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Experts continue seal death probe
By John Richardson
Portland Press Herald
25th October 2004
Federal scientists and local experts are still looking for whatever killed or sickened hundreds of seals along the Maine coast this summer despite fading hopes of finding an easy explanation.
Reports of stranded seals have slowed to normal rates in recent weeks, much to the relief of seal rescuers and rehabilitation workers. But researchers here and in laboratories down the East Coast continue to actively search for clues about what happened to the harbour seals and what it might say about the health of the ocean.
"We haven't found the one thing that's doing it," said Greg Early, a Massachusetts researcher and one of the leaders of the federal team investigating Maine's seal deaths. "We're peeling the onion, but we're still finding more layers."
The mystery began in July with a surge in the number of hotline calls to the Northeast Marine Animal Lifeline. The Westbrook-based network rescues sick or injured seals, tests and examines them and nurses the animals back to health. The calls kept coming and continued at an unprecedented pace through August, says Greg Jakush, founder of the lifeline.
"We're at case 766 right now for the year. Our average is 350 to 375 per year," Jakush said.
Most of the animals have been harbour seals, the species most common to the Maine coast. The reports included 305 dead harbour seal pups and 164 dead adult seals. Those numbers are up dramatically from past years, when only a handful of dead adult harbour seals were typically reported.
The lifeline's rehabilitation centre bustled with as many as 47 sick or injured seals at one time this summer, straining its finances and the network of volunteer rescuers who rush to beaches when the hotline receives reports.
"We've really made them work hard this summer," said Jeff Sargent of Parsonsfield, an animal care technician who was still busy last week feeding and cleaning up after 22 seal pups in rehab. The organization has already rehabilitated and released 94 seals this year, about double the usual number.
The phenomenon made headlines in late August after the discovery of 27 dead adult harbour seals on Stratton Island off Prouts Neck in Saco Bay.
"That was about 30 animals, over a two- to three-week period, out on a little haul-out," Early said. "And that was it. After that it stopped. That was unusual by anybody's measuring stick."
Scientists say it's possible the Stratton Island die-off and the other reports are separate incidents. But the island also is in the middle of a well-defined stranding zone that stretches from Kittery to Boothbay.
"That spot is like the glowing red centre of things," Early said.
As a result of the reports, the National Marine Fisheries Service declared an "unusual mortality event," and assigned a team of about 10 contracted scientists to investigate.
Such investigations were once rare but have become more common in New England and other coastal zones around the country in recent years.
One team investigated the death of as many as 21 humpback whales found floating off the New England coast last summer. They eventually pointed blame at a natural toxin known as domoic acid, which has so far not been found in Maine seals.
A second team was created last fall in Maine to investigate the deaths of at least nine minke whales and 60 adult harbour seal along the coast. That unusual event was never explained, and the case has since been folded into this summer's probe to see if there may be a link.
Scientists in labs in South Carolina, Washington, D.C., Connecticut and Cape Cod have been testing tissue and blood samples from the Maine seals, as well as examining entire carcasses found on beaches here.
Some easy explanations have been ruled out. There is no evidence that human interactions, including gunshots or fishing gear entanglements, are to blame, the experts say.
Diagnostic testing on blood and tissues is continuing, Early says. But preliminary results do not implicate other top suspects, such as food poisoning from toxic red tide algae or diseases such as distemper.
"We're at the stage of things right now that it's getting unlikely that one of those is going to crop up," Early said.
The team can do more detailed testing for other possible causes, but first needs to rule out more obvious theories, he says.
Investigators will consider whether the increased stranding reports may simply be the result of an influx of seals to the area, although there is so far no evidence to support that. Whale watch boats witnessed such a population shift this summer by humpback and finback whales that bypassed their usual feeding grounds off the New England coast and were seen in larger numbers off Nova Scotia.
The researchers also want to make sure the increase in dead seal reports did not simply result from more people looking for them and knowing whom to call.
Increasing public awareness has steadily boosted the call rate the last few years, Jakush says. And there was a noticeable spike after news reports about the Stratton Island die-off in August. But, he says, the overall increase from last year appears to be too dramatic to be a result of better reporting.
The absence of an easy explanation suggests it could be a long and complex case, Early says. "It might be something that will take us a couple of years to figure out," he said.
Rescuers are especially relieved, therefore, that the pace of reports slowed in September and is now more back to normal. The most recent reports have turned up animals that died weeks ago, Jakush says.
"July and August really seems to be the time when whatever was going on happened," he said.
That has not slowed the search for a cause, however, according to Jakush and Early. Scientists and federal officials want to solve the mystery not only to protect harbour seals, but to find out if marine ecosystems are at risk.
"The thing about marine mammals is they're probably the best bio-indicators of the health of the oceans we have, because they are the top of the food chain," Jakush said.
Commercial fisheries, endangered whales and humans all rely on healthy oceans, Early says, and scientists see dying seals as a potential warning sign for the rest of us. "It's the canary in the coal mine," he said.
Staff Writer John Richardson can be contacted at 791 - 6324 or at:
jrichardson@pressherald.com
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