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Clams

This area has a great diversity of clam species, but it is still unclear which species would be the most profitable for culture. An examination of this question will be one of the major focuses of RAM's hatchery and trial grow out programs. Currently, the only seed that are readily available commercially are for Japanese littleneck clams and geoduck clams. The larval stages of all of the commercial clams are very similar, and they can all be reared in a hatchery using very similar procedures. The eggs develop into swimming larvae that rapidly form shells, and the larvae are ready to set to the bottom looking much like normal clams after 2 to 3 weeks. With a hatchery, it does not matter if a species occurs naturally in harvestable quantities. Only a few specimens are needed as each female typically spawns millions of eggs.

All of the commercial species of clam live by filtering minute single-celled algae out of the water. Unfortunately, this area has certain species of algae that can produce toxins, and when these particular species bloom, the bivalves become toxic. Different clam species respond differently to the toxin. Some concentrate and hold the toxin while others do not. In all cases, there needs to be a testing program to assure that the clams are safe to eat, but even with the same water conditions, some species will regularly test out as safe while others are toxic.

Japanese Littleneck Clams (also called Manila or asari)

This species was originally brought to the west coast incidentally and now is common on the beaches in southern British Columbia and the Washington State. It does not occur naturally this far north. This species has become the dominant cultured clam species in Washington State and British Columbia, and the seed are readily and cheaply available. Unfortunately, this species has not done well in trial grow out projects in this area. manila clam and native littleneck

Native Littleneck Clam

This species can be common on beaches along the northern BC coast. It is very similar to the Japanese littleneck and the two species used to be sold together as if they were a single species. It is considered to be somewhat inferior with respect to having a shorter shelf life and inferior flavor (in limited taste tests). Also in southern populations the shells do not always pop open reliably when steamed, though this does not seem to be a problem in Alaskan populations. The most attractive characteristic of this species is that it apparently stops feeding when there are toxic algal blooms, and it consistently contains the least amount of toxin.

Geoducks

The only species of clam in this area that supports a commercial fishery of any size is the geoduck clam. This species is being produced in hatcheries and there are a number of grow-out operations in progress. The short-term problem with geoducks is that the seed are very fragile, and hatcheries cannot produce them as cheaply. Because they are so expensive, the common practice is to protect them in covered pipes that are burred in the sediment. This is the most expensive species to grow, by far. The long-term problem with growing geoducks is that they may take seven years to reach market size. Geoducks command the highest prices when they are still alive, and they stay alive for about 6 days after being taken out of the water. When geoducks go toxic, all of the toxin is stored in their digestive gland which can be easily removed. (However, removing the gland kills them and reduces their value. Geoducks taste very good raw, and they sell for much higher prices than any of the other local species.

geoducks in Hong Kong Photo from Wikipedia.
Geoducks being sold in Hong Kong. (Hong Kong dollars are worth about 13 cents, so the prices are about $30.00 Canadian each.


Butter Clam

Butter clams are typically the most abundant clams on intertidal north coast beaches. Unfortunately, it is also the most notorious for concentrating and holding toxin.
butter clam


Cockles

This species seems to be one that is preferred by the local native population. It grows just below the surface of the sediment which makes it the easiest to dig for home use. It would be a priority project of RAM to enhance a convenient local beach for non-commercial cockle digging. It is not known how competitive this species would be in global clam markets. It is apparently not very good tasting raw (I watched Japanese clam buyers sampling freshly caught cockles and spitting it out with dismay upon tasting it. (There is a very similar looking cockle in Japan that tastes wonderful raw.)

basket cockle


Soft-shelled clam

This species has been introduced globally, incidentally, or otherwise. It is the mainstay of East Coast clam bakes, and supports large commercial fisheries wherever it is present in large numbers. It occurs in only small numbers in this area, but may be a desirable cultured species.
Soft shelled clams Mya arenaria
Soft-shelled clam. Photo from Wikipedia


Panomya ampla

Not much is known about this species as it generally occurs subtidally (though there is a report of it being intertidal in Glacier Bay, Alaska). I have eaten it raw and it is delectable. It is similar in taste to a geoduck but more tender. It would be my number one pick as having the potential for most profitable clam for this area. When the brown membrane is removed, it has striking color characteristics

Panomya ampla covered with a discrete brown membrane that peels off.
Photo © 1997 Madelon Mottet



Website
© 2008 Madelon Mottet

Contact information:
RAM Marine Station
333 9th Ave. W, Prince Rupert, British Columbia V8J 2S6, Canada
Telephone/Fax 1-250-624-2097
email: madelon.mottet@gmail.com or Allen Johnson at abalone55@hotmail.com