Foraging behaviour and prey size spectra of larval herring Clupea harengus

Abstract

Four size groups of larval herring were studied when preying on six size groups of copepods. Larval swimming and attack behaviour changed with prey size and were related to the ratio between prey length and larval length. The effective search rate showed a maximum when prey length was 0.027 of larval length. In the field investigations, the relative prey size spectra of six size groups of larvae were described. The widths of these spectra were not significantly different and they all attained maxima when the relative length of prey was about 0.028 of larval length. Thus, larval foraging was, to a large extent, determined by the relative size of prey, with significant selection for the preferred sizes. -from Author