Marine scientists said Tuesday that a die-off of bottlenose dolphins along the Atlantic seaboard is the largest in a quarter-century and is almost certainly from the same cause as the 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 federal National Marine Fisheries Service.
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 PCB (polychlorinated biphenyl) and other chemicals in the water, but they have not linked anything else to the die-off.
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," Rowles said.
It is not clear what started the recent die-off.
The virus poses no threat to humans, but secondary infections could be dangerous. Authorities urged people to stay away from stranded dolphins.