145 whales die on remote New Zealand beach

AFP Yahoo News 26 Nov 18;

Up to 145 pilot whales have died in a mass stranding on a remote part of a small New Zealand island, authorities said Monday.

The stranding was discovered by a hiker late Saturday on Stewart Island, 30 kilometres (19 miles) off the southern coast of the South Island.

Half of the whales were already dead and due to the condition of the remaining whales and the remote, difficult to access location, the decision was made to euthanise the remainder.

"Sadly, the likelihood of being able to successfully re-float the remaining whales was extremely low," said Ren Leppens, the Department of Conservation's operations manager on Stewart Island.

"The remote location, lack of nearby personnel and the whales' deteriorating condition meant the most humane thing to do was to euthanise.

"However, it's always a heart-breaking decision to make."

It was one of four strandings discovered on New Zealand shores over the weekend.

Whale strandings are relatively common on New Zealand shores, with the conservation department responding to an average 85 incidents a year, mostly of single animals.

On Sunday, 10 pygmy killer whales stranded at 90 Mile Beach at the top of the North Island. Two have since died and attempts will be made Tuesday to re-float the survivors.

A sperm whale which beached on nearby Doubtful Bay died overnight on Saturday, while the body of a dead female pygmy sperm whale was found at Ohiwa on the west coast of the North Island.

Exactly why whales and dolphins strand is not fully known but factors can include sickness, navigational error, geographical features, a rapidly falling tide, being chased by a predator, or extreme weather.

51 pilot whales die in another mass stranding in New Zealand
NICK PERRY Associated Press Yahoo News 30 Nov 18;

WELLINGTON, New Zealand (AP) — Fifty-one pilot whales died Friday in a mass stranding in New Zealand, less than a week after 145 pilot whales and nine pygmy killer whales perished in two other unrelated strandings.

In the latest stranding, up to 90 pilot whales beached themselves late Thursday at Hanson Bay on the remote Chatham Islands, said the Department of Conservation.

When staff arrived, they found up to 40 of the whales had refloated themselves but another 50 had died on the beach. The department said one beached whale remained alive, which staff decided to euthanize due to its poor condition.

The Chatham Islands are about 800 kilometers (500 miles) east of New Zealand's main islands and are home to about 600 people.

Last weekend, 145 pilot whales died on Stewart Island. By the time conservation workers arrived there, about 75 of the whales were already dead and they decided to euthanize the others by shooting them due to their poor condition and the remote location.

On Sunday, 10 pygmy killer whales were found stranded at Ninety Mile Beach on the North Island.

Despite the efforts of 200 staff and volunteers, who managed to refloat eight of the whales after transporting them to a beach where conditions were calmer, all but one of the whales ended up stranding themselves again by Wednesday. Those whales were also euthanized.

Dr. Dave Lundquist, a technical adviser on marine species, said in a video released by the Conservation Department that there was no evidence to suggest the strandings were linked.

"You're talking about strandings across the entire breadth of New Zealand in a very short period of time, which naturally does cause everyone to reflect on whether those might have something to do with one another," he said.

Lundquist said that while scientists don't typically know why individual whale strandings occur, they believe there are probably a range of reasons. He said they could be caused by whales navigating incorrectly, trying to escape from predators, or some of them suffering injuries or illness. He said there could also be man-made factors like underwater noise.

"In many of those cases, it's probably a combination of those factors," he said.

Whale strandings are most common in New Zealand during the Southern Hemisphere spring and summer.


New Zealand beached whales: Why are so many getting stranded?
Gareth Evans BBC 30 Nov 18;

The pictures are striking: dozens of whales lie stranded on an idyllic beach in a remote part of New Zealand.

The group were found by a walker on Stewart Island earlier this week. And just a few days later, a further 51 pilot whales died after becoming stranded on a beach on the Chatham Islands.

While whale strandings are not uncommon, they usually involve just a single animal rather than a whole group. The recent flurry of mass strandings has brought a renewed focus on the mysterious, and rare, phenomenon.

So why does it happen? While the exact reasons remain unclear, experts say many different factors could play a part.

Sickness and injury

"Quite often animals that turn up on a beach are getting exhausted, they're malnourished, or they haven't eaten because they're ill," says Dr Simon Ingram, a Professor of Marine Conservation at the University of Plymouth.

"They can be in the final stages of being ill or die at sea and end up getting washed up on a beach," he adds.

But Dr Ingram says that sickness or injury mainly plays a part when a single animal is found stranded.

"The trouble is that in a huge number of animals it's quite likely that some of them are going to be ill anyway," he explains.

It's also true that there have been cases where groups of healthy whales have ended up getting stranded. So what could be behind these cases?

Navigational mistakes

Some experts say that certain aspects of the coastline or sea bed can disorientate whales, especially if they roam outside of their usual habitat.

"Some places like the tip of New Zealand are hotspots for stranding," says Dr Ingram.

"Sometimes this is due to geographic features of the coastline. If there's a feature like a peninsular or headland then animals that should be in deeper [waters] may suddenly find themselves in a confusing, shallow, bay."

Shallow water can pose a risk to pilot whales in particular because of the way in which they navigate and communicate.

"These animals forage and feed largely by echolocation," says Dr Andrew Brownlow, a veterinary pathologist who has undertaken post-mortems on stranded pilot whales in Scotland. "So they use sound to navigate and communicate and find their prey."

"Using echolocation in areas with very shallow, silty mud is like trying to walk through a forest on a foggy day," he explains, "It's very hard to get your bearings and see clearly."

This combination of shallow waters and confused, muddled, echolocation is a serious danger and may lead to mass strandings.

"They end up coming into shallow areas and get stranded by the receding tide, so the natural lay-of-the-land is a real risk factor for these animals," Dr Brownlow says.

Following the leader

But if a single whale gets injured or lost, why do they end up beached in such large numbers? Experts say the answer lies in their herd-like behaviour.

"It's a problem you get with these very social animals that tend to, for reasons we have never been clear on, end up following either a sick leader onto the beach or end up getting lost as a group," Dr Brownlow says.

"This particular species seems to be very prone to that herd behaviour."

It means that if one pilot whale encounters a problem then it can have an impact on the entire group.

Dr Brownlow points to one case in 2015 when around 30 whales became stranded on the Isle of Skye, off Scotland's west coast.

"We think that was because one of the females was having trouble giving birth and was in a lot distress," he explains. "She came into shallow waters, and all the other members of the group followed her onto the beach."

Warming waters

Another possible cause of strandings, some experts suggest, is warmer water temperatures.

"We've had an unusual week, which we haven't got to the bottom of, and it's fair to say it's been an entirely unusual year," Dr Karen Stockin, a marine mammal scientist based at New Zealand's Massey University, told AFP news agency after the latest mass stranding.

"I suspect a lot of that has been driven by the warmer sea surface temperatures that we're seeing at the moment."

She explained: "That's likely affecting where the prey is moving and as a consequence we're seeing prey moving and [whale] species following."

New Zealand's summer begins on Saturday and Dr Stockin warned that there could be more beachings to come.

"We're just going into stranding season now, this is only the beginning of it and we're very mindful of the fact that this a very busy start," she said.

While Dr Stockin says that global warming may be playing apart in the rising sea temperatures, most experts say that it's important not to jump to conclusions about the role of humans in these cases.

"Pilot whales have probably been stranding in New Zealand since before people lived there," Dr Ingram says. "It's probably not anything to do with what humans have done."

"It's a very dynamic ecosystem that these animals are in, so I would be very cautious in making any connection between these examples and climate change."