Western Australia is witnessing heartbreaking images as a pod of pilot whales became stranded on a beach late on Tuesday (July 25, 2023). The most recent reports indicate that 51 whales have perished. Authorities are frantically trying to get the 46 people who are still on the beach back into the water.
Sadly, there are occasionally pilot whale strandings in WA and other Australian states. They have also happened in Scotland and New Zealand recently. But given the behavior the whales displayed before to being beached, this stranding is exceptional.
On Monday night, the long-finned pilot whale pod started gathering off Cheynes Beach. They remained in a “huddle” on Tuesday, raising fears a stranding was imminent.
I (Kate Sprogis) am a marine biologist who specializes in marine mammals. I am based at the University of Western Australia’s Albany campus, about 70 kilometers from where the stranding occurred. Sadly, the chances of survival for the remaining whales is very low and time is fast running out.
Understanding pilot whales
There are two species of pilot whales: short-finned (which live mainly in tropical and warm-temperate regions) and long-finned (generally found in colder waters). The long-finned pilot whales, as its name suggests, have longer pectoral fins than their relatives.
The pilot whales stranded at Cheynes Beach are long-finned. They are generally found offshore, in the deep open ocean. We rarely see them close to the coast. This makes the species hard to study.
Pilot whales are, however, known to inhabit Bremer Canyon, a very deep ocean area 70 kilometers off the WA coast.
What happened at Cheynes Beach?
The whales were discovered late on Monday at Cheynes Beach swimming in the shallows. On Tuesday morning, a representative from the Department of Biodiversity, Conservation, and Attractions called me and inquired about the odd huddling behavior. I was immediately concerned.
A huddle of healthy pilot whales does not develop, therefore something was clearly wrong. The pod was seen in the department’s drone footage creating an extremely tight ball, moving into a line, then resuming its spherical shape. Additionally, the pod was oddly located in relatively shallow coastal water.
We suspected the behavior was a precursor to a stranding. In case of a stranding, the department was ready with its whale stranding equipment and had personnel on duty. Unfortunately, it did.
By 4pm on Tuesday, almost 100 whales had beached themselves. Officials monitored them overnight. By Wednesday morning, 51 had died.
This is unsurprising. And sadly, the chance of survival for the remaining whales is very low. Cold, windy conditions means the whales are susceptible to hypothermia. Additionally, this confluence of conditions can be lethal if the whales are already ill, which is occasionally the case with beached whales.
Whales are also unaccustomed to the force of gravity that prevails on land. When whales are stranded, the weight of their own bodies might cause their organs to collapse.
In some cases, long-finned pilot whales have been known to survive after being stranded. But time is of the essence.
Why did the whales beach themselves?
In 2015, another pod of pilot whales beached itself in Bunbury, north of Albany. Sadly, 12 died. At the time, I and a colleague conducted necropsies scientific examinations of animals after death but the findings were inconclusive.
Whale strandings cannot be predicted and we do not know exactly why they occur. But in the case of pilot whales, their social behavior offers some clues.
Elephants and pilot whales both live in close-knit family groupings and are social animals. It is believed that large numbers of individuals can become stranded at once when the ailing matriarch of the group swims into shallow water, leading the others to follow or be “piloted.”
Whales may also become stranded due to an external stress. For example, whales use sound to communicate, navigate and search for food. Loud man-made underwater noises can disrupt this system.
What next?
Officials at Cheynes Beach are trying to refloat the whales. Researchers are also taking biopsy samples and nasal swabs from the dead whales.
To learn more about this stranding occurrence, experts will analyse the samples and swabs. I anticipate they will look for evidence of illness such as influenza or cetacean morbillivirus, as well as stress from underwater noise.
You might also be wondering what everyday people can do to help. If you observe marine mammals behaving unusually or getting stranded, alert authorities. And please stand aside to let authorities and other experts do their work. This is vital for the welfare of the animals and the safety of both helpers and bystanders.
Right now, I feel a bit helpless. I would like to be able to answer everyone’s primary question: why do pilot whales become stranded? It is a long-standing mystery in marine mammal science, and we don’t really know the answer.
More research is needed. Funding is required for scientists to attend mass strandings, gather and analyze samples, and report their findings. That increases our chances of solving this challenging puzzle.
