With the expansion of large-scale Eastern oyster restoration efforts in Maryland's portion of the Chesapeake Bay, developing efforts in the northeastern states of Massachusetts, Connecticut, New York, and New Jersey, and similar efforts to restore the Olympia oyster in the Pacific Northwest (Oregon, Washington, British Columbia), these findings are particularly timely and applicable. We measured length and density of spat settling on oyster cultch deployed at deep (3 m) and shallow (1 m) depths at six sites in areas with low salinity and. Greater recruits of oyster spat occurred on the sheltered inshore at the upstream of the natural oyster reef than on the reef and the nearby open coast ( p < 0.05).

This unprecedented recruitment enhancement is significantly correlated to the large stock on the sanctuary reefs and a strong indicator of restoration success and longterm sustainability, as these reefs are well past the average age of senescence (five years) for restored reefs. The oyster Crassostrea sikamea recruitment appeared as a continuous process from June through late November or early December, with the peak in August. In 2012, an oyster shellstring survey in the GWR revealed the highest mean oyster settlement for any Bay tributary since such surveys began nearly 70 years ago. Analysis of publicly available oyster spat (young juvenile oysters) settlement data revealed the reestablishment of a steadier, historic pattern of oyster settlement and recruitment potential in the Great Wicomico River (GWR), where local stocks have been greatly enhanced by a large sanctuary reef network constructed in 2004. Historically, oyster recruitment was higher, more reliable, and more stock-driven, with weather exerting less, though still significant influence. Recruitment spikes helped sustain the fishery at a small, variable level for years post-collapse, as fishers took advantage of these strong year classes. Occasional recruitment spikes occurred, driven primarily by seasonal drought. Oyster (Crassostrea virginica) recruitment in Chesapeake Bay, USA, dropped precipitously as stocks declined (1920s-1985), then collapsed (1986-present).

Oyster spat recruitment