Ecoprofile rays and skates on the Dutch continental shelf and North Sea

Abstract

Several species of rays and skates were common in Dutch territorial waters at the beginning of the century and there was a directed fisheries on these species. During the 1930's a decline in landings was seen and shortly after the Second World War there were few rays left on the Dutch continental shelf. At the present time only two species of ray are caught in Dutch waters (the starry ray, Raja radiata, and the stingray, Dasyatis pastinaca), neither are commercially important. The starry ray has replaced the thornback ray (R. clavata) as the most abundant species. Although total mortality (natural + fisheries) on adult rays is above the theoretical replacement level for a number of species, the same species are still present off the British coast. This area is possibly a source of individuals for other parts of the North Sea. It is as yet unclear which stage in the development (i.e survival of adults, eggs or juveniles) is the one limiting the ecolonisation of Dutch coastal waters by the endemic species.