Last update:

18th April 2008

Quick links:

What are shellfish waters?

How are shellfish waters monitored?

Shellfish waters in the South West

Quantity and value of shellfish landings in the South West

Regional shellfish waters

Dart estuary shellfishery

Bathing waters

Estuaries

Rivers

Groundwater

Drinking water

Discharges & releases

Diffuse pollution

Blue Flag seaside awards

Useful websites:

Environment Agency - shellfisheries

Shellfish Waters Directive

Shellfish Hygiene Directive

Marine and Fisheries Agency - landings

Dart Estuary Environmental Management (DEEM)

Food Standards Agency - shellfish

Defra - fish landings

Shellfish waters

New on this page...

• Updated page, including shellfish waters in the South West, quality of shellfish waters, shellfish waters and health
• Cleaner Coasts, Healthier Seas - state of the marine environment in England and Wales
• Defra launches consultation on draft Marine Bill and Shoreline Management Plans

Shellfish are a significant part of the fishing industry, making up nearly one-third of the catch in England and Wales. In the South West, this increases to almost half (44%) of the total landings.

The South West contains almost 27% (33 out of 124) of designated shellfish waters in England and Wales under the EC Shellfish Waters Directive, the water quality in which are consistently of good.

What are shellfish waters and why are they monitored?

Shellfish harvesting is commercially important and makes up nearly one-third of the total catch in England and Wales.

Shellfish waters are locations where shellfish grow and reproduce. Shellfish are types of molluscs and species include:

• Common edible cockle (Cerastoderma edule)
• Blue mussel (Mytilus edulis)
• Native or Flat Oyster (Ostrea edulis)
• Pacific Oyster (Crassostrea gigas)
• Hard clam (Mercenaria mercenaria)
• Thick trough shell (Spisula solida)
• Manila clam (Tapes philippinarum)
• Razor clams (Ensis arcuatus)
• Great or King scallop (Pecten maximus)
• Gapers (Mya arenaria)
• Palourde, native clam or carpet shell clam (Venerupis senegalensis)
  

Shellfish are vulnerable to pollution because they are filter feeders. They draw water across their sieve-like gills, where contaminants like micro-organisms, heavy metals and organic material can accumulate.

The Environment Agency monitor the quality of shellfish waters to prevent them becoming contaminated, as there is a risk poor water quality could mean that shellfish become contaminated, which could then affect the people who eat them.

Levels of contamination in the shellfish themselves are monitored by the Food Standards Agency to make sure that the harvested shellfish are safe to eat.

How are shellfish waters monitored?

Good water quality in areas where shellfish live is essential to prevent contamination of shellfish. Bottom feeders, such as oysters and mussels, can be particularly sensitive to pollution and contaminates as they are filter-feeders (drawing water across their sieve-like gills which can rapidly accumulate micro-organisms, heavy metals and organic contaminants).

Designated Shellfish waters are required to meet the standards set in the EC Shellfish Waters Directive and Shellfish Hygiene Directive.

The Shellfish Waters Directive aims to protect shellfish populations by setting water quality standards in areas where shellfish grow and reproduce. It requires the monitoring of specific substances, which can threaten the survival of shellfish or inhibit their growth, in the water where the shellfish live. This Directive is administered by Defra and implemented by the Environment Agency in England and Wales.

The Shellfish Waters Directive sets environmental standards for the quality of the waters where shellfish live in order to promote healthy shellfish growth. The quality of commercially harvested shellfish intended for human consumption must comply with the EU Food Hygiene Regulations (852 / 853 / 854), which took effect on 1 January 2006. Details of these standards can be found here.

Shellfish Waters in the South West

The South West contains almost 27% (33 out of 124) of designated shellfish waters in England and Wales under the EC Shellfish Waters Directive, the water quality in which are consistently of good.

Shellfisheries are an important part of the fishing industry in the South West, with shellfish landed recording a value of over £8 million in the region's major fishing ports in 2006. Find out more about fisheries in the South West here.

Shellfisheries are an important part of the fishing industry in the South West. In 2006, the UK fleet landed 12,761 tonnes of shellfish into major ports in the South West, worth £17,221,000.

Source: Marine and Fisheries Agency (2007)

Quality of shellfish waters in the South West

Water quality in South West shellfish waters is consistently good, with 97% (32 out of the 33 shellfish waters in the region) meeting the mandatory standards of the EC Shellfish Waters Directive in both 2005 and 2006.

Non-compliance at designated shellfish waters in the South West 1994 - 2006

Source: Environment Agency (2007)

In 2005, Tresillian Shellfish water did not meet standards when it failed the dissolved oxygen standards. Whilst in 2006 it was the Lynher Estuary that failed, again for dissolved oxygen. Both of these shellfish waters recorded two results slightly below the EQS (environmental quality standards), the cause of these failures is currently unknown.

EC Designated Shellfish Waters in England & Wales

In 2006, 20 out of 124 designated shellfish waters failed to comply with the standards set by the Shellfish Waters Directive. These failures were due to a number of parameters including dissolved oxygen and Zinc. The number of monitored waters that fail to comply with the Directive decreased from 1999 to 2001, but has increased since 2001 to 2006.

National Shellfish Waters Compliance 1999 to 2006

Data for shellfish waters not meeting these standards in England and Wales is available here.

Shellfish and human health

The health standards for shellfish for human consumption is controlled by the Shellfish Hygiene Directive and is administered by DEFRA and the Food Standards Agency. This Directive monitors the suitability of shellfish for human consumption.

Bivalve production areas are classified according to the level of treatment they require prior to their sale (from A to C grade, where grade A sites require no pre-treatment and grade C sites require intensive purification).

Production areas are categorised by the level of microbiological contamination, namely the level of E. coli contamination found in shellfish sampled from a site. These areas are classified as Class A, B, C or prohibited:

• Class A - shellfish contain less than 230 E. coli per 100 grams of flesh
• Class B - shellfish contain less than 4,600 E. coli per 100 grams of flesh
• Class C - shellfish contain less than 46,000 E. coli per 100 grams of flesh
• Prohibited area - above 46,000 E. coli per 100 grams of flesh

Results for 2007/2008 show that the majority of South West shellfish waters fell into the Class B classification.

A more local perspective

Shellfisheries in the Dart Estuary

The Dart Estuary is an important location for shellfish in the South West and work undertaken by the Dart Estuary Environmental Management (DEEM) continues to lead to significant improvements in water quality.

Prospects for the cultivation of molluscan shellfish (most notably, oysters and mussels) depend upon maintaining the quality of the estuary waters. With the notable exception of scallops, which don't prosper in the estuary's conditions, the great majority of bivalve molluscs are sedentary - they neither swim, crawl, nor walk away. They simply sit there and filter all day, feeding on the plankton, exchanging oxygen across their gills, absorbing everything that comes their way. As such they are wonderful indicators of environmental water quality, like 'miners' canaries' for the estuary.

The designated shellfish area at Waddeton is administered by Devon Sea Fisheries Committee, which has powers to grant licences 'to cultivate and harvest shellfish'. DEEM, through its efforts to ensure the health of the river and estuary, is keen to encourage sustainable shellfish production as a contribution to the economic well-being of the local community and to play a role in the development of shellfish farming across the region.