Whale Strandings Are a Still a Mystery to Marine Science

An imache of a pilot whale, a species prone to strandings

Strandings are one of those bizarre and depressing happenings in the animal kingdom that humans still haven’t really worked out an answer for.

Right now, on the southern coast of Western Australia, 97 long-finned pilot whales have stranded themselves on Cheynes Beach. The beach is about 60kms east of Albany and, overnight, 51 of the whales sadly died. Marine rescue teams and vets are currently trying to keep the remaining whales alive, but the prospects are not good.

“People are trying to make sure the animals stay wet, and then a vet will make an assessment of the animal’s condition while it’s out on the edge of the water, before we look at moving it into deeper water,” Parks and Wildlife spokesman, Jeremy Friend, has said.

“Overwhelming” numbers of locals have arrived at the beach to help out and some whales have been successfully put back out to sea. Others have simply returned and re-stranded themselves.

It’s not uncommon for events like this to happen. In October last year, 477 pilot whales stranded themselves on New Zealand’s remote Chatham Islands. The month before, 230 whales did the same in Tasmania.

In New Zealand, a hotspot for marine mammal strandings, more than 5,000 events like these have occurred since 1840. Western Australia is another, with 732 stranding events recorded between 1981 and 2010.

It’s a deeply disturbing sight to see cetaceans – the family group including whales and dolphins – wash themselves up on the shore. These are highly intelligent creatures, well adapted to life under the sea. So what would drive them to come ashore and succumb to the effects of gravity? Scientists have some ideas as to why whales beach themselves, but there are no concrete answers. Here’s what we do know about it.

Why Do Whales Beach?

No two whale beachings are the same, although some share similar patterns. Individual strandings are usually caused by death, illness, or injury at sea. Mass strandings are less common, although Pilot whales, like the ones at Cheynes Beach, seem particularly prone to strandings.

Social dynamics amongst whales are thought to be key to understanding strandings. Whales may gather around an ill or injured companion, leading to the stranding of a whole pod. Others can follow dolphins or other cetaceans into shallow waters where they get stuck. Environmental factors, like the use of underwater sonar and deep-sea mining, are also thought to cause injury and disorientation in cetaceans, leading to strandings. Geomagnetic disruption caused by solar storms may also be throwing whales off balance.

The whales at Cheynes Beach are long-finned pilot whales, which typically inhabit cold, deep ocean waters, unlike their more tropical cousins, the short-finned pilot whales. This means it’s hard for scientists to study them and understand their behaviour.

Around 70 km off the WA coastline is the Bremer Canyon, a deep tough of cold water where long-finned pilot whales are commonly found. The whales at Cheynes Beach may have come from here. Looking at the beach, and at other sites where whales often strand, like Cape Cod in the US, there seems to be a pattern of hook-shaped coastline being an issue for some species. This may not be the case with this current stranding, however.

The whales were seen grouping together in shallow water on Monday evening. Kate Sprogis, an Adjunct Research Fellow at the University of Western Australia’s Oceans Institute, was contacted about the whales on Tuesday and has written that she knew something was immediately off.

“Healthy pilot whales do not form huddles, so something seemed very wrong,” she has said

“The pod was forming a very tight ball, then moving into a line, then back into the ball shape. And the pod was in very shallow coastal water, which is odd”.

She writes that although whale strandings cannot be predicted and remain a mystery, pilot whales strong social connections could offer clues as to why they seem to strand more than others.

“Pilot whales are similar to elephants in that they live in tight-knit family groups,” she writes.

“It’s thought mass strandings may occur when the matriarch of the group is sick and swims into shallow water, and the others follow, or are ‘piloted’.”

Are Whale Strandings Increasing?

In the UK, all cetacean strandings since 1990 have been investigated by the UK Cetacean Strandings Investigation Programme (CSIP), a government-funded body. What they’ve found is that human activity in the oceans is likely causing an increase in strandings.

Between 2010 and 2014, there were roughly 570 strandings worldwide each year. Between 2015 and 2019, that number has risen to 890. They say that bycatch, entanglement, shipping noise, whale watching, underwater explosions, oil and gas exploration, cable laying, pollution, and climate change are contributing to the increase.

Marine mammals are considered ‘sentinel species’ – animals that represent the overall health of ecosystems. Since they’re at the top of the food chain, what happens to whales tells us a lot about what is happening in the rest of the ocean.

For marine scientists, there is no one cause of cetacean strandings. Each event is often influenced by a number of different negative influences coming together that results in a stranding. For each species of whale, those factors are also different. It’s also unclear whether whale strandings are becoming more common, or we’ve just got better at reporting and recording them.

Throughout the 20th and 21st centuries, many whale species were hunted close to extinction. Since the International Whaling Commission’s moratorium on commercial whaling in 1986, just three countries continue to hunt whales, although in decreasing numbers. ‘Great whale’ species like the blue whale, humpback, and fin whale are generally thought to have bounced back in some areas.

Humans need whales more than ever right now. According to the International Monetary Fund, one whale is worth 1000 trees when it comes to saving the planet. As they swim, they spread nutrient-rich waste that acts as fertiliser for phytoplankton which sucks in carbon dioxide, reducing greenhouse gasses in the atmosphere.

While we may never really know the exact cause of each stranding, its vital we do everything we can to ensure we see fewer of them in the future.

Related: The Ocean Is Scary: Your Two-Minute Guide to the Titanic Shipwreck

Related: It’s Time to Flipper Coin: These Sydney Spots Are Perfect for Whale Watching

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