About 250 pilot whales have died after stranding on New Zealand’s remote Chatham Island, the government said Saturday. Refloating the animals wasn’t an option because of the shark risk in that area.
“We do not actively refloat whales on the Chatham Islands due to the risk of shark attack to both humans and the whales themselves,” New Zealand’s conservation department said in a statement.
The pilot whales were first seen beached on Friday on the northwest of the island. The conversation department said a trained team euthanized surviving whales to prevent further suffering.
“All the stranded pilot whales are now deceased, and their bodies will be left to decompose naturally on site,” the conservation department said.
In September, almost 200 whales died on a beach in Australia’s remote island of Tasmania.
Scientists still do not understand why mass strandings happen. This could be caused by pods getting off track after feeding too close to shore.
Pilot whales are extremely social animals and can remain with pod mates who wander into danger. That sometimes happens when sick whales swim to shore, and other pod members follow, trying to respond to the trapped whale’s distress signals.
Others believe gently declining beaches confuse the whales’ sonar, making them think they are in open waters.
Olaf Meynecke, a researcher at Australia’s Griffith University, said that pilot whales use sophisticated sonar to find prey and for orientation. He links whale and dolphin strandings to changes in electromagnetic fields.
“These changes can be caused by solar storms or earthquakes, but there is also a strong connection between active sonar, for example naval sonar, and dolphin strandings, including pilot whales,” Meynecke said.
Karen Stockin, a whale stranding expert at New Zealand’s Massey University, told Phys.org that whale strandings could become more common as shipping traffic, human use of the seas, and chemical pollution all increase.