NOAA Pegs Morbillivirus as Tentative Cause of East Coast Dolphin Deaths

A viral infection may be the cause of the unusually high number of dolphins deaths recorded this summer on the US East coast, according to information NOAA released Tuesday. The news comes as a virtual confirmation of what marine mammal experts have expected was the source of the mass dolphin deaths.

Throughout the summer bottlenose dolphins have been washing ashore dead or near death across the coasts of six mid-Atlantic states. Earlier this month NOAA declared the spate of dolphin death, which exceed nine times the annual average, an "unusual mortality event" (UME). An overwhelming majority of the strandings have been reported in Virginia.

In an update to its webpage regarding the UME, NOAA wrote Tuesday that based on preliminary diagnostic testing and discussion with disease experts, it was declared the "tentative cause of the UME is being attributed to cetacean morbillivirus."

Of the 27 bottlenose specimens tested to date, 100 percent were confirmed positive or suspect positive for morbillivirus, NOAA said.

Morbillivirus is a marine mammal condition similar to distemper in dogs, attacking the central nervous system and causing difficulty breathing, vomiting, diarrhea, brain swelling and often death.

So far this year, 488 bottlenose dolphins have been stranded on beaches between North Carolina and New York, according to the latest NOAA data. That's only two less than the total number of dolphins found stranded in the same area in the past three years combined.

Morbillivirus has taken a toll on dolphin populations before. A quarter century ago more than 740 bottlenose dolphins died as a result of a morbillivirus outbreak that affected dolphins in waters from New Jersey to Florida in 1987-1988, NOAA reported.

There is not much wildlife officials can do to combat the virus ravaging dolphins populations.

"It has to run its course," Virginia Aquarium and Marine Science Center spokeswoman Linda Candler told AFP earlier this month. "You can't immunize a wild population, unfortunately."

In an email to the APF, Fionna Matheson of NOAA Fisheries said that little can be done to help dolphins that are already sick, though it's possible to do some damage control by minimizing the stress caused to dolphins by human activity.

"If there is a link to things humans are doing that may make the dolphins more susceptible to disease (e.g., exposure to pollution, malnutrition from lack of prey, stress from disturbance), then we can certainly strive to mitigate those threats."