Contagious Cancer in Shellfish Sparks Investigation by International Team of Scientists

Multimillion-dollar grant enables investigators to turn the tide on transmissible cancers in shellfish on both U.S. coasts

SEATTLE, WA – February 9, 2023 – Michael Metzger, PhD, Assistant Investigator at Pacific Northwest Research Institute, in Seattle, WA, and a team of global co-investigators will study how a virus-like cancer spreads among basket cockles on the Pacific Coast and soft-shell clams on the Atlantic Coast through a $3 million grant from the National Science Foundation’s Division of Ocean Sciences.

“We don’t normally think of cancer as an infectious disease,” said Dr. Metzger. “But several transmissible cancers have recently been found in the wild, causing significant mortality—and marine bivalves, such as mussels, oysters, cockles, scallops, and clams appear particularly susceptible.”

What is unique about this cancer compared to human cancers is that it is transmissible. The cancerous cells themselves spread from one animal to another, much like a virus. This strain of cancer is known to negatively affect the marine environment, commercial aquaculture industries, and Native American communities that rely on bivalves as traditional food sources.

The newly funded project brings together a diverse team of marine biologists, population geneticists, mathematical modelers, cancer biologists, and genomic/molecular biologists from the following organizations and institutions across the globe: Suquamish Tribe, Puget Sound Restoration Fund (PSRF), Western Washington University, Bigelow Laboratory for Ocean Sciences (Maine) and Gloucester Marine Genomics Institute (Massachusetts), and City, University of London.

Over the next five years, the interdisciplinary collaborative will collect samples, analyze genomes, develop mathematical models, and measure disease progression.

“It takes expertise in tribal resource management, marine conservation, and infectious disease ecology to solve this complex problem,” said Ryan Crim, a PSRF marine biologist who has been working with the Suquamish Tribe in Washington state to restore marine habitats for more than a decade.

They found infectious cancer prevalent in local basket cockles, a favorite subsistence species for Tribal members that has become scarce in recent years.

“Understanding exactly how these bivalves fight or bounce back from this cancer directly impacts the survival of those species and the people who rely on them.”

Michael Metzger, PhD
PNRI Assistant Investigator

Elizabeth Unsell, a marine biologist with the Suquamish Tribe, explained that the Tribe is motivated to work to restore local populations and learn more about the threats they may be facing.

“Increasing our awareness and understanding of the presence and severity of transmissible  cancer in this favored bivalve species will give us tools to better understand population dynamics and inform management decisions,” said Unsell.

On the eastern U.S. coast, soft-shell clams are consistently one of the most valuable fisheries for Massachusetts each year and the species has a strong cultural and historical relevance in the region. Transmissible cancer in soft-shell clams has caused major losses in Massachusetts in the past, severely impacting the commercial fishery.

“By gaining a better understanding of the infection dynamics and mechanisms of transmissible cancer in soft-shell clams, we will be more effective at preventing or managing the disease to better conserve this precious natural resource,” said Tim O’Donnell, a freshwater and marine fish researcher at Gloucester Marine Genomics Institute.

“Understanding exactly how these bivalves fight or bounce back from this cancer directly impacts the survival of those species and the people who rely on them,” Dr. Metzger said. “If successful, we will come away with a far better understanding of how these transmissible cancers spread and what we can do to stop them.”

“I’m grateful that the NSF values this kind of interdisciplinary research,” Dr. Metzger said. “Without their funding, we couldn’t launch a study like this connecting genomic analysis of the cancers with multi-year ecological surveys and modeling to understand all the factors involved in disease spread.”


About PNRI:
Pacific Northwest Research Institute (PNRI) is a nonprofit biomedical research institute, where scientists are using innovative approaches in genetics and genomics to tackle some of the most difficult problems in science and medicine. The institute was founded 67 years ago in Seattle, Washington, as a place where scientists were free to pursue discoveries that promised the highest chance of improving human health. The goal was at the beginning, and remains today, to conduct foundational science leading to impactful medical innovations. To learn more, visit

Media contact:
Louise Maxwell