Researchers are tracking a contagious melanoma in brown bullhead catfish discovered in a lake on the Quebec-Vermont border [1, 2].
The discovery marks a rare biological event that could threaten freshwater ecosystems across North America if the disease continues to spread. Because the cancer is transmissible, it behaves more like an infectious disease than a typical genetic mutation.
Scientists, including fisheries biologist Scott Young and post-doctoral fellow Zoe Clarke, are currently testing whether the melanoma has spread from the original site in Quebec to the province of New Brunswick [1, 2]. The disease is described as a transmissible melanoma, though some reports have characterized it as a "flesh-eating" cancer [2, 4].
"We are testing to see if melanoma has spread from catfish in Quebec to New Brunswick," Crystal Garrett said [1].
This is the first known instance of a transmissible cancer appearing in freshwater fish [3]. According to researchers, it is only the fourth known transmissible cancer in recorded history [4].
The impact on the local population has been severe. Approximately 38,000 fish have died from the disease in the affected lake [5].
"This is the first known transmissible cancer in freshwater fish," Zoe Clarke said [3].
Researchers are monitoring the spread to assess the overall ecological risk, and to develop potential mitigation strategies to protect other waterways [1, 3]. The effort to track the movement of the cancer has continued through August [4, 5].
“This is the first known transmissible cancer in freshwater fish.”
The emergence of a transmissible cancer in a freshwater species suggests a rare evolutionary leap where cancer cells can move between individuals. If the disease is confirmed in New Brunswick, it would indicate that the melanoma can survive transit between separate bodies of water, potentially increasing the risk to diverse fish populations across the continent.
