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Providing evidence to improve practice

Individual study: Direct setting of Crassostrea virginica larvae in a tidal tributary: applications for shellfish restoration and aquaculture

Published source details

Steppe C., Fredriksson D., Wallendorf L., Nikolov M. & Mayer R. (2016) Direct setting of Crassostrea virginica larvae in a tidal tributary: applications for shellfish restoration and aquaculture. Marine Ecology Progress Series, 546, 97-112


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Transplant/release captive-bred or hatchery-reared species - Transplant/release molluscs Subtidal Benthic Invertebrate Conservation

A replicated, randomized, controlled study in 2012 in one oyster reef area in Chesapeake Bay, North Atlantic Ocean, USA (Steppe et al. 2016a) found that restoring oyster reefs by releasing hatchery-reared larvae of Eastern oyster Crassostrea virginica using a direct setting technique resulted in higher average initial spat (young oyster) settlement (2.4–8.4 spat/shell) compared to using a traditional remote technique (0.6–4.6). In addition, using the direct technique 61% of the settled spat survived the winter, resulting in higher spat abundance at the restored site (189/m2) compared to an adjacent non-restored site (6/m2). No comparison of survival was made with spat released using the traditional remote technique. Larvae were released in summer 2012. Direct setting consisted of placing twelve trays (32 x 24 x 15 cm) filled with 30 oyster shells in one area of oyster reef at 2–3 m depth, and releasing approximately 2 x 106 hatchery-reared Eastern oyster larvae directly over it. Remote setting consisted of adding approximately 104 larvae to two tanks, each with six spat-collector bags (55 x 20 x 1.5 cm) containing 20 shells each. Three days after larval release, five shells/tray or /bag were retrieved, and the number of spat/shell counted. After winter 2012/2013, spat were counted on 20 shells/tray for the direct technique. Spat on nearby non-restored reef were counted in six 24 x 36 cm quadrats.

 

A replicated, randomized, controlled study in 2012 and 2013 of twelve plots (trays) in one oyster reef area in Chesapeake Bay, North Atlantic Ocean, USA (Steppe et al. 2016b) found that after release, hatchery-reared larvae of Eastern oyster Crassostrea virginica settled and survived equally on cleaned and natural oyster shells for a month. In 2012 and 2013, three days after release, initial spat settlement was similar on cleaned (2012: 8.4 spat/shell; 2013: 3.1) and natural shells (2012: 2.4; 2013: 4.9). After a month, the number of surviving spat was similar on cleaned (2012: 1.3; 2013: 2.9) and natural shells (2012: 1.0; 2013: 1.4). Twelve trays (32 x 24 x 15 cm) filled with 30 oyster shells were placed in one area of oyster reef at 2–3 m depth. Six contained cleaned shells, six contained natural shells. In summer 2012, 2 x 106 hatchery-reared Eastern oyster larvae were released using a direct setting technique. Shells were retrieved after 3 days (5/tray) and one month (20/tray), and the number of spat/shell counted. Shells were replaced afterwards. This was repeated in 2013.

(Summarised by Anaëlle Lemasson)