De ecologie van de 0-groep schol (<i>Pleuronectus platessa</i> L.) op het Balgzand: 1. Aantalsverloop, verspreiding en getijdenmigratie

Abstract

This paper describes the results of a field investigation of the density, dispersion and tidal migration of 0-group plaice (Pleuronectes platessa) on the Balgzand, a tidal area in the western Waddenzee. Settlement of the plaice, which enter the area by the tidal inlets in spring, occurs on the tidal flats. During their first month following settlement the animals do not migrate from the area of settlement. After settlement has been completed there follows a marked reduction in the density of the animals. About this time, the first-settled specimens commence a tidal migration involving a movement during ebb tide periods to the small channels which connect the tidal flats with the Amsteldiep. Possibly, the decrease in numbers is associated with predation occurring at low tide in these small channels. Each individual plaice spends a particular length of timein the intertidal area before beginning to migrate. Once each specimen has developed migratory behaviour, the population as a whole migrates onto the flats and back into the surrounding channels. Neither the dispersion pattern, nor its tidal rhythmicity varies for the rest of the season