Illustration of Oysters

Oysters

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Ocean Wise Recommended

Ocean Wise

Variety

Eastern oyster

Crassostrea virginica

Method

Wild

Dredge, Tong

Location

US Gulf of Mexico

Overall Rating

3.2 - 3.6 / 5

Summary

Commercial oyster landings were at an all-time high in the late 1800’s and early 1900’s, but the population decreased sharply in the mid 1900’s due to several factors including disease, overharvesting, and pollution. Currently, about two thirds of all oysters are wild-caught, and most of them originate from the Gulf of Mexico.

The population in the Gulf of Mexico is moderately abundant. The eastern oysters have a low vulnerability to fishing pressure because they are fast to mature. However, population abundance can vary greatly and is susceptible to declines due to pollution, loss of habitat, weather events, predation, and disease.

Each state manages the eastern oyster individually. The stocks are generally well managed, as all states have established size limits, seasons, gear restrictions, and area-specific closures. Both fishery-independent and fishery-dependent research is conducted. Of some concern is the fact that none of the states have a total allowable catch established, except for Florida.

The eastern oyster is harvested using tongs or dredges that are dragged over sandy or silty substrate which is covered in 100% oyster shells, both living and dead. This means that only oysters are harvested. Occasionally, a predator of the oyster called the oyster drill, found attached to the oyster, is also caught, but this amount of bycatch is minimal.

Although dredges are known to cause habitat damage to hard bottom substrate, eastern oysters are harvested in sandy and mud bottom substrate, where damage is minimal. There are conflicting opinions on whether hand tongs cause damage to oyster reefs, but all states have a habitat replenishment program in place that serve to minimize any possible negative effects of hand tonging.

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Ocean Wise Recommended

Ocean Wise

Variety

Oysters - various

Crassostrea spp., Ostrea spp., Saccostera spp.

Method

Farmed

Off-bottom culture, On-bottom culture

Location

Worldwide

Overall Rating

8.1 / 10

Summary

Oyster production has increased sharply since the 1990’s, and oysters represent the greatest proportion of molluscs cultured. Oysters are cultured either in suspension (off-bottom culture) where they are grown on rafts, racks, or stakes, or can be grown on the sea floor (on-bottom culture) where they are sown in beds and harvested after grow-out.

As oysters are filter feeders, no external feed is used as the individuals derive nutrition directly from the surrounding ocean. Broodstock is sourced from natural settlement, or from hatcheries. Domesticated sources of broodstock may be geneticially different from wild populations, but the vast majority of oysters are sourced from natural settlement. Management measures include export regulations, health codes, farm siting etc. Best Management Practices help to reduce risk of disease and pathogens.

Oysters are broadcast spawners, therefore escape of larvae to the open ocean is possible. There is concern over the impact of escapes if the cultured oysters are raised in non-native environments. However, in some areas, oysters are fully established, having been introduced over 10 years ago. Risk of disease and parasite transmission to wild populations is low due to biosecurity measures and production practices.

There is the possibility of changes to the sediment directly below farms due to biodeposition, but these impacts are minimal and do not extend beyond the farm site. Oyster farming has been observed to positively affect the ecosystem by removing excess nutrients from water.

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Ocean Wise Recommended

Ocean Wise

Variety

Eastern oyster

Crassostrea virginica

Method

Wild

Hand rake, Tong

Location

Canada: Gulf of St. Lawrence

Overall Rating

3.3 / 5

Summary

The eastern oyster is found in the Canadian Southern Gulf of St Lawrence in New Brunswick, Prince Edward Island and Nova Scotia. Although abundance is unknown, management regulates the fishery via minimum size limits and fishing seasons. Eastern oysters are harvested by hand using tongs and rakes. This method of harvest is selective and causes minimal bycatch. Minimal habitat damage is caused. Between 2012-2014, landings have not surpassed 2,000 mt. Aquaculture produces about 2-3 times the amount of wild eastern oyster product on the market, with Prince Edward Island being the major producer.

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Ocean Wise Recommended

Ocean Wise

Eco-Certification:

Food Alliance Shellfish

Variety

Oysters

Multiple Species

Method

Farmed

Various

Location

Worldwide

Eco-Certification

Food Alliance Shellfish

Summary

In 2012 Seafood Watch completed a comprehensive study of different eco-certification programs to determine if any would be equivalent to their sustainability standards. As a result of this study this aquaculture eco-certification were determined to be equivalent to an Ocean Wise recommendation. Learn more about our recommendation policy here.

 

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  • Various
Ocean Wise Recommended

Ocean Wise

Eco-Certification:

Aquaculture Stewardship Council (ASC)

Variety

Oysters

Multiple Species

Method

Farmed

Various

Location

Worldwide

Eco-Certification

Aquaculture Stewardship Council (ASC)

Summary

In 2012 Seafood Watch completed a comprehensive study of different eco-certification programs to determine if any would be equivalent to their sustainability standards. As a result of this study this aquaculture eco-certification were determined to be equivalent to an Ocean Wise recommendation. Learn more about our recommendation policy here.

 

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  • Various
Ocean Wise Recommended

Ocean Wise

Eco-Certification:

Canadian Organic

Variety

Oysters

Multiple Species

Method

Farmed

Various

Location

Canada

Eco-Certification

Canadian Organic

Summary

In 2012 Seafood Watch completed a comprehensive study of different eco-certification programs to determine if any would be equivalent to their sustainability standards. As a result of this study this aquaculture eco-certification were determined to be equivalent to an Ocean Wise recommendation. Learn more about our recommendation policy here.

 

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  • Various
Ocean Wise Recommended

Ocean Wise

Eco-Certification:

Marine Stewardship Council (MSC) - Dutch Oyster Association oyster fishery

Variety

European flat oyster

Ostrea edulis

Method

Wild

Dredge

Location

Oosterschelde, Lake Grevelingen

Eco-Certification

Marine Stewardship Council (MSC)
Dutch Oyster Association oyster fishery

Summary

Ocean Wise recommends some Marine Stewardship Council (MSC) certified fisheries, but not all. Learn more about how the MSC certification was bench-marked to Ocean Wise.

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Ocean Wise Recommended

Ocean Wise

Eco-Certification:

Marine Stewardship Council (MSC) - Limfjord oyster dredge fishery

Variety

European flat oyster

Ostrea edulis

Method

Wild

Dredge

Location

Western Limfjord, Denmark

Eco-Certification

Marine Stewardship Council (MSC)
Limfjord oyster dredge fishery

Summary

Ocean Wise recommends some Marine Stewardship Council (MSC) certified fisheries, but not all. Learn more about how the MSC certification was bench-marked to Ocean Wise.

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Ocean Wise Recommended

Ocean Wise

Eco-Certification:

Marine Stewardship Council (MSC) - Australia Silver Lipped Pearl Oyster

Variety

Oysters

Pinctada maxima

Method

Hand harvest

Location

Western Australia

Eco-Certification

Marine Stewardship Council (MSC)
Australia Silver Lipped Pearl Oyster

Summary

Ocean Wise recommends some Marine Stewardship Council (MSC) certified fisheries, but not all. Learn more about how the MSC certification was bench-marked to Ocean Wise.

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Ocean Wise Recommended

Ocean Wise

Eco-Certification:

Marine Stewardship Council (MSC) - Dutch Oyster Association oyster fishery

Variety

Pacific Oyster

Crassostrea gigas

Method

Wild

Dredge

Location

Oosterschelde, Lake Grevelingen

Eco-Certification

Marine Stewardship Council (MSC)
Dutch Oyster Association oyster fishery

Summary

Ocean Wise recommends some Marine Stewardship Council (MSC) certified fisheries, but not all. Learn more about how the MSC certification was bench-marked to Ocean Wise.

Learn more about harvest methods