Recruitment of oysters in Mobile Bay

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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
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Alabama Oyster Fishery
1,200,000
1,000,000
800,000
Landings (kg meat)
600,000
50 yr average
400,000
200,000
0
1950
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
Opal (3) Erin (2)
Ethel (3)
Frederic (3)
Elena (3)
Camille (5)
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Habitat Availability Alabama Oyster Habitat
(1972)
Live oyster reef
Buried oyster shell deposits
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Habitat Assessment
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Addressing Restoration Challenges
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Oyster Recruitment 2006-2007

• 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.

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Spat Recruitment Methods
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Predation Oyster Drills
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Comparison to Hoese et al. 1972

• 14 sites, same locations in 2006-07
• Concrete tile, same as 2006-2007
• Horizontal plate orientation
• 2-3 week deployments
• April-November
• Salinity and temperature ranges were similar
• Plates moored using fixed pilings

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Hoese et al. 1972 Spatial Pattern
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(No Transcript)
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CR15
CR16
CR14
Spat/m2/day
Larvae/1000L 30-100 µ
Larvae/1000 l 100-500 µ
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Transport

• Transport Model

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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
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Average by region Summer 2007
0.08
b
0.07
b
b
0.06
0.05
ab
Portion of Spat Mortality/Day
0.04
a
0.03
0.02
0.01
0
Bon Secour
Cedar Point
Dauphin Island
Middle Bay
Mississippi
Sound
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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

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