Testing Direct Setting of Crassostrea virginica larvae

Currently, the primary method to seed oyster beds for aquaculture and restoration efforts is remote setting, a technique that consist of setting hatchery-reared larvae that are transported to prepared planting sites. While remote setting has proven to be an effective technique, it requires excessive material handling and substrate is becoming more expensive as supply becomes limiting. Direct setting is an alternative setting technique that could potentially reduce material handling and the use of substrate. This study tested the feasibility of direct setting marked Crassostrea virginica larvae on submerged oyster reefs without an enclosure. We placed three identical artificial oyster reefs containing 31 shell bags into the Cooperative Oxford Lab Sanctuary (COLS) and 3 days later released 1.7 x10⁶ calcein marked larvae at each reef located in 4.5 m of water. Reefs were removed from the COLS 1 week later and processed for number of bags with spat in each reef and confirmed larval origin using a blue light excitation. Of the 31 shell bags from site 1, 23 bags had shell with spat. Site 2 had 19 bags containing shells with spat, and site 3 had 15 bags containing shell with spat. A calcein mark was examined on 100% of spat on shell. Direct setting of C. virginica larvae for restoration and aquaculture purposes could provide an alternative setting method.