Endangered whale died from ship strike
A large whale that washed ashore, already dead, south of Dewey Beach on May 20 was apparently killed when struck by a ship.
“We detected the whale had been presumably been struck by some type of large ship,” said Suzanne Thurman, executive director of the Marine Education, Research & Rehabilitation Institute Inc. (MERR), this week.
Coastal Point • JESSE PRYOR
The juvenile sei whale that beached south of Dewey last week was determined to have been fatally struck by a large, ship. Sei whales are considered the fastest swimming cetaceans, topping out at about 34.5 mph.Thurman said the juvenile male sei (pronounced “say” or “sigh”) whale had sustained fractures to its skull and to both its upper and lower jaws, apparently when struck by the ship.
Sei whales (Balaenoptera borealis), Thurman said, do spend time near surface as they feed on small fish, squid and krill using a filter-type feeding process that utilizes the comb-like baleen they have instead of teeth. An average sei whale eats about 2,000 pounds of food per day, according to NOAA Fisheries’ Office of Protected Resources.
“They use a skimming behavior to feed,” Thurman explained. “So they could potentially be there if a large ship was in the area. And these ships are so large they tend not to even see the whales.”
Thurman noted that tests on the samples of the animal’s flesh that had been taken after its beaching last week had not yet been completed, as they take quite a long time to perform. She said such tests, while unlikely to contradict the apparent cause of death as a ship strike – “It definitely would have died from that impact,” Thurman emphasized – were done to potentially reveal any underlying condition that could have caused the animal to have been weakened when swimming and thus made it more likely for it to have been struck.
Under normal circumstances, sei whales are considered the fastest swimming cetaceans, reaching top speeds of 34.5 mph, according to NOAA.
The whale, measuring 41 feet, 9 inches long, and weighing about 55,000 pounds, was a juvenile male, Thurman noted. Male sei whales can grow to be 59 feet long and weigh 100,000 pounds. While the animal was enormous compared to most of the marine mammals beachgoers see in the area, neither its length nor its weight made this whale one of the largest marine mammals to ever wash up along these shores, as had been rumored last week.
“Far from it,” Thurman said, noting that just three years ago, in 2006, a dead fin whale that washed up on the beach in the Middlesex community near South Bethany had measured 55 feet long and somewhere between 70,000 and 100,000 pounds.
And while fin whales – the second largest whale species and second largest animal on Earth, with a similar appearance to sei whales – are not uncommonly washed up along the East Coast, Thurman said it was also not unheard of for blue whales to wash up on the Atlantic shore. Blue whales are the Earth’s largest animal.
Sei whales get their name from the Norwegian word “seje,” meaning pollack, with which they are often found in the waters surrounding Norway.
The species is endangered and is protected under the U.S. Marine Mammal Protection Act (MMPA), as its population level has been deemed to have fallen below the optimum level for sustainability, with just 80,000 individuals estimated to exist worldwide, according to NOAA. Their population, along with blue and fin whales, were decimated by commercial whaling in the 19th and 20th centuries.
Thurman said that, while the sei whales themselves are rare, it is even more rare for them to be stranded onshore alive or to wash up onshore dead, due to their preferred environment.
“They’re deep-water animals,” she noted. “They spend their time out near the continental shelf. But they occasionally follow food in.”
After the whale’s remains were examined and samples taken for testing, it was towed off the beach by tractors for disposal.
