Whale myths busted
Why did hundreds of whales become stranded at Farewell Spit last week? The truth is, no one knows for sure. But everyone seems to have a theory. We asked Professor Liz Slooten, of the New Zealand Whale and Dolphin Trust, and Jo Halliday of Whale Rescue, to apply some good, old-fashioned science to some of the most widespread whale stranding myths. Pilot whales aren’t actually whales. Firstly, we need to get this straight. Pilot whales aren’t whales.
‘‘They are in the family of delphinidae so, technically, they are a dolphin, not a whale,’’ Slooten said.
She said it was a ‘‘good question’’ why they were called pilot whales. ‘‘I guess they are much bigger than dolphins.’’
Orca, better known as killer whales, also weren’t whales, Slooten said.
‘‘People would never think a killer whale is a dolphin.’’
So the mass ‘‘whale stranding’’ at Farewell Spit was, strictly speaking, a mass dolphin stranding. The full moon lunar eclipse There was a partial lunar eclipse on February 11 that caused a King Tide, and some people suggested that might have caused the dolphins (still feels wrong writing that) to strand.
But the pilot whales stranded on February 10.
In the same way that the full moon is often blamed for humans acting up, some people thought it might have had something to do with driving the pilot whales onto the beach.
Slooten said she was not aware of any scientific evidence for this theory. Solar storms A research programme being undertaken this year by NASA will look at whether solar storms contribute to strandings.
Solar storms are said to disturb the magnetic-field in the solar system, wreaking havoc on satellite systems and power grids.
It has been suggested that they may also disrupt the whales’ navigational senses.
Slooten said studies have shown that there was ‘‘no correlation’’ between magnetic anomalies and whale strandings in New Zealand. Whale (read: dolphin) strandings are ‘like a car crash’ Slooten said without biopsy results from the stranded pilot whales, it was impossible to point the finger at any one cause.
‘‘It’s often difficult with these types of things to tease out the natural and human causes.’’
She said sometimes an individual in the pod might become sick and the rest of them refuse to abandon it.
‘‘The reason that about half the time with group strandings, they have very strong social bonds. They live in large groups. All the individuals are closely related. If one individual is in trouble, the rest of the group won’t leave.’’
Farewell Spit was also notorious for strandings.
‘‘Certainly the topography of that area at Farewell Spit with the spit sticking way out into Cook Strait and very shallow water on the inside of Farewell Spit, it’s not at all helpful. It’s much more likely for a mass stranding of whales, all of which are healthy, to happen in a location like that.’’
Slooten compared the stranding to a car accident.
Factors such as speed, weather, road conditions, alcohol, fatigue and vehicle malfunctions can contribute to a car crash.
It’s likely that a variety of factors compounded to cause the mass stranding at Farewell Spit, she said.
It’s not the most helpful answer, but without intensive studies on hundreds of whale strandings it was impossible to jump to any educated conclusion. Seismic blasting boats operating offshore The largest seismic testing ship in the world, the Amazon Warrior, is currently searching for oil off the East Coast of New Zealand.
It operates by blasting airguns in the water and a report commissioned by environmental group Greenpeace found it can stress and even deafen whales.
Whale Rescue co-founder Jo Halliday said the blasting has often been blamed for whale strandings. However, she said evidence for this was inconclusive.
‘‘There are well-known places around New Zealand, like Farewell Spit, where whales strand, and they have done even before the seismic blasting started offshore,’’ she said.
‘‘We can’t blame it on any one thing like the blasting, but that’s not to say there isn’t some damage made to these animals by these activities.’’ Farewell Spit is a ‘whale trap’ Halliday said Farewell Spit was a well-known ‘‘whale trap’’, and like Slooten, she believed the topography of the land might be to blame for the strandings.
‘‘The Spit just juts out and it has a very gradual sloping beach,’’ she said.
‘‘The whales are swimming through the Cook Straight, and if they veer off into Farewell Spit, they start using their sonar echolocation to get directions but then they might disorientate and get lost because they can’t find a way out,’’ she said.
Halliday compared it to driving through an unfamiliar city with numerous distractions.
When the driver becomes stressed, they might fail to follow the GPS directions properly and become lost.
‘‘[The whales] end up being slightly overwhelmed, and their echolocation doesn’t pick up on how to get out,’’ she said.
Add a King Tide into the mix, and you have a perfect recipe for a stranding.
‘‘The King Tide would have created higher levels of water at the high tide, so the whales might have perceived that they had enough water, but when the tide goes out they are left high and dry,’’ she said.
Pilot whales were highly complex social creatures that live in large family groups, often meeting with other family groups to feed, socialise and mate.
‘‘It’s highly likely the pod that stranded was made up of lots and lots of family groups. By meeting other extended family groups they have the opportunity to mix up the gene pool, as well as meeting up
just to socialise,’’ she said. She doubted they will ever know for sure why the hundreds of pilot whales stranded on Farewell Spit last weekend.
‘‘But we do know that it’s the time of the year these animals are commonly sighted socialising with one another in that area.’’