An estimated 240 pilot whales that became stranded on remote Pitt Island in the Pacific Ocean are now dead, just days after 215 whales died after becoming beached on nearby Chatham Island, New Zealand’s conservation office has said.
Two “super pods” of pilot whales beached on the two islands in the remote chain and the surviving animals, which could not be refloated, were euthanised, New Zealand’s Department of Conservation said on Tuesday.
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On Saturday, 215 pilot whales were found stranded on Chatham Island, and another 240 were reported on Pitt Island on Monday, the department said.
Dave Lundquist, marine technical adviser at New Zealand’s Department of Conservation, said a technical team had assessed the situation of the stranded whales and the decision was made to euthanise the surviving animals.
“This decision is never taken lightly, but in cases like this it is the kindest option,” Lundquist said in an email message.
The conservation department did not try to refloat whales in the area due to the risk of shark attack to humans and whales, he said.
Daren Grover, general manager at charity Project Jonah, which deals with stranded whales, said there were also not enough people in the area to help with refloating.
“These mass strandings are distressing events, and while we always hope surviving whales are able to be refloated, this wasn’t an option here,” the organisation said in a Facebook post following the discovery of the 215 stranded whales on Chatham Island.
Sadly, there has been a second mass stranding of pilot whales on the Chatham Islands, this time on Rangiauria/Pitt Island, about 40km south from the stranding over the weekend.
Reports suggest up to 250 whales in this second stranding event. pic.twitter.com/WgrFSOrtE8
— Project Jonah (@ProjectJonah) October 10, 2022
Pitt and Chatham islands are the largest islands in the Chatham Islands archipelago which lies about 840km (522 miles) off the east coast of New Zealand’s South Island.
About 800 people live on the larger Chatham Island, with 40 people living on Pitt Island.
Grover said given the position of the archipelago near where subtropical and sub-Antarctic oceans meet, there was an abundance of sea life in the area which attracted whales.
Nearby New Zealand and neighbouring Australia are hot spots for mass whale strandings owing to large colonies of pilot whales living in the deep oceans surrounding the two island nations.
Scientists do not fully understand why mass strandings occur, but some researchers think pods go off track after feeding too close to shore.
The Chatham Islands recorded its largest ever stranding in 1918 when more than 1,000 animals died in a single event.
Pilot whales – which can grow to more than six metres (20 feet) long – are highly sociable, so they may follow pod-mates who stray into danger.
Last month, almost 200 pilot whales died on a beach in Australia’s remote western Tasmania. State wildlife services managed to refloat 44 of the mammals.