Schelpdierbestanden in de Nederlandse kustzone in 2017

Samenvatting

The exploitation of wild shellfish has developed from free fisheries to a strongly regulated commercial activity, in which economic and ecological objectives are both aimed for. Within the framework of this policy an annual stock estimate is made for the economic important species: razor shell (Ensis directus) and cut-through shell (Spisula subtruncata), and other less economic species. The survey covers the entire Dutch coastal zone, and is commissioned by the Ministry of Economic Affairs. The fieldwork for the 23 th successive survey since 1995 was carried out in spring 2017. The principle objective of this survey is the assessment of the stock sizes of the economically important species Ensis directus and Spisula subtruncata in the Dutch coastal zone, including the Natura-2000 areas: “Noordzeekustzone”, “Voordelta”, “Vlakte van de Raan”, and the mouth of the Westerschelde estuary. In addition to the two most important species, we also report on the occurrence of three species of occasional economic importance: otter shell (Lutraria lutraria), striped venus clam (Chamelea striatula), and banded wedge shell (Donax vittatus). For the Dutch coastal zone the total stock size was estimated at 397.2 million kg fresh weight for razor shells, and 1,281.7 million kg fresh weight of cut-through shells. Stocks of the the other species were estimated at 18.1 million kg fresh weight for striped venus clams, 38.0 million kg fresh weight of banded wedge shells and 4,931 million individuals of otter shells. The stock of razor shells showed a sharp increase and was found to be the highest since 1995. The same can be said for the cut-through shells, where the stock of biomass increased to a level which is the highest since 1995. Also the stock of the otter shell and the banded wedge shell increased where the stock of the striped venus clam showed a slight decrease.