Marine scientists said Tuesday that a die-off of bottlenose dolphins along the U.S. Atlantic coast is the largest in a quarter-century and is almost certainly from the same cause as a 1987-88 outbreak: cetacean morbillivirus, which is spreading throughout the population.
From New York to North Carolina, 357 dead or dying dolphins have washed ashore since July 1, and authorities have received numerous additional reports of carcasses floating in the ocean, said Teri Rowles, director of the marine mammal health and stranding response program for the National Marine Fisheries Service. More than half the carcasses have come ashore in Virginia, she said.
The measleslike virus has been confirmed or is suspected in 32 of 33 dolphins tested so far, Rowles said. Marine officials are looking at the possibility of other factors, including high levels of polychlorinated biphenyl and other chemicals in the water.
From 2007 to 2012, the average number of yearly strandings in the same states was 36, Rowles said. The last big outbreak, in 1987 and 1988, killed more than 700 dolphins.
"If, indeed, this plays out the way that die-off occurred, we're looking at the die-off being higher and the morbillivirus spreading southward," Rowles said.
The virus poses no threat to humans, but secondary infections could be dangerous. Authorities urged people to stay away from stranded dolphins.
It is not clear what started the most recent die-off, but Jerry Saliki, a virologist at the University of Georgia, said some animals carry the virus naturally and that when a population's collective immunity declines, the virus can take hold and spread. This appears to happen episodically and continues until a sufficient number of dolphins are exposed and develop immunity, he said.
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