Whale mortality event declared in Delaware, region

A dead, decomposing whale washed into shallow water at Port Mahon several days ago, but strong onshore winds and stormy weather are hampering efforts to recover the animal and study it to determine how it died and whether it is part of a bigger coastwide issue.

Suzanne Thurman, executive director of the Marine Education, Research and Rehabilitation Institute, Delaware's marine mammal stranding team, said the whale appears to be a juvenile humpback.

If confirmed, it would be the fourth humpback to strand in Delaware waters in less than a year, and it could be an important clue for scientists. Four humpbacks also have stranded off the coast of Virginia, and there was a stranding last fall off Long Island. For Delaware, four humpbacks over a short time is an unusually high number of strandings.

As a result, the National Oceanic and Atmospheric Administration Marine Fisheries has declared an unusual mortality event for the large marine mammals, but the agency isn't sharing information about that decision just yet. More details are expected to be provided on Thursday, a NOAA Fisheries spokeswoman said Tuesday.

An unusual mortality event is declared when higher-than-normal numbers of marine mammals die for unknown reasons. When marine mammals die unexpectedly, it can be a signal of a problem with ocean health. The last unusual mortality event in our area was the 2013-2015 bottlenose dolphin die-off in the mid-Atlantic. It was linked to cetacean morbillivirus, an illness that causes pneumonialike symptoms in marine mammals.

Last fall, humpbacks along the Atlantic coast from the Caribbean to Canada were removed from the federal endangered species list. The whales are found in waters around the world, and scientists determined there are 14 distinct population groups. The whales found off the Delaware, Maryland and Virginia coast are all part of the delisted West Indies population. It took decades for that population to rebound.

Humpbacks, like other large whales, were targets of commercial fishing. They were designated endangered in June 1970 under the Endangered Species Conservation Act, and once the 1973 Endangered Species Act replaced the law, they stayed on the list.

The whales are among the most popular for people who go on whale-watching trips. They rise out of the water and come crashing down, sending a stream of sea spray. They are vocal animals, and they are believed to use clicks and songs to communicate. The are vulnerable to entanglement in fishing gear and ship strikes.

Thurman said that one of the recent dead whales was found at the Port of Wilmington entangled in fishing gear, she said. It was impossible to determine what happened to the two other animals because they were so decomposed. One drifted around near the entrance to Delaware Bay before washing ashore in Ocean City, Maryland, and another stranded at Bethany Beach. None of the Delaware whales survived.

Thurman said the problem with the whale at Port Mahon is that it has already been floating in the water for several days and is beginning to deteriorate.

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"The seas are very rough," she said.

Once the weather breaks, they are considering bringing in a boat to remove it, but that presents challenges because "it's going to have to be a boat with some heft," she said. The whale likely weighs about 1,500 pounds per foot. She estimated that it is 25 to 30 feet long. The question remains whether a large boat can navigate the shallow waters near Port Mahon.

They also considered towing the whale onto the beach, but the shoreline at Port Mahon is armored with heavy rocks. Thurman said she fears that the whale might fall apart and the remaining pieces would cause odor issues in the area.

The other three humpbacks that stranded in Delaware also were juveniles, she said.

In February, a decomposed humpback washed ashore at Chincoteague National Wildlife Refuge.

It was the fourth humpback whale to wash ashore in Virginia since January.

The Chincoteague whale was between 30 and 36 feet long.

Contact Molly Murray at (302) 463-3334 or mmurray@delawareonline.com. Follow her on Twitter @MollyMurraytnj.