http://eastham.wickedlocal.com/news/...inked-to-virus
Gray and harbor seals have lured sharks in increasing numbers into Cape Cod waters, with tragic results, but the burgeoning seal population is taking a hit from viruses.
The National Oceanic and Atmospheric Administration has issued an unusual mortality event alert for both species of seal in the Gulf of Maine.
From July 1 to Aug. 29 (when the alert was issued) 599 seals were found dead (137) or ill and stranded (462) on New England shores. In the few weeks since that number has soared to 921. Most of those were in Maine (629), with 147 in New Hampshire and 125 in Massachusetts.
The dead or dying seals have been located mostly to the north but a couple were found as far south as Plymouth in Cape Cod Bay.
For comparison the nearly 500 seals found last month is roughly 10 times the number that stranded in August of 2017.
“That is attributed to the influences of disease,” noted Terri Rowles, NOAA’s Marine Mammal Health and Stranding Program coordinator.
“The strandings began with an uptick in July. Those (921) are confirmed cases. There are probably hundreds of unconfirmed cases, which means the animal carcass wasn’t there or there was no blood or it was inaccessible to the stranding network.”
NOAA’s labs have been conducting necropsies on some of the seals.
“The diagnostic labs are working every day to keep up,” Rowles said. “The preliminary results from the seals found that some seals tested positive for phocine distemper, which is related to canine distemper, or avian influenza. Both of those are viruses.”
Phocine distemper was responsible for killing 20,000 gray and harbor seals in Europe in 1988 over eight months, and 30,000 in 2002 – in both cases cutting the population in half. It also caused an increase in deaths in seals in the Gulf of Maine in 2006.
“It’s too soon to know what each virus contributes to the event or if it’s the two together,” Rowles said.
Sick animals are lethargic and coughing on the beach. Because the disease is related to canine distemper people should keep their pets away from beached seals and stay 100 yards away. There’s also some concern the flu could cross over to humans.
The stranded seal hotline is 866-755-6622. Both diseases are respiratory and affect the lungs as well as the brain.
“Distemper seems to have cycles in the population, possibly related to herd immunity,” added Dr. Tracey Goldstein, of the testing lab at the University of California-Davis.
“There was an outbreak on the East Coast in 2011 and as the population of protected seals decreases, the animals are more susceptible to infection. The timing of pupping season means more animals are in dense contact and the virus can expand through the population quickly.”
Harbor seals pup off the coast of Maine starting in June and return to the Cape in the fall. The seals around the Cape now are mostly the larger (500-880 pound) gray seals. The No. 1 breeding spot in world for gray seals is now Muskeget Island in Nantucket Sound.
That’s remarkable considering there were virtually no gray seals in Massachusetts 50 years ago. Now there are 30,000 to 50,000 swimming around Cape Cod, according to Shelley Dawicki of the NOAA Fisheries Science Center.
“The bounties stopped (1962 in Massachusetts, 1945 in Maine) and the Marine Mammal Protection Act was passed in 1972,” Dawicki noted. “After that the seals started to gradually return from the north.”
The harbor seals returned first in number by the 1980s but gray seals remained rare as their refuge was the more distant Sable Island, far off Nova Scotia. The first five gray seal pups were recorded on Musketget Island in 1988.
Seal counts at Muskeget rose from 2,010 in 1994 to 15,756 in 2011. On Cape the population now is greatest around the Monomoy Wild Life Refuge but the seals, like the sharks, are everywhere and growing in numbers on the Outer and Upper Cape.
“The gray seals are here year round,” Dawicki said. “They pup in December and January. They like to haul out on the sand. Jeremy point in Wellfleet and Chatham have lots of seals. The harbor seals are smaller (150-250 pounds) and you see them on jetties on Nantucket and Woods Hole.”
NOAA has a seal tagging program to try to track where the go. They will swim quite far out to sea so they are not always inshore feeding along the beaches, and seals from the Cape can mingle with seals from infected populations further north.
Dawicki pointed out that while shark sightings are up so are the number of people looking, and the sharks, as well as seals prior to the bounties, have always been around.