New England scientists are still investigating the cause of death of more than 162 harbor seals in Maine, New Hampshire and Massachusetts. Scientists took notice when an unexplained increase in mortality rate occurred in predominantly young seal pups between September and November 2011. This slideshow could not be started. Try refreshing the page or viewing it in another browser.
Necropsies on five seal carcasses, revealed an influenza virus, H3N8, linked to the deaths. According to scientists, H3N8 influenza virus appears to have a low risk for transmission to humans.
Tony Lacasse, spokesman for the New England Aquarium in Boston said, “As far as Maine is concerned, the event had primarily been a Cape Elizabeth event and hadn’t gotten into Portland Harbor or Casco Bay.
“The epicenter of the seal die-off was the New Hampshire coastline, most of it happening more in Ipswich and further north, and in Maine in York County.”
Lacasse said the New England Aquarium “scientists were seeing a very quick decline to pneumonia, and [a] very symptomatic
Maggie Mooney-Sues, Communications Officer with NOAA Fishery Service out of Gloucester, Mass., concurred.
She said when seal “pups have some level of natural mortality they look emaciated and these animals appeared with a healthy layer of blubber” indicating the quick decline reported by scientists.
“It took a couple of months before scientists were able to identify a Type-A strain, and the worry is that it would be potentially transferable to people,” Lacasse said. We didn’t know how virulent the strain was [at that time].”
According to Lacasse, the New England Aquarium, in cooperation with NOAA identified that it was a type of virus common to dogs and, “H3NA is a mammalian virus first identified as an equine flu and that showed up in early 2000 in greyhounds in Florida.”
“What is significant is it is still a very specific genotype, but the thinking is, and this is not a hard and fast rule, that the virus is probably avian in origin, and probably from water fowl… with the virus changing in birds, with water fowl being so migratory,” Lacasse said.
According to Mooney-Sues, the investigation is far from over. “Further testing is being done right now, and first is determining the actual cause of mortality, if we can. It takes quite a bit of time,” she said.
“When this was declared an unusual mortality event (UME) we [at NOAA] bring in a team of biologists and experts in these types of influenza that sit on a panel and working group.
“They review all the existing data and try to collect data over the largest possible time frame, and data from any other species and a lot of other information. With that they can determine the actual start and end dates of the event, with the spike from the months of September to November,” she said.
Mooney-Sues’ Gloucester, Mass., NOAA office serves part of Maine, since Maine is no longer part of a stranding network.
“The NOAA Fishery Service is required to establish a National Stranded Animal Program and we put out nationally a request for proposals (RFP), in which people openly compete to become a member of the stranding program, to be authorized to pick up animals, test them, collect samples; all part of a broader reach with the community.
“The Maine Dept. of Marine Resources had a stranding network and submitted a proposal and was not selected among national candidates, and so we are now covering part of the Maine coast ourselves and we encourage the Maine DMR to submit a proposal again when the competition opens up so we can get someone to fill that void,” Mooney-Sues said.
One reason to have a stranding network is to be able to quickly respond to instances like the seal die-off, and carcasses washing up along the coastline, Mooney-Sues said.
“Our office is here in Gloucester, and understand, all the calls that were taken by the Maine DMR, now go into the same phone line and are redirected to us,” she said.
Though any increase in wildlife mortality caused by disease is distressing, the primary concern is the influenza virus being transmitted between species.
“Anyone having contact with the animal world is always risky. We carry pathogens that may be transmitted to them, and they carry pathogens that [our immune systems] have no experience with and there’s always a worry of a jump [of a virus],” Lacasse said.
For example, according to Lacasse, in the late 1980s and early 1990s, a very close relative of the distemper virus that affects dogs killed the harbor seals in northern Germany, Sweden and parts of Finland.
“It had an 80 to 90 percent mortality rate for young seals. The population has never recovered yet. It was from a family of viruses called morbilli and what happened there, there was just no reason. It was probably transmitted by a dog,” Lacasse said.
Lacasse segued into discussing the continual need to educate the public on keeping a safe distance from seals. He said people don’t understand “it is a marine animal and seals go out of the water every day, and they are not in trouble.”
He also believes, if an animal is not in “tip-top” condition and people get too close, their presence is “going to stress the animal and actually can help with its demise,” Lacasse said.
Lacasse said, “In the case of seals, it is recommended to stay 150 feet away. [Any closer and] there’s the worry of transmission to those that are immune compromised, are very elderly or young, and particularly to kids under the age of five who are still developing an immune system.”
People need to keep their dogs on a leash, or under strict voice command and within sight, Lacasse said. “All they have to do is run behind a sand dune and find a seal carcass and the dog could pick up a virus and might even transmit it to humans,” he said.
Though the numbers of dead seals has dropped off dramatically since November, Lacasse believes, “the virus is still out there.”
The New England Aquarium scientists and veterinarians will soon be watching the winter migration of young harp seals from the Maritime Provinces to the coastline of Maine, New Hampshire and Massachusetts for any problems, Lacasse said.
Coincidentally, harp seal numbers are down and Lacasse said it is thought the decrease is caused by a reduction in surface area of ice platforms the harp seals use as primary breeding grounds.
“A decrease in the ice platforms resulted in a high pup mortality. There was also a die-off of young harp seals in the northern Maritimes and Canada late last fall (2010) and we don’t really know the origin of that die-off, and we don’t know if they were exposed to a virus,” he said.
“So we’ll be watching the young harp seals this winter. The mortality rate from mid-September to mid-November was increased three to four times normal, and now [in January 2012], it is almost back to normal, but there’s no question the virus is clearly still out there and if we get a new group of young [harp] seals in the area, about the same size… we’ll just have to see. We need a good, fresh carcass,” Lacasse said.
Lacasse said the New England Aquarium has numerous veterinarians to immediately collect a carcass for study, and “Maine doesn’t. NOAA is handling a lot of the Maine area right now. The Maine Marine Animal coordinator was laid off,” he said.
For more information, link into the Northeast UME (Unusual Mortality Event) page at www.nmfs.noaa.gov/pr/health/mmume/pinniped_northeast2011.htm for updates on the investigation into the cause of the event.
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