Scientists Investigate Fatal Humpback Stranding

By: Alan Pollock

Topics: Marine Mammals

Weighing an estimated 24,000 pounds, the dead humpback was placed in the back of a truck at Old Mill Boatyard Monday. It was trucked to Bourne where crews conducted a necropsy to try and determine why it became stranded. CHATHAM HARBORMASTER PHOTO

Following Ambitious Rescue Attempt

CHATHAM — Despite a valiant rescue effort, a young humpback whale stranded outside Stage Harbor early Saturday died before it could be moved from the shoal where it had beached itself.

The 31-foot male, estimated to be three or four years old, stranded on a sand bar about 200 yards south of Crescent Beach, off Morris Island, and was first spotted early Saturday morning. Harbormaster Stuart Smith responded to evaluate the animal and found it stuck on the sand just east of the Stage Harbor channel. While he said he hoped to intervene before the tide fell completely, it was clear that the water was too shallow, and deeper water was too far away. Smith took a photo of the whale and sent it to the marine mammal stranding team of the International Fund for Animal Welfare (IFAW), which arrived at about 9 a.m.

A team of around 15 people including IFAW veterinarian Sarah Sharp covered the whale with a wet cloth and poured water on it to keep it cool; the animal could be heard breathing, but became less active as the hours passed. The whale appeared healthy, Sharp said.

IFAW launched a specialized pontoon rescue system from Ryder's Cove. The system, usually used to rescue pilot whales, proved too small for the humpback. Instead, rescuers, assisted by the Chatham harbormaster and U.S. Coast Guard, tried to pull the whale to deeper water using straps, according to Misty Niemeyer, stranding coordinator with the IFAW marine mammal rescue and research program.

“The strap kept coming off as we tried to tow it,” Smith said. The Harwich Harbormaster’s office also assisted in the effort.

As the tide came in, it became increasingly difficult for rescuers to work in the water, and the currents were strong, Niemeyer said. Still, staff and volunteers spent the entire day trying to rescue the whale. At low tide, the whale was in only about 12 inches of water, but even at high tide, the whale animal was not completely covered. For that reason, it lacked the buoyancy to re-float itself, IFAW spokesman Rodger Correa said.

With the tide dropping again, crews resolved to return to the scene Sunday morning to try a new rescue attempt, but they arrived to find that the humpback had not survived the night.

On Monday, the effort shifted to trying to determine why the whale grounded itself.

“At this point we just don’t know,” Correa said. “We hope to have more insight on if the whale had any preexisting conditions that could have contributed to the stranding event.” The whale was towed to Old Mill Boat Yard, and on Monday morning a large crane was used to lift it out of the water and on to a truck.

“It should be noted that the estimated weight of this whale was 24,000 lbs., so approximately 12 tons,” Correa said. That’s about the weight of six average-sized automobiles.

The dead whale was taken to the Bourne town transfer station where a team performed a necropsy to find possible clues about its health. The animal was carefully measured and examined, with samples sent off for laboratory analysis.

Experts from the Provincetown-based Center for Coastal Studies hoped to identify the individual whale by comparing its fluke markings with those of previously identified humpbacks, but that might not prove possible.

“It is sometimes difficult to get a ‘match’ if it is a younger whale without a longer sighting history,” Correa said.

It's uncertain how the whale got into the maze of shoals east of the Stage Harbor channel. Niemeyer said humpbacks are common in Nantucket Sound, and the young whale might have been pursuing food and “may have gotten a little too close and gotten stuck.” There was no obvious sign of anything wrong with the animal, she added.

Humpback whales are a federally protected species under the Marine Mammal Protection Act. Populations in the western Atlantic are part of the West Indies population and migrate from the Caribbean along the East Coast of North America. This population is not considered endangered, but other populations of humpbacks in the world are.

Federal fisheries researchers point out that an unexpected die-off of humpbacks, known as an “unusual mortality event,” has been taking place since 2016. Since that time, 24 humpbacks have stranded in Massachusetts waters, among 135 strandings between Florida and Maine. Some of the animals showed evidence of having been struck by large ocean-going vessels, but ship strikes do not appear to account for all of the deaths.

Tim Wood contributed to this story.