(DRAFT) - Taxonomy
Species oyster, Pacific
Species Id M060003
Date 26 AUG 96
TAXONOMY
NAME - oyster, Pacific
OTHER COMMON NAMES - Pacific oyster
ELEMENT CODE -
CATEGORY - Aquatic Molluscs
PHYLUM AND SUBPHYLUM - Mollusca,
CLASS AND SUBCLASS - Bivalvia,
ORDER AND SUBORDER - Ostreoida,
FAMILY AND SUBFAMILY - Ostreidae,
GENUS AND SUBGENUS - Crassostrea,
SPECIES AND SSP - gigas,
SCIENTIFIC NAME - Crassostrea gigas
AUTHORITY - Thunberg, 1793
TAXONOMY REFERENCES - 186
COMMENTS ON TAXONOMY -
Other common names include Giant oyster, Japanese oyster, and Giant Pacific
oyster *10*.
Taxonomy - 1 (DRAFT) - Status
Species oyster, Pacific
Species Id M060003
Date 26 AUG 96
STATUS
Coded Status
Commercial/consumption
Commercial
REFERENCES FOR STATUS - 10
COMMENTS ON STATUS -
The commercial fishery for this species has grown rapidly since its
introduction from Japan to the west coast of the United States in 1903. The
United States now consumes almost 60 percent of the world's total oyster
production. The Pacific oyster is a dominant shellfish in a growing United
States aquiculture industry along the Pacific Coast. 60-70 percent of the
Pacific oyster production is marketed in the Pacific Coast States.
Washington State leads all others for the production of Pacific oysters
which comprise 25 percent of all shellfish landings in Washington State.
The landed dollar value of this species in Washington State was 3.8 million
in 1982 *10*.
Status - 1 (DRAFT) - Distribution
Species oyster, Pacific
Species Id M060003
Date 26 AUG 96
DISTRIBUTION
Distribution - 1 HABITAT ASSOCIATIONS
HABITAT - MARINE
NATIONAL WETLAND INVENTORY CODES
NWI NWICLS NWIMOD NWISPEC
Marine
Marine, intertidal V
REFERENCES FOR NWI - 10
ANIMAL/PLANT SPECIES ASSOCIATIONS -
Mytilicola orientalis
Cliona celata
Plydora ciliata
Vibrio anguillarum
Protogonyalax catenella
Gonyaulax catenella
Ceratium fusus
Gymnodinium splendices
REFERENCES FOR SPECIES ASSOCIATIONS - 10
Habitat Associations - 1 (DRAFT) - Food Habits
Species oyster, Pacific
Species Id M060003
Date 26 AUG 96
FOOD HABITS
TROPHIC LEVEL -
FILTER FEEDER
REFERENCES FOR TROPHIC LEVEL - 10
LIFESTAGE FOOD FOOD PART
General Microorganisms Not Applicable
General Phytoplankton Not Applicable
General Protozoans Not Applicable
General Bacteria Not Applicable
REFERENCES FOR GENERAL FOOD - 10
COMMENTS ON FOOD -
They consume phytoplankton, bacteria and protozoa which are filtered from
the water *10*.
Food Habits - 1 (DRAFT) - Environment Associations
Species oyster, Pacific
Species Id M060003
Date 26 AUG 96
ENVIRONMENTAL ASSOCIATIONS
G = General A = Adult
LIM = Limiting RA = Resting Adult
J = Juvenile FA = Feeding Adult
RJ = Resting Juvenile BA = Breeding Adult
FJ = Feeding Juvenile P = Pupae
L = Larvae E = Egg
RL = Resting Larvae
FL = Feeding Larvae
LIFESTAGE ENVIRONMENTAL ASSOCIATIONS
G Water Temperature: Between 21-27 degrees C
G Water Temperature: Between 15-21 degrees C
G Water Temperature: Below 15 degrees C
G Water Temperature: Specified in Comments
G Relation to Substrate: Attached - normally sessile
G Relation to Substrate: Specified in Comments
A Substrate: Specified in Comments
A Turbidity: Clear water but tolerate periodic cloudiness
REFERENCES FOR ENVIRONMENTAL ASSOC_ - 10
REFERENCES FOR BREEDING ADULT ENVIRONMENTAL ASSOC_ - 10
REFERENCES FOR RESTING JUVENILE ENVIRONMENTAL ASSOC_ - 10
COMMENTS ON ENVIRONMENTAL ASSOCIATIONS -
Pacific oysters live and grow in water temperatures from 4-24 degrees C
although they are able to survive temperatures as low as -4 degrees C when
exposed by high tide. They begin dying at salinities of 10 ppt. High
mortalities result from siltation. Excessive turbidity can tumble the
oysters and knock off their fragile shell edges or stir up bottom sediments
causing silt accumulation over the oyster *10*.
COMMENTS ON FEEDING ADULT ENVIRONTAL ASSOC_ -
The optimum temperature for water transport through adult oysters is 20
degrees C. The optimum salinity for water transport is 25-35 ppt. At 13 ppt
little water is pumped through the gills and at 10.5 ppt harmful effects
are apparent *10*.
COMMENTS ON BREEDING ADULT ENVIRONMENTAL ASSOC_ -
The gametes are not released until the water temperature reaches 19 degrees
C *10*.
COMMENTS ON RESTING LARVAE ENVIRONMENTAL ASSOC_ -
The larvae can survive temperatures below 15 degrees C for short periods
of time and can survive temperatures as high as 30 degrees C. The larval
period increases from 18 days at 72 degrees F to 30 days at 64 degrees F.
Larval setting increases as the temperature increases between 15 and 30
degrees C, but declines at 35 degrees C. The larvae were unaffected by
Environment Associations - 1 (DRAFT) - Environment Associations
Species oyster, Pacific
Species Id M060003
Date 26 AUG 96
constant salinities from 16-34 ppt. The optimum conditions for setting are
30 degrees C with salinities of about 30 ppt. Larval mortality was 27
percent at .25 g/l and 27 percent at .50 g/l *10*.
Environment Associations - 2 (DRAFT) - Life History
Species oyster, Pacific
Species Id M060003
Date 26 AUG 96
LIFE HISTORY
Physical Description: The shell of this species is extremely rough,
extensively fluted, and laminated. The lower valve is deeply cupped and the
upper valve is generally flat. The shells are usually whitish with many
purple streaks and spots radiating away from the umbo. The shape of the
shell varies with the environment. The interior of the shell is white, with
a single muscle scar that is sometimes dark, but never purple or black. The
maximum length is ten inches, but normally the length is from 4-6 inches. It
differs from Crassostrea virginica in never having a purple or black muscle
scar, and from Ostrea lurida in its extremely large size and heavy shell. In
addition, the inside of an O. lurida shell is iridescent green *10*.
Reproduction: Pacific oysters are protandrous hermaphrodites. They change
sex, but their timing is erratic and seasonal. The young are functionally
male during their first spawning, while about half remain male for their
second spawning. The adults function as seperate male or female animals in
any given reproductive season, but a change of sex from male to female often
occurs at some point in life. Sexual maturity is reached during the first
year. They spawn annually in certain coastal waters of British Columbia when
the water temperature is approximately 19.5 degrees C. Oysters carry spawn
during July and August. Once the spawning temperature has been reached,
usually in July or August, spawning is synchronous. Under natural
conditions, simultaneous release of sperm and eggs into the water column is
attained through mutual stimulation. This species is highly prolific and an
average market-sized female (3 inches long) can produce 50-100 million eggs
in a single spawning. The fertilized eggs are spherical, and 45-62 um in
diameter. The egg is multilayered, with membranes that divide the jellylike
outer coat from the small nucleus. The germinal vesicle is eccentrically
located within the nucleolus. Temperature plays a major role in the
development of the fertilized oyster egg. A decrease from 24.5 degrees C to
22.5 degrees C doubled the time required for the formation of trochophore
larvae. Fertilized eggs reach the veliger stage in 72 hours at 14 degrees C,
and in 28 hours at 22 degrees C *10*. Behavior: The pelagic larvae are
planktotrophic, feeding on phytoplankton and growing over a period of 2-3
weeks. They are freeswimming in the larval stage and when they reach a
length of about .30 mm they attach to the bottom or hard surface as spat.
When contact is made with the foot, the larvae crawls onto the surface, and
if suitable, attaches by the left valve. The adult is a filter feeder and
the various particles are sorted by size using mucus secretions. They ingest
bacteria, protozoa, a wide variety of phytoplankton, larval forms of other
invertebrate animals, detritus and some inorganic material. Crabs and
starfish can be serious predators on the young and adults. They are also
preyed on by the Japanese oyster drill (Ocinebra japonica) and by the
predatory flatworm (Pseudostylochus ostreophagus). Mud shrimp also dig
burrows that make the beds too soft for the oyster culture *10*. Origin:
This species was introduced from Japan to the western coast of the United
States in 1903. Limiting factors: This species is limited by temperatures
between 4-24 dregrees C, long periods of exposure to air and dinoflagellate
blooms. Crabs and starfish can be serious predators on young and adults.
Parasites include Mytilicola orientalis (copepod) boring sponges (Cliona
celata) and sea worms (Plydora ciliata). They are not greatly affected by
disease although there are occasional outbreaks of focal necrosis
Life History - 1 (DRAFT) - Life History
Species oyster, Pacific
Species Id M060003
Date 26 AUG 96
(bacterium) and, bacillary necrosis (Vibrio anguillarum)*10*. Population
parameters: This species can produce from 50-100 million eggs in a single
spawning. Sexual maturity is reached during the first year *10*.
Aquatic/terrestrial associations: Predators include crabs and starfish
(Japanese oyster drill, Dungeness crab, rock crab and graceful crab. Mud
shrimp dig burrows that retain water at low tide and make the beds too soft
for oyster culture *10*.
REFERENCES FOR LIFE HISTORY- 10
Life History - 2 (DRAFT) - Management Practices
Species oyster, Pacific
Species Id M060003
Date 26 AUG 96
MANAGEMENT PRACTICES
RESULT MANAGEMENT PRACTICE
Adverse Wastewater disposal/assimilation
Beneficial Predator control
Beneficial Controlling undesirable invertebrate species
Existing Applying pesticides
REFERENCES FOR ADVERSE MANAGEMENT PRACTICES - 10
REFERENCES FOR EXISTING MANAGEMENT PRACTICES - 10
COMMENTS ON MANAGEMENT PRACTICES -
A major long-term concern to the oyster industry in the Pacific Northwest is
the present and potential future loss to water quality because of pollution
(sewage, industrial waste and pulp mill effluents). Starfish can be
controlled by removal. The Japanese oyster drill can be controlled somewhat
by collecting the egg cases before they hatch and careful oyster farming
practices. The pesticide Sevin has been used controversially as a control
agent for ghost shrimp in Washington *10*.
Management Practices - 1 (DRAFT) - References
Species oyster, Pacific
Species Id M060003
Date 26 AUG 96
References
10* Pauley, G.B., B. Van Der Raay, and D. Troutt. 1988. Species
Profiles: life histories and environmental requirements of coastal
fishes and invertebrates (Pacific Northwest)--Pacific oyster. U.S.
Fish and Wildl. Serv. Biol. Rep. 82(11.85). U.S. Army Corps of
Engineers, TR EL-82.4. 28pp.
186 * Turgeon, D.D., A.E. Bogan, E.V. Coan, W.K. Emerson, W.G.
Lyons, W.L. Pratt, C.F.E. Roper, A. Scheltema, F.G. Thompson,
J.D. Williams. 1988. Common and scientific names of aquatic
invertebrates from the United States and Canada: mollusks.
References - 1