A pod of more than a dozen orcas has gone missing, after struggling for about a day in frigid Japanese waters trying to escape the trap of drifting ice. It is not known what happened to them, but it is feared that they are dead.
Fishermen near the island of Hokkaido first noticed the group struggling in the thick slush early Tuesday. Drone images and videos show at least 12 orcas, including several minors, struggling in a confined space closed by a strong ice drift about 1 kilometer offshore.
From Wednesday morning, the trapping area was emptyraising hopes that the animals may have escaped into the open waters of the Sea of Okhotsk, according to Japanese media organization NHK.
But a pod of 17 orcas was spotted stuck in an ice drift on Tuesday afternoon, 2 kilometers northeast of the original site. NHK reports.
“Killer whales are not ice-adapted whales; they are not comfortable in this area,” says Colin Garroway at the University of Manitoba in Canada. “So they would definitely… experience the stress of confinement, and they would probably starve.”
Cetaceans that live full-time in Arctic areas, such as narwhals (Monodon monoceros) and belugas (Delphinapterus leucas), sometimes find themselves trapped in ice. Killer whales (Killer whale), however, generally avoid thick ice and thus entrapment.
However, sometimes they find themselves in freezing waters at the wrong time. In a 2016 reviewscientists found there have been 17 cases of a total of 100 orcas trapped in ice in the northern hemisphere – almost half of them in Japan's Sea of Okhotsk – since 1840. The trappings usually end by the death of animals, explains Garroway.
Scientists believe that even killer whales would have “broken free» After becoming trapped in the ice, they likely die as they struggle against other ice drifts while trying to reach open water.
A 2019 study of orcas trapped in ice suggests that mammals can live up to 50 days on body fat before starving during trapping. It says sightings of orcas trapped in ice have become more common in recent years, as Arctic ice melts and curious orcas attempt to explore new territories.
Global warming could certainly play a role, says Garroway, whose team is currently studying the environmental effects of the gradual northward movement of orcas. But entrapment cases may also simply appear more common because people report them more.
“It's really hard to separate global warming – which is a prediction – from the simple fact that we're just more able to find them, see them, write about them, and care about them more,” he says.