Why do whales beach themselves?

Drive 01/12/2018

Another mass stranding of pilot whales in New Zealand has scientists scratching their heads.

Fifty-one pilot whales died after becoming stranded on a beach on the Chatham Islands, while 30 to 40 stranded whales in the pod returned safely to sea.

Fifty whales were found dead and one was still alive on Thursday. The Department of Conservation euthanised the surviving whale due to its poor condition.

Karen Stockin, associate professor at Massey University, says it’s still unclear why so many whales have stranded themselves, but could be related to the tides, environmental factors, and pod composition.

Eight whales were stranded in Northland. Photo: Newshub.

She says pilot whales in particularly are “a very social species” and may refloat themselves depending on the leader in the pod. But if the pod leader is a female, there can be factors that may keep her from refloating.

“[Females] are hardly going to lead a pod away from the beach if one of their own calves remains stuck on the beach,” she told RadioLIVE.

On the other hand, some isolated whale strandings are deliberate in order for the whales to return to the surface to breathe. This happens when the whale is having trouble getting to the surface on their own.

“Where we’ve got a single-stranded animal, there’s usually a high incidence of ill health in that animal than what you would expect in a mass stranding.”

Dr Stockin says a mass stranding can occur when one or two whales are injured or sick, which  subsequently brings the rest of the pod in with them.

Over 200 whales have died in separate incidents over the past week in New Zealand, with ten pygmy killer whales found stranded in Northland on Sunday and a whopping 145 pilot whales found dead on Stewart Island last week.

The Department of Conservation is taking skin and blubber samples from the Chatham Islands stranding for further analysis.

Listen to the full interviewabove.

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