1. 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 1

2. Alabama Oyster Fishery
1,200,000
1,000,000
800,000
Landings (kg meat)
600,000
400,000
50 yr average
200,000
1950
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
Opal (3)& Erin (2)
Ethel (3)
Frederic (3)
Elena (3)
Camille (5)
Fisheries Habitat Program 2

3. Habitat Availability: Alabama Oyster Habitat (1972)
Live oyster reef
Buried oyster shell deposits
Fisheries Habitat Program 3

4. Habitat Assessment 4

5. Addressing Restoration Challenges
Predation
Dissolved Oxygen
Larval supply
200
100 10 5 2 1
# spat m-2 d-1
(Hoese et al. 1972)
Fisheries Habitat Program 5

6. 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 via plankton pump samples.
Discrete mark & recapture experiments for post-settlement mortality
Validation of a 3-D bio-physical transport model.
Fisheries Habitat Program 6

7. Spat Recruitment Methods
Fisheries Habitat Program 7

8. Fisheries Habitat Program
Predation: Oyster Drills
Fisheries Habitat Program 8

9. Comparison to Hoese et al. 1972
14 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

10. Hoese et al. 1972: Spatial Pattern
200
100 10 5 2 1
# spat m-2 d-1
(Hoese et al. 1972)

11. Spat/m2/day
CR11
CR12
CR13
Larvae/1000L μ μ

12. CR14 CR15 CR16 Spat/m2/day Larvae/1000L 30-100 μ Larvae/1000 l
Larval Concentration and Settlement shows consistent spatial distribution, Highest larval and spat number near Cedar point and EMS.
1. What processes can cause to this consistent spatial gradient.
2. What processes can responsible for the differences of distribution ?
Larvae/1000 l μ 12

13. Transport
Transport Model

14. 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.
Middle Bay
Miss. Sound
Cedar Pt.
Bon Secour
Dauphin Island

15. Average by region Summer 2007
0.08 b
0.07 b b
0.06
0.05
Portion of Spat Mortality/Day ab
0.04 a
0.03
0.02
0.01
Bon Secour
Cedar Point
Dauphin Island
Middle Bay
Mississippi
Sound

16. 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

17. 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.

18. Tech Support, boat time, fishing volunteers and graduate students
Acknowledgements
Tech Support, boat time, fishing volunteers and graduate students