VARIATIONS IN SETTLEMENT AND GROWTH OF 0-GROUP PLAICE (PLEURONECTES-PLATESSA L) IN THE DUTCH WADDEN SEA AS DETERMINED BY OTOLITH MICROSTRUCTURE ANALYSIS

Larval growth, date of settlement, and subsequent growth of O-group plaice were compared in the eastern (Dollard) and western (Texel) parts of the Dutch Wadden Sea in autumn 1988. Daily increment analysis in otoliths with SEM showed that specimens sampled in the Texel region, and at 2 Dollard stations, hatched early in the season, had a shorter larval period (50 to 61 d) with high growth rates, and early settlement. All specimens caught at the other 6 stations hatched later, had a long larval phase (62 to 82 d) and settled later in the season. Estimates of maximum growth based on optimal feeding conditions and the prevailing water temperatures in both tidal basins were compared to the growth rates observed in the field. According to previous studies, plaice in the Texel region have optimal growth. All late settlers in the Dollard and part of the early settlers also had optimal growth. However, some early settlers in the Dollard had significantly lower growth rates than the batch of synchronously settled specimens from the Texel region.