A confirmed case of transmissible cancer in brown bullhead fish from Lake Memphremagog marks a world first for freshwater species, according to a study published Wednesday in the scientific journal Nature. Researchers at the University of Vermont identified the condition as a form of skin cancer known as melanoma that spreads between animals like a virus, offering new insight into how malignant cells survive and move beyond a primary host.
The investigation began in 2012 when fishermen and biologists observed black spots on brown bullheads in the cross-border lake shared by Quebec and Vermont, as stated in a university release. Within two years, nearly a third of the fish population displayed the same lesions. Julie Dragon, a scientist at the University of Vermont and co-supervisor of the research, noted that investigators initially suspected a virus before recognizing that the condition behaved more like parasites passing between fish. Subsequent analysis of cancer cells from multiple specimens revealed that the cellular material was related, confirming direct transmission between animals.
Precedents in the Animal Kingdom and Human Safety
This development represents the fourth transmissible cancer identified in the animal kingdom, and the first documented case in a fish or any freshwater species. Prior examples include devastating facial tumors in Tasmanian devils that reduced populations by nearly 90 percent, a transmissible venereal tumor in dogs, and leukemia-like contagious diseases affecting clams, mussels, and other mollusks. Despite the contagiousness of the affliction among fish, the research team confirmed it poses no known risk to humans, reassuring the public regarding Lake Memphremagog’s drinking water system, which serves more than 175,000 people. However, Mark Henderson, a fish specialist and co-director of the study at the university’s Rubenstein School of Environment and Natural Resources, stated that he personally would not consume fish displaying tumors.
Did You Know? The affected waters of Lake Memphremagog serve more than 175,000 people for drinking water, yet researchers have confirmed that the contagious fish cancer presents no known danger to human health.
Environmental Investigation and Future Research Directions
Investigators are still working to determine the precise mechanism by which the tumors spread between fish, alongside the underlying cause of the condition. Potential triggers under evaluation include pollution, environmental stress, or climate change. Natural arsenic represents one possible factor, as researchers have documented the same cancer in fish residing in lakes and ponds across Vermont, New Hampshire, Maine, and New Brunswick that sit far away from waste dumps or toxic discharge sites. Experts suggest these populations could provide valuable opportunities to observe how cancer evolves over time.
Expert Insight: Examining how abnormal cells adapt and travel outside their original host helps scientists isolate the biological boundaries that normally contain disease, providing a clearer baseline for understanding cellular containment failure.
Frequently Asked Questions
What species is affected by this transmissible cancer?
The condition impacts the brown bullhead, marking the first time a contagious cancer has been documented in a freshwater species or any fish.
Is the water safe for human consumption?
Yes. The research team confirmed that the contagious fish cancer poses no known threat to human health, and the drinking water supply for more than 175,000 residents relying on Lake Memphremagog remains secure.
What caused the outbreak in the lake?
The exact origin remains under investigation, though researchers are exploring potential links to pollution, environmental stress, climate change, and naturally occurring arsenic.
What are the broader implications for cancer research as these freshwater fish continue to be studied?
Worth a look