Light, temperature, nauplii concentrations, and prey capture by first feeding pollock larvae Theragra chalcogramma

Abstract

Digestion rate of 1st feeding larvae of pollock T. chalcogramma fed copepod nauplii averaged 5.0 h. Threshold light levels at which larvae captured prey were between 0.2 and 0.4 lx. Larvae reared and fed at 5.5.degree. C were more successful at capturing nauplii than cohorts reared and fed at 3.0.degree. C when feeding at low prey concentrations. Yolk sac larvae feeding on wild copepod nauplii at concentrations of 50, 14, 12, 10 and 8 l-1 were similarly successful at capturing prey with averages of 10-14% of them feeding. At nauplii concentrations of 6 and 2 l-1, 5 and 2% of the larvae captured prey, respectively. In all feeding and prey concentration observations, there was a wide range in the percentage of larvae with prey. Some larvae can successfully initiate feeding at prey concentrations previously observed in the southeastern Bering Sea.