Chesapeake Bay Introduced Species Database

Crassostrea gigas

Common name(s):
Pacific Oyster
The Pacific Oyster is native to the Indo-West Pacific and is the most widely transplanted shellfish in the world, introduced to at least 42 countries. Incredibly there are no established populations in western Atlantic waters, in spite of illegal or unofficial introductions in Atlantic waters near Chesapeake Bay and Delaware Bay. But the introduction of Pacific Oysters was considered as a possible means of replacing or supplementing native stocks of the Eastern Oyster (Crassostrea virginica), which has been devastated by disease and overharvest. Both the Pacific Oyster and the Chinese River Oyster (C. ariakensis) were investigated for possible introduction until 1998 following research in the Bay, which including the stocking of sterile oysters. But initial studies found that the Chinese River Oyster had better growth and survival under East Coast conditions than the Pacific Oyster, and so further research and political interest shifted to the Chinese River Oyster. Ironically, early plantings of the Pacific Oyster in the 1950s in Delaware Bay are one of the possible means of introduction of MSX (Haplosporidium nelsoni), one of the diseases that lead to the decline of Eastern Oysters. The Pacific Oyster was, however, successfully introduced to Puget Sound WA in 1902 to replace the Olympic Oyster (Ostreola conchaphila), which was devastated by overfishing.
Image courtesy of Paul Fofonoff.

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Environmental Tolerances

For Survival
For Reproduction
Temperature (ºC)
3 35 16 30
Salinity (‰)
10 42 10 30
null null    
Salinity Range

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Age and Growth

Minimum Adult Size (mm)
40 40
Typical Adult Size (mm)
110 110
Maximum Adult Size (mm)
450 450
Typical Longevity (yrs)
null null
Maximum Longevity (yrs)
null null

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Reproductive Season
June June August
Typical Number of Young
per Reproductive Event
Sexuality Mode(s)
Mode(s) of Asexual Reproduction
Fertilization Type(s)
More than One Reproductive
Event per Year
Reproductive Strategy
Egg/Seed Form

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Minimum Typical Maximum
Egg/Seed Development Time (days)
null 1 null
Larval/Seed Development Period (days)
null 11 30
Male Maturation Age (yrs)
1 2  
Female Maturation Age (yrs)
1 2  
Larval/Seed Form  

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Locomotion and Abundance in Chesapeake

planktonic absent
sessile absent
sessile unknown

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Habitat Preferences

Primary Horizontal Habitats
unstructured oyster reefs; marinas and docks; coarse woody debris; rocky oyster reefs; marinas and docks; coarse woody debris; rocky
Secondary Horizontal Habitats
Reproductive Horizontal Habitats
n/a n/a
Vertical Habitats
planktonic epibenthic epibenthic
Substrate Type
none oyster; rock; shell; wood oyster; rock; shell; wood
Tidal Height Location
subtidal subtidal; low intertidal subtidal; low intertidal
Wave Exposure
moderate; low; protected
Water Flow
slow; fast

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Trophic Interactions

Trophic Status
planktotrophic suspension feeder suspension feeder
Common Food/Prey Items
phytoplankton, detritus, bacteria phytoplankton, detritus phytoplankton, detritus
Common Competitors
Crassostrea virginica Crassostrea virginica Crassostrea virginica
Common Consumers
zooplankton, ctenophores; adult bivalves Hapsporidium spp. (nelsoni); Perkinsus marinus; sponges; annelids (Polydora spp.); gastropods [Urosalpinx cinerea (Oyster Drill); Eupleura caudata (Thick-lipped Oyster Drill), others}; crabs (Xanthidae and others) Haplosporidium spp. (nelsoni); Perkinsus marinus; sponges; annelids (Polydora spp.); gastropods [Urosalpinx cinerea (Oyster Drill); Eupleura caudata (Thick-lipped Oyster Drill), others}; crabs (Xanthidae and others)

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Life History: Environmental Tolerances: Temperature- Crassostrea gigas (Pacific Oysters) shows signs of metabolic stress at 30 C (Shpigel et al. 1992). The optimum range for spawning is 20-25 C (Mann et al. 1991). Spawning and larval development is limited below 20 C (His et al. 1989; Quayle 1969). Salinity- Based on our criteria, C. gigas is euryhaline, surviving over 3 salinity zones (meso-euhaline), but compared to C. virginica and C. ariakensis, its salinity range is restricted, with substantial growth and reproduction occurring only above 20 ppt. (His et al. 1989; Mann et al. 1991; Nell and Holliday 1988). Consequently, its potential range is likely to be restricted to lower Chesapeake Bay, below the mouth of the Rappahannock River (Gottleib and Schweighofer 1996; Mann et al. 1991).Optimum salinities for reproduction and larval growth are 20-30 ppt (His et al. 1989; Mann et al. 1991; Nell and Holliday 1988).

Reproduction: Reproductive Season - These dates were the months of gamete release in quarantined flumes at ambient Gloucester Point VA, York River temperatures and salinities (Barber 1996).

C. gigas is absent in Chesapeake Bay at this time, to the best of our knowledge.
Community Ecology: Habitat Preferences: Primary Horizontal Habitats, Substrates - C. gigas can set on a wide range of hard substrates, (Quayle 1969) including cherry tree branches and bamboo, used as spat collectors in Japan, or oyster shells (Galtsoff 1932).

This data was last modified on Tuesday, February 4th, 2014.
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