The death of around 200 pilot whales on a Tasmanian beach has raised questions again about what causes such mass strandings and whether they can be prevented.
With the help of Karen Stockin, a whale stranding expert at New Zealand’s Massey University, here are the answers to five key questions:
What causes mass strandings?
Scientists are still trying to figure that out. You know there are multiple types of stranding events, with multiple explanations that can overlap. The causes can be natural, based on bathymetry – the shape of the seabed – or they can be species-specific.
Pilot whales and several smaller species of dolphins are known for regularly stranding en masse, Stockin said, particularly in the southern hemisphere. In some cases, a sick whale headed for shore and a whole pod unknowingly followed them.
Does it happen in certain areas?
There are some global hotspots. In the southern hemisphere, Tasmania and New Zealand’s Golden Bay have seen multiple cases, and in the northern hemisphere, another hotspot is the US bay of Cape Cod, Massachusetts.
In these areas there are similarities between the topography of the beaches and the environmental conditions. For example, Cape Cod and Golden Bay share distinctive narrow shoreline and shallow waters with large tidal fluctuations. Some people call such areas “whale traps” because of the speed at which the tide can recede.
Are strandings becoming more common?
Possibly. Strandings are natural phenomena and have been documented since Aristotle. However, the health of the oceans has deteriorated in recent decades.
Strandings could become more common as human use of the oceans, shipping and chemical pollution increase.
Animal diseases – outbreaks of disease affecting 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 into the effects of climate change on 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 whales to come closer to shore.
For example, recent research based on current climate prediction models suggests that the distribution of sperm whales and blue whales in New Zealand could vary significantly by 2050.
Can strandings be prevented?
Not really. Because stranding occurs for a variety of reasons, there is no one-size-fits-all solution. But Stockin said that with a better understanding of whether and how man-made changes are causing more mass strandings, solutions could be found.
