Recent mass stranding of pilot whales is one of the worst in New Zealand history

Photo credit: Project Jonah New Zealand

Photo credit: Project Jonah New Zealand

Last week, Farewell spit became culprit to another series of mass strandings. The crisis began early on Friday when a pod of 416 pilot whales (which are actually dolphins) were found stranded, with hundreds more following over the course of the weekend. This most recent mass stranding is one of the worst on record for New Zealand.

Approximately 300 dolphins and whales become stranded annually in New Zealand. There are around five hotspots where most of the incidents occur with Farewell spit being the most infamous. All of these stranding hotspots have something in common and that’s the presence of shallow water which is thought to cause the marine mammals to beach.

On the tip of the South Island, Farewell spit is a 26km hook shaped land form at northern end of Golden Bay in the Tasman Sea. It’s home to a number of low tide sand banks and there are deep channels within which marine mammals can swim through. When the tide withdraws very rapidly especially at a spring tide it leaves the sand banks exposed and traps any marine mammals.

The gentle sloping sand of Farewell spit means that it’s a struggle for the dolphins to detect that the water is getting shallower using echolocation. This in combination with the fact that pilot whales form strong social bonds is the reason why the strandings are often fatal. Pilot whales get their name because they often follow a single leader.

The Department of Conservation were notified on Thursday evening that a pod of pilot whales had ventured into the shallow waters, but they did not act until the following morning. Unfortunately it was too late for 75% of the pod which were dead upon discovery.

A total of 120 survivors were refloated and dozens of volunteers formed a human chain in the water to prevent them from beaching again. The refloat was mostly successful with only 20 whales restranding themselves. Unfortunately these 20 individuals were later euthanised. A further 240 pilot whales became stranded on Saturday afternoon from a separate pod, the majority of which were able to refloat themselves at high tide overnight. By Sunday morning only 17 pilot whales remained and these were successfully refloated.

As low tide approached early Sunday evening, approximately 300 pilot whales were seen swimming out of Golden Bay and heading towards the deep-water safety of Cook Strait. On Monday morning no pilot whales were found on the beach. A huge thank you to everyone involved in the past few distressing days. The end is in sight and hopefully all that remains is the clean-up process.

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Lucy Grable

Lucy Grable

MSc Species Identification and Survey Skills student at Reading Uni | BSc Marine Zoology | Website Editor MARINElife | Zanzibar humpback whale researcher|Marine wildlife enthusiast

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