DIET OF MINKE WHALES BALAENOPTERA-ACUTOROSTRATA IN THE NORTHWESTERN PART OF THE NORTH PACIFIC IN SUMMER, 1994 AND 1995

The forestomach contents of 114 minke whales Balaenoptera acutorostrat a randomly sampled in the northwestern part of the North Pacific in th e summer of 1994 and 1995 were analyzed. Twelve prey species consistin g of 7 fishes, 4 euphausiids and 1 copepod were identified. Pacific sa ury Cololabis saira was the most important prey species, occurring in 77.2% of the stomachs and composing 80.6% of the weight ingested, with some spatial and temporal variation. Japanese anchovy Engraulis japon icus was the next most important prey species, occurring in 14.0% of t he stomachs and composing 6.7% of the weight ingested. Diurnal changes in the mean forestomach content weight and in the relative freshness of the forestomach contents showed little change between 06:00-18:00 h . The minke whales fed mainly on pelagic schooling fishes at the surfa ce in the daytime.