Latitudinal and Ontogenetic Shifts in the Diet of Arctic Cod (Boreogadus saida) in the Pacific Arctic and Bering Sea

Arctic cod (Boreogadus saida) is a nodal species in Arctic marine foodwebs as an important prey of many birds, marine mammals, and other fishes, as well as an abundant predator of a variety of zooplankton.  In the Pacific Arctic, the summer distribution of Arctic cod extends southward into the central Bering Sea during colder years.  In this study we examine the summer diet of Arctic cod across a latitudinal gradient in the U.S. Pacific Arctic, extending from the southern limit of their distribution in the eastern Bering Sea to the northern margins of the Chukchi Sea continental shelf.  Stomachs were collected from demersal and pelagic trawls conducted between 1999 and 2012, and across a range of predator sizes (3-26 cm).  Our results indicate differences in prey composition within the geographic and size ranges examined.  In the Bering Sea, Arctic cod primarily preyed upon benthic amphipods, euphausiids, and copepods with a general shift toward more benthic-associated prey as predator size increased.  In the Chukchi Sea, copepods were the dominant prey followed by shrimp, benthic amphipods, and euphausiids.