Eastern Townships | Cancerous fish in Memphremagog

A significant proportion of brown bullheads in Lake Memphremagog have melanomas and sometimes metastases, environmental authorities in Quebec and Vermont recently discovered. A study has been launched on the subject to try to determine the causes.

These fish have “brown bullhead melanoma,” a cancer that causes “species of black spots and hyperpigmentation of the affected areas,” explained to The Press biologist Jean-Sébastien Messier, from the Ministry of the Environment, the Fight against Climate Change, Wildlife and Parks (MELCCFP) of Quebec.

The spots may be present on the brown bullhead’s skin, fins or mouth (Ameiurus nebulosus), a very common freshwater fish in Quebec.

“There may be visible metastases on certain organs, it can affect almost the whole body, perhaps even the bones”, adds the biologist, specifying that he does not know for the moment to what extent these tumors are incurable.

The phenomenon is worrying, judge Jean-Sébastien Messier. “We don’t know the extent that it can take, the consequences that it can have. [La barbotte brune] is an important component of biodiversity. »

” I’ve never seen that ”

Brown bullheads affected by melanoma were first reported in Vermont around 2012, but the phenomenon had practically not been observed in Quebec until now: only two reports have been made since 2018.

Florent Philibert is one of those who informed the Quebec authorities of the problem, after having fished half a dozen affected bullheads, in the summer of 2022, not far from the border.

“Sometimes the spot was so big that it covered the whole head,” he told The Press.

The first reports were made in the United States because the bullhead is more fished there than in Quebec, supposes Jean-Sébastien Messier.

Study in progress

The MELCCFP carried out a sampling in mid-May as part of a study on the subject conducted in the United States; About a hundred bullheads were sampled in three different places in Memphremagog.

“Around 30% of fish over 20 centimeters were affected, showed symptoms of the disease,” said Jean-Sébastien Messier, adding that a sampling carried out by Vermont environmental authorities on the American side of the lake gave similar results.

The genetic analysis of the specimens taken, which will be carried out in the United States, should make it possible to better understand the disease, its incidence and its causes.

The fact that the portrait of the situation is similar over the hundred square kilometers of Memphremagog “complicates the hypotheses”, explains Jean-Sébastien Messier.

The hypothesis that the disease is caused by a release of contaminants at a specific location in the lake seems unlikely, because only the fish in this sector would be affected if this were the case, he explains, pointing out that bullhead brown does not travel long distances.

It is more likely a combination of factors, postulates the biologist, evoking ultraviolet radiation, a virus, genetics or pollution.

Landfill site

Some point to leachate from the Coventry landfill near Newport, which is discharged into a tributary of the Memphremagog after treatment, but which still contains perfluoroalkyl and polyfluoroalkyl substances (PFAS), commonly known as eternal pollutants.

This is in particular because the first samples of affected bullheads were made in this sector, indicates Jean-Sébastien Messier.

“Now there are areas of the lake where there is no spring [de contamination possible] which could be singled out, and we still see it, ”he says, explaining that more in-depth analyzes are necessary to be able to move forward on a cause.

another lake

Brown bullhead melanoma has also been observed in fish in Lac Thor in Stratford, Estrie (formerly called Lac Maskinongé), but nowhere else for now.

“There could certainly be some in other bodies of water”, believes Jean-Sébastien Messier, who invites fishermen to report any fish caught showing anomalies to the email address [email protected]. ca, ideally with a photo and the exact location of the sighting.

Spots similar to brown bullhead melanoma have also been observed on bass caught in Lake Memphremagog this spring, notably by Florent Philibert.

This “spotted bass” disease is documented in the United States, but still relatively unknown in Quebec, says Jean-Sébastien Messier.

In both cases, it is not recommended to eat the affected fish, he stresses, even if there is nothing to indicate that there is an issue for human health.