by In July this year, lifeguards headed to Traigh Mhor beach on the Isle of Lewis, off the west coast of Scotland, to reach a stranded pod of long-finned pilot whales. Most had already died. One was refloated and survived. The others were killed with a rifle.
It was one of the largest mass stranding events (MSE) in the UK, and the team recovered samples of the organs and tissues of each member of the group. Although grueling and disturbing, the work revealed an unparalleled and baffling view of an entire community of whales.
Most stranded cetaceans (whales, dolphins or porpoises) appear alone and are already dead. MSEs are less common and mass strandings of live people are even rarer, but there have been many in recent years. In the Scottish case, the main cause of death was stranding, according to Dr Andrew Brownlow, director of the Scottish Marine Animal Stranding Program (Smass), who was in Lewis and spent months analyzing the samples. As mammals, whales need to breathe, and most of them drowned, caught in the waves and winds on the steep beach.
What baffles Brownlow is what brought them there. Mass strandings have been recorded throughout history, he notes, “since before we industrialized our oceans.” Whales can run aground while fleeing predators, become trapped by tides, weather and topography, or simply get lost.
“But our impact on marine ecosystems today is multiple and widespread, and the pace of these events is increasing,” says Brownlow.
So why were those whales there? Pilot whales live in deep water and are rarely seen near the coast in the northern Minch, the strait that separates Lewis from the mainland. Their bodies did not show injuries from having been hit by boats or caught in nets or ropes. There was no evidence of ingestion of plastic or other marine debris. They were healthy, their fat layers were thick, and they had no major diseases or parasites. Their stomachs were empty, suggesting they had not been hunting there.
It takes a lot to kill one orca, let alone 50 of them. But perhaps his life in a group is also his Achilles heel.
Whales rely on their hearing, and many mass strandings have been linked to human noises: dozens of common dolphins died in Falmouth in 2008 after Navy exercises; and in 2011, military artillery detonated off Kyle of Durness led to the stranding of more than 70 pilot whales. Very loud sounds, such as explosions, can cause physical trauma to your sensitive ears. However, Brownlow found no evidence of this either.
However, other underwater noises may be difficult to detect in an autopsy, but can be fatally disorienting or distressing, similar to blindfolding and suddenly scaring a group of humans near the top of a cliff. A report from Marine Scotland is awaited on the underwater noise before the stranding.
Meanwhile, the next stage of Brownlow’s research will look for more subtle clues, with genetic, isotopic and microbiological testing. Levels of heavy metals such as mercury are rising in UK seas, and persistent organic pollutants are having significant effects on the health of cetaceans, apparently causing a decline in Scotland’s native orca population by rendering them infertile.
“You are what you eat, so whale bodies can paint a picture of the health of the ocean,” says Browlow.
An intriguing clue? The presence of some very young calves. Two appeared to be newborns and two more females appeared to have become stranded while giving birth. Perhaps this is what brought them to the coast, but why did so many die? Why didn’t more escape?
Responders to mass strandings around the world tell a common story: that understanding whale society is as important as taking samples of their bodies. The vast majority of MSEs involve pilot whales: in 2020, 120 were stranded in Sri Lanka; In October 2022, almost 500 people died in New Zealand. These animals live in large, close-knit multigenerational groups of mothers and their young. The name “pilot whale” is believed to come from the belief that each group was led by a pilot or leader. Both killer whales and pilot whales experience menopause, which is rare in other species, and menopausal female killer whales lead their pods.
According to research, different populations of cetaceans have unique ways of life. They teach these ways to each other, creating what are effectively whale “cultures.” Some care for their elderly and disabled; others form nurseries and feed each other’s babies.
Spend time watching pilot whales and you’ll be surprised at how much they play, touch, and interact. They have evolved to survive in the sea by staying together and following their leader. It takes a lot to kill a seven-meter-long, three-ton superpredator full of teeth, let alone 50 of them. But perhaps his life in a group is also his Achilles heel.
We tried to push them back into the sea, but they kept coming back to the beach as if they wanted to commit suicide.
Sri Lankan fishermen
“Strong social bonding is a powerful part of what it means to be a pilot whale, but it also leads to these problematic events,” says Dr Rob Deaville from the UK’s Stranded Cetacean Research Programme. Whatever first causes some whales to approach shore, their social cohesion often seems to mean that the entire group approaches as well.
That social bond also allows whales to be exploited by hunters. In the Faroe Islands, hundreds of pilot whales are killed annually in a hunt called the Grind. If whalers identify and move the largest matriarchs, the entire pod will follow them into shallow waters, where they will be slowly slaughtered with long knives.
In July this year, 97 pilot whales were stranded near Albany, Western Australia. Drone footage showed the whales huddled offshore for hours, huddled together with their heads together. In the 2020 Sri Lanka stranding, fisherman Upul Ranjith told conservation news website Mongabay: “They first appeared as a dark speck on the horizon and continued moving towards the shore like a giant wave.”
A stranded whale is not doomed. Rescuers often “refloat” whales using inflatable mattresses. Daren Grover of the Jonah Project in New Zealand says his group has learned not to drag them: lifting a whale by its delicate tail fins is like pulling an elephant by its trunk. But even when healthy whales are helped back to the sea, they are not safe. “Those close social bonds mean that the whale will simply turn around and want to return to its pod,” he explains.
This view was echoed by Sri Lankan fishermen. “We tried to push them back into the sea, but they kept coming back to the beach as if they wanted to commit suicide,” they told Mongabay. To try to counter this, Grover’s teams wait until they are all ready before launching them into the sea together.
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Our reactions towards cetaceans are not universally compassionate and can be peculiar. Deaville once arrived at a stranded sperm whale and discovered that the animal’s five-foot penis was missing. Years later, he heard that someone had taken it to impress his girlfriend. After he “stinked up the whole house,” she “threw him into a roundabout.”
However, human attitudes are changing. Dr. Asha de Vos, a scientist involved in the Sri Lanka stranding, described an astonishing scene illuminated only by car headlights as choppy waves crashed over the rescuers. “There must have been a whole village there, mostly fishermen fighting to save the whales.”
At dawn, about 120 whales swam away together. Only three died.
De Vos’ most vivid memory was of another social mammal… us. “People came together to put themselves in compromising positions to protect these very unknown creatures. “Animals they have never seen or heard of.”
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As we learn about the true nature of these enigmatic social animals, the scientists responding feel the stakes are high to save them. “Will we ever be able to quantify the emotional distress of losing your pod?” Deaville asks. “The story of that animal [in Lewis] who lost their entire family is quite profound.”
“What are we losing here with these events?” Brownlow says. “This is not just an assessment of the number of animals or even their genetic diversity. “You are losing a culture.”
