The movement of cod and haddock larvae onto the shoals of Georges Bank

Abstract

Larval haddock and cod spawned on northeastern Georges Bank during spring have continuous recruitment to the shoal central part of the bank (< 55 m) as they develop and are advected along the southern flank in a sheared flow field. Larval age distribution data from an intensive grid of sampling stations across the flank in spring of 1981 and 1983 show a consistent cross‐shelf age gradient, with older larvae found nearer the shoals. The estimated average shoalward movement of larvae is 0 . 65 cm s −1 , which is consistent with both estimated dispersion rates and observed and predicted near bottom cross‐isobath currents of < 1‐2 cm s −1 . The retention of larvae on the shoals of Georges Bank appears to be enhanced by their residing nearer to the bottom in waters shallower than 70 m, but the degree to which their swimming behaviour interacts with currents remains uncertain.