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Clam, Razor, clams

Ensis spp.

Method of production - Caught at sea
Capture method - Electrical fishing
Capture area - North East Atlantic (FAO 27)
Stock area - UK
Stock detail - All Areas
Certification -
Fish type - Shellfish

Sustainability rating Click for explaination of rating

This fish, caught by the methods and in the area listed above, is the least sustainable fish to eat and should be avoided. Click on the rating icon above to read more and on the alternatives tab below to find sustainable fish to eat.


Sustainability overview

Avoid eating clams harvested using illegal methods such as electrical fishing. Choose clams harvested in the wild by sustainable methods such as hand-gathering only. Avoid eating undersized animals (less than 10cm) and wild clams harvested during the spawning season (May - September).

Biology

Razor clams are bivalve molluscs. There are 6 species found in British intertidal waters. 2 are of commercial importance, namely Ensis siliqua and E arcuatus. E directus was introduced to European waters probably in 1978 through tanker ballast water. Spawning occurs in summer. Fertilised eggs develop into mobile larvae hours after fertilisation. The larval phase includes several stages and lasts for about 3-4 weeks, during which time they drift with the current. The larval phase ends when larvae settle, attaching themselves to sand or shell by byssal threads. At around 0.5cm length juveniles burrow into sand. Relative to other commercially important bivalves Ensis are long-lived, slow growing, and attain sexual maturity late in life. They may survive to 10-15 years and an average adult can reach a size of 12.5cm, although growth will cease by age 10. E.siliqua and E.arcuatus can live in excess of 20 years. Maturity is reached at sizes above 100mm. They are filter feeders and normally lie vertically in the sediment with 2 small siphons, through which they feed, visible on the surface. Razor clams burrow into the sediment around the extreme low water mark and in the shallow subtidal and are capable of rapid burrowing if disturbed.

Stock information

Stock area
UK

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Stock information
Widely distributed in intertidal waters throughout UK and temperate waters. Since the expansion of the fishery there have been no stock assessments and improved information on the state of the stocks is required.

Management

Various bodies e.g. Natural England, Cefas, Sea Fishery Committees, Local Authorities etc. have responsibility for their protection or management in UK coastal waters. Razor clam fisheries in Scotland emerged in the 1990s. Landings rose sharply to reach 718 t in 2009 with a value of 1,754,000. The sharp rise in landings since 2006 is thought to be related to the increasing use of illegal electrical fishing methods and concerns are being expressed over the sustainability of the fishery. In the Scottish clam fishery there is currently no limit on catch or effort and the only managment measures relating to Ensis are the EU MLS of 100mm; some restrictions on the use of mobile gears; and the requirement for all commercial fishing vesels to report catch weights and area of capture.

Capture information

Electrical fishing for razor clams is illegal. Electrical fishing was banned in the EU in 1998 to prevent irresponsible and dangerous fishing practices (including: electrical fishing, explosives and poison). In response to the increase in illegal electrical fishing, changes to the vessel fishing licence relating to the carriage of electrical equipment were introduced in 2010. Electrical fishing works by using electrical currents to produce a response in the target species. The intense electrical field, emitted by electrodes towed slowly across the seabed, stimulate Ensis to temporarily leave their burrows. They are then collected most commonly by a diver following the fishing vessel, or alternatively by a dredge drawn across the surface of the seabed. Potentially detrimental effects associated with this type of fishing have been identified as disruption and damage of benthic habitats due to fishing activities; the release of pollutants (particularly metals e.g. copper) from electrolysis at the electrodes; and effects of electrical fields on Ensis and non-target fish and invertebrates. Razor clams are often harvested as juveniles before they have reached maturity. Avoid eating undersized animals, always choose or collect razor clams above 10cm, the current EU Minimum Landing Size (MLS). A MLS of at least 130mm has been recommended to ensure Ensis are not harvested before reaching maturity.

Read more about capture methods


References

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