A naturally occurring plankton boom, known as red tide, has kept tribal geoduck divers from harvesting the shellfish. Blooms are not uncommon, but they generally occur in the summer, when warm weather and sunshine create ideal conditions.
"It is unusual to have a biotoxin closure this time of year," said David Winfrey, a shellfish biologist with Puyallup Tribe. A bloom hit the Tribe's harvesting area in November, prompting a halt to harvesting. He said such winter blooms occur about once every eight to 10 years. "Why this happens is not well understood, even by high-level academics."
Between 85 and 110 members of Puyallup Tribe harvest geoducks. The clams have long been part of the traditional diet of the Native people of Puget Sound.
David Winfrey said the first tribal member to harvest geoducks commercially began in the 1970s. Back then divers would sell their catch from the back of their trucks along the side of the road, making little money.
Things changed when geoducks were marketed to Asian customers. They became popular across the Pacific Ocean, especially in China. Geoducks are considered a delicacy, an item eaten in restaurants for business meetings and special occasions.
In 2011, tribal divers were getting $24 a pound for geoducks. The average clam weighs two to three pounds. By the time they go through several middlemen and land on the plate of a diner in China, they cost up to $150 a pound.
Geoducks are a popular dish for Chinese New Year, which falls on Feb. 10.
The harvesting season ends in late March. The fall quarter ended Dec. 31. Quotas are set for divers and generally these are not carried over. However, because of the closure, Puyallup Tribal Council passed a resolution allowing the third and fourth quarters to be combined.
The plankton develops what are call cysts. George Stearns, also a shellfish biologist with the tribe, said this allows it to form a thicker cell wall. It is believed to be a survival mechanism.
David Winfrey said geoducks are not actively feeding this time of year. They do continue to take in enough water to get oxygen to their gills, and some cysts enter the clams this way.
Washington State Department of Health tests for toxin levels. One method is to lower cages with mussels into the water. Mussels are able to rid the cysts from their systems without suffering damage. Another is to cut open a geoduck, remove a gut ball and examine it under a microscope. David Winfrey said this material is sometimes injected into a laboratory mouse, which is then observed by scientists.
Geoducks tainted with the toxin can cause paralytic shellfish poisoning to a person who eats them. This is a severe illness that in some cases is fatal.
Toxin levels were quite high during testing the first week of December. They dropped considerably by the third and fourth weeks of the month, but then spiked upward. In order for harvesting to be allowed, two samples in a row that fall below the closure level are needed.
Tribal officials remain optimistic that divers will soon be able to harvest the valuable clams. "This is a tribal right," said Nancy Shippentower-Games, director of the Tribe's Shellfish Department. "We have an obligation to protect this resource."
Puyallup Tribal News will provide an update on this issue in the next issue.