The nursery function of the intertidal areas in the western Wadden Sea for 0-group sole Solea solea (L.)

Data over the periods 1975–1982 and 1991–2000 were used to study the function of the intertidal flats in the western Dutch Wadden Sea as a nursery area for sole. Settlement of larval sole occurred from May onwards, whereby the timing of settlement was inversely related to water temperature in spring. Maximum densities of between 50 and 100 ind. (103 m2)−1 could be found around the end of June. Hereafter, densities decreased due to migration into deeper waters and from the end of August onwards no 0-group sole were present on the intertidal flats. Growth during this period normally appears to be density-independent and a mean population size of about 70–80 mm was reached in August. Growth at Balgzand and also in other areas appeared not to be maximal according to the predictions of a maximum growth model. It is suggested that differences in food composition and availability in terms of searching and handling time might explain this discrepancy. There was no relationship between peak density in the intertidal and year-class strength in the western Wadden Sea or with ultimate recruitment. In contrast, year-class strength in the subtidal part of the western Wadden Sea did show a significant positive relationship with recruitment. The intertidal area only functioned as an important area of settlement for 0-group sole and as a nursery area for a relatively short period during the first months of settlement.