

Harbor and gray seals are dying by the hundreds from Southern Maine to northern Massachusetts, apparently from a combination of a measles-like illness and the flu.

Late last month, the federal government declared the summer’s toll on seals an “unusual mortality event,” meaning federal resources would be provided to help understand and cope with the deaths.

Teams have responded to more than 600 reports of dead or dying harbor and gray seals, but there are probably more that have gone unreported or washed up on private property, said Mike Asaro, chief of the marine mammal and sea turtle branch of the National Oceanic and Atmospheric Administration (NOAA). “The total could be up to 1,000 at this point. We just don’t know,” he said.

Marine mammal stranding agencies always expect to find some sick and deceased animals this time of year, as a percentage of newborn pups fail to thrive after weaning. But the carcasses washing up on New England beaches reveal an epidemic that’s touching all ages, said Katie Pugliares-Bonner, a senior biologist and necropsy coordinator for the New England Aquarium in Boston.