Golden Bay whale stranding: Busting the myths

A mass stranding of pilot whales at Golden Bay's Farewell Spit has prompted a number of theories as to what caused it.

More than 300 whales died when the pod stranded, and volunteers have spent the weekend trying desperate to refloat and save those who remained on the beach.

But why did so many pilot whales strand in the first place - the biggest beaching in Golden Bay's history?

Marine biologist Dr Victoria Metcalf spoke to Newshub to address some of the myths.

The full moon drove them to strand

Pilot whale stranding (Ross Wearing / Newshub.)
(Ross Wearing / Newshub.)

On February 11, a full moon shone upon New Zealand's waters. It meant the high tide was higher than usual, stranding the whales further up the beach.

But the blame for the stranding hasn't just been put on the high tide. Instead, some online theorise the moon itself drove the whales to strand.

"The moon seems to be blamed for all sorts of possible things, but in all reality I think lunar cycles don't affect things as much as they are purported to," Dr Metcalf says.

"I don't think there's enough research to be able to say [there's a link between stranding behaviour and the lunar cycle], but I think it would be hard to say anything conclusive about the moon."

They pre-empted Sunday's earthquake near Culverden

Pilot whale stranding (Ross Wearing / Newshub.)
(Ross Wearing / Newshub.)

A magnitude 5.2 earthquake hit near Culverden on Sunday morning, one of a number of aftershocks from the Kaikoura earthquake.

For centuries animals have been thought to be able to predict earthquakes, with further research being undertaken to see if there's any truth in the matter.

But Dr Metcalf says because the quake was land-based, it's unlikely to be related to the stranding.

"There's certainly some evidence to suggest they might be affected by underwater seismic quakes, but this was not in that zone, so I think it would be unlikely," she says.

"I guess it's possible that they could alter their behaviour before the quake occurred... I don't think there's that much data at the moment to support that."

A solar storm threw off their sonar

Pilot whale stranding (Ross Wearing / Newshub.)
(Ross Wearing / Newshub.)

Earlier this month NASA announced a study into whether severe solar storms, which affect Earth's magnetic fields, may lead whales, dolphins and porpoises to strand.

The timing has sparked concerns, and confusion, over whether or not this pod's stranding was related.

"I think that's tenuous," Dr Metcalf says.

"If a solar storm was influencing that geo-magnetic navigation system, then that is a possibility."

NASA has only just launched this study - it has no firm conclusions yet.

Seismic blasting boats are operating offshore

Pilot whale stranding (Ross Wearing / Newshub.)
(Ross Wearing / Newshub.)

The largest seismic testing ship in the world, the Amazon Warrior, is currently in New Zealand, searching for oil off the east coast.

It operates by blasting airguns in the water and a report commissioned by environmental group Greenpeace found it can stress and even deafen whales.

Dr Metcalf says out of all the theories for the stranding, this one has "more validity".

"There's a reasonable body of research into that overseas, particularly in the Mediterranean, and that definitely there is a relationship between seismic testing, maybe sonar use, and strandings," she says.

"But I'm not sure about this particular situation."

What was behind the stranding?

Pilot whale stranding (Ross Wearing / Newshub.)
(Ross Wearing / Newshub.)

Dr Metcalf says it's unlikely the stranding was caused by one singular event, as it's usually more complex than that.

As pilot whales are very social creatures, mass events such as this one can often be caused by first one being stuck, then others coming to try and help.

"Once they're in that shallow water of Golden Bay it's really challenging for them with their sonar and they may have got confused," Dr Metcalf says.

"At least one of them may have been beached and sent out a distress call to the others, and caused the rest of them to come in and then strand themselves."

While there's little evidence to support most of the theories prompted by this stranding, she's pleased people are interested - particularly in the human impact on wildlife and the environment.

"Researchers are doing a lot of research into this as well, and it probably takes both a public and a scientist approach to really figure out why whales strand."