Panopea generosa

Illustration of a Geoduck

Also Known As

  • King Clam
  • Elephant Clam
  • Gweduck
  • Goeduck
  • Goiduck

U.S. farmed geoducks are a smart seafood choice because they are sustainably grown and harvested under U.S. state and federal regulations.

Environmental Impact

Geoducks provide net environmental benefits by removing excess nutrients and improving water quality.


Growing geoducks requires no feed – they filter phytoplankton directly from the water column.

Farming Methods

Geoducks are planted in PVC pipes on intertidal beaches until they are large enough to burrow into the sediment.

Human Health

Shellfish toxins and bacteria occur naturally in the environment and can cause foodborne illnesses. State and federal regulations require monitoring of farmed geoducks to ensure they are safe to eat.

  • Availability

    Available year-round.

  • Source

    Washington State and Alaska.

  • Taste

    The neck is tough and crunchy while the belly meat is tender and sweet.

  • Health Benefits

    Geoducks are excellent sources of protein and iron.

U.S. Farming


  • Permitting for shellfish aquaculture is governed by federal, state and local governments.
  • The federal agencies involved are NOAA, the Army Corps of Engineers, Fish & Wildlife Service, US Department of Agriculture, the Environmental Protection Agency, the Food and Drug Administration, the Bureau of Ocean Energy Management and the Coast Guard.
  • Shellfish farms must adhere to federal regulations including those in the Magnuson-Stevens Fishery Conservation & Management Act, the Endangered Species Act, the National Environmental Policy Act and the Clean Water Act.
  • Information on shellfish aquaculture permitting can be found in the Shellfish Growers Guide.
  • A variety of shellfish aquaculture tools, including maps and models, are available to coastal managers.

Farming Methods

  • Juvenile geoduck (seed) production:
    • Geoduck larvae are bred in on-land hatcheries and fed a diet of algae.
    • Larvae set within three weeks and are grown in tanks with shallow sand until they reach about 4-6 mm.
  • Grow-out:
    • Geoduck seed are planted in PVC pipes in the sediment of intertidal beaches.
    • The PVC pipes, often covered by nets, protect the juvenile geoducks until they grow large enough to burrow into the sediment, safe from predators.
    • Grow-out can take 4-7 years for a geoduck to reach harvest size of 2 pounds.


  • In 2016 the United States produced 9.7 million pounds of clams, including geoducks, valued at $138 million.

The Science

Environmental Considerations

  • Habitat:
    • Geoduck farming can have minimal impacts within the first 1-2 years of grow-out when PVC pipe and net are present, but these effects disappear after removal.
    • Geoduck harvesting causes minimal impacts on the benthic communities.
    • PVC pipe and net can affect eelgrass growth, so geoduck farms are not planted where eelgrass is present.
  • Feeds:
    • Once past the larval stage, geoducks do not need to be fed because they filter their food from the water column.

Ecosystem Services‎

  • Water quality improvements:
    • Geoducks are filter-feeders, removing algae, organic matter and excess nutrients from the water column as they grow and improving water quality.
    • When geoducks are harvested, excess nutrients, such as nitrogen and phosphorus, are removed from the ecosystem.

Human Health

  • Shellfish toxins:
    • Shellfish poisoning is an illness that can occur from eating contaminated shellfish.
    • Geoducks can assimilate the toxins that cause shellfish poisoning from the algae on which they feed.
    • Early warning systems exist to detect harmful algal blooms that produce toxins.
    • New technologies, such as the Environmental Sample Processor, provide near real-time detection of harmful algal species.
    • For more information on identification, prevention and monitoring of harmful algal blooms, read about the NOAA Ocean Service Harmful Algal Bloom programs.
  • Public health officials monitor shellfish from growing areas to ensure they are safe to eat.

Physical Description

  • Geoducks are characterized by a small shell and very long siphon, or "neck."
  • The long “neck” has two openings at the end – one for taking in oxygen and phytoplankton and one for releasing excess water.


  • Geoducks are long-lived; the oldest ever recorded was 168 years old.
  • Geoducks burrow into the sediment about 1 foot per year to a depth of 3 feet.
  • In the first 3-5 years, geoducks grow to 1.5 pounds, though they make not reach maximum size, about 7 pounds, for 15 years.
  • Females release between 1 and 2 million eggs per spawn.

Last updated: 04/02/2019