Contagious cancers occur in clams and other bivalves, and some can even spread between different species of bivalves.
The threshold for closure is set at 80 parts per million, but concentration in those areas were found to be as high as 1,300 parts per million.The warning applies to oysters, clams, scallops, mussels and geoduck.
Shellfish in the Puget Sound tested positive for the prescription opioid oxycodone, and this was not the only drug found by the Washington Department of Fish and Wildlife.
Researchers with Southeast Alaska Tribal Ocean Research found high levels of Paralytic Shellfish Toxin in a population of mollusks at Auke Recreation Area in Juneau on Friday.