(DRAFT) - Taxonomy
Species oyster, American
Species Id M060170
Date 26 AUG 96
TAXONOMY
NAME - oyster, American
OTHER COMMON NAMES - oyster and eastern oyster
ELEMENT CODE - 09/09/87
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 - virginica,
SCIENTIFIC NAME - Crassostrea virginica
AUTHORITY - Gmelin, 1791
TAXONOMY REFERENCES - 186 and 20
COMMENTS ON TAXONOMY -
Other common name is eastern oyster *20*.
Taxonomy - 1 (DRAFT) - Status
Species oyster, American
Species Id M060170
Date 26 AUG 96
STATUS
Coded Status
Commercial
Commercial/consumption
Depleted
REFERENCES FOR STATUS - 20 and 136
COMMENTS ON STATUS -
Oysters are valued as a luxury food item *20*.
American oysters are prominent members of the benthic community in
Chesapeake Bay and contribute substantially to the economy of the region.
Oysters have recently experienced severe declines in abundance. Intense
fishing pressure, loss of habitat, and water quality degradation have been
blamed for declines in the abundance of this species *136*.
Status - 1 (DRAFT) - Distribution
Species oyster, American
Species Id M060170
Date 26 AUG 96
DISTRIBUTION
Distribution - 1 HABITAT ASSOCIATIONS
HABITAT - Aquatic
REFERENCES FOR HABITAT - 142 and 20
LAND USE -
Water
Bays and Estuaries
REFERENCES FOR LAND USE - 142 and 20
NATIONAL WETLAND INVENTORY CODES
NWI NWICLS NWIMOD NWISPEC
Marine FL.
Estuarine FL.
Marine FL4
Estuarine FL4
Marine OW0
Estuarine OW0
Marine RB.
Estuarine RB.
Marine L
Marine L
Estuarine L
Estuarine L
Marine M
Marine N
Marine P
Marine R
Marine V
Marine V
Estuarine V
Estuarine V
Marine 1
Marine 1
Estuarine 1
Estuarine 1
Marine 2
Marine 2
Estuarine 2
Estuarine 2
Marine 3
Marine 3
Estuarine 3
Estuarine 3
Marine 4
Marine 4
Estuarine 4
Estuarine 4
Marine FL1
Marine FL1
Estuarine FL1
Estuarine FL1
Marine FL4
Marine FL4
Estuarine FL4
Estuarine FL4
Habitat Associations - 1
NWI NWICLS NWIMOD NWISPEC
Marine OW0
Marine OW0
Estuarine OW0
Estuarine OW0
Marine RB.
Marine RB.
Estuarine RB.
Estuarine RB.
Marine RF.
Marine RF.
Estuarine RF.
Estuarine RF.
Marine RF2
Marine RF2
Estuarine RF2
Estuarine RF2
Marine L
Marine L
Marine L
Estuarine L
Estuarine L
Estuarine L
Marine M
Marine M
Estuarine M
Estuarine M
Marine N
Marine N
Estuarine N
Estuarine N
Marine P
Marine P
Estuarine P
Estuarine P
Marine R
Marine R
Estuarine R
Estuarine R
Marine V
Marine V
Marine V
Estuarine V
Estuarine V
Estuarine V
Marine 1
Marine 1
Marine 1
Estuarine 1
Estuarine 1
Estuarine 1
Marine 2
Marine 2
Marine 2
Estuarine 2
Estuarine 2
Estuarine 2
Marine 3
Marine 3
Marine 3
Habitat Associations - 2
NWI NWICLS NWIMOD NWISPEC
Estuarine 3
Estuarine 3
Estuarine 3
Marine 4
Marine 4
Marine 4
Estuarine 4
Estuarine 4
Estuarine 4
Marine EM5
Marine EM5
Estuarine EM5
Estuarine EM5
Marine FL4
Marine FL4
Estuarine FL4
Estuarine FL4
Marine RB.
Marine RB.
Estuarine RB.
Estuarine RB.
Marine RF.
Marine RF.
Estuarine RF.
Estuarine RF.
Marine RF2
Marine RF2
Estuarine RF2
Estuarine RF2
Marine L
Marine L
Estuarine L
Estuarine L
Marine M
Marine M
Estuarine M
Estuarine M
Marine N
Marine N
Estuarine N
Estuarine N
Marine P
Marine P
Estuarine P
Estuarine P
Marine R
Marine R
Estuarine R
Estuarine R
Marine V
Marine V
Estuarine V
Estuarine V
Marine FL.
Estuarine FL.
Marine FL4
Estuarine FL4
Marine RB.
Estuarine RB.
Habitat Associations - 3
NWI NWICLS NWIMOD NWISPEC
Marine RF.
Estuarine RF.
Marine RF2
Estuarine RF2
Marine FL3 L
Estuarine RF. L
Marine RF3 M
Estuarine FL3 M
Marine RF. N
Estuarine RF3 N
Marine FL. P
Estuarine FL. P
Marine R
Estuarine R
Marine V
Estuarine V
Marine 1
Estuarine 1
Marine 2
Estuarine 2
Marine 3
Estuarine 3
Marine 4
Estuarine 4
Marine
Marine
Marine
Estuarine
Estuarine
Estuarine
Estuarine
Marine
REFERENCES FOR NWI - 142
ANIMAL/PLANT SPECIES ASSOCIATIONS -
barnalces
mussels
protozoans
crabs
snails
flatworms
Haplosporidium nelsoni
Perkinsus marinus
REFERENCES FOR SPECIES ASSOCIATIONS - 136
COMMENTS ON SPECIES ASSOCIATIONS -
Fecal and pseudofecal material is important in sediment production and
deposition, providing sites for remineralizing bacterial action, and as food
source for deposit feeders. The hard shell provides a substrate for
numberous epifaunal organisms such as barnacles and mussels. These
characteristics make the oyster an important member of the benthic community
throughout the Chesapeake Bay. Oysters, especially in the juvenile stages,
are subject to heavy parasitism and predation by many organisms including
protozoans, crabs, snails, and flatworms *136*.
Oysters diseases, notably Haplosporidium nelsoni ("MSX") and Perkinsus
marinus ("dermo"), have caused significant mortality in the lower Bay. The
Habitat Associations - 4 organisms causing these diseases require the higher salinities of the lower
Bay to proliferate. The devastating oyster diseases, MSX and dermo, may not
be restricted by salinity. Infection rate may be related to the oyster's
cellular responses to salinity. In the Choptank River, at salinities < 13
ppt, MSX has been observed *136*.
HABITAT SUITABILITY MODELS -
Estuarine V1 Percentage of bottom covered with suitable clutch. minimum 0%;
maximum 100%; optimum 50% or greater. Estuarine V2 Mean summer water
salinity. minimum 5ppt; maximum 40ppt; optimum 10-30ppt. Estuarine V3 Mean
abundance of living oysters (gregarious factor). minimum 0 oysters/sq.
meter; maximum unknown; optimum greater than 25 oysters/sq. meter. Estuarine
V4 Historic mean water salinity. minimum 5ppt; maximum 40ppt; optimum
10-20ppt. Estuarine V5 Mean interval between killing floods. minimum 1 year;
maximum unknown; optimum greater than 3 years. Estuarine V6 mean substrate
firmness (penetrometer value). minimum 0; maximum unknown; optimum greater
than 1 kg/sq. cm. Estuarine V7 Mean predator abundance (southern oyster
drills). minimum 0, maximum unknown, hyperbolic decline (S.I.=1 at 0.1
drills/sq. meter, SI=0.03 at 2 drills/sq. meter). Estuarine V8 Mean disease
intensity (Perkinsus marinus; coded by intensity). minimum 0; maximum 5;
optimum 0-1.
COMMENTS ON HABITAT SUITABILITY MODELS -
ASSUMPTIONS: V1-Clean, unfolded clutch material such as natural or planted
shells are optimal for metamorphosing larvae. Small shells, shell hash,
gravel, rocks, and other solid material are suitable. Optimal coverage of
bottom with clutch material is >= 50%. Clutch ammounts and coverage may be
increased by planting shells. V2-Metamorphosing oyster larvae will set
(attach) at salinities between 5b and 35 ppt. Optimal setting occurs between
10 and 30 ppt and maximum setting occurs between about 18 and 22 ppt.
V3-Oyster larvae set (attach) gregariously in the natural environment in
response to water borne pheromones, mantle fluid, metabolites, and shell
leachates from living oysters and/or their remains. After spontaneous
setting of spat on old clutch, their presence will stimulate more larvae to
set in the immediate vicinity. Optimal abundance of oysters for this factor
is set at >= 25/sq. meter. V4-Oysters survive over a salinity range of 5 to
40+ ppt but flourish within a range of 10 to 25 ppt provided predatore,
pathogens, or shell pests are limited. The optimal historic salinity mean is
between 10 and 20 ppt. V5-Prolonged exposure to fresh water will kill 50 to
100% of the oysters in a given area. Significant mortalities occur with
exposures of <=2 ppt for several weeks. Recovery to preflooded population
levels requires 2 to 3 years under optimal salinity conditions. V6-Optimal
substrates support the weight of an oyster and usually contain >=10% (by
volume) of shell or other material (e.g., rocks) and a mixture of sand,
silt, and clay particals. Soft muds (>80% silt and/or clay) and shifting
sands (>80% sand) are unsuitable for oysters unless clutch is planted.
Penetrometer values of >=1 kg/sq. cm are optimal for substrate firmness on
oyster reefs. V7-The southern oyster drill (Thais haemastoma) is the most
destructive predator in the Gulf of Mexico and capabel of killing >50% of
the oysters on any reef with salinities of >=18 ppt. Predation is a function
of the drills' relative size and abundance. The total absence of drills is
considered optimal, and the presence of >=1 drill/sq. meter of >4-cm length
is considered unacceptable. V8-The protazoan Perkinsus marinus is the most
prevalent and lethal oyster pathogen in the Gulf of Mexico. It will kill
>50% of the infected oysters on a given reef. The total absence of the
pathogen is optimal for adult and seed oysters. Oysters with "medium-heavy"
to "heavy" infections (intensity codes of 5 and 6, respectively) will
succumb. NOTE: In addition to these assumptions it should be noticed that
this model was developed for OYSTERS IN THE GULF OF MEXICO. The authors note
that oysters that exist north of Cape Hatteras are physiologically
dissimilar to those in the Gulf of Mexico.*142*
Habitat Associations - 5 REFERENCES FOR HABITAT SUITABILITY MODELS - 142
Habitat Associations - 6 (DRAFT) - Food Habits
Species oyster, American
Species Id M060170
Date 26 AUG 96
FOOD HABITS
TROPHIC LEVEL -
FILTERER
REFERENCES FOR TROPHIC LEVEL - 20 and 136
LIFESTAGE FOOD FOOD PART
General Plants Not Applicable
General Chrysophyta Not Applicable
General Haptophyceae Not Applicable
General Bacillariophyceae Not Applicable
General Animals Not Applicable
General Crustaceans Not Applicable
General Ostracods Not Applicable
Important Plants Not Applicable
Important Chrysophyta Not Applicable
Larva Plants Not Applicable
Larva Chrysophyta Not Applicable
Adult Microorganisms
Adult Bacteria
Adult Protozoans
Adult Plants Not Applicable
General Microorganisms
General Bacteria
General Protozoans
Adult Chrysophyta Not Applicable
Adult Haptophyceae Not Applicable
Adult Bacillariophyceae Not Applicable
Adult Animals Not Applicable
Adult Crustaceans Not Applicable
Adult Ostracods Not Applicable
General Algae Not Specified
General Bacteria Not Specified
General Detritus Not Specified
REFERENCES FOR GENERAL FOOD - 136
REFERENCES FOR ADULT FOOD - 20
REFERENCES FOR LARVAE FOOD - 20
COMMENTS ON FOOD -
The American oyster is an epibenthic suspension feeder, ingesting a variety
of algae, bacteria, and small detrital particles, most within a range of
3-35 um. Capture efficiency decreases rapidly at particle sizes < 3 um.
Particles filtered but not ingested by the oyster are eliminated as
pseudofeces. Fecal and pseudofecal material is important in sediment
producion and deposition, providing sites for remineralizing bacterial
action, and as food source fo deposit feeders *136*.
Food Habits - 1 (DRAFT) - Food Habits
Species oyster, American
Species Id M060170
Date 26 AUG 96
COMMENTS ON ADULT FOOD -
Adult oysters filter large quantities of brackish water and remove naked
flagellates. They most effectively filter particles in the 3-4 micrometer
range. The filtration rate is independent of the available food supply, the
stage of tide, or time of day. If food is absent, however, the valves are
closed most of the time. In Chesapeake Bay, oysters ingested the
predominant diatom plankton which changes seasonally. Dinoflagellates,
ostracods, small eggs, and terrestrial pollen were also ingested *20*.
COMMENTS ON LARVAE FOOD -
Oyster larvae feed largely on plankton, particularly small, naked
flagellates. The larvae do not consume bacteria *20*.
Food Habits - 2 (DRAFT) - Environment Associations
Species oyster, American
Species Id M060170
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 Air Temperature: Specified in Comments
G Water Temperature: Between 21-27 degrees C
G Water Temperature: Specified in Comments
G Dissolved Oxygen: Specified in Comments
G Water pH: Between 6.5-8.5
G Substrate: Mud or silt
G Substrate: Rocks
G Tidal marsh features: mud flats
G Estuarine habitat zone: bay
G Estuarine habitat zone: sound
G Currents: tidal
G Turbidity: Clear water
G Relation to Substrate: Occurs on substrate [not penetrating]
G Relation to Substrate: Occurs in substrate [penetrating]
G Relation to Substrate: Attached - normally sessile
G Bottom Type [Aquatic]: Pebble
G Bottom Type [Aquatic]: Gravel
G Bottom Type [Aquatic]: Organic debris
G Bottom Type [Aquatic]: Sand
G Stability of Bottom: Stable
G Water Velocity [Instream Flow Group Increments]: Greater than 3.5 fps
G Water Level: Permanently flooded areas
G Water Depth Preference: Less than 1 ft.
G Water Depth Preference: 1-5 ft.
G Water Depth Preference: 5-10 ft.
G Water Depth Preference: 10-25 ft.
G Water Depth Preference: 25-50 ft.
G Water Depth Preference: 50-100 ft.
G Water Depth Preference: 100-200 ft.
G Water Depth Preference: 200-500 ft.
G Water Depth Preference: 500-1000 ft.
G Water Depth Preference: 1000-1500 ft.
G Water Depth Preference: Greater than 1500 ft.
G Elevation: Below sea level
G Coastal Features: Reefs
G Coastal Wetlands: Sounds and bays
LIM Water Temperature: Specified in Comments
LIM Dissolved Oxygen: Specified in Comments
LIM Water pH: Between 6.5-8.5
LIM Turbidity: Murky water [High turbidity]
Environment Associations - 1 (DRAFT) - Environment Associations
Species oyster, American
Species Id M060170
Date 26 AUG 96
LIFESTAGE ENVIRONMENTAL ASSOCIATIONS
LIM Coastal Features: Reefs
LIM Water Temperature: Specified in Comments
LIM Dissolved Oxygen: Specified in Comments
LIM Water pH: Between 6.5-8.5
LIM Turbidity: Clear water
LIM Coastal Wetlands: Sounds and bays
LIM Estuarine habitat zone: bay
LIM Estuarine habitat zone: sound
LIM Estuarine habitat zone: offshore
LIM Water Temperature: Specified in Comments
LIM Dissolved Oxygen: Specified in Comments
LIM Water pH: Between 6.5-8.5
LIM Relation to Substrate: Occurs on substrate [not penetrating]
LIM Relation to Substrate: Attached - normally sessile
LIM Bottom Type [Aquatic]: Mud or silt
LIM Bottom Type [Aquatic]: Rubble
LIM Stability of Bottom: Stable
LIM Water Velocity [Instream Flow Group Increments]: Greater than 3.5 fps
LIM Estuarine habitat zone: bay
LIM Estuarine habitat zone: sound
LIM Estuarine habitat zone: offshore
LIM Currents: tidal
LIM Water Temperature: Specified in Comments
LIM Dissolved Oxygen: Specified in Comments
LIM Water pH: Between 6.5-8.5
LIM Relation to Substrate: Occurs on substrate [not penetrating]
LIM Relation to Substrate: Attached - normally sessile
LIM Bottom Type [Aquatic]: Sand
LIM Bottom Type [Aquatic]: Mud or silt
LIM Bottom Type [Aquatic]: Gravel
LIM Bottom Type [Aquatic]: Rubble
LIM Stability of Bottom: Stable
LIM Water Velocity [Instream Flow Group Increments]: Greater than 3.5 fps
LIM Coastal Wetlands: Sounds and bays
LIM Estuarine habitat zone: bay
LIM Estuarine habitat zone: sound
LIM Estuarine habitat zone: offshore
LIM Currents: tidal
G Substrate: Specified in Comments
BA Water Temperature: Between 15-21 degrees C
BA Water Temperature: Between 21-27 degrees C
BA Water Temperature: Specified in Comments
L Water Temperature: Specified in Comments
L Relation to Substrate: Attached - normally sessile
L Relation to Substrate: Specified in Comments
G Turbidity: Specified in Comments
A Turbidity: Specified in Comments
FA Turbidity: Specified in Comments
G Water Depth Preference: Less than 1 ft.
G Water Depth Preference: 1-5 ft.
G Water Depth Preference: 5-10 ft.
G Water Depth Preference: 10-25 ft.
Environment Associations - 2 (DRAFT) - Environment Associations
Species oyster, American
Species Id M060170
Date 26 AUG 96
LIFESTAGE ENVIRONMENTAL ASSOCIATIONS
G Water Depth Preference: 25-50 ft.
G Water Depth Preference: Specified in Comments
G Dissolved Oxygen: Specified in Comments
REFERENCES FOR ENVIRONMENTAL ASSOC_ - 20, 142, 25 and 136
REFERENCES FOR LIMITING ENVIRONMENTAL ASSOC_ - 20, 142 and 25
REFERENCES FOR ADULT ENVIRONMENTAL ASSOC_ - 136
REFERENCES FOR FEEDING ADULT ENVIRONMENTAL ASSOC_ - 136
REFERENCES FOR BREEDING ADULT ENVIRONMENTAL ASSOC_ - 136
REFERENCES FOR LARVAE ENVIRONMENTAL ASSOC_ - 136
COMMENTS ON ENVIRONMENTAL ASSOCIATIONS -
Water temp. from -2 to 36 degrees C, optimum 20 to 30, critical
thermal maximum = 48 degrees C. At low tide may be exposed to air
temperatures from well below freezing to above 49 degrees C.
Salinities of 20-35 ppt were required for normal embryo development in
Chesapeake Bay, optimum = 28 ppt. 0 Dissolved Oxygen- oysters are
facultative anaerobes.*136*
All Chesapeake oysters are subtidal. American oysters prefer a firm
substrate: pilings, hard rock bottoms, and substrates firmed with the
oyster shells of previous generations *136*.
Oysters are sensitive to both turbidity and sedimentation. The observation
that the upstream limit of producing oyster bars has shifted downstream
several miles in historic times is evidence of the impact of sedimentation.
Areas of good circulation produce better setting and survival of young
oysters. Most oysters in the Chesapeake are found in areas less than 10 m
deep in which circulation patterns promote adequate levels of dissolved
oxygen *136*.
COMMENTS ON ADULT ENVIRONMENTAL ASSOC_ -
Excessive sediment deposition smothers adults and prevents setting of spat
*136*.
COMMENTS ON FEEDING ADULT ENVIRONTAL ASSOC_ -
Currents are important to American oysters. The volume of water
immediately above an oyster bed must be renewed 72 times every 24 hr for
maximum feeding; therefore, oysters require a moderate current.*25*
Adult feeding rates are depressed at suspended solids concentrations above
24 mg/l and feeding ceases at concentrations above approximately 50 mg/l.
Food availability is another significant factor dictating their survival.
Foods of critical sizes are needed for the different life stages; with the
cell sizes generally ranging form 3-35 um *136*.
Environment Associations - 3 (DRAFT) - Environment Associations
Species oyster, American
Species Id M060170
Date 26 AUG 96
COMMENTS ON BREEDING ADULT ENVIRONMENTAL ASSOC_ -
Exposure to 35 degree C water accelerated gametogenesis and spawning, but
subsequent spawning was prevented. Spawning temperatures for three
distinct races were determined. Requirements were as follows: the northern
race (New England), 16.4 degrees C; the mid-Atlantic race, 20 degrees C;
the Gulf of Mexico race, 25 degrees C. Low salinity inhibits gonadal
maturation in oysters in Chesapeake Bay and Long Island Sound.
Reproductive failure may be a direct effect of salinity or might be caused
by inadequate feeding at low salinity.*25*
The American oyster in the Chesapeake Bay spawns in the summer when water
temperatures exceed 15 oC. Heavy spawning is likely to occur at 22-23 oC.
Sperm and eggs are released into the water where fertilization occurs,
producing free-swimming larvae *136*.
COMMENTS ON JUVENILE ENVIRONMENTAL ASSOC_ -
Areas of good circulation produce better setting and survival of young
oysters *136*.
COMMENTS ON RESTING JUVENILE ENVIRONMENTAL ASSOC_ -
Maximum setting occurs on horizontal surfaces. They prefer to set on the
bottom rather than on panels suspended in the water column.*25* It is
theorized that rising temperature over tidal flats during the flood tides
stimulates setting. Swimming larvae have positive phototaxis, which
becomes negative with increased temperature. Currents also influence
setting patterns.*25*
COMMENTS ON LARVAE ENVIRONMENTAL ASSOC_ -
Sperm and eggs are released into the water where fertilization occurs,
producing free-swimming larvae. The duration of the larval stage varies
with temperature, lasting sometimes as few as 7 to 10 days, but most often
between 2 to 3 weeks before the larvae set and became sessile organisms
*136*.
COMMENTS ON RESTING LARVAE ENVIRONMENTAL ASSOC_ -
Younger larvae stay in the water column about 1.0 m below the surface.
Older larvae remain near the bottom in the halocline of estuaries during
flood tide and rise nearer the surface during the ebb tide.*25*
COMMENTS ON FEEDING LARVAE ENVIRONMENTAL ASSOC_ -
It was found that gradually rising salinities stimulate older larvae to
swim and falling salinities cause them to sink. It is theorized that
varied swimming patterns associated with changes in salinity may allow
larvae to avoid being flushed from the estuaries or may even be a transport
mechanism within the estuary.*25*
Environment Associations - 4 (DRAFT) - Life History
Species oyster, American
Species Id M060170
Date 26 AUG 96
LIFE HISTORY
PHYSICAL DESCRIPTION: A mollusk with 2 hinged shells- the left valve is
almost always thicker and heavier than the right and more deeply cupped. The
oyster is cemented to the substrate on its left valve. Hinge teeth are
absent, but a buttress on the right valve fits into a depression on the
left. There is no gap between the valves when fully closed;*136*
REPRODUCTION: In Chesapeake Bay spawning occurs at 21-24 degrees C. Eggs
hatch about 6 hours after fertilization, larvae are meroplanktonic and
remain in water column for 2-3 weeks after hatching then they seek a solid
surface for attachment (process is called setting). Newly set oysters are
called spat;*136*
BEHAVIOR: sessile filter feeder;
SPECIES INTERACTIONS: Adults destroyed by gastropod oyster drills
(Urosalpinx cinerea & Eupleura caudata), the southern oyster drill (Thais
haemastoma), the whelk (Busycon canaliculatum), the starfish (Astreias
forbesi), and the crab (Cancer irroratus, Callinectes spidus, and Carcinus
maenas). Spat are preyed on by the flatworm (Stylochus ellipticus) and
larvae are consumed by filter feeders, including the bay anemone (Diadumene
leucolena). Competition for space exists with other benthic mollusks.*136*
All Chesapeake oysters are subtidal. American oysters prefer a firm
substrate: pilings, hard rock bottoms, and substrates firmed with the oyster
shells of previous generations. The American oyster in the Chesapeake Bay
spawns in the summer when water temperatures exceed 15 oC. Heavy spawning is
likely to occur at 22-23 oC. Sperm and eggs are released into the water
where fertilization occurs, producing free-swimming larvae. The duration of
the larval stage varies with temperature, lasting sometimes as few as 7 to
10 days, but most often between 2 to 3 weeks before the larvae set and
became sessile organisms *136*.
REFERENCES FOR LIFE HISTORY- 20, 25, 142 and 136
Life History - 1 (DRAFT) - Management Practices
Species oyster, American
Species Id M060170
Date 26 AUG 96
MANAGEMENT PRACTICES
RESULT MANAGEMENT PRACTICE
Beneficial Mariculture activities
Existing Mariculture activities
Beneficial Controlling pollution [thermal, chemical, physical]
Beneficial Controlling sedimentation
Beneficial Regulating commercial harvest gear types
Existing Regulating commercial harvest gear types
Beneficial Regulating commercial harvest levels
Existing Regulating commercial harvest levels
Beneficial Regulating harvest - restricting number of hunters
Existing Regulating harvest - restricting number of hunters
Beneficial Regulating harvest - setting size limits
Existing Regulating harvest - setting size limits
Beneficial Regulating harvest of species being described
Existing Regulating harvest of species being described
Beneficial
Adverse Shoreline modification/development
REFERENCES FOR BENEFICIAL MANAGEMENT PRACTICES - 20 and 25
REFERENCES FOR ADVERSE MANAGEMENT PRACTICES - 25
REFERENCES FOR EXISTING MANAGEMENT PRACTICES - 25 and 20
COMMENTS ON MANAGEMENT PRACTICES -
Because oysters occur in estuarine areas, they are vulnerable to disturbance
by development projects. Because of shoreline development, the amount of
setting area has declined. Heavy mortality due to predation has also
contributed to declining stocks. Harvests in the Gulf of Mexico and the
South Atlantic have remained stable for the last 30 years, however, harvests
in the mid-Atlantic and Chesapeake Bay have declined.
Soft muddy substrates may be improved by adding clam or oyster shells for
spat development.*25*
Management Practices - 1 (DRAFT) - References
Species oyster, American
Species Id M060170
Date 26 AUG 96
References
20* Stanley, J, M. Sellers. 1986. Species Profiles: Life Histories
and Environmental Requirements of Coastal Fishes and
Invertebrates (Gulf of Mexico) -- American Oyster. U.S. Fish and
Wildlife Service Biol. Rep. 82(11.64) pp 25.
*25* Sellers, M., Stanley, J. 1984. Species Profiles: Life Histories
and Environmental Requirments of Coastal Fishes and
Invertebrates (North Atlantic) -- American Oyster. U.S. Fish and
Wildlife Service Biol. Rep. 82(11.23) pp 16.
136 * Chesapeake Bay Program. 1988. Habitat Requirements for
Chesapeake Bay Living Resources. Chesapeake Executive
Council pp 86.
142* Cake, E. W. Jr. 1983. Habitat Suitability Index Models: Gulf of
Mexico American Oyster. U.S. Fish and Wildlife Service Biol.
Rep. 82(10.57) pp 37.
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