Clam, Manila (Farmed)

Ruditapes philippinarium

Method of production — Farmed
Production country — UK
Production method — All
Picture of Clam, Manila (Farmed)

Sustainability rating one info

Sustainability overview

All Manila clams in the UK are progeny of broodstock imported from the west coast of USA. They are grown in trays on trestles in the sea before planting out in ground plots or seabed. Only a small number of Manila clams are farmed for the table in UK (5 tonnes, 2012), the biggest production is seed for ongrowing. Clams may be harvested by manual digging or raking, or by mechanical methods, e.g. suction or hydraulic dredge. Manual harvesting methods cause less disturbance to sediment than mechanical methods. Shellfish farming is a low-impact method of producing farmed seafood and high quality water standards are required for cultivation of shellfish for human consumption.

Feed Resources

Criterion Score: 6

Manila clam are a non-fed species as they filter feed nutrients from the surrounding water column.

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Environmental Impacts

Criterion Score: 0

Shellfish culture tends to be a low impact form of aquaculture. It is a non-native species that has spread to estuaries surrounding the aquaculture sites. It is unknown is there is any disease risk with this species.

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Fish Health and Welfare

Criterion Score: 1

Health and welfare criteria do not apply to shellfish species. There is a potential problem with widespread disease but this lacks data for the UK.

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Management

Criterion Score: 2

Regulations are either in place or do not apply for the cultivation of shellfish. Regulations are only considered to be partially effective as there is evidence for species invasion.

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Production method

All

Clams may be harvested by hand-gathering or manual digging or raking, or by mechanical methods, e.g. suction or hydraulic dredge. Manual harvesting methods cause less disturbance to sediment than mechanical methods.

Biology

A bivalve mollusc with distinctive black and white shell markings, it is native to the waters of east Asia. Now widespread throughout the western world, with introductions made accidentally with oysters into North America, and deliberately as hatchery broodstock into Europe. In the wild it is found burrowing on coarse sediment in intertidal waters. Matures at about 2 years, with a corresponding shell size of about 2cm. Maximum size about 6.5-7.5cm. Spawning occurs in summer months.

References

CEFAS. Aquaculture Statistics for the UK. 2012. Available online at: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/405469/Aquaculture_Statistics_UK_2012.pdf. Accessed 05/09/2018

FAO 2005-2018. Cultured Aquatic Species Information Programme. Ruditapes philippinarum. Cultured Aquatic Species Information Programme. Text by Goulletquer, P. In: FAO Fisheries and Aquaculture Department [online]. Rome. Updated 1 January 2005. [Cited 6 September 2018]. Accessed 21/09/2015.
>br>Invasion in tidal zones on complex coastlines: modelling larvae of the non-native Manila clam in the UK.2012 Herbert. R.J.H. et.al. Journal of Biogeography (39)585-599

Benefits to shorebirds from invasion of non-native shellfish. 2007 Proceedings of the Royal Society, B. 274, 1449-1455

DEFRA. Shellfisheries: Several and Regulating Orders. Available online at:https://www.gov.uk/guidance/shellfisheries-several-orders-and-regulating-orders. Accessed 21/09/2015.