Ostrea edulisat shipwrecks in the Dutch North Sea

Abstract During diving expeditions in July and September 2019 two live European flat oysters (Ostrea edulis) were observed by SCUBA divers. The first oyster was found lying amongst coarse shelly material in the scour hole around shipwreck #3251, 37 nautical miles north west of Texel (NL). The second oyster was found on the Gustav Nachtigal wreck, 6 nautical miles north of Schiermonnikoog (NL). Additional shipwrecks were also inspected for O. edulis individuals but no live specimens were observed, although on 9 out of 11 inspected locations empty, fossil O. edulis shells were found. The September dive on the #3251 shipwreck revealed the presence of several large empty flat oyster shells, some of which were attached to each other, with up to three individuals in a cluster. This implies that the area around the #3251 shipwreck was a suitable location for flat oysters in the past and that oyster larvae are still capable of reaching the location. The findings suggest that shipwrecks and their surroundings are promising locations for future O. edulis restoration projects.