Stomach contents of North-East Arctic cod and possible changes in the diet the last years

Abstract

A stomach sampling program has been carried out in connection with the construction of a multispecies modell for the Barents Sea. The results on the contents of 8410 cos (Gadus morhua) stomachs sampled in 1982-1985 are presented. The samples were collected by bottom- and pelagic trawl onboard Norwegian research vessels during routine surveys in the Barents Sea and the Spitsbergen area. For cod > 20 cm the major prey species in percent wet weight of the stomach content were capelin (Mallotus villosus) (40 %), deep sea shrimp (Pandalus borealis) (20 %) and redfish (Sebastes spp. ) (7 %). Capelin was the dominating prey species during the first part of the year. In the diet of smaller cod the most important prey species were shrimp (13 %), krill (Euphausiacea) (9 %), amphipods (16 %) and other small crustaceans (11 %). Since 1982 there has been a drop in the average stomach contents weights of cod > 20 cm in periods with a high content of capelin and since 1984 the relative importance of deep sea shrimp as prey species has been reduced. A preliminary estimate of the cod’s annual food consumption shows a consume of 2-3 times the biomass of the cod stock.