July has been a deadly month for bottlenose dolphins along the East Coast. In Virginia alone, 42 died in July, up from four during the same time in 2012.
Bottlenose dolphin carcasses are washing up on U.S. East Coast beaches in increasing numbers this year, and experts are at a loss to explain why.
The highest concentrations of carcasses have been found in the lower Chesapeake Bay area, off Maryland and Virginia, and off New Jersey and New York, said Joan Barns, public relations manager for the Virginia Aquarium Stranding Response Team.
As of this past weekend, the dolphin death toll for 2013 had reached 100 in Virginia, surpassing the typical 64 or so animals usually recovered during this time period.
Maggie Mooney-Seus of the National Oceanic and Atmospheric Administration's Fisheries Service said that July numbers indicated a particularly high spike.
According to the NOAA, New York had only one reported death in July 2012; this year there were 15. Delaware and Maryland had zero last year in July, but this year there were one and seven, respectively. New Jersey had four deaths last year, compared with 20 last month, and Virginia's toll of four in July 2012 hit 42 animals in July this year.
There have also been multiple reports of "floaters" — dead dolphins that have yet to wash ashore. Barns said the Virginia stranding response team has lacked the resources to get to carcasses in time to recover them.
Identifying the cause of the higher death toll is proving difficult. Because of the remote locations where the dead animals are washing ashore, the carcasses spend a good amount of time decomposing before being discovered and recovered. Animals still floating at sea start to decompose within 24 hours, losing skin first, then are preyed upon by other sea creatures.
Stranding response teams examine the freshest bodies first in hopes of comparing the findings to carcasses found in different areas.
The cause of the dolphin deaths has yet to be determined, Mooney-Seus told Reuters.
But Virginia experts said early findings indicated it appears to be "more of a sickness," said Susan Barco, research coordinator at the Virginia Aquarium and Marine Science Center Foundation.
"This is really frightening because these animals are sentinels of ocean health. Strandings have been much more common in the past few decades and we think it's an indication of the health of our ecosystem," she said.
NOAA is now analyzing information collected by marine stranding response centers along the East Coast. Typical causes of death can include disease, human interaction and accidental entrapment in fishing nets.
"It's absolutely alarming," said Barco.
Bottlenose dolphins live in pods of two to 15 animals along the Eastern Seaboard from New Jersey to Florida. The mammals spend most of the year in the temperate southern waters, then move to the bays, sounds and open waters of the Mid-Atlantic from May to October, Bob Schoelkopf, the director of the Marine Mammal Stranding Center in Brigantine, N.J., said in an interview with Reuters.
It could take several months to determine what led to the deaths, he said.
Barns noted that dolphins are very social animals. If the die-offs end up being tied to a communicable disease, the spread of it would have been quite easy. "If it is a virus," Barns said, "then deaths could be tied to weakened immune systems that allowed something else to kill off the animals. Unraveling what is happening can be quite complex."
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