Growth-dependent mortality of larval plaice Pleuronectes platessa in the North Sea

Abstract

Otoliths of larval plaice were studied over 3 yr in samples from offshore locations and from larvae immigrating into a nursery ground. Growth-dependent mortality was demonstrated to have operated in all years by comparing back-calculated otolith growth from both sample sites and survival ratios for larvae with different otolith growth rates. A distinction was made between mortality due to differences in growth, i.e. a longer larval-stage duration (growth-dependent), and mortality due to heavier predation on smaller or more vulnerable larvae (size-selective). It is argued that no size-selective mortality need have occurred, and that the observed differences in survival may have originated exclusively from differences in growth rate.