ABUNDANCE AND TAXA COMPOSITION OF COPEPOD NAUPLII OVER SOUTHEASTERN BERING SEA DEEP-WATER SPAWNING GROUNDS OF WALLEYE POLLOCK, THERAGRA-CHALCOGRAMMA

This project examined the abundance, taxa, stage and size of copepod n auplii available as prey for walleye pollock larvae in its deep water spawning grounds of the southeastern Bering Sea. Nauplii of the genera Oithona, Eucalanus, and Metridia were the most commonly encounted typ es while Pseudocalanus and Microcalanus were rare. There was marked in terannual variation in the taxa and abundance of copepod nauplii coexi sting with the pollock larvae. Stages I-IV of Oithona were present at 0 to 8 l(-1) at different depths. Individual stages III-VI of Metridia nauplii occurred at 0 to 6 l(-1), while Eucalanus nauplii were presen t at 0.1 to 9 l(-1), depending on stage and depth. Nauplii III-IV of t he genera Pseudocalanus and III-VI Microcalanus were usually present a t less than l l(-1). In 1992, 54 to 56% of the nauplii had body length s of 150-350 mu m which are typical of those found in stomachs of firs t-feeding pollock larvae. In 1993 corresponding estimates were 64 to 6 8%. Copepod nauplii with body lengths of 150-350 mu m were generally p resent at 1 to 15 l(-1) but at one station their counts exceeded 20 l( -1).