Avian flu has not only killed thousands of Quebec birds. It also led to a marked increase in mortality among harbor seals in the St. Lawrence. The impact these deaths will have on the pinniped population remains to be determined.
The Quebec Marine Mammal Emergency Network has identified an unusually high number of dead or sick harbor seals in the St. Lawrence River so far this year. A total of 93 carcasses were found, including 73 only in June.
“In fact, the number of harbor seals found so far this year represents an increase of regarding eight times the annual average of recent years,” said veterinarian Stéphane Lair, director of the Quebec Center for Wild Animal Health, in a text published on tuesday on the Healthy Wildlife blog.
In an attempt to understand this marked increase in deaths, authorities have sent seal carcasses and field samples to the Quebec regional center of the Canadian Wildlife Health Network, where they will be analyzed. “The results obtained so far indicate that the increased mortality observed in these harbor seals is associated with infections with the highly pathogenic H5N1 avian influenza virus,” writes Dr.r Stephane Lair. A point of view shared by Fisheries and Oceans Canada.
“Although the risks of transmission of this influenza virus to humans and domestic animals seem low, it is recommended not to approach, and especially not to touch, a sick or dead seal. We will also prevent contact between our pets and seals or dead birds,” said Mr. Lair.
For now, the impact of these deaths on the harbor seal population remains to be determined, according to the veterinarian. This species is the only one to remain all year round in the St. Lawrence. It is also the least abundant of the four species that frequent the estuary and the gulf. According to Fisheries and Oceans Canada, there are between 20,000 and 30,000 harbor seals in the area.
Could H5N1 also reach other species of marine mammals, such as the beluga? “Transmission presumably requires fairly close contact, so in my opinion it is unlikely. But I think it will be important to watch this closely. We will probably sample the next carcasses, ”explains the Dr Lair.
For the moment, the other species of seals observed in the St. Lawrence, including the very abundant gray seal, would not be affected by avian flu, specifies Jean-François Gosselin, biologist at Fisheries and Oceans Canada.
dead birds
For now, the positive cases in harbor seals all come from Bas-Saint-Laurent, a region where many cases of avian flu have been identified in wild birds. This virus caused the death of thousands of birds of several species in Quebec, including snow geese, Canada geese, common eiders and northern gannets. Several species that feed on dead infected birds — turkey vultures, bald eagles, corvids and gulls, among others — have also been affected.
In the Magdalen Islands, where tourist traffic is in full swing at the moment, more than 5,000 bird carcasses have been collected so far. The imposing colony of northern gannets on Bonaventure Island, which numbers more than 100,000 individuals, is also affected by avian flu.
According to the Ministère des Forêts, de la Faune et des Parcs, “it must now be considered that the highly pathogenic H5N1 avian influenza virus has spread to all regions of Quebec”. the web site pancanadien which monitors the evolution of the disease also shows that the virus is now present on a large scale throughout Quebec. In particular, cases have been identified in the regions of Montreal, Estrie, Mauricie, Quebec and Lac-Saint-Jean.