A dolphin plague could reach Southeastern North Carolina waters.
“We hoped it would run its course in these very localized populations in the Chesapeake Bay, but it didn’t, and that’s not a good sign,” said Bill McLellan, coordinator for the state’s Marine Mammal Stranding Program and a research biologist with the University of North Carolina Wilmington. “We’re just kind of holding on to see if it comes. All animals south of Cape Hatteras are now suspect.”
From July 1 to Aug. 28, at least 333 bottlenose dolphins washed ashore along the East Coast. More than 30 of those surfaced in North Carolina, all north of Cape Hatteras. The deaths are attributed to a resurgence of morbillivirus, a measles-like illness that killed 50 percent of the Atlantic dolphin population in a similar outbreak in 1987.
McLellan, then working at the Smithsonian, was one of the primary investigators on the 1987 outbreak in Virginia. Researchers in the state stranding network noticed a sizable uptick in dolphin mortalities that summer and were particularly concerned by the number of live mammals stranded on the shore.
“Live bottlenose dolphins are really a rare occurrence for us,” McLellan said. “They’re alive on the beach or in the sound or on a sandbar, not just swimming around. These coastal bottlenose dolphins, I don’t think it’s in their makeup to do that. That gave a different significance to this right away.”
And now it’s happening again. About two weeks ago, stranding coordinators in the Outer Banks began noticing an increase in beached dolphins, once more with a fair amount of live mammals lying on the sand.
“That immediately put us into the middle of it,” said McLellan, who quickly left for the Outer Banks with Ann Pabst, the state stranding program’s co-director. “We went to help lead the necropsies, and sent samples out immediately to labs at the University of California Davis and the University of Illinois.”
Tissue sampling focuses mostly on the dolphins’ lungs and lymph nodes, which most clearly show symptoms of the virus - notably, a significant collection of fluid and congestion in the chest cavity. The samples are processed and shipped from a UNCW lab. So far, samples from six North Carolina dolphins have shown a probability of morbillivirus.
“Basically, you have a really nasty flu,” McLellan said. “That leads to pneumonia, is kind of what we’re seeing in these animals. They’re heavily congested, and their lungs are sopping wet, and the lymph nodes are working to clear the fluid.”
At this point, there’s no immunization or medical treatment for morbillivirus. McLellan’s team assesses the health of each live dolphin that appears on the beach, but once the virus is active, there are few options for rehabilitation.
“It’s a hard situation to discuss, but right now these animals are extremely sick,” he said. “They’re not able to stay at the surface. They’re not able to breathe well because their lungs are full of fluid. The animals are just not in the best of shape. We will humanely euthanize them on the beach.”
During the 1987 outbreak, the virus spread continuously south as infected dolphins migrated to warmer waters for the winter. In the next two months, dolphins in North Carolina will begin taking that southern track, swimming as far south as Florida. With no treatment or immunization available, researchers will simply monitor the progression, a process hindered by decreased funding for the state stranding program.
“We’re watching funds trickling away while mortality goes through the roof,” McLellan said. “People are getting squeezed in the middle. If this moves south and gets the rest of the state involved, it’s going to be all hands on deck.”