West Coast Clams Are Coming Down With Cancer

Soft-shelled clams living along the West Coast are getting a contagious and deadly form of cancer, scientists have warned. The outbreak was found in Washington state's Puget Sound, where it has infected about three-quarters of the clams in one large area called Triangle Cove. Researchers at the Pacific Northwest Research Institute say the disease could spread further down the coast if it is not carefully watched.

The cancer is called bivalve transmissible neoplasia, and it spreads between clams through seawater. Scientists say it has no known direct effect on human health, and the clams are still safe to eat. However, the disease is a big threat to the ocean ecosystem and to other shellfish that are already struggling because of pollution and warming ocean temperatures.

Officials in Oregon are now paying attention. A spokesperson for Oregon's Department of Fish and Wildlife warned this week that the cancer could spread south from Washington into Oregon waters. Right now, there is 'currently a low risk,' said Meghan Dugan, speaking to Portland's KOIN 6 news station. Still, Oregon does not yet have its own program to monitor for the disease, which means it could go undetected.

Soft-shelled clams play a very important role in the ocean. They act like natural water filters, cleaning out tiny plants and bacteria called plankton from the water, according to the nonprofit Blue Ocean Society. Without enough clams, the health of the whole coastal ecosystem could suffer.

Clams are already under stress from climate change. A major heat wave in 2021 killed large numbers of shellfish in the Pacific Northwest, with some species literally cooking alive on Puget Sound beaches. Pollution and warmer water can also make clams weaker and more likely to get sick, according to the Environmental Protection Agency's National Estuary Program.

This cancer was previously found in clams on the East Coast of the United States, but it had never been seen in West Coast clam populations before. Scientists first detected it in Puget Sound in 2022, and they studied the area through 2024. Genetic testing showed that the West Coast cancer comes from the same family of cancers found in Atlantic clams and Japanese clam species.

The good news is that the outbreak seems to be in its early stages. Scientists cannot stop it yet, but catching it early gives them a rare chance to watch how wild clams fight the disease. Researchers are still trying to figure out exactly how the cancer got to Washington waters.

Michael Metzger, an associate investigator at the Pacific Northwest Research Institute, explained the mystery this way: 'The most likely explanation is accidental human-assisted transport of an infected clam or seawater containing cancer cells, but we don't yet have evidence that allows us to determine the precise route.' He added that learning how these cancers travel between regions will be key to handling future outbreaks. Scientists are now working hard to find answers.

There are things people can do to help slow the spread of the disease. Checking ships for hitchhiking shellfish that may carry the cancer is one important step. Reducing ocean pollution may also help keep clams healthier and less likely to get sick in the first place.