Seal deaths could be result of new strain of virus
By Emily Aronson
10th October 2004
Portsmouth - While mutilated seals found on area beaches caused a commotion earlier this year, a group of harbour seals dying of natural causes have recently gained the attention of biologists up and down the Gulf of Maine.
Although it is not uncommon for dead seals to turn up on area beaches, marine biologists this past week confirmed an unusually high number of dead seals have been found on area beaches, especially on the southern coast of Maine.
"This (season) was definitely a lot higher than we have ever seen," said Greg Jakush, director of Marine Animal Lifeline which covers Kittery to Rockland, Maine.
Jakush said unlike the handful of decapitated seals found earlier this year, these seals do not appear to have died by human hands.
Jakush explained MAL tracks all stranded seals, which accounts for both dead and beached seals that wind up on dry land.
On average, MAL responds to 350 to 400 stranded seals a year, Jakush said. As of a week ago, MAL had responded to 750 strandings so far this year.
"We first started noticing something wrong about the third week of June," Jakush said, adding they had only 200 stranded cases for the year up until June.
Over the next three months, the number of stranded seals grew steadily, ultimately levelling off after the first week of September, Jakush said.
"We were dispatching 10 to 12 crews a day," Jakush said.
But nearly four months after the number of seal deaths started to explode, the reason why is still a mystery.
"Every individual animal ... was displaying different priorities or cause of death," Jakush said. "There was no smoking gun."
Jakush said the MAL sent tissue from the dead seals to the National Marine Fisheries Service in Boston for testing, but they have yet to come to any conclusions.
Teri Frady, spokeswoman for NMFS, said many of the dead seals were quite deteriorated once they were discovered, making it difficult to test their tissue or stomach content, which might provide clues to the cause of death.
"There’s nothing definitive that came out of our examination of those animals," Frady said. "It’s still mysterious, I’m afraid."
Connie Merigo, director of the stranding program at the New England Aquarium in Boston, keeps track of stranded seal cases along New Hampshire’s coastline. Merigo said New Hampshire also had an increased number of seal deaths this year, but not as many as in Maine.
Merigo said most of the cases she has dealt with this year have been seal pups that seem unable to make it on their own after their weaning period ends.
Merigo also did not know the reason for the increased deaths, but said the entire Gulf of Maine ecosystem has been off kilter this year. She said this year’s long, cold winter might have caused unusual marine species to be inhabiting the Gulf of Maine, while animals common to the gulf have all but disappeared this year.
Susan Shaw, director of the Marine Environmental Research Institute in Maine, said one possibility could be a marine mammal virus, similar to the phocine distemper virus that killed 20,000 harbour seals in Europe in 1988.
Although Shaw called it "very speculative," she said the fact the deaths occurred in harbour seals, many of which are pups, could signal a virus.
"This virus has affected marine animals around the world in polluted areas," Shaw said.
The Research Institute recently released a study showing harbour seals in the Gulf of Maine were contaminated with high levels of pollutants like PCBs, DDT, and mercury.
Shaw said chemicals like these have the most dire effect on pups. Seals that do not die from the contamination many times have a compromised immune system because of the chemicals.
"It’s a story that around the world is similar - marine mammals are really at risk," she said.