Whale Strandings: Five Questions Answered

The death of around 200 pilot whales to a Tasmanian beach renewed questions about the causes of these massive strandings and the possibility of preventing them.

With the help of Karen Stockin, whale stranding expert at Massey University of New Zealand, here are the answers to five key questions:

What causes mass strandings?

Scientists are still trying to figure this out. They know that there are multiple types of stranding events, with multiple explanations that may overlap. The causes can be natural, based on bathymetry – the shape of the ocean floor – or they can be species-specific.

Pilot whales and several species of smaller dolphins are known to strand regularly, especially in the southern hemisphere, Stockin said. In some cases, a sick whale has made its way to shore and a whole pod has unwittingly followed them.

Does this happen in certain areas?

There are a few global hotspots. In the Southern Hemisphere, Tasmania and New Zealand’s Golden Bay have seen several cases, and in the Northern Hemisphere, US Cape Cod Bay, Massachusetts, is another hotspot.

In these areas, there are similarities between beach topography and environmental conditions. For example, Cape Cod and Golden Bay share a narrow, prominent coastal feature and shallow waters with large tidal variations. Some people call these areas “whale traps” because of how quickly the tide can retreat.

Are strandings becoming more frequent?

Maybe. Strandings are natural phenomena and have been documented since the time of Aristotle. However, the health of the oceans has deteriorated in recent decades.

Strandings could become more common as human use of the seas, shipping traffic and chemical pollution increase.

Epizootic diseases – outbreaks that affect a specific animal species – could also lead to more. But there’s still a lot to understand about the phenomenon, Stockin said.

Is climate change a factor?

Research on how climate change affects marine mammals is still in its infancy. Experts know that climate change can lead to changes in the distribution of prey and predators. For some species, this can cause the whales to move closer to shore.

For example, recent research based on current climate prediction models suggests that by 2050, the distribution of sperm whales and blue whales in New Zealand could vary significantly.

Can strandings be avoided?

Not really. As strandings occur for a multitude of reasons, there is no single solution. But Stockin said by better understanding if and how human-induced changes are causing more mass strandings, solutions could be found.