Recruitment of oysters in Mobile Bay Sean Powers, Kyeong Park, C-K Kim, Jason Herrmann, and Ben LaCour UNIVERSITY OF SOUTH ALABAMA DAUPHIN ISLAND SEA LAB Fisheries Habitat Program
Alabama Oyster Fishery Frederic (3) Opal (3)& Erin (2) Camille (5) Ethel (3) Elena (3) 50 yr average 0 200, , , ,000 1,000,000 1,200, Landings (kg meat) Fisheries Habitat Program
Habitat Availability: Alabama Oyster Habitat (1972) Live oyster reefBuried oyster shell deposits Fisheries Habitat Program
Habitat Assessment
Addressing Restoration Challenges Dissolved Oxygen Larval supply # spat m -2 d -1 (Hoese et al. 1972) Predation Fisheries Habitat Program
Oyster Recruitment: Survey 18 sites throughout Mobile Bay every three weeks for oyster settlement. Survey 18 sites throughout Mobile Bay every three weeks for oyster settlement. Jan 2006 – Dec 2007 Jan 2006 – Dec 2007 Synoptic measurements of larval supply via plankton pump samples. Synoptic measurements of larval supply via plankton pump samples. Discrete mark & recapture experiments for post- settlement mortality Discrete mark & recapture experiments for post- settlement mortality Validation of a 3-D bio- physical transport model. Validation of a 3-D bio- physical transport model. Fisheries Habitat Program
Spat Recruitment Methods Fisheries Habitat Program
Predation: Oyster Drills Fisheries Habitat Program
Comparison to Hoese et al sites, same locations in Concrete tile, same as Horizontal plate orientation 2-3 week deployments April-November Salinity and temperature ranges were similar Plates moored using fixed pilings
Hoese et al. 1972: Spatial Pattern # spat m -2 d -1 (Hoese et al. 1972)
Spat/m2/day CR11CR12CR13 Larvae/1000L μ Larvae/1000L μ
CR15CR16 Spat/m2/day Larvae/1000L μ Larvae/1000 l μ CR14
Transport Transport Model
Post-settlement Mortality Mark & recapture experiments with newly settled larvae 7-11 mm SH set on concrete tiles by the Auburn Hatchery. Experiments conducted for 5- 7 days. Miss. Sound Middle Bay Bon Secour Cedar Pt. Dauphin Island
Average by region Summer 2007 ab b a b b Bon SecourCedar PointDauphin IslandMiddle BayMississippi Sound Portion of Spat Mortality/Day
Implications for Restoration Further support for high success of reefs in western portion of the study area. Fisheries enhancement should focus attention in these areas. Possibility for spawning sanctuaries in Bon Secour Bay. High retention possible Low post-settlement mortality
Sanctuary positioning Results of the Park and Kim biophysical transport model indicating concentrations of dye released at Shellbank (upper panel) after 6 days and Fish River Reef after 10 days. Release location is indicated by the red star.
Acknowledgements Tech Support, boat time, fishing volunteers and graduate students