Pacific Oyster

The Science

trilax.org

Taxonomic description

  • Elongated, sculpted shell with rounded radial folds (wavy) [3].
  • Shell is rounded with fluting when grown on hard substrate; oval, smooth on soft substrate
  • Shell color is usually white with purple streaks & spots, inside of shell is white with a purple hue over muscle scar[1,2]
  • Shell length is normally 10-15 cm (4-6’), but as long as 38 cm (15’) [1]

Distribution

  • Occurs naturally in estuarine & coastal waters of Japan and Southeast Asia [1,2]
  • Introduced around the world as a way to revive exploited oyster stocks [2]
  • In No. America, it occurs from southeastern Alaska to Baja California 

Life history

  • Can live up to 30 years, but fully mature and able to reproduce after 1 year [2]
  • Grows 2.5 cm  (1”) per year. [3]
  • Begins life as a male, but after a year functions as a female [3]
  • Spawning is temperature dependent, usually occurring when warm (i.e., often summer breeders) 
  • Minimum reproduction temperature is 15° C (59° F), maximum temperature is 34° C (93.2° F) [3]
  • Fertilization occurs externally, free-swimming larvae group together to find suitable habitats on which to settle [3]

Habitat

  • Found in sheltered waters, from slightly above sea level to subtidal depths of 3 meters (9.8 ft)  [3]
  • Settles on hard surfaces, such as rocks, pier pilings, shells of adult oysters or other shellfish species [3]
  • Filter feeder, feeds on phytoplankton & detritus in the water
  • Predators include seastars, crabs, benthic feeding fish, and wading birds [3]

The Fishery

Carlsbad Aquafarm

Seasonal availability

  • Available year-round when farm-raised

Managing authority

  • Growing methods & product are regulated by federal, state & local agencies (e.g., Army Corps of Engineers (lead), NOAA, U.S. Fish & Wildlife Service, US. Dept of Agriculture, Food & Drug Administration, County Dept of Public Health) [5]
  • Pacific Coast Shellfish Growers Association is an industry-based organization that includes & represents growers along the U.S. Pacific coast in establishing science-based farming practices, & ensuring environmental protection, shellfish safety, & support with regulatory, technology & marketing updates. 

Gear type

  • Grown in trays submerged in a local embayment. Removed every 3 weeks, rinsed, and put in tumbler, which mimics wave action & breaks off the leading edge where shell grows. When put back in trays, oyster repairs shell, resulting in a deeper, cupped shape shell & fatter oyster [6]
  • No fertilizers, chemicals or antibiotics added-food is naturally occurring phytoplankton.

Status of the fishery

  • Most U.S. farms produce their own juvenile oysters (called “seed”) from selected broodstock [5].

Potential ecosystem impacts

  • Aquaculture reduces the pressure on local natural populations and limits the need for imported seafood.
  • Shells are recycled for uses in the environment (e.g., nest material for endangered least terns or used in construction by humans) [6]
  • This oyster is potentially invasive in local ecosystems due to culinary preference of this Japanese species over the native (i.e., it is prevalent), fast growth and reproductive rates, and tolerance to a wide range of environmental conditions [6, 7, 8]
  • Potentially contributes to spread of other introduced species (e.g., Atlantic oyster drill)
  • Improves water quality through its feeding activity which removes algae and particulates.

The Seafood

Riaboo, openfoodsource.com

Edible portions

  • Entire contents of the shell

Culinary uses

  • Local oysters are available fresh; imported can be found canned, or frozen [12]
  • Shucking, or opening, the oyster requires a special shucking knife inserted into the shell to pry it open, and to cut the hinge and adductor muscle in order to remove meat [e.g. 13].
  • Many people prefer raw oyster, but they can also be roasted, steamed, fried, scalloped, stewed, baked, stuffed, boiled, marinated, poached and sautéed
  • Used in various recipes, such as oyster stew, pan fried oysters, scalloped oysters with fennel, glazed oysters on crab and leeks, and chicken with oysters and straw mushrooms [e.g. 14

Description of meat

  • The sweet and mild flavor is highly valued
  • Has a salty kick with a delicious buttery texture 

Nutritional information  

Seasonal availability

  • Available farm fresh in San Diego year-round

Toxicity report

  • There are no reported contaminants from local farm raised oyster [15]; wild caught oyster from San Diego are not recommended for consumption without bay water quality and oyster toxicity analyses.

References

1. Moore, T.O., J.D. Moore. 2008. Culture of oysters. Status of the fisheries report.  California Dept. of Fish and Wildlife.

2. Nehring, S. 2011. NOBANIS – Invasive Alien Species Fact Sheet – Crassostrea gigas. – From: Online Database of the European Network on Invasive Alien Species - NOBANIS www.nobanis.org.

3. NIMPIS 2013, Crassostrea gigas reproduction and habitat, National Introduced Marine Pest Information System. www.marinepests.gov.au/nimpis

4. http://animals.nationalgeographic.com/animals/invertebrates/oyster/

5. FishWatch. 2013. Pacific oyster. NOAA FishWatch U.S. Seafood Facts. www.fishwatch.gov/seafood_profiles/species/oyster/species_pages/pacific_...

6. Carlsbad Aquafarm. Prod. Brian Robles and Cindy Kendrick. Green-Scene, 2013. YouTube.

7. University of California Davis. 1996. California Oyster Culture.California Aquaculture. University of California, Davis Department of Animal Science, 

8. Johnson, C.S. “A new oyster invades” http://caseagrantnews.org/2013/07/02/a-new-oyster-invades/ July 2013. 

9. Washington Dept of Fish and Wildlife. 2013. http://wdfw.wa.gov/fishing/shellfish/oysters/facts.html

10. Seafood Health Facts. Pacific Oyster, 2013. <http://seafoodhealthfacts.org/seafood_choices/oysters.php>.

11. Moore, T. 2008. Pacific Oyster, Crassostrea gigas. Status of the Fisheries Report 2008. California Dept of Fish & Wildlife. http://dfg.ca.gov/serp.html?q=pacific+oyster&cx=001779225245372747843%3A...

12. EDF Seafood Selector. 2013. Monterey Bay Aquarium Foundation .http://seafood.edf.org/oysters.

13.  SeafishTheAuthority, 2013. How to prepare Pacific Oysters.  www.youtube.com/watch?v=qchyv_HrSHc.

14. Pacific Coast Shellfish Growers Association, 2013. http://pcsga.org.previewdns.com/recipes-nutrition/.

15. The Super Green List. 2013. Monterey Bay Aquarium Seafood Watch. www.montereybayaquarium.org/cr/cr_seafoodwatch/sfw_health.aspx

16. Main, E. 2013. 6 Surprising Facts about oysteres. Rodale News. www.rodale.com/benefits-eating-oysters-0?page=1