Title: Oyster Culture in Georgia: Growout
1Oyster 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 (912) 598-2348
2Georgia 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
3Georgia 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
4Oyster 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
5Half 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
6Oyster 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
7Oyster 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
8Possible 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
9TransplantingShellfish 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)
10Thinning 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
11OysterclearNew 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
12Summary 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
13MarketingGulf 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)
14MarketingWest 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
15MarketingIs 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
16Marketing 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)