RAZOR CLAM               

The Atlantic Jackknife, aka the Razor Clam (Ensis directs) is getting more attention in recent years, as a potential aquaculture species.  They are tasty and versatile, but since they are difficult to capture, and usually accessibly only during very low tides, they can be hard to find in the marketplace.  Those who have attempted to dig a razor will attest to the fact that move surprisingly fast, and can burrow very deeply into the sediment.  It takes a quick but gentle hand with the clam rake, to get to one and to pull one from its burrow, because the foot will hold on very strongly - a razor clam likes to stay home!  Oddly enough however, razor clams will often come up to the surface and emerge halfway or more, if a small amount of salt is sprinkled on the razor clams' burrow, at low tide.  Click here for a video from Maine Sea Grant, showing salting for razor clams.

Biology and Predators

Razor clams occur naturally in the Western Atlantic, from Labrador through South Carolina. They prefer sandy substrates in the lower intertidal and immediate subtidal zone, although they will occur to some extend in mud and gravel.  Sexes are separate, and eggs are fertilized externally during spawning, which is often in June.  Available data indicate fairly rapid growth for the species in favorable conditions, and quite rapid in the hatchery and nursery; from 0.5mm/day in the early stages, and upwards of 0.3mm/day in growout cages.  Predators of the razor clam include a variety of shorebirds, the green crab (Carcinas maenas), moon snail (Euspira heros) and the milky ribbon worm (Cerebratulus lacteus).

Market

The market for razor clams in the Northeast is sporadic, but there are indications that the market could be grown, if a steady supply of product were available.  Work by Leavitt and others (see below) indicated that there is both a live and a processed market, and that the minimum size for the live market was generally above 3 inches, though 4 inches is preferred.  Given the growth rates cited in publications and recent work, it appears likely that a market-size product is attainable in two growing seasons, here in the Northeast.  Prices generally range from $2.50 to $6.00 per pound to the producer.

Production Details

To date, production attempts have focused on two or three main methods, bottom seeding in plots with a mesh predator screen over the top, a screened-in enclosure to keep the razor clams confined and protected, and sediment-filled containers, placed on the bottom, and with predator screening.  Like soft-shell and hard clams, razor clams need to be in sediment for good growth - they undergo stress when exposed, and they also expend too much energy via the adductor muscle, in trying to keep the valves of the shell closed.  Since razors can swim and can excavate burrows up to a half-meter below the sediment, keeping them protected and contained is an issue.  The links below will provide readers with a sense of the equipment used in prior experiments.

Disease and Health

To date, no diseases specific to E. directus have been identified, and no specific human health risks have been identified, although like other bivalves, razor clams are filter feeders, and can accumulate biotoxins from harmful algal blooms. 

NRAC Project - 2011

In 2011, the Northeast Regional Aquaculture Center funded a project entitled: Optimization of Hatchery and Culture Technology for Razor Clams".  Hatchery work will be conducted in early 2012, at the University of Maine's Darling Marine Center, in Walpole, Maine, at the Blount Hatchery of Roger Williams University in Bristol, Rhode Island, and the Aquacultural Research Corporation, in Dennis, MA.  The goal is to refine and improve hatchery production, and to produce 1 million razor clam seed.  It is expected that the seed produced from the project will serve as the basis for growout trials with industry participants in both states.  Collaborators on that project include Paul Rawson (University of Maine, School of Marine Sciences), Dale Leavitt (Roger Williams University), Diane Murphy (Cape Cod Cooperative Extension, and Woods Hole Sea Grant), Michael Devin (UMaine Darling Marine Center) and Dana Morse (Maine Sea Grant, Univ. of Maine Cooperative Extension). 

Shellfish growers in these states can expect a workshop in early 2012, so that growers can review earlier growout trials, and make suggestions about the kind of equipment and siting would help the successful farm production of razor clams. Those interested in the progress of this project should check back on this page, to see updates, photos and other material as the project moves ahead.

For more reading, click on the following links

- A Fact Sheet on Razor Clams (Northeast Regional Aquaculture Center #217, by Dale Leavitt)

- Final Report to NRAC, by Bill Burt, et al., 2005: "An industry directed feasibility study of the razor clam (Ensis directus) as a candidate for intertidal and shallow subtidal culture in the northeastern U.S."

- A Cultivation Guide for Razor Clams, translated from Danish, Fruedendahl and Nielsen, 2005

- PDF summary of a Power Point slide show by Dale Leavitt, summarizing the NRAC razor clam project from 2005

- A New York Times story, in the Dining and Wine section, from Feb, 2011, on razor clams