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Slow death of sperm whale stuck in maze-like Japanese bay raises alarm over impact of global warming

Tokyo — The slow disappearance of a wandering whale that spent its final days in Osaka Bay not only saddened viewers across Japan, but it also alarmed cetacean experts who called the whale the latest victim of the global warming.

“The whales were getting lost about every three years,” Yasunobu Nabeshima, a visiting researcher at the Osaka Museum of Natural History, told CBS News. “Until now, this was a rare phenomenon. But these incidents have increased.”

sperm whale (Physeter macrocephalus), side view
A file photo shows a sperm whale swimming near the Ogasawara Islands, Tokyo Prefecture, Japan.


This month’s tragedy marks the second case in as many years.

Nabeshima said global warming has narrowed the temperature gap between the Pacific Ocean and Osaka Bay, making the powerful Kuroshio Current “a conveyor belt of warm water” that propels whales from their usual haunts into the depths of the ocean to the shallow waters along the coast.

The most recent episode began in mid-January, when the sperm whale, one of the world’s heaviest animals, was first sighted off the coast of Nishinomiya City, Hyogo Prefecture. Television cameras and local authorities carefully followed the doomed whale as it swam uselessly east toward Osaka.

Deprived of its main food, the giant squid, the whale’s beak became visibly listless.

Unlike easy-to-navigate Japanese ports like Kobe, Osaka Bay, which serves Japan’s third-largest city, is a maze of artificial islands and buried peninsulas, teeming with theme parks and shopping malls as well as warehouses and industrial facilities. It’s effectively a death trap for marine mammals, with many nooks and crannies and bounded by docks and breakwaters that can prevent the creatures from finding their way back to the blue water.

Osaka Bay in Japan aerial view from the plane
An aerial photo shows some of the reclaimed coves, docks and islands of Osaka Bay in Japan.

Taro Hama/Getty

Another sperm whale died near the mouth of the Yodo River in Osaka in January 2023. Nabeshima of the Osaka Museum told CBS News that a pod of short-beaked common dolphins got stuck in the Osaka Bay last fall and that they could be seen from Yumeshima, an artificial island and site of Expo 2025, which opens in April. Sea turtles have also been stranded in the area.

The severely emaciated body of the last sperm whale victim, a male weighing more than 30 tonnes and measuring 15 meters long, was found and temporarily buried after authorities decided it would be cheaper than transporting the carcass to the sea. After two years, the skeleton will be recovered and donated to a local museum.

Roaming whales can be a real headache for local governments. The cost to taxpayers of burying the stranded sperm whale at sea last year was more than half a million dollars, 10 times the cost of a land burial, according to the Mainichi daily.

Viewers were able to see in real time the whale, lying on its side, its enormous jaws open in a “V”, tied to the dock then carefully placed in an enormous sling. In a delicate procedure that lasted more than an hour, a seaside crane carefully lifted the carcass and placed it on a flatbed truck, which transported it to its resting place temporary.

A researcher told local MBS TV that the creature would first undergo forensic analysis to determine its cause of death, age, history of injuries and illness, as well as a DNA test. to determine its origin. The whale trapped last year was 46 years old. Sperm whales have been recorded to live up to 62 years.

Experts also planned to search the creature’s intestines for pieces of ambergris, an extremely rare and strange waxy substance produced by sperm whales from undigested pieces of squid and other cephalopods. Known as “floating gold” and found in only 1-5% of sperm whales, ambergris is used in French perfumery. In 2021, one piece sold for $1.5 million.

Osaka Bay cityscape
Osaka Bay, Japan.


Scientists have called for new measures to keep these powerful animals out of harm’s way, including sensor-activated “acoustic deterrents” placed in the Kii Strait, the entrance to the Inland Sea from the Pacific Ocean, to prevent whales from venturing close to the coast.

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