ASBURY PARK, N.J. — An unusually high number of dead humpback whales washing ashore along the Atlantic coast has prompted marine mammal experts to open a federal investigation of the cause.
But the cause may never be fully determined, according to experts.
Since January 2016, 41 of the mammals have washed ashore from North Carolina to Maine. The only cause of death determined so far are cases in which the whales showed signs of being hit by a vessel. But ship strikes only account for a quarter of the deaths.
The high number of deaths forced the country's top marine agency, the National Oceanic and Atmospheric Administration, to declare an "Unusual Mortality Event," prompting the federal probe.
"This begins the process of an investigation ... that could take months to years to complete," NOAA stranding coordinator Mendy Garron said in a conference call with journalists Thursday.
Four of the 41 dead humpback whales washed up on New Jersey beaches. The most recent stranding occurred in January on an island just below the southern tip of Long Beach Island.
"That whale remains there today as we speak. We have trouble getting out there. Because of the tides, we only have a 20-minute window," said Bob Schoelkopf, director of the Marine Mammal Stranding Center.
He said the whale was about 35 feet long. The center could not determine the cause of death.
Another humpback whale continues to decompose on the edge of a marsh along the Cohansey River on the north shore of Delaware Bay in Salem County. The whale came into the Delaware Bay this winter and had operators of the Salem Nuclear Power Plant worried it might get lodged in the intake pipe, Schoelkopf said.
He does not know the cause of that whale's death either.
TheUnusual Mortality Event was declared because the number strandings exceed the annual average for the Greater Atlantic Region, which extends from Maine to Virginia.
"It's a marked increase in the magnitude when compared with prior records," Garron said.
Twenty-six of the deaths occurred in 2016. Fifteen have already died this year. Experts expect to see an average of 14 strandings per year.
Additionally, experts said the 41 whales is a low estimate. The agency said it does not observe every animal death. Some fall to their grave on the ocean floor, unable to be accounted for.
Necropsies — surgical exams of dead animals — have been performed on 20 of the 41 whale carcasses. Ten of the whales were killed after being hit by ships. They displayed evidence of blunt force trauma and deep cuts in their bodies from propeller blades.
The other 10 are baffling the experts. They have no signs of infectious disease or abnormal level of biotoxins — a poisonous substance produced by a living organism, such as algae, that could cause death in a marine mammal.
"We haven't got all the test results back. We're still combing through the results, it could change," said Deborah Fauquier, veterinary medical officer, NOAA Fisheries Office of Protected Resources.
They may never get an answer. UMEs were issued for humpbacks in 2003, 2005 and 2006 and a cause was never determined, Fauquier said.
The humpback population on the East Coast was once endangered. There's an estimated 10,400 to 10,752 today and they're considered a stable stock. Fauquier said humpbacks were recently taken off the endangered species list, but they are still protected by law.
The news came just a day after a decomposed whale washed up on a Toms River beach in New Jersey. That whale is believed to be a sei whale, according to the Marine Mammal Stranding Center in Brigantine, which documented the stranding. Its cause of death is not part of the federal investigation.
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