The National Oceanic and Atmospheric Administration (NOAA) announced that a measles-like virus is responsible for hundreds of bottlenose dolphin strandings along the mid-Atlantic coast this summer.
Since early July, unusually high numbers of dead or dying bottlenose dolphins have washed ashore from New York to North Carolina. About 155 dolphins strand in the mid-Atlantic from January to late August during a normal year, but this year almost 500 dolphins washed ashore in the same time period. The sudden increase prompted NOAA to declare an Unusual Mortality Event for bottlenose dolphins.
More than 100 dolphins have beached themselves in Cape Cod, Massachusetts this winter, and no one knows why.
In the northeastern United States, it’s normal for about 230 animals to beach themselves over the course of a year. But this year, 129 common dolphins have been found on Cape Cod beaches in the past month.
Examinations of the dolphins haven’t found any sign of illness or injury, adding to the mystery. Beaching or “stranding” happens when an animal gets trapped in shallow water and can’t swim back out to the ocean. This can be caused by disorientation from an unfamiliar landscape, loud noises, illness, or more. Because dolphins form strong bonds, they may follow each other and become stranded in groups.
One factor in Cape Cod might be an unseasonably warm winter, which kept the harbor free from ice and open to wandering dolphins. Combined with the geography of the Cape Cod harbor area—much shallower and confined than the open ocean—and dolphins’ habits of sticking close to their family members, these dolphins could easily find themselves in trouble.
The International Fund for Animal Welfare has been working to save the stranded dolphins and discover the cause of the mass stranding. To date they have been able to release 37 of the stranded dolphins back into the water.
Mass strandings are mysterious events. We may never know the cause, but we hope it comes to an end soon.