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Panopea generosa
Four live specimens of Panopea generosa in a seafood tank
Scientific classification
Species:P. generosa
Binomial name
Panopea generosa
Gould, 1850
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Panopea generosa
Four live specimens of Panopea generosa in a seafood tank
Scientific classification
Species:P. generosa
Binomial name
Panopea generosa
Gould, 1850

The geoduck (/ˈɡdʌk/ "gooey duck"), scientific name Panopea generosa, is a species of very large, edible, saltwater clam in the family Hiatellidae.[1][2] The common name is derived from a Lushootseed (Nisqually) word gʷídəq.

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.


The name of this clam (/ˈɡdʌk/ "gooey duck") is derived from a Lushootseed (Nisqually) word gʷídəq[3][4] either a word composed of a first element of unknown meaning and əq meaning "genitals" (referring to the shape of the clam),[5] or a phrase meaning "dig deep".[6] 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.[2]


Native to the west coast of Canada and the northwest coast of the United States (primarily Washington and British Columbia), these marine bivalve mollusks are the largest burrowing clams in the world, weighing in at an average of 1.5 pounds (0.68 kg) at maturity, but specimens weighing over 15 pounds (6.8 kg) and as much as 2 meters (over 6.5 ft) in length are not unheard of.[citation needed]

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.[7]

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.[8] 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.[9] In the Puget Sound, studies indicate that the recovery time for a harvested tract is 39 years.[10]

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.[11] This estimate is used to predict the two percent allowed for commercial harvesting.[11]


Main article: Geoduck aquaculture
Seafood geoduck display in a Chinese restaurant in Hong Kong

The world's first geoduck fishery was created in 1970, but demand for the half-forgotten clam was low due to its texture[citation needed]. As of 2011, these clams sell in China for over $150/lb (US$330/kg).[12][13]

The geoduck's high market value has created an $80-million US industry, with harvesting occurring in the states of Alaska, Washington, and Oregon 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.[14]

As of 2007, 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.[15] 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.

Environmental impact[edit]

Investigation of environmental impacts is just now[when?] beginning to occur. Demand has also led to a rapidly developing aquaculture industry. Geoduck aquaculture on 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. Currently less than 0.001% of Puget Sound is dedicated to geoduck farming.[citation needed] Geoduck farms use "predator exclusion devices" in which to plant the seed geoducks. These devices are PVC pipes 10 to 14 inches (250 to 360 mm) long, 4 to 6 inches (100 to 150 mm) in diameter, pushed into the tideland sediment. There are approximately 20,000 to 43,500 of these PVC pipes planted per 1 acre (0.40 ha) on tidelands. These nursery tubes typically stay in the beach for the first year or two of a crop cycle.

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

The Environmental Defense Fund has done extensive studies of aquaculture and has found that bivalves (oysters, mussels, and clams) are beneficial to the marine environment.[16] The water must be certifiably clean to plant geoducks commercially. This is a requirement of the Washington State Department of Health Office of Shellfish and Water Protection and of the Interstate Shellfish Sanitation Council.[17]

Geoduck farming grow-out and harvest practices are highly controversial.[18] These practices have created serious conflicts with shoreline property owners;[19][20][21][22][23] concerns from nongovernmental organization (NGOs) (e.g., Tacoma Audubon and Sierra Club); and others simply interested in the health of Puget Sound. The shoreline development groups have expressed concerns including lack of regulation, aesthetics, effects on native geoduck populations, impacts on wildlife, farm debris, intensive farming/harvest techniques, agricultural densities of geoducks, carrying capacity of low-flushing inlets, near-shore habitat destruction, over enrichment of sediments from intensive shellfish bio deposits and the permanent conversion of natural ecosystems to intensive commercial agricultural use on the tidelands of Puget Sound. Shoreline developers are particularly concerned because they see shellfish farming as an impediment to continued bulkheading, upland deforestation and septic tank installation. The main objectives of the newly created Puget Sound Partnership include habitat preservation, habitat restoration, preservation of biodiversity and recovery of imperiled species (salmon).[24]

As mandated by 2007 legislation, the Washington State Shellfish Aquaculture Regulatory Committee stakeholder group, including industry, agency and citizen representatives has convened to discuss regulation of this industry.[25][26] Counties such as Pierce County have also begun to develop regulations covering tideland impacts from geoduck farming, something against which Taylor Shellfish has filed a suit.

Although some marine shoreline owners take issue with the visual impacts, a more important concern is their impact on the marine environment. Concerns arise over the use of PVC tubes, as poorly maintained farms may lose tubes, which can end up in subtidal areas, uncollected. Attempts to have industry mark tubes identifying the grower have been met with strong resistance.

Geoduck for sale at Tsukiji fish market in Tokyo

Geoducks are farmed in the intertidal zone, resulting in the farming operation's being visible only 2–3% of daylight hours. However, since the lowest tides in the summer are during mid-day, the visual and recreational impact of the tubes is greatest at the very time when the people of Puget Sound are likely to be using the beach. During summer, a citizen group shows that the average percentage of time during daylight hours that the farms are visible is 19% per day and the number of days from Memorial Day weekend to Labor Day that farms are visible some portion of the day is 76%.[27] This is calculated for geoducks planted to a +2 tidal level in Thurston County, Washington, one of the counties of South Puget Sound. When calculated for a +3 tidal elevation (where geoducks are never farmed), the amount of visibility rises to an average per day of 23% of daylight hours and 87% of the days of the summer.

Impacts on tideland include placing as many as 44,000 PVC pipes per acre on privately held tidelands; removal of this "artificial reef" one to three years later; then harvest after five to six years. While these practices may have short-term impacts to the tidelands, these impacts are not nearly as great as the documented impacts from upland residential development including bulkheading of the shoreline (disrupting the natural beach creation process), deforestation of the upland (creating increased storm water run-off) and placing of septic systems in the shoreline habitat (creating nitrogen loading of the coastal waters)[citation needed]. Fortunately, these upland impacts are readily dealt with through enforcement of existing regulations. Unfortunately, there are no meaningful regulations controlling geoduck farming and whatever the tideland impacts may be, whether short-term or long-term.

A January 2008 Washington Sea Grant paper, commissioned by the state of Washington to determine what studies existed on Geoduck aquaculture, found virtually no peer-reviewed research existed.[28] Studies have been funded to determine short- and long-term environmental and genetic impacts.[29] In southern Puget Sound, research has shown that the effect of geoduck farming on large mobile animals is ambiguous.[30]

In Puget Sound, subtidal densities in the wild (0.3 individuals per square foot or fewer) are below farmed densities of ~2 geoducks per square foot.[31] Each year new hatchery brood stock is taken from the wild stock. Farmed animals are not used as brood stock so genetically, farmed geoduck are the same as wild stocks. Moreover, wild geoduck occupy the intertidal zone down to 300 feet (91 m) below sea level. DNR and the tribes comanage the wild fishery and only harvest geoduck between the 18-to-70-foot (5.5 to 21.3 m) depths. The annual leased harvest of the wild geoduck population by the Washington State Department of Natural Resources Geoduck Fisheries Program is about 4,000,000 pounds (1,800,000 kg) a year.[32]

Wildlife interactions are a concern and geoduck growers are adapting growing techniques to minimize these effects.[citation needed] A 2004 draft biological assessment, commissioned by three of the largest commercial shellfish companies in the Puget Sound region, examined the impacts of geoduck farming and identified no long-term effects on threatened or endangered species.[33]

Farm debris includes displaced net tops, rubber bands, and PVC tubes. The net tops used on the nursery pipes can come off and float away onto other beaches as debris and the rubber bands also can become debris in Puget Sound. To offset these environmental impacts, most geoduck farmers have embraced environmental codes of practice including regular maintenance and debris clean-up of their own farms. 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 (92 m3) collected to date has been related to geoduck farming. Unfortunately, because of the currents in Puget Sound, nets and tubing can be found far from any poorly maintained geoduck operations.[citation needed] This lack of control over loose gear remains a significant enough problem that bonding requirements are being considered as part of regulations being developed.

Harvesting takes place every four to six years. Water pressure hoses using up to 50 US gallons (190 l) per minute are used to extract the geoducks buried under 2–3 feet (0.61–0.91 m) of sediment depth. There are no environmental impact studies related to intertidal harvest of geoduck As of August 2006, although the subtidal environmental impact studies done for the fisheries in BC and WA have found no detrimental effects in harvesting the clams. Geoduck farming is conducted in clean, uncontaminated sediments only, so concern is limited to short-term increases in turbidity and short-term effect on benthic organisms.[citation needed] The Department of Natural Resources of Washington State conducted the environmental impact study. DNR is itself in the business of leasing subtidal lands for commercial geoduck harvest and starting this year, intertidal lands for commercial geoduck farming.

Culinary uses[edit]

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.[34] A team of American and Italian researchers analyzed bivalves and found they were rich in amino acids that trigger increased levels of sex hormones.[35] Their high zinc content aids the production of testosterone.[36] 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.


In December 2013, China imposed an indefinite ban of geoduck and other "double-shell aquatic animals" – such as clams, oysters, mussels, and scallops – that were imported from the west coast of the United States. Chinese officials claimed to have found in an Alaskan shipment high levels of paralytic shellfish poisoning, a biotoxin that shellfish can accumulate, which when eaten by humans, can cause severe illness or even death. Companies exporting the product claim that Chinese inspectors were using a standard more rigorous than considered safe for human consumption. A shipment from Washington state was high in arsenic.[37] Some 90% of the geoduck catch is exported to China, leading to fears of layoffs for divers and other workers involved in the operations. The National Oceanic and Atmospheric Administration (NOAA) is in negotiations with China's government to reopen trade.[38][39]

In popular culture[edit]








  1. ^ Panopea generosa Gould, 1850.  Retrieved through: World Register of Marine Species on 28 December 2010.
  2. ^ a b Vadopalas, B.; T. W. Pietsch & C. S. Friedman (2010). "The proper name for the geoduck: resurrection of Panopea generosa Gould, 1850, from the synonymy of Panopea abrupta (Conrad, 1849) (Bivalvia: Myoida: Hiatellidae)". Malacologia 52 (1): 169–173. doi:10.4002/040.052.0111. Retrieved 2 March 2012. 
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  40. ^ "Duckumentary home". Retrieved 2012-06-05. 
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External links[edit]