Rare Contagious Cancer Found in Fish from Quebec and U.S. Lakes

The discovery of a contagious cancer in fish from Quebec and U.S. lakes has sent shockwaves through the scientific community. This phenomenon, where melanoma tumors spread from one individual to another, is extremely rare, observed only three other times before: in Tasmanian devils, dogs, and shellfish.

Researchers first encountered the issue when anglers reported strange black spots and lumps on brown bullhead catfish from Lake Memphremagog, which straddles the border between Quebec and Vermont. Initially, there were concerns that these lesions were caused by carcinogens washed into the lake after a massive flood in 2012. However, genetic testing revealed something more insidious: the tumors were not just a result of environmental contamination but seemed to be transmitted among the fish themselves.

The researchers’ findings are striking – the melanoma tumors on infected fish were genetically similar to each other and less similar to their host. This is a significant departure from what typically occurs with cancer, where tumor cells mutate from the host’s cells and resemble them. The fact that these cancer cells are more alike than they are to the fish they’re found on suggests a form of contagiousness unprecedented in nature.

The theory is that this disease may be transmitted during spawning, when adult fish form clusters and come into contact with each other’s spines. This raises questions about the role of social behavior in the spread of cancer among aquatic species. While it’s not yet clear whether the disease can be transmitted from one fish to another, even in a lab setting, genetic evidence is “totally compelling,” according to Stephen Goff, a Columbia University researcher.

The discovery has significant implications for our understanding of the natural world. It suggests that the boundaries between species are not always clear-cut and that diseases can spread across taxonomic lines with ease. This challenges traditional views of cancer as a purely individual disease process.

As researchers continue to study this phenomenon, they need to be cautious in declaring something a transmissible disease without conclusive evidence. However, it’s clear that this warrants further investigation and monitoring. The Quebec government has already taken steps by recommending not eating catfish with tumors, despite there being no evidence of harm to human health. This raises questions about the risks associated with consuming fish from affected lakes.

The discovery should prompt us to reevaluate our relationship with nature and the potential risks associated with aquatic activities. The health of our fish populations is a reflection of the health of our planet as a whole. As researchers continue to explore the mysteries of contagious cancer in fish, they may uncover more about the intricate web of life that binds us all together – and perhaps even ourselves.