Jamestown S’Klallam, WDFW partner on Strait Geoduck Study

Due to its popularity with harvesters and shellfish lovers, scientists are learning more about geoduck clams found in the Strait of Juan de Fuca.

During the past two years, the Jamestown S’Klallam Tribe, Lower Elwha Klallam Tribe and Washington Department of Fish and Wildlife (WDFW) have been collecting age and genetic data from these particular bivalves found in the Strait.

Geoduck is currently managed as a single Puget Sound stock,” said Kelly Toy, Jamestown S’Klallam’s shellfish management biologist. “But there may be regional differences that exist between geoducks in the Strait and other regions within Puget Sound. Gathering age and genetic data specific to geoducks in the Strait will help us determine if there are regional differences and develop a model that would help improve the sustainability of the Strait’s geoduck resource.”

WDFW shellfish researcher Bob Sizemore reaches for another geoduck sample to weigh.

When modeling this fishery, we use age data to determine the harvest rate,” said Bob Sizemore, a WDFW shellfish research scientist. “The age information is much better in the Central and South Puget Sound regions. To improve the age structure information in the Strait, we are taking a sample of about 600 geoducks along Dungeness Spit. We also used this opportunity to take tissue samples from the same animals for genetic analysis.”

Strait geoduck data was last collected in the 1970s and 1980s until 2012, when the co-managers started collecting tissue and shell samples.

To gather the age data, they shuck the shell completely. The shells are cut at the hinge, also called the umbo. Scientists then count the rings found in the cross-section of shell to determine its age.

The shells are categorized by age class, so scientists can determine what years were good for geoduck, suggesting good survival that year. The information also helps fisheries managers make better data-based decisions about population structure and harvest management strategies.