Clam, Razor, clams

Ensis spp.

Method of production — Caught at sea
Capture method — Hand-gathering
Capture area — North East Atlantic (FAO 27)
Stock area — Scotland
Stock detail — All Areas
Picture of Clam, Razor, clams

Sustainability rating three info

Sustainability overview

Updated: November 2019.

The stock status of razor clams in Scotland is unknown, but there are concerns that the stocks may be too low and fishing pressure may be too high.

In Scotland, there is currently a trial for electrical fishing of razor clams. For the lifetime of this trial (from 1st February 2018 onwards), all other forms of razor clam fishing are prohibited except for traditional hand gathering from the shore. Therefore the Scottish dredge fishery is currently illegal and is red-rated by default.

The electrofishing trial was introduced to tackle widespread illegal electrical fishing for razor clams, which was difficult to catch ‘in the act’ and therefore not well policed prior to the trial. At its peak, the criminal fishery was believed to be making upwards of 65,000 pounds a day - more lucrative than the illegal drugs trade. However, there are widespread concerns about the approach to the trial, as it is not considered to be scientific. It therefore also receives a default red-rating, in-line with MCS’s approach to electrical fishing and pulse trawling.

Hand gatherers may take up to 30 clams per person per day. As this level of hand gathering is unlikely to sustain a large commercial fishery, and given the historical high levels of illegal razor clam fishing, MCS urges buyers to carefully check the sources of their razor clams.


Razor clams are bivalve molluscs. There are 6 species found in British intertidal waters. 2 are of commercial importance: Ensis siliqua and E arcuatus. Spawning occurs in summer, and 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. They then 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. They 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: 0.75 info

Stock Area


Stock information

Two razor clam species are of commercial importance in the UK: Ensis siliqua and Ensis arcuatus (also known as Ensis magnus). Neither species has a stock assessment. The vulnerability of razor clams to fishing is low (10 out of 100), but the size of their populations and current and historical levels of fishing mortality are completely unknown, and there is concern for biomass and fishing mortality.

Razor clams around Scotland have, in the past, been subject to significant levels of illegal electrofishing. To tackle this, an electrofishing trial is now being conducted in the area. However, it is on a relatively large scale, and therefore could be continuing to allow high levels of exploitation on a potentially already depleted stock. Vessels in the trial are subject to a daily catch limit (450kg) and a maximum of 110 days at sea. With 24 vessels licensed by the end of January 2019, this amounts to 1,188 tonnes of clams being removed annually from Scottish waters. Razor clams have slow growth rates and their populations take a long time to recover. Intense harvesting has been shown to impact community structure, resulting in very slow rebuilding timeframes. Once fished, razor clam beds can be re-colonised, but only if there are sufficient clams in surrounding areas.

The electrofishing trial is collecting data that will in future be used for stock assessments, including length-weight relationships, size at maturity, landings, spawning times and locations of different populations.


Criterion score: 0.5 info

In Scotland, there is currently a trial for electrical fishing of razor clams. For the lifetime of this trial (from 1st February 2018 onwards - there is no end date), all other forms of razor clam fishing are prohibited except for traditional hand gathering from the shore. Hand gatherers may take up to 30 clams per person per day. There are few other measures to protect the razor clam fishery. There is a minimum landing size (MLS) of 100 mm applied to Ensis species for all European stocks, but this is often lower than the size at which they mature.

Capture Information

Criterion score: 0 info

Hand gathering razor clams on the shore is considered an environmentally friendly method, as it is highly selective and has a low impact on the habitat.


Marine Scotland Compliance Team Pers. Comm. 2016

North Atlantic Fisheries Intelligence Group. 2017. Illegal trading Scottish Razor Clams. Available at:

Marine Scotland. The Razor clams (PROHIBITION ON FISHING AND LANDING) (SCOTLAND) ORDER 2017. 2017. SSI 2017/419. Available at:

Marine Scotland. 2017. Final Business and Regulatory Impact Assessment. Available at:

Fishing News. 2017. LECTROFISHING RAZOR CLAM TRIALS IN SCOTLAND. 10.04. 2017. Available at:

Seafood Source. 2015. Illegal razor clam fishers caught in the act. 21.09.2015. Available at:

BBC. 2017. Illegal clam fishermen 'track' fishery protection vessels. 18.04.2017. Available at:

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:

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.

Palomares, M.L.D. and Pauly, D. (Editors), 2019. SeaLifeBase. Ensis magnus: arched razor shell. Available at [Accessed on 07.11.2-19].

Palomares, M.L.D. and Pauly, D. (Editors), 2019. SeaLifeBase. Ensis siliqua: sword razor shell. Available at [Accessed on 07.11.2-19].

Scottish Environment Link, 2016. Consultation Response to electrofishing for razor clams in Scotland by the Scottish Environment LINK Marine Group: September 2016. Available at [Accessed on 07.11.2019].

Scottish Government, 2019. Electrofishing for Razor Clams. Available at [Accessed on 07.11.2019].