For more than a decade, anglers on Lake Memphremagog — which straddles the Québec-Vermont border — have been catching brown bullhead catfish marked with distinctive black lesions.
In 2019, scientists from the United States Geological Survey (USGS) and the Vermont Fish and Wildlife Department confirmed the lesions to be malignant melanoma. Yet, until recently, there was no confirmed explanation for how the disease emerged.
