Dead shells important for return flat oysters in the Wadden Sea

In particular, empty cockleshells provide the main settlement substrate for flat oyster larvae. But also Japanese oysters and many other shellfish species are suitable for the flat oyster. The differences are mainly determined by the supply of suitable substrate.

[Translate to english:] Platte oester, Ostrea edulis. Foto: Eric Gibus via

The occurence of the flat oyster was researched in July and September 2017 by Bureau Waardenburg, Wageningen Marine Research and Altenburg & Wymenga on behalf of PRW. The researchers announced in October that it can be stated with certainty that the flat oyster is present in the Wadden Sea. Now that the research is complete, there are more interesting data.

In this report the results of a short survey of flat oysters (Ostrea edulis) in the Western Wadden
Sea are presented. Ten sites were visited and flat oysters were found on nine locations in the Eijerlandse gat. Empty
cockleshells and live and dead Pacific oysters provided the main settlement substrate. The presence
of larvae was detected in water samples by microscopic inspection and DNA analysis at several
locations in the Eijerlandse gat. The results show that flat oysters have returned to the Wadden Sea
after its extinction in the last century, but still occurs at low densities.

Download the report Flat oysters in the Eijerlandse Gat, Wadden Sea. Results of a survey in 2017. van der Have, T.M., P. Kamermans, E. van der Zee., 2017. Bureau Waardenburg Rapportnr. 17-231, Bureau Waardenburg, Culemborg.