Oyster Culture in Georgia: Growout

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Oyster Culture in GeorgiaGrowout Marketing

• Alan Power, Ph.D.
• Marine Extension Service
• Shellfish Research Laboratory
• University of Georgia
• 20 Ocean Science Circle
• Savannah, GA 31411-1011
• Tel [phone]

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Georgia Oyster Fishery

• Eastern Oyster, Crassostrea virginica
• 1908 Georgia led country in landings
• today virtually non-existent
• supplemental fishery- clammers, crabbers harvest
  oysters by manually gathering intertidally, break
  clumps up, labor intensive, poor appearance

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Georgia Historical Oyster Landings
Ibs Raw Meat
Value ()
200,000
180,000
160,000
140,000
120,000
100,000
80,000
60,000
40,000
20,000
0
1972
1974
1976
1978
1980
1982
1984
1986
1988
1990
1992
1994
1996
1998
2000
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Oyster Culture Techniques
Bags on Racks
Stick Culture
Trays
Rafts
Long Line
British Columbia Shellfish Growers Information
Resource System www.bcsga.ca/bcsgirs/main/sgmain.h
tm
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Half Shell/ Shucking/ RoastProduction Cycle

• half shell requires single seed
• nursery upweller, bags, trays
• growout subtidal (LL/R)- trays, bags
  intertidal- bags on racks
• shuck/ roast product from cultch set seed
• nursery subtidal (LL/R)- trays, bags
  intertidal- bags, sticks
• growout subtidal (LL/R)- sticks, string shell
  cultch intertidal- bags, sticks

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Oyster Culture in GeorgiaWhy Why Not?

• Advantages
• market size (3) in 18 mo. vs 3 years north
• not spat limited
• unpolluted grow out areas
• Problems
• oyster spat- densely packed clumps
• long spawning season- poor meat yields
• markets long narrow oysters not suitable for
  shucking or half shell trade
• small home market- local oyster roasts

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Oyster Spat Fouling Problem

• overabundant spat- problems growing in floating
  rafts, intertidal trays, or suspended subtidally
• recruitment in Georgia- May to Oct
• spatial and temporal variability
• 300-7600 spat m2/mo., peak July-Sept
• higher subtidally than intertidally
• higher in smaller sheltered tidal marsh creeks
  than more open water areas

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Possible Solutions

• triploid oysters
• grow faster reach size before recruit?
• lower market size
• 3-size at maturity up north, here in 1st yr
• would be cleaner but marketable?
• alternative culture techniques
• transplant during recruit. period
• regular thinning and spat killing
• new technology- Oysterclear/Freshwrap

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TransplantingShellfish Lab Experiments

• collect spatfall (or obtain single spat from
  hatchery) after peak recruit. period, grow in
  floating trays/ upweller/ suspended intertidal
  mesh bags
• transplant to areas of lower recruitment during
  spawning season
• to bags placed intertidally on the bottom
• to areas far up tidal creeks where oyster cover
  is low (high tidal flushing rates)

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Thinning Spat RemovalQueensland Australia

• collect natural spatfall after peak recruit.
  period with oystersticks
• grow spat on these sticks, perform regular
  culling to ensure fast growth and regular shape
• during subsequent recruitment period remove
  excess spat manually or by a 3 second immersion
  in water heated to 82oC

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OysterclearNew Australian Product

• Wattyl Protective Marine Coatings
• http//pcm.wattyl.com.au
• protective coating for oyster shell
• inhibit spat and other fouling
• hot melt coating, dip oyster, dries immediately,
  back in water
• oyster grows, areas exposed,however fouling more
  severe on older areas
• during harvesting coating falls off
• non toxic, not antifoulant, food based

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Summary GA Possible Culture Techniques

• collect spatfall after peak/ obtain single spat
  from hatchery at this time
• grow in upweller/floating trays/bags
  (subtidally), or on collection sticks/mesh bags
  (off bottom intertidally)
• transplant up tidal creek/on bottom
  intertidally/kill excess spat with hot water
  dips/cover in protective oysterclear during
  next recruit. event.
• harvestwinter fatter summer triploids

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MarketingGulf Outlook

• Sept. 02 Seafood Business
• Gulf production, price outlook good everywhere
  except Texas
• Louisiana- increase in farmed oysters
• Mississippi- production on upswing
• continued strong demand- price increase for Gulf
  oysters (4.50-5.50 a pound for meats)
• market for IQF oysters on halfshell grown rapidly
  (25-30 cents a piece), also pressure treated
  oysters (35 cents)

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MarketingWest Coast Outlook

• Sept. 02 Seafood Business
• West Coast market for live oysters never better
• live price remains stable (2.75-4 a dozen)
• market for shucked meats weak
• price fallen 20 percent last year

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MarketingIs There a Demand?

• Feb. 03 Seafood Business
• identify a need to increase supply to meet
  demand- Gulf harvest down 60, Ches. Bay down,
  Pacific Coast stable, imports stable
• particular demand for boutique oysters high
  quality, names and flavors reflecting local
  harvest areas
• promotion NB, e.g. regional oyster festivals-
  Oyster Olympics

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Marketing Summary

• demand for high quality half shell oysters
• raw meat market dominating through cryogenic
  freezing/ pressure treating to reduce vibrio
• increase home roast market through promotion-
  2001 SC vs GA
• 257,568 lbs. meat, 1,066,578 versus
  8,528 Ibs (1/30th), 22,254 (1/50th)