Scientists have discovered that brown bullhead catfish in Lake Memphremagog are spreading a transmissible skin cancer to one another.
Key facts
- •Approximately 30% of the brown bullhead catfish population in Lake Memphremagog currently exhibits the melanoma.
- •The cancer cells appear to be clones that spread from host to host rather than originating within each individual fish.
- •Researchers suspect the cancer is transmitted through physical contact, potentially during spawning when fish cluster together.
- •The study was conducted by researchers from the University of Vermont, the University of Cambridge, and the Vermont Fish & Wildlife Department.
- •The findings were published in the journal Nature on a Wednesday.
Researchers have identified a transmissible form of melanoma spreading among brown bullhead catfish in Lake Memphremagog, which spans the border of Vermont and Quebec. The discovery, detailed in a study published in the journal Nature, marks the first time a transmissible cancer has been documented in fish. The condition manifests as dark, tar-like blemishes on the fish's skin, fins, mouths, and eyes.
By the numbers
Discovery and Investigation
The Vermont Fish & Wildlife Department first noticed the unusual markings during a 2013 fish census. While anglers had reported seeing the blotches the previous year, the condition appeared suddenly. Initially, biologists suspected environmental pollutants from a nearby landfill or UV radiation might be causing the tumors, but testing revealed no significant toxin levels. Subsequent attempts to link the cancer to a virus also proved unsuccessful.
Genetic Evidence of Transmission
Data scientist Julie Dragon and her colleagues conducted whole genome sequencing on the fish and their tumors. They discovered that the tumors were genetically distinct from the host fish but closely resembled one another. This suggests the cancers are clones that originated in a single fish and have since spread to others. Researchers believe the cancer may be transmitted when fish aggregate and accidentally scratch each other with their sharp pectoral spines during spawning.
Broader Scientific Implications
Transmissible cancers are rare, previously identified only in Tasmanian devils, dogs, and certain molluscs. Experts suggest that studying these catfish could provide insights into how cancer cells metastasize and migrate in other species, including humans. Researchers are now investigating whether similar transmissible cancers exist in other bodies of water, noting that historical accounts, such as those by Henry David Thoreau, may have described similar conditions in the past.
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This article was independently rewritten by ManyPress editorial AI from reporting originally published by NPR Health.
