shelf region of the Chukchi Sea during ice-free periods (1 August to 27 September) with a focus on Arctic cod (Boreogadus saida), a key species in Arctic ecosystems. These surveys indicate that midwater fishes are dominated by age-0 Arctic cod, with large numbers of age-0 walleye pollock (Gadus chalcogrammus) found in the region for the first time. Age-0 Arctic cod abundances were significantly larger than observed in previous surveys. Age-0 Arctic cod were distributed north of 68 °N with the highest densities in the northeastern Chukchi Sea, and age-0 pollock were found throughout the region north of 66 °N. Additional key pelagic species included capelin (Mallotus villosus), saffron cod (Eleginus gracilis), and Pacific cod (Gadus macrocephalus). These three species were primarily found in coastal areas between 66.5-72 °N. As had been previously observed, sizeable populations of age-0 Arctic cod were observed in the northern Chukchi Sea, which suggests that this area is an important nursery ground. The increase in age-0 pollock abundance suggests that environmental conditions now enable species from the south to colonize the Chukchi Sea, at least on a seasonal basis.