Seafood of the Week - Geoduck

Four live specimens of Panopea generosa in a seafood tank

The geoduck (/ˈɡuːiːdʌk/ "gooey duck"), scientific name Panopea generosa, is a species of very large, edible, saltwater clam in the family Hiatellidae. The common name is derived from a Lushootseed (Nisqually) word gʷídəq meaning "dig deep".
The geoduck is native to the west coast of North America. The shell of the clam ranges from 15 centimetres (5.9 in) to over 20 centimetres (7.9 in) in length, but the extremely long siphons make the clam itself much longer than this: the "neck" or siphons alone can be 1 metre (3.3 ft) in length. The geoduck is both one of the largest clams in the world, and one of the longest-lived animals of any type. As adults they have very few predators other than humans.
These clams were not fished commercially until the 1970s, but in recent decades a huge demand from Asian markets has developed, and the clams are now farmed as well as being harvested in the wild. The clams currently sell for huge sums of money, which has made poaching a problem. Farming techniques are under scrutiny for their possible negative environmental impact.








The name of this clam (/ˈɡuːiːdʌk/ "gooey duck") is derived from a Lushootseed (Nisqually) word gʷídəq meaning "dig deep". Alternate spellings include gweduc, gweduck, goeduck, and goiduck. It is sometimes known as the mud duck, king clam, or when translated literally from Chinese, the elephant-trunk clam.
Between 1983 and 2010, the scientific name of this clam was confused with that of an extinct clam, Panopea abrupta (Conrad, 1849) in the scientific literature.

An ostensibly record-setting geoduck, Ye Olde Curiosity Shop, Seattle, Washington.

Native to the northwest coast of the United States and west coast of Canada (primarily Washington and British Columbia), these marine bivalve mollusks are the largest burrowing clams in the world, weighing in at an average of one to three pounds (0.5–1.5 kg) at maturity, but specimens weighing over 15 pounds (7.5 kg) and as much as 2 meters (over 6.5 ft) in length are not unheard of.
A related species, Panopea zelandica, is found in New Zealand and has been harvested commercially since 1989. The largest quantities have come from Golden Bay in the South Island where 100 tonnes were harvested in one year. There is a growing concern over the increase of parasites in the Puget Sound population of geoduck. Whether these microsporidium-like parasitic species were introduced by commercial farming is being studied by Sea Grant. Research to date does indicate their presence, with these parasites passed directly to Chinese who consume raw geoduck. Their long term effect on the human body is unknown at this time.
Geoducks are one of the longest-living organisms in the animal kingdom. The oldest recorded specimen was 168 years old, but individuals over 100 years old are rare. Scientists speculate that the geoduck's longevity is the result of low wear and tear. A geoduck sucks water containing plankton down through its long siphon, filters this for food and ejects its refuse out through a separate hole in the siphon. Adult geoducks have few natural predators, which may also contribute to their longevity. In Alaska, sea otters and dogfish have proved capable of dislodging 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. However, due to a low rate of recruitment and a high rate of mortality for geoduck eggs, larvae and post-settled juveniles, populations are slow to rebound. In the Puget Sound, studies indicate that the recovery time for a harvested tract is 39 years.
Biomass densities in Southeast Alaska are estimated by divers, then inflated by twenty percent to account for geoducks not visible at the time of survey. This estimate is used to predict the two percent allowed for commercial harvesting.








The world's first geoduck fishery was created in 1970, but demand for the half-forgotten clam was low due to its texture. As of 2011, these clams sell in China for over $150/lb (US$330/kg).
The geoduck's high market value has created an $80-million U.S. 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 to ensure revenues are received, 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 Oceans. The Washington State Department of Health tests water and flesh to assure clams are not filtering and holding pollutants, an ongoing problem. With the rise in price has come the inevitable problems with poaching, and with it the possibility some could be harvested from unsafe areas.
As of the 2007 season, advances in the testing system for contaminated clams have allowed geoduck harvesters to deliver live clams more consistently. The new testing system determines the viability of clams from tested beds before the harvesters fish the area. Previous methods tested clams after harvest. This advancement has meant that 90 percent of clams were delivered live to market in 2007. In 2001, only 10 percent were live. Because geoduck have a much higher market value live—an additional $2 to $3 per pound—this development has helped to stimulate the burgeoning industry.

Seafood geoduck display in a Chinese restaurant in Hong Kong

The large, meaty siphon is prized for its savory flavor and crunchy texture. Geoduck is regarded by some as an aphrodisiac because of its phallic shape. A team of American and Italian researchers analyzed bivalves and found they were rich in amino acids that trigger increased levels of sex hormones. Their high zinc content aids the production of testosterone. It is very popular in China, where it is considered a delicacy, mostly eaten cooked in a fondue-style Chinese hot pot. In Korean cuisine, geoducks are eaten raw with spicy chili sauce, sautéed, or in soups and stews. In Japan, geoduck is prepared as raw sashimi, dipped in soy sauce and wasabi. On Japanese menus in cheaper sushi restaurants, geoduck is sometimes substituted for tresus keenae, a species of horse clam, and labeled mirugai or mirukuigai. It is considered to have a texture similar to an ark shell (known in Japanese as akagai). Mirugai is sometimes translated into English as "giant clam," and it is distinguished from himejako sushi which is made from Tridacna gigas.