Occurrence of Arctic Cod (<i>Boreogadus saida</i>) Schools and Their Vulnerability to Predation in the Canadian High Arctic

Abstract

We document the occurrence of large schools of Arctic cod (Boreogadus saida) in the Barrow Strait region of the eastern Canadian Arctic during the open water season. Schools were most frequently observed near shore, often in depressions inside bays. Schools ranged up to 130 000 sq m surface area and contained on the order of 4 x 10**8 fish, weighing 12 000 tonnes. Evidence indicates that schools form before the arrival of predators, but when they occur in shallow water, they are often subjected to intense predation by thousands of seabirds and marine mammals, primarily black-legged kittiwakes (Rissa tridactyla), northern fulmars (Fulmarus glacialis), harp seals (Phoca groenlandicus), beluga (Delphinapterus leucas) and narwhal (Monodon monoceros). The reasons for such schooling behaviour are unknown.