The Jamestown S’Klallam Tribe is testing a variety of shellfish species for Diarrhetic Shellfish Poisoning (DSP).
After discovering dangerous levels of the toxin in Sequim Bay last summer, the tribe wants to understand better how shellfish are affected by DSP. If shellfish contaminated with high levels of the toxin is ingested by humans, it can cause severe flu-like symptoms. Cooking or freezing the shellfish does not kill the toxin.
“We learned last year that different types of shellfish react differently to DSP toxins in the water,” said Lohna O’Rourke, the tribe’s environmental biologist. “One example we found is that clams and oysters seem to be less sensitive to the toxin than mussels or may flush it out of their systems at different rates.
“It’s important for the tribe to understand this to help reduce economic and cultural hardships as a result of shutting down all shellfish harvesting at the same time. If we can be selective when shutting down harvesting due to a DSP event, all the better,” she said.
The tribe is collecting and testing several dozen shellfish on a weekly basis through the summer from Sequim Bay State Park and the tribe’s tidelands at the south end of Sequim Bay.
DSP toxins are typically found in the fat of shellfish, which is tested in the tribe’s laboratory using Jellett rapid test kits. The same samples are sent to the National Oceanic and Atmospheric Administration’s lab in Seattle for verification of DSP toxins using specialized equipment.
In addition, the tribe will try to determine what environmental conditions play a part in the growth of the phytoplankton that produces DSP toxins and whether a combination of the density of the plankton in the water and the on-site testing can be used asd early warning for DSP events.
The toxin first was found in high concentrations in mussels that were harvested from Sequim Bay State Park in June 2011. As a precaution, the state Department of Health shut down harvesting last summer and the tribe recalled all shellfish harvested by tribal diggers.
DSP has always been present in the marine environment but last summer was the first confirmed DSP illness case in the United States, said Kelly Toy, the tribe’s shellfish manager.