In a three-month span this fall, 146 seals have been found dead along New England shores and in the Gulf of Maine, more than three times the average. Wildlife officials have been scrambling to determine the cause for the recent mortality spike; NOAA has declared the rash of deaths an Unusual Mortality Event.
Now, after an initial round of tests, they may have found the culprit. Five seal carcasses examined by toxicology experts at the New England Aquarium tested positive for Influenza A, according to a report released by NOAA. Further testing will be done in the coming weeks to determine what specific strain of Influenza A infected the seals. Officials caution that other factors, biological or environmental, haven’t been ruled out.
“This is five seals, keep in mind, of the 146,” said Maggie Mooney-Seus, a NOAA spokeswoman.
Flu is a familiar enemy to the harbor seal population, according to Mendy Garron, a National Marine Fishery Service regional marine mammal stranding coordinator. There have been similar outbreaks in the early 80s and mid 90s. The seal population also suffered an outbreak of a distemper-like virus in 2006. There is little wildlife officials can do, but document and wait, Garron said.
“You have to let it run its course,” Garron said.
The harbor seal population has been robust in recent years, and there is little evidence that the flu will put much of a dent in overall seal numbers. In fact, disease outbreaks often happen in large animal populations due to the close proximity of individuals, said Mooney-Seus.
But in Maine, documenting seal strandings recently got harder. In the past, the northern half of the Maine coast was monitored by organizations like the University of New England in Biddeford and the College of Atlantic in Bar Harbor, while the southern coast was monitored by state officials.
But the state ran out of funds to monitor marine mammal strandings in mid-September, leaving a gap in coverage that NOAA officials have had to fill. Many organizations throughout the nation compete each year for the $4 million in funding, said Garron. The state used federal grant money to fund their monitoring program in the past couple of years, but it didn’t win the money this year and program-funding dried up right when the seal epidemic was first being identified.
“It was a very bad coincidence,” said Garron.
Even in a normal year, mortality rates for seal pups hovers around 50 percent. But typically, a seal carcass will be emaciated, showing that the seal starved after failing to get adequate nourishment. The seals that have washed up on shore during the last few months often have had thick layers of blubber and lesions on their skin.
Reports of stranded seals or seal carcasses in New England have trended downward in recent weeks, leading wildlife officials to be guardedly optimistic that the outbreak may be winding down.
Wildlife officials warn people to keep their distance from stranded seals. Some strains of flu can be transmitted between seals and humans. In fact, wildlife officials who handled seals that died of flu in the last epidemic also contracted the flu, said Garron. Beachgoers also should make sure to keep their pets away from seals. Seals and dogs transmit illnesses easily between each other, since they are genetically similar. And anyone convicted of harassing a marine mammal can be fined up to $50,000 and face up to a year in jail.
Check back for updates to this story.