An estimate of the sustainable rate of shell extraction from the Dutch Wadden Sea

1. Shell production by cockles Cerastoderma edule was studied to examine whether or not the present licensed rate of shell extraction in the Dutch Wadden Sea exceeds the current rate of shell addition to the exploitable stocks. 2. Long‐term data on numbers of cockles and weights of their shells were used to estimate their annual production on Balgzand, a 50‐km 2 tidal flat area in the western‐most part of the Wadden Sea. During the 1969–97 period, it amounted to an average of 125 g m –2 , including 107 g m –2 of shells large enough to be exploitable for shell‐lime fishery. 3. The very irregula... Mehr ...