Clam, Razor, clams

Ensis spp.

Method of production — Caught at sea
Capture method — Dredge
Capture area — North East Atlantic (FAO 27)
Stock area — Scotland
Stock detail

All Areas


Picture of Clam, Razor, clams

Sustainability rating five info

Sustainability overview

Illegal razors known as razor fish or spoots. There are two commercially important species found in Scottish waters Ensis arcuatus, (called bendies) and the larger pod razor Ensis siliqua. They are a very valuable shellfish stock but there is a prevalenta illegal market. Though razor clam can be caught by dredges, it is believed that almost all razor clams have been caught by fishing with electricitya. The main market is for the live E. siliqua, exported to the Far East, predominantly China.

Electrofishing is more popular a method than dredging because it is very efficient, and yields a higher quality, more valuable product than dredging. While there are strict management measures in place to limit razor clam fishing e.g. licences and a minimum landing size, the level of illegal fishing is likely high and harvesting is only allowed if it is for a scientific investigation or it they are harvested by traditional hand gathering.

The stock status of razor clams in this area is unknown, trials to determine their population is underway.

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. E. arcuatus reaches sexual maturity between 73 and 130 mm and E. siliqua mature between 118 - 140 mm in Scotland. 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

Criterion score: 1 info

Stock Area

Scotland

Stock information

There are no assessments to determine the abundance and fishing mortality. The abundance and level of fishing on the stock is unknown. It is too early to tell if the abundance of razor clams is lower than historical levels (Fox, 2018), however, exploitation levels and illegal fishing rates have been high. Therefore, there is concern for biomass and fishing mortality and resilience is high.

Management

Criterion score: 1 info

There a few measures to protect the razor clam fishery; there are no catch limits. There is a minimum landing size (MLS) of 100 mm applied to the genus for all European stocks, but this is often lower than the size at which they mature.

Marine Scotland implemented the Razor Clams Order in April 2017. This prohibited fishing for and landing razor clams in Scottish waters, except i) for scientific investigation authorised by Scottish Ministers; and ii) for traditional hand gathering of razor clams from the shore (where taking 30 razor clams per day is permitted).

Capture Information

Criterion score: 1 info

Hydraulic dredging are effective at removing the target species but yields high levels of bycatch (e.g. in the Clyde, only 25 % of the catch are Ensis species). There are restrictions for dredging to protect sensitive habitats (Inshore Fishing (Scotland) Act 1984). Dredge-caught razor clams however, are of poorer quality: the valves may be chipped or broken and the clams may accumulate grit. There are examples of where intensive dredging has cause irreparable damage to the biodiversity and food webs. Razor clams are found burrowed in sandy inter-tidal and sub-tidal areas or mud and sand environments.

References

Marine Scotland Compliance Team Pers. Comm. 2016

North Atlantic Fisheries Intelligence Group. 2017. Illegal trading Scottish Razor Clams. Available at: https://fishcrime.com/wp-content/uploads/2017/11/Nick-Branigan.pdf

Marine Scotland. The Razor clams (PROHIBITION ON FISHING AND LANDING) (SCOTLAND) ORDER 2017. 2017. SSI 2017/419. Available at: http://www.legislation.gov.uk/ssi/2017/419/pdfs/ssipn_20170419_en.pdf

Marine Scotland. 2017. Final Business and Regulatory Impact Assessment. Available at: http://www.legislation.gov.uk/ssi/2017/419/pdfs/ssifia_20170419_en.pdf

Fishing News. 2017. LECTROFISHING RAZOR CLAM TRIALS IN SCOTLAND. 10.04. 2017. Available at: http://fishingnews.co.uk/news/electrofishing-razor-clam-trials-in-scotland/

Seafood Source. 2015. Illegal razor clam fishers caught in the act. 21.09.2015. Available at: https://www.seafoodsource.com/news/food-safety-health/illegal-razor-clam-fishers-caught-in-the-act

Marine Scotland. 2017. Electrofishing for Razor Clams. Available at: http://www.gov.scot/Topics/marine/Sea-Fisheries/management/razors

BBC. 2017. Illegal clam fishermen 'track' fishery protection vessels. 18.04.2017. Available at: http://www.bbc.co.uk/news/uk-scotland-39623279

Appleby, T. and Harrison, J. (2017) Brexit and the future of Scottish fisheries key legal issues in a changing regulatory landscape. Journal of Water Law, 25 (3). pp. 124-132. ISSN 1478-5277 Available from: http://eprints.uwe.ac.uk/32821

Fox, C. 2017. To Develop the Methodology to Undertake Stock Assessments on Razor Fish Using Combinations of Video Monitoring and Electrofishing Gear. Fishing Industry Science Alliance (FISA) Project 09/15. Scottish Marine and Freshwater Science 8, 6. Marine Scotland Science, Aberdeen.

Murray F, Copland P, Boulcott P, Rovertson M, Bailey N (2014) Electrofishing for razor clams (Ensis siliqua and E. arquatus): Effects on survival and recovery of target and non-target species. Scottish Marine and Freshwater Science 14, Marine Scotland Science, Aberdeen, 50 pp.

Fox, C. 2018. Report on Razor Clam Surveys in the Sound of Harris and the Ayrshire Coast of the Clyde (Girvan to North Bay) Scottish Marine and Freshwater Science Vol 9 No 3.

Constantino, R., Gaspar, M. B., Pereira, F., Carvalho, S., Cardia, J., Matias, D. and Monteiro, C. C. (2009), Environmental impact of razor clam harvesting using salt in Ria Formosa lagoon (Southern Portugal) and subsequent recovery of associated benthic communities. Aquatic Conserv: Mar. Freshw. Ecosyst., 19: 542-553. doi:10.1002/aqc.995 .