Oyster, Pacific, oysters

Crassostrea gigas

Method of production — Farmed
Production country — UK
Production method — Bottom & suspension culture
Picture of Oyster, Pacific, oysters

Sustainability rating one info

Sustainability overview

Oyster beds are generally privately owned and managed. Shellfish farming is a low-impact method of aquaculture and high quality water standards are required for cultivation of shellfish for human consumption. Dredging can cause disruption to the seabed and has a higher associated bycatch than manual harvesting techniques, but is less suited to deeper water for practical reasons. Some growers may hand-gather their stock by diving or by net to enhance quality.

Feed Resources

Criterion Score: 6

Oysters are a non-fed shellfish species who get all of their nutrient requirements from the surrounding water.

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Environmental Impacts

Criterion Score: -1

Pacific oyster shellfish culture is low impact, as no chemicals are used, escapes are not relevant for a wild settling species and there is no lethal predator control. However Pacific oysters are non native to the UK and can impact/out compete Native oysters which are a protected species.

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Fish Health and Welfare

Criterion Score: 2

Welfare standards are not applicable to cultured shellfish species.

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Management

Criterion Score: 2

Management measures and regulations are in place for the farming of native oysters and are mostly effective except the issue of impacts on Native oysters. Pacific oysters are non native to the UK and can impact/out compete Native oysters which are a protected species. .

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Production method

Bottom & suspension culture

Oysters are bred in hatcheries and then grown on in the sea - usually in semi-rigid plastic mesh bags, supported by steel trestles secured in intertidal waters. They can also be grown in suspended mesh nets.

Biology

Oysters belong to the commercially important group of bivalve molluscs which also includes mussels, clams and cockles. The Pacific oyster, now widely distributed, originated in northeastern Asia. Pacific oysters, as with many oyster species, develop first as males, spawn, and then later develop into females. Spawning occurs in the summer.

References

FAO 2005-2018. Cultured Aquatic Species Information Programme. Crassostrea gigas. Cultured Aquatic Species Information Programme. Text by Helm, M.M. In: FAO Fisheries and Aquaculture Department [online]. Rome. Updated 13 April 2005. [Cited 7 September 2018].

JNCC. Native Oyster. Available online at:http://www.naturalengland.org.uk/ourwork/marine/mpa/mcz/features/species/nativeoyster.aspx. Accessed 06/09/2018

JNCC. Crassostrea gigas. Available online at:http://jncc.defra.gov.uk/page-1714. Accessed 06/09/2018

JNCC. Native Oyster (Ostrea edulis) beds. Available online at: http://jncc.defra.gov.uk/page-6025. Accessed 06/09/2018

Association of Scottish Shellfish Growers Code of Practice. Available online at: assg.org.uk/code-of-practice/4536619829.