Nature documentaries showcasing Antarctica’s wildlife have often played a key role in inspiring people to fall in love with the White Continent. In recent years, few sequences have amazed viewers as much as the dramatic behaviour of pack ice killer whales, shown in the BBC’s Frozen Planet and Frozen Planet II series hunting seals by breaking up their ice floes with a remarkable behaviour known as ‘wave washing’.
We spoke to Dr Leigh Hickmott, a whale biologist specialising in killer whales who worked as a consultant on Frozen Planet II and other series, about studying these remarkable creatures, the threats they face from climate change, and what the Antarctic cruise industry is doing to help to protect them.
All killer whales are not the same
‘All my research is in the Western Antarctic Peninsula, in an area called Marguerite Bay off Adelaide Island,’ says Leigh, who has been studying whales for nearly 30 years. ‘In Antarctica, I’m interested in large-scale ecosystem change, looking at what’s happening to the Antarctic ecosystem and using its apex consumers as indicators for the health of the entire food web.’
His first research trips were in collaboration with National Geographic-Lindblad Expeditions, who have a long tradition of working with guest scientists, but his current research and filming expeditions all use sailboats to better access the pack ice where the killer whales live and hunt. (‘Being cheek by jowl with a bunk mate in a washing machine for a week,’ is how he describes crossing the Drake Passage by sailboat).
To help better understand the pack ice killer whales, Leigh runs through the different types of orca found in Antarctica. Under an expert’s eye, their classic black and white profile quickly shades into a variety of different whales, according to factors like their size, shape of the white eye patch, and grey saddle behind their dorsal fin.
These subtleties might be hard for an amateur to discern, but the differences (called ecotypes) are big enough, Leigh suggests, that if they were different colours we’d have no trouble recognising them as different subspecies, or even species.
‘There are differences in the food that they eat, the size of their family units and how they vocalise and operate – differences in their culture. Even though they might look the same, you can have different ecotypes passing by one another in Antarctica and they’ll have nothing to do with each other, to our knowledge.’ Genetic analysis has shown that these different ecotypes split from each other around 150,000 years ago.
The largest ecotype is the Type A killer whale, which Leigh describes as having the classic black-and-white profile as well as being the largest orca, and is the variety most commonly seen by cruise ship travellers along the Western Antarctic Peninsula. Their main prey are minke whales and elephant seals. The smallest killer whale is the Type C, which is restricted to the Ross Sea, while the Type D is a Subantarctic form found more in the Southern Ocean, particularly around Cape Horn.
But it’s the Type B killer whales that Leigh is excited by, especially the B1 ecotype: the pack ice killer whales made famous by Frozen Planet.
The life of a pack ice killer whale
Antarctica’s pack ice killer whales are small in number but with a highly sophisticated lifestyle. They work together to produce subsurface waves to break up the ice that seals use to rest on, then more waves to wash the seals into the water.
‘Killer whales use cultural transmission, passing information from adults down through the generations,’ says Leigh, explaining how this hunting behaviour is taught. ‘They have female-led societies, and individuals in some populations have been documented as being over 100 years old.’
Pack ice killer whale sons live with their mothers their entire life, with the females investing in their sons to increase their chances of siring calves. ‘Mum and her daughters play a role in feeding the whole group all the time – it’s all about catching prey and sharing prey. On average they need to consume about one 450 kg seal a day – equivalent to around a fifth of their body weight.
‘It’s a boom or bust culture, says Leigh. ‘At certain times of year, with lots of seal pups for example, they’ll take advantage and feed 24 hours a day, moving from one kill to the next. Then when you have lean times, they rely on the fat reserve of their blubber to get them through.’
Pack ice killer whales and the threat of climate change
These killer whales now face a future of very lean times, as climate change has turned pack ice into one of the most endangered ecosystems on the planet.
When we’re in the field looking for pack ice killer whales, we try to go to the core areas that we know hold pack ice for longer throughout the summer and into the autumn, where the killer whales are foraging,’ says Leigh.
As pack ice breaks up and disappears more quickly, the animals have to travel further to find seals to feed on, expending more energy and using up their body fat. For adult females, who share their food with their sons or are producing milk to nurse their calves, that becomes a big issue. Raising offspring takes a long time in killer whale society – even gestation takes 18 months – so the increasing fragility of the ecosystem brings a long-term challenge.
‘Killer whales are very wide ranging, but they’re also creatures of habit. They won’t necessarily diversify from some of their feeding behaviours. That’s something that’s been seen in killer whale populations in other parts of the world,’ says Leigh. The B1 population in the Western Antarctic Peninsula of around a hundred animals has recently been shown to be declining by about 5% a year.
‘Pack-ice killer whales have evolved this amazing hunting technique that involves them looking out of the water at their prey and then figuring out what they’re going to do with it. They’re incredibly efficient at wave-washing, but what we don’t know about is their success rates when they’re trying to catch seals in open water, so there’s a chance that we might lose that wave-washing culture.’
Leigh cautions that the picture remains a complex one. Research has also shown that Antarctica’s Type A killer whale population is actually increasing, as the minke whales become less able to move into the ice to evade their hunters – but what this means for animals that are as long-lived as humans, and how interactions between ecotypes might play out is still to be fully understood.
An acoustic protection for pack ice killer whales
One side effect of the reduced duration and extent of pack ice on the Peninsula is that some areas have become more accessible to polar cruise ships, especially those heading for the Antarctic Circle.
‘When I first went to Antarctica, we could rarely get through the Gullet [a narrow channel between Adelaide Island and the mainland Peninsula] because it was so choked with ice and it would stay choked all season, and now we’re in a situation where it’s open every season.’ For a cruise ship captain that has the advantage of not having to navigate back into the Drake Passage and lose time and the opportunity for landings. But as Leigh points out, this is also a key area where pack ice killer whales are foraging at a crucial time of year where they’re building up their fat reserves.
Together with his late colleague Ben Wallace, Leigh proposed an Acoustic Awareness Zone for the area to IAATO (the International Association of Antarctica Tour Operators), inspired by the speed restrictions for whales already in place in the Gerlache Strait, as well as the guidelines used for watching killer whales in the Pacific Northwest. ‘These animals are using communication in their foraging, choosing when to be silent and when to make calls to re-find one another. If you’re impacting that, that’s a big deal.
IAATO were immediately on board, and after discussions and trials with captains about how a scheme could operate, a mandatory Acoustic Awareness Zone in this pack ice killer whale foraging ground began operating in the 2025/26 season.
Mitigation measures include allowing only one ship at a time in the area, reducing speed of vessels to a maximum of 10 knots, keeping engines to a minimum and completely avoiding the use of thrusters, and a strict no-go zone of 400 metres when whales are observed.
Pack ice killer whales can travel a hundred miles a day if they want. A pod seen around Adelaide Island one day could easily be spotted at the northern tip of the Peninsula the next. But the creation of the Acoustic Awareness Zone is a reminder that as the fragility of Antarctica is increasingly understood, stewardship must always be at the heart of tourism to the region.
For Leigh, the Acoustic Awareness Zone points to a better way forward for ships operating in the area as a whole, and a wider acknowledgement that humans have made the world’s seas a noisy place for all whales – and for us to take measures to mitigate that disturbance wherever we can.
‘This could be that beginning drop in the ocean of being mindful of the noise that we make, and being more gentle as we pass through Antarctica’s stunning yet fragile landscapes.’
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