Geoduck

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Introduction

The geoduck clam, Panopea abrupta, is native to the Pacific Ocean and is a valuable shellfish species harvested commercially on Canada's west coast. Increasing demand in Asian markets make geoduck an attractive species for aquaculture development. Technology for geoduck aquaculture in British Columbia has been refined and developed over a number of years. The industry is poised to move forward into commercial development and expansion.

Interest in geoduck aquaculture began in the early 1990s.  Since that time, significant resources have been invested in developing and refining geoduck hatchery, nursery and culture methods in British Columbia. In response to considerable interest in access to new lands and to a workable policy framework for geoduck aquaculture, the Ministry of Agriculture and Lands in British Columbia, Fisheries and Oceans Canada, First Nations and stakeholders have been working co-operatively over the last decade to foster the responsible development of geoduck aquaculture in British Columbia.

Basic description

Juvenile geoducks

Geoducks are a bivalve shellfish (an animal with two shells) that live burrowed under the ocean floor, or substrate. Cultured geoducks have a five to seven year culture cycle weighing an average of 1 kg (2.2 lbs) when harvested for the retail market. They have a large meaty siphon, or neck, extending from their large oval-shaped shell. The tip of the siphon pokes slightly out of the sandy bottom and is referred to as 'the show', allowing experienced harvesters to identify where the clam is buried.

Geoducks are harvested by scuba divers using high-pressure water, delivered through a long nozzle that loosens the substrate around the clam and allows the diver to gently lift the clams out without damaging the animal. Harvested geoducks are shipped to processing plants where they are packed and delivered live to Asian markets. Harvest can occur any time throughout the year.

Subtidal geoduck culture in British Columbia (showing predator protection meshing).
Photo courtesy of Underwater Harvesters' Association.

Subtidal geoduck culture in British Columbia (after predator protection meshing has been removed).
Photo courtesy of Underwater Harvesters' Association.

Background

Larval and young juvenile geoducks are raised in hatcheries from healthy, robust broodstock. It takes about a year until the seed is ready to be transferred, or 'planted', into inter-tidal or sub-tidal beds. There are two planting methods. In inter-tidal areas, when geoduck seed reaches 10 mm in length, the animals are planted in plastic tubes (usually four clams per tube) that are buried in the ocean floor. The tubes are typically removed after two years. Alternatively, 25-30 mm sized animals can be transferred directly onto the ocean floor using an underwater mechanical seeder. This method is used primarily in sub-tidal areas where tubing can shift due to high currents.

Geoducks are small when they are planted and vulnerable to predation by crabs, sea stars, and various fish species. Strong netting is secured over the planting beds and is removed approximately one year later, once the geoducks are established. The geoducks remain untouched on the aquaculture tenure for another three to five years until they reach the desired market size (about one kilogram). Geoduck farmers do not feed their stock. Like other bivalve shellfish, such as mussels and oysters, geoducks are filter feeders that consume nutrients that naturally exist in the water column (microscopic algae and plankton). For a more detailed description of the hatchery and grow-out process, please read the species profile prepared by the BC Shellfish Growers Association.

Intertidal geoduck culture in Washington

Research Activity

In 2004, DFO conducted a scientific review that examined potential, but unassessed effects of geoduck farming and harvest. DFO expressly prepared the report to identify any potential risks of geoduck aquaculture as a responsible first step in the management of the resource. The Department then introduced new procedures and regulations to mitigate those risks, prior to allowing new sites to develop. At the same time, DFO adopted a cautious, phased approach to expansion, in conjunction with the Province of British Columbia, by limiting the number of sites and selecting locations prior to tenure applications. Furthermore, DFO has recently undertaken extensive scientific research to assess potential impacts of geoduck culture and harvest in both the intertidal and subtidal environments.

DFO, in cooperation with the BC Ministry of Agriculture and Lands and industry, are confident that the necessary information is being collected to move cautiously forward with commercial-scale geoduck farming. The peer-reviewed studies that will flow from this gradual expansion process will allow the partners, and interested members of the public, to assess potential effects of geoduck farming in a realistic, controlled manner. In turn, this analysis will inform management action and ultimately lead to an environmentally sustainable geoduck aquaculture industry in British Columbia.

For more information

British Columbia's Ministry of Agriculture and Lands - Geoduck Aquaculture

• Provides interim policy documents that outline the conditions in which geoduck aquaculture will occur on existing shellfish farms and how new applications will be accepted and assessed.  Maps provided.

BC Shellfish Growers Association - Species Profile

• Provides a detailed description of how geoduck clams are grown.

BC Seafood Online - Fact Sheets - Geoduck

Geoduck Clam: Anatomy, Histology, Development, Pathology, Parasites and Symbionts

• Technical description of this species was produced by DFO Science Branch (last updated in May 2003)

Underwater Harvesters Association

• This site focuses primarily on the commercial harvest and co-management of the wild geoduck fishery with DFO, provides an abundant amount of information about the geoduck, and explains the enhancement work underway to strengthen the long term sustainability of the resource using hatchery techniques (video). The scientific and practical knowledge gained by these enhancement efforts are benefiting the development of a geoduck aquaculture industry in British Columbia.

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