Necropsy performed on right whale found about 23 miles off Ocean City

Animal likely was killed by collision with freighter

August 24, 2002|By Frank D. Roylance | Frank D. Roylance,SUN STAFF

A 36-foot northern right whale found floating off Ocean City this week was the apparent victim of a collision with a ship.

The whale's badly decomposed carcass was towed to Assateague National Seashore yesterday morning, where investigators found evidence of severe trauma.

"There were concentric propeller wound patterns along the back of the animal. It would have had to be a big screw freighter," said David Schofield, manager of ocean health programs for the National Aquarium in Baltimore. "It does not look like an injury that was survivable."

The endangered northern right whale (Eubalaena glacialis) is a surface feeder that consumes tiny ocean organisms called copepods by filtering them through baleen plates in its mouth.

Adults grow to 50 or 55 feet in length. Only about 300 are thought to remain in the North Atlantic after centuries of whaling and decades of high mortality because of ship strikes and becoming entangled in fishing gear.

The whales have enjoyed improved reproductive success in the past two years, with at least 50 born, according to Tony LaCasse, a spokesman for the New England Aquarium. But mortality rates, especially among the young, remain high.

Schofield said more right whales have been sighted recently off Maryland. But that is normally between January and April, as they migrate northward to summer feeding grounds near Nova Scotia.

"To have one here in the middle of summer is very strange," he said.

The Maryland whale, an immature female, was spotted about 23 miles off Ocean City about 10 a.m. Thursday by anglers on a recreational fishing boat.

It appeared to have been dead at least a week, Schofield said. It's possible the animal drifted, or was dragged south from Canadian waters by the vessel that killed it.

The Coast Guard station at Ocean City dispatched a 47-foot motor lifeboat, which tied a rope to the whale's tail and began towing it toward shore.

"If it had been another species, most likely it would not have been towed in," said Master Chief Petty Officer Tim Grant. But with the right whale's survival in jeopardy, the National Marine Fisheries Service wants scientists to have all the data they can gather.

The cutter Ibis took up the tow, which ended six hours later off Assateague Island, about a mile south of the Ocean City inlet.

After the carcass was hauled onto the beach yesterday, Amy Nolton of the New England Aquarium led a necropsy on the animal. Skin samples were taken for genetic studies, and even its whale lice were collected. Most of its bones were saved for eventual study and display.

Although most of the whale's tissue was too badly decomposed to be of scientific use, Schofield said Nolton made sketches of light-colored patches, called callosities, on its head.

Extensive studies of right whales have produced a comprehensive record of each observed animal, identified by its distinctive callosity pattern.

If Nolton finds a match for the Maryland whale, that will help scientists complete their record of its life history. "If it's a new animal, it may mean there's hope, and there are more animals out there than is normally understood," Schofield said.

Stranded whales, even carcasses such as this one, serve as "ambassadors from the ocean," Schofield said. "They are important for our understanding of the ocean's health, and how we impact the daily lives of these animals."

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