Growth differences in larval plaice Pleuronectes platessa in the Southern Bight of the North Sea as indicated by otolith increments and RNA/DNA ratios

Abstract

Somatic and otolith growth of larval plaice Pleuronectes platessa was studied under field and experimental conditions. Rearing experiments at 6 and 9 degree C demonstrated a relation between somatic and otolith growth, and a larger size-at-stage for fast growing larvae. In the field, 2 groups of larval plaice were caught at dates 2 wk apart in the southern North Sea in March 1988, and growth was examined using 4 methods: size-at-age, size-at-developmental stage, otolith increment widths, and RNA /DNA ratios. All methods yielded the same result. Larvae captured on 22 March had been growing faster then larvae caught on 8-9 March. Larvae from 22 March were larger at the same age, and had attained a larger size at the same developmental stage. Slow growth led to relatively large otoliths.