Sean P. Powers, Kevan Gregalis and Kenneth L. Heck, Jr. University of South Alabama & the Dauphin Island Sea Lab the Dauphin Island Sea Lab RESTORATION OF OYSTER REEFS IN COASTAL ALABAMA Fisheries Habitat Program

Alabama Oyster Habitat (1972) Live oyster reefBuried oyster shell deposits Fisheries Habitat Program

Alabama Oyster Fishery (Source: NMFS) Frederic (3) Opal (3)& Erin (2) Camille (5) Ethel (3) Elena (3) 50 yr average Fisheries Habitat Program

USA OYSTER REEF PROGRAM to develop the scientific understanding necessary to direct oyster restoration and enhancement in Alabama coastal waters. to assist in the development of a long-term strategy for sustained productivity of Alabama’s oyster resources and the associated ecological benefits that accrue from healthy oyster-based habitat. to provide this information to state and federal management agencies, the fishing industry and the general public through outreach activities. Fisheries Habitat Program

Restoration Challenges Larval recruitment Hypoxic and anoxic bottom waters Predation New State Regulations (Dredging) Fisheries Habitat Program

Oyster Recruitment Survey 18 sites throughout Mobile Bay every three weeks for oyster settlement. Jan 2006 – Dec 2007 Synoptic measurements of larval supply Fisheries Habitat Program

Spat Recruitment Methods Fisheries Habitat Program

Hoese 1972, Spat survey # spat m -2 d -1 (Hoese et al. 1972) Fisheries Habitat Program

Hypoxia Based on studies by May, Schroeder, Saoud, and Wallace Fisheries Habitat Program

Predation: Oyster Drills Fisheries Habitat Program

Predation

Reef Elevation u High Relief (1.0 m) Low Relief (0.1 m) 2.5 m 1 m 2 m Anoxic Hypoxic Normoxic

Mobile Bay Results: June # Live Oysters / m 2 Cedar Point ReefSand ReefShellbank Reef # Live Oysters / m # Live Spat / m 2 Cedar Point ReefSand ReefShellbank Reef Site # Live Spat / m # Dead Spat / m 2 Cedar Point ReefSand ReefShellbank Reef Site Fisheries Habitat Program

High vs. Low relief LowHigh Reef Height # Live Spat / m 2 LowHigh Reef Height No effect of vertical relief on average size or total oysters Fisheries Habitat Program

Oyster Mortality Assays Oyster Mortality Rate Cedar Point ReefSand ReefShellbank Reef Site High Low Oyster Mortality Rate Cedar Point ReefSand ReefShellbank Reef Site High relief Low relief A B C * Fisheries Habitat Program

Restoration Challenges: Mobile Bay Dissolved Oxygen Larval supply # spat m -2 d -1 (Hoese et al. 1972) Predation Fisheries Habitat Program

Conclusions Persistence of structure following three major hurricanes. Greater vertical relief of reefs can enhance recruitment. Cost: Benefit ratio falls short of the 10:1 necessary to justify high relief reefs from a fisheries perspective. Because reefs are colonized by other sessile invertebrates, low oyster density does not mean in absence of ecological function. Fisheries Habitat Program

New Strategies Expand areal coverage of low relief reefs at Cedar Point and Sand Reef D.O. studies at white house reef Seed oyster reefs at Shellbank with Hatchery seed and establish spawning sanctuary Fisheries Habitat Program

Spawner sanctuary in Bon Secor 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. Fisheries Habitat Program