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The geoduck (pronounced ),* Panopea abrupta or Panope generosa, is a species of large saltwater clam, also known as the king clam or elephant trunk clam.

The name is derived from a Nisqualli Indian word meaning "dig deep", and its phonemically counterintuitive spelling is likely the result of poor transcription. Alternate spellings include gweduc, gweduck and goiduck.

Native to the Pacific Coast of the United States and Canada (primarily Washington, British Columbia, and Southeast Alaska), it is the largest burrowing clam in the world, weighing in at an average of one to three pounds (0.5 - 1.5 kg) at maturity, but specimens weighing over 10 pounds (5 kg) and as much as a metre (3 feet) in length are not unheard of.

It has a life expectancy of more than 100 years, with the oldest recorded at over 160 years. Scientists speculate that the geoduck's longevity is the result of low wear and tear. A geoduck sucks plankton down through its long siphon, filters them for food and ejects its refuse out through a separate hole in the siphon. Geoducks have few natural predators which may also contribute to their longevity. In Alaska, sea otters and dogfish have proved capable of dislodging adult geoducks. Starfish also attack and feed on the exposed geoduck siphon.

Geoducks are broadcast spawners. A female geoduck produces about 5 billion eggs in her century-long lifespan—in comparison, a human female produces about 500 viable ova during the course of her life. It is possible that this fact, in conjunction with the phallic shape of the siphon, has led to the belief that the shellfish has aphrodisiac properties.

Industry & impact

The world's first geoduck fishery was created in 1970, but demand for the semi-forgotten clam was low. Today, they sell in Asia for up to US$30/lb (US$65/kg). The Jumbo clam, like abalone, is highly regarded in Chinese cuisine. Its large, meaty siphon is prized for its tasty (umami) flavour and crunchy texture. It is extremely popular in Hong Kong, China and Japan, where it is considered a rare taste treat. Geoduck is mostly eaten cooked in a fondue-style Chinese hot pot or raw sashimi style, dipped in soy sauce and wasabi. On Japanese menus, geoduck is called mirugai (海松貝) or mirukuigai (水松喰貝). (Although mirugai is sometimes translated to English as "Giant Clam", it is distinguished from "Himejako" sushi made from Tridacna gigas.)

The geoduck's high market value has created an 80-million-U.S.-dollar annual industry, with harvesting occurring in both Washington state and the province of British Columbia. It is one of the most closely regulated fisheries in both countries; in Washington, Department of Natural Resources staff are on the water continually, monitoring harvests, and the same is true in Canada where the Underwater Harvesters' Association manages the Canadian Fishery in conjunction with Canada's Department of Fisheries and Ocean. Demand has also led to a rapidly developing aquaculture industry.

Geoduck aquaculture on leased private tidelands in Puget Sound, particularly in South Puget Sound, has been steadily growing over the last ten years, averaging about 10 new acres of cultivation per year. Geoduck farms use "predator exclusion devices" in which to plant the seed geoducks. These devices are 10-14 inch long, 4-6 inch diameter PVC pipes pushed into the sediment of the tideland. There are approximately 25,000 to 43,500 of these pipes planted per acre of PVC pipes on tidelands. These nursery tubes typically stay in the beach for the first two years of a crop cycle. Although some marine shoreline owners take issue with the visual impact of this, the tubes are actually only visible 6-8% of daylight hours over a 6-year crop cycle. The reason for the low visibility is because geoduck are farmed in the lower elevations of the beach and are covered by water most of the time.

The Environmental Defense Fund has done extensive studies of aquaculture and has found that the net benefits of bi-valve aquaculture like geoduck clams are very beneficial to the marine environment. The primary reason for this is because geoduck clams are filter feeders and eat micro algae which proliferates as more nitrogen enters the marine ecosystem. Increases in nitrogen are due to more septic systems as well as bigger flows from city sewage systems throughout Puget Sound, increasing quantities of pet wastes, and increased fertilizer use from farms and lawns. When farmed geoduck clams (which ingest and retain nitrogen in their tissues) are harvested there is a net reduction in nitrogen in the marine ecosystem.

The netting tops used on the nursery pipes can come off and float away onto other beaches as debris and the rubber bands also become refuse in Puget Sound. To offset these environmental impacts geoduck farmers have been proactive in using biodegadeable rubberbands. In addition, the industry now does two annual beach cleanups to collect marine debris from all beaches in areas where they farm. Although as much as 20% of the debris collected in each cleanup has been aquaculture related, less than 5% of the 120 cubic yards collected to date has been related to geoduck farming. In many cases, these tidelands have been traditionally used for recreational surface water activity.

Harvesting takes place every 4-6 years. Water pressure hoses using up to 50 gallons of water per minute are used to liquify the sediment in order to extract the geoducks. There are no programmatic environmental impact studies related to intertidal farming of geoduck as of June 2006, although the sub-tidal environmental impact studies done for the fisheries in BC and WA have found no detrimental effects in harvesting the clams.

Trivia

  • Writer/director James Gunn has stated that the geoduck was the inspiration for the slug-like alien parasites in his 2006 horror/comedy Slither.

External links

Bivalves | Chinese cuisine | Japanese seafood | Edible molluscs

 

This article is licensed under the GNU Free Documentation License. It uses material from the "Geoduck".

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