Necropsies may solve dolphin deaths

PHILADELPHIA – With four more dolphins found washed up on the South Jersey coast late last week, officials are awaiting additional necropsy results from the University of Pennsylvania’s School of Veterinary Medicine for clues.

Twenty-five bottlenose dolphins have been found dead or dying in New Jersey since July 9. Forty-four have also washed up in Virginia this summer, with five discovered Thursday. Delaware and Maryland are also reporting higher-than-normal dolphin deaths.

Pneumonia is the first suspect when there is a spike in dolphin deaths, said Perry Habecker, chief of large-animal pathology at the veterinary school’s New Bolton campus.

But he cautioned that “knowing a cause doesn’t always mean we can do something about it.”

“We look at one animal at a time,” Habecker said, dissecting each to extract tissues and organs, including the heart, lungs, liver, kidneys, stomach and brain, to determine the cause of death. “It’s not pretty, but that’s how it’s done.”

Bob Schoelkopf, director of the Marine Mammal Stranding Center in Brigantine, N.J., that is shipping carcasses to the university for necropsy, said results thus far show four cases of pneumonia and one of morbillivirus, a measles-like virus blamed for killing 742 dolphins in the 1980s.

A brain worm infection – which is harder to detect – can also be a culprit, Habecker said.

Two dead dolphins were found Friday in Avalon and another in Lower Township, Schoelkopf said.

Necropsies on multiple dolphins might reveal a pattern, Habecker said.

Declaring an epidemic in the Mid-Atlantic dolphin population, he said, would fall to state environmental officials and the stranding center, a federally designated entity for retrieving dead or stranded marine mammals.

Habecker said “human interaction” – such as aggressive commercial fishing, toxic wastes and even plastic bags – can contribute to spikes of mortality in marine mammal populations.

“We find a lot of strange stuff,” Habecker said, but some animals “never get a definitive diagnosis” of cause of death. And when there are multiple causes of death in a population, he said, “It’s hard to know what’s clinically relevant.”

Rich Mallon-Day, executive director of the Outer Banks Center for Dolphin Research in Cape Hatteras, N.C., said studies in Tampa Bay have shown that morbillivirus outbreaks evidently occur every 20 to 25 years in that area.