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Maine seals are the latest species to be affected by persistent strain of avian flu

Northeast Fisheries Observer Program

Since May, 92 stranded seals have been found along the Maine coast from Biddeford to Boothbay. And starting in June, the vast majority were found dead. The National Oceanic and Atmospheric Administration says the rate is triple what's typically seen this time of year. And Lynda Doughty, the executive director of Marine Mammals of Maine, said there are no signs that strandings are abating.

"We continue to get daily reports of either live or deceased seals up and down our coastline," Doughty said.

Marine Mammals of Maine recently sent samples from eight stranded harbor seals for lab testing; four came back positive for avian flu. Maine seals are the first marine mammals to contract avian flu under the current outbreak in the US, which was first detected in January in an American widgeon in South Carolina. Since then, the flu has been found in 90 different wild bird species across dozens of states. In Maine, those species include Canada Geese, bald eagles terns and eiders. The disease has also spread to backyard and commercial poultry flocks, affecting more than 900 birds in Maine and 40 million nationwide. Julianna Lenoch, National Wildlife Disease Program Coordinator for the USDA, said avian flu has also spread to other mammals.

"Including red fox, striped skunk, raccoon, Virginia opossum, bobcat, fisher, and coyote," she said. "So that list is all terrestrial, or land-based mammals. So the seal is the first marine mammal that we've seen the spillover in, but this is not unexpected."

Avian flu has been detected in seal populations going back decades. But Bryan Richards of the USGS National Wildlife Health Center says the current outbreak is behaving differently than previous ones.

"This is substantially different than the outbreak we experienced in 2015, with more species, bigger numbers, more substantial mortality, and this tremendously larger geographic footprint.," Richards said. "So essentially, there's a lot more virus out there in the environment this time around."

Federal scientists say they don't know whether climate change is playing a role. Historically, warmer temperatures have actually helped dissipate influenza. For now, scientists are determining whether the seal deaths in Maine can be classified as an unusual mortality event, which would trigger additional resources and funding to investigate. Officials are advising people who see stranded seals to steer clear of the animals and call the Maine Marine Animal Reporting Hotline at 800-532-9551.