Cancer is ravaging the shellfish population in West Coast waters favored by top US restaurants

These clams are in a jam.Scientists warn that along the West Coast, legions of soft-shell clams are contracting a deadly, highly contagious cancer.Known as bivalve transmissible neoplasia, the cancer is spread when living cancer cells pass from one animal to another through seawater.While the disease has previously been found in soft-shell clams along the Atlantic Coast, this is the first time it has been identified on the West Coast.A study published last month revealed that more than three-quarters of clams at two locations in Washington state waters were affected by the cancer, making it one of the most grievous outbreaks ever documented.Clams and other shellfish found naturally and farmed in the chilly inland waterways of the Pacific Northwest are prized by top restaurants all over the country and beyond.

The cancer was first detected in Washington’s Puget Sound in 2022, when 45% of the clam population was affected; however, that number jumped to 75% in just two years.While the disease has no impact on humans and experts underscore that the clams are safe for consumption, the cancer is taking its toll.“We were surprised to find a transmissible cancer spreading at this level in Pacific Northwest clams,” said Michael Metzger, Ph.D., senior author of the study and Associate Investigator at Pacific Northwest Research Institute (PNRI). “The scale of the outbreak makes it an important system for understanding how these rare cancers emerge and move through wild populations.”Scientists underscored that the disease threatens not just the clams but the ecosystem as a whole, as clams filter both plankton and bacteria, making them a vital part of the marine environment.

Researchers noted that the affected clam species are not native to the West Coast and “were likely intentionally introduced from the Atlantic populations of clams in the 1870s.”The study also revealed that soft-shell clams in Puget Sound include hybrids of two closely related species: My...