Dispersion and mortality of yolk-sac herring (Clupea harengus L.) larvae from a spawning ground to the west of the Outer Hebrides

Abstract

A patch of herring larvae located within 24 h of hatching from a spawning bed on the shelf west of the Outer Hebrides, was followed for 7 days. Dispersion of the larvae was modelled using simple turbulent diffusion theory. The mortality rate, estimated from the rate of decrease in the total population size, was −2% day ⁻¹ over the tracking period which is very much less than rates calculated for herring larvae in other areas by previous investigators. Successive observations of the length, weight, and the incidence of food in the intestines of larvae, indicated that feeding commenced 5 days after hatching and that the growth rate was 0.17 mm day ⁻¹ .