What do stranded whales tell us about our oceans?

A whale’s tail whirls high in the air, stopping at the apex of its journey before hitting the hard, rocky ground with a thud. The noise is sickening, the sound of two things coming together that should never meet. Megafauna encounters are rare in the UK, so it’s truly shocking to see this colossal creature stranded on the Cornish coast last March, gasping for air. Later we find out that it is a 19 meter long and 80 ton fin whale – the second largest creature on earth.

Some of the first on the spot are members of the British Divers Marine Life Rescue Service (BDMLR), one of several organizations called when a cetacean (whale, dolphin or porpoise) falls ashore. Reports of strandings of whales off UK coasts have reached record levels in recent years, with numerous mass strandings and greater biodiversity on the beaches. As far back as 2023 there were reports of a fin whale stranded in Cornwall in January and a stranded bottlenose dolphin dying off the Yorkshire coast this month.

Since 1990 all cetacean strandings have been investigated by the UK Cetacean Strandings Investigation Program (CSIP), which is jointly funded by the UK, Welsh and Scottish Governments. His findings point to a changing marine environment where human impact is heavily affecting marine life.

  • Simon Myers, a Clean Ocean Sailing volunteer, tries to keep the beached fin whale wet while waiting for the British Divers Marine Life Rescue Service (BDMLR) to arrive

The average number of stranded whales increased to about 890 per year between 2015 and 2019, up from 570 from 2010 to 2014, according to Rob Deaville, project manager at CSIP. Andrew Brownlow, Lecturer in Veterinary Epidemiology and Director of the Scottish Marine Animal Stranding Scheme (SMASS) says: “Over the last five years we have seen an increase in the number of strandings year on year. There are more animals that are being reported to us.”

For many of the scientists who study the health of whale populations, the link between the increase in strandings and increased human activity in the oceans is clear. “The vast majority of strandings are inevitably attributed to negative anthropogenic impacts on the marine environment,” says Dr. Kevin Robinson of the Cetacean Research and Rescue Unit, a Scotland-based marine conservation organization.

Evidence from the study of cetaceans and beached cetaceans can be used as a guide to marine health. “Whales and dolphins are at the top of the food chain – their fate determines the fate of the rest of the marine ecosystem. They’re really good indicators of ecosystem health and the state of the marine environment,” says Dr. Peter Evans, director of the Sea Watch Foundation and honorary professor at Bangor University.

  • The whale’s tail, damaged by the sharp rocks on the shore, top left. BDMLR members measure and examine the body of the stranded fin whale for signs of life

Cetacean species are adversely affected by overfishing, bycatch, entanglement, ship noise and traffic, ship collisions and propeller strikes. In addition, commercial whale watching, marine activities such as low-frequency sonar and underwater explosions, oil and gas exploration, pile driving, cable laying, wellhead decommissioning, poisoning, pollution, and the climate crisis can all lead to strandings.

However, strandings have also occurred throughout history due to natural causes such as illness, disease or injury. CSIP’s job is to determine the cause of each death they investigate. “There’s certainly some level of natural mortality, the question has always been, are we seeing more or are we seeing other species or are we seeing some that’s due to what we’re doing out there,” says Deaville.

Deaville cites injuries and fatalities as a result of bycatch – the catching of non-target species while fishing – as “the most important direct anthropogenic factor in the mortality of beached whales in the UK for 30 years”.

“Bycatch is a big, big burden on whales around the world,” he adds. CSIP data shows that between 1990 and 2019, out of about 4,050 dissections of whales found off the UK coast and in good enough condition to be examined, 782 diagnosed the aftermath of bycatch and gear entanglement as the leading cause of death, says Deaville .

Brownlow suggests the situation could be even worse than the numbers suggest. “There’s potentially a huge amount of underreporting,” he says.

There is strong evidence that chemicals such as organochlorins – common ingredients in pesticides – and polychlorinated biphenyls (PCBs), a group of banned but still widespread and highly carcinogenic chemical compounds, have highly toxic effects on whale health. “We’re really concerned about circuit boards,” says Deaville. Despite being banned for several decades, their resistance to mining means much of the production has found its way into the oceans. “They have a really toxic effect on life,” says Deaville.

  • Rob Deaville of the Cetacean Strandings Investigation Program (CSIP) is about to perform an autopsy on a porpoise to determine the cause of death

The concern for whales in particular is that as PCBs move through the food chain, they ‘biomagnify’, becoming more concentrated and toxic at every level. In 2016, a killer whale nicknamed Lulu was found dead on the Isle of Tiree in Scotland. It was found to have one of the highest concentrations of toxic pollutants ever measured in any marine mammal, with a CSIP toxicology report showing an “astronomically high” PCB load that the team suspects may have prevented it from ever occurring bear boy.

“We now think there are just a few orcas left on the west coast,” says Deaville. “They have been studied for 30 years and have not had a calf during that time. Lulu was a woman who happily should have had calves. She was about 20 and her ovaries showed no sign of ever properly riding a bike. Their PCB value was around 1,000 mg per kilogram. At 10mg per kilogram you would see potentially serious effects.” Deaville doesn’t believe the UK west coast community can survive the PCB pollution found in Lulu. “We contend that what we did decades ago is contributing to a localized eradication of the killer whale population… I think we will lose our killer whales off British shores, probably in my lifetime.”

Despite the long list of anthropogenic factors routinely found to be contributing to the suffering, trauma or death of many of the 24 whale species stranded in UK waters since 1990, an increase in strandings alone does not necessarily mean bad news for some ‘because it could mean there are more animals out there,” says Deaville.

“One possible reason is the moratorium on commercial whaling that went into effect in the mid-1980s,” Brownlow says. “We’re now 30 years downstream from that and the populations we wanted to protect are starting to recover.” In 2008, humpback whales were downgraded to “Least Concern” by the International Union for Conservation of Nature.

In 2022, BDMLR received nearly 3,000 calls about strandings off the UK coast. In the event of a live stranding, the organization’s team of trained medical volunteers will assess whether a rescue attempt can be made. A creature the size of a dolphin and in relatively good health can sometimes be attempted to revive the animal.

But rescue is not always possible. Back in Cornwall, when Dan Jarvis, Director of Animal Welfare and Conservation at BDMLR, approaches the stranded Fin Whale, he can immediately tell that the animal is malnourished. “He was in really poor nutritional status, so obviously he hadn’t eaten for a while – possibly due to an infection or illness,” he says.

The whale could not be saved and entered its agony, opening its mouth wide and raising its tail in the air.

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