Results of 2019 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 (27 August to 26 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 70 °N with the highest densities in the northeastern Chukchi Sea, west of 164 °W. Age-0 pollock were found between 66-72 °N. Additional key pelagic species included capelin (Mallotus villosus), saffron cod (Eleginus gracilis), Pacific cod (Gadus macrocephalus), and Pacific herring (Clupea pallasii). These four species were primarily found in coastal areas between 66.5-72 °N. 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. Age-0 Arctic cod not found in significant abundance in the central and southern Chukchi as in previous surveys, indicating that changes in the environment may be restricting the southern extent of their distribution.