The slap of an enormous tail upon grey waters as a humpback whale leaps from the sea is becoming an increasingly possible – although still rare – natural thrill around Britain.
The 30-tonne, 15 metre-long migratory giants are being spotted in growing numbers and locations this winter from Kent to the Isles of Scilly.
There have been 17 sightings of the whales around the Isles of Scilly between 29 December and 8 January this year. Several individuals spotted include one called Pi because of the distinctive markings on her fluke (the lobes of her tail), who has turned up for a winter vacation around the archipelago every year since 2019.
More unusually, humpback whales have also been seen in the eastern English Channel, close to the coast at Deal, Kent, and Eastbourne, Sussex. The Deal and Eastbourne sightings were within an hour.
“I know humpback whales are fast but they are not that fast,” said Thea Taylor of the Sussex Dolphin Project. This means that the sightings were of at least two individuals.
The humpback whales are migrating from their feeding grounds near Tromsø, Norway, to warmer waters around the Cape Verde islands, where they rest and breed.
Traditionally, the whales move around the western side of Britain but some are now swimming down the east coast and through the Strait of Dover – possibly re-establishing ancestral routes that were abandoned when so many humpbacks were slaughtered by 19th- and 20th-century whale-hunters.
Experts say the sightings could be a positive sign that the humpback whales’ global population of 84,000 mature animals is recovering following the ban on commercial hunting in 1986.
But the growing number of winter sightings may also be linked to the changing availability of food. Humpbacks are filter feeders, scooping up huge quantities of plankton, tiny crustaceans and small fish.
“We’re seeing a lot of bait fish – smaller fish like anchovies – around the south west coasts,” said Ruth Williams, the head of marine conservation for the Wildlife Trusts. “They are very quick reproductively, and with climate change their stocks are moving up closer to our waters.”
Wildlife tour guide Carl Chapman reports a fisher seeing a likely humpback off the East Anglian coast late last year alongside a large gathering of minke whales, drawn to an exceptional gathering of spawning herring.
He believes the presence of more whales around Britain’s coasts is because warming waters are causing a more northerly distribution of prey. According to Chapman, in recent autumns, there has also been a more northerly distribution of cory’s, great and sooty shearwaters – fish-feeding birds typically seen further south in the Bay of Biscay, which supports this theory.
Marine scientists caution that there is no conclusive evidence for any theories yet – and reasons for their presence around Britain include the more alarming suggestion that underfed individuals are compelled to pause their southerly migrations to feed.
Williams warned whale-watchers not to disturb the whales by getting too close in boats. “These individuals might be stopping off because they are vulnerable and need to feed so we ask boat owners to give them space.”
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“It’s hard not to see a humpback breaching and not want to protect the ocean,” said Emily Cooper, science communicator for the Marine Conservation Society. “But there are a number of not so great reasons for more sightings – whales and marine life are facing a huge number of pressures, including getting caught in ‘ghost’ fishing nets, and oceans becoming busier and busier, with more noise pollution. All have the potential to alter whale behaviour.”
There are concerns that humpbacks taking the easterly migration route around Britain must pass through crowded shipping lanes and beside windfarms and new power cable installations that could disorient them or lead to collisions or strandings.
“The Dover Strait is a very small area of water, very narrow, and incredibly busy – not only shipping but a lot of industrial fishing,” said Taylor. “There are always concerns about collisions with large shipping vessels. We know so far they seem to be hugging the coast going past Kent and Sussex – we hope they continue to do that and stay out of the busiest shipping lanes.”
The humpbacks’ appearance off the Kent coast is also raising fears about the impact of new subsea electricity cables for new offshore windfarms on marine mammals.
Emma Waller, planning and policy officer for Kent Wildlife Trust, said that National Grid’s Sea Link project, which plans to install an underwater cable between Kent and Suffolk, had not undertaken enough research on its impact on whales, seals and other marine mammals and its landfall at Pegwell Bay could disrupt marine ecosystems.
“The sightings underline the need for these large offshore projects like Sea Link to fully consider their impacts on marine mammals,” said Waller. “Their current approach lacks adequate mitigation for marine mammals. Renewable energy is vital, but it must not come at the expense of wildlife when alternative options are available.
“There needs to be a review of the standards of ecological surveys for such projects – we need to understand what these impacts and implications are going to be.”
