Inside the bodies of giant humpback whales are clues about how climate change is transforming Antarctica. As sea ice continues to decline at an alarming rate in the fragile Antarctic Peninsula, scientists working with the wildlife charity WWF are carrying out up-close health checks on the massive marine mammals there. The BBC’s Victoria Gill and Kate Stephens crossed the Southern Ocean, with the researchers, on a mission to follow and study the whales of this remote, frozen wilderness.
At 03:00 in the morning there is an almighty crash. Every drawer in our cabin is flung open and contents hurled against the wall. We hit a 12-metre wave.
I’m not a seafarer; this is alarming, but apparently not unusual on the Drake Passage – the stretch of the notoriously rough Southern Ocean we are on. We’re aboard a 200-passenger tourist ship, with a team of wildlife scientists, on our way to the Antarctic Peninsula.
One of the researchers, Dr Natalia Botero-Acosta has an arresting piece of equipment in her hand luggage – a custom-made crossbow. “It’s not a weapon,” she explains. “It’s a scientific tool we use to collect whale skin and blubber samples.”
Using the crossbow and a drone, the researchers will carry out up-close health checks on every humpback whale they can find, to work out if these massive mammals are getting enough to eat.
It is an important question – not just for mighty, 40-tonne humpbacks that travel thousands of kilometres to gorge themselves in the cold seas – but for the health of the ocean and our planet.
In the rich, freezing seas off the peninsula, penguins, seals and many whales feed on Antarctic krill.
These diminutive, almost unimaginably numerous, shrimp-like creatures thrive under sea ice. As the climate warms up, scientists are racing to understand what that means for this ice-dependent food supply.
Early on our first Antarctic morning, in mercifully calm coastal waters, we set out on a small, inflatable boat called a zodiac.
Cloud is descending and it is starting to snow. Leading our Antarctic whale research mission is Chris Johnson, who is the wildlife charity WWF’s global expert on whale conservation.
In conditions like this,” says Chris, “the best way to find whales is to listen – we’ll switch off the zodiac engine and close our eyes.”
The silence is transformational. Multiple, overlapping blows of whale exhalations echo off mountains that rise vertically out of glassy water. Gigantic, hungry humpbacks are feeding in this bay. All around our small boat, animals are breathing, then diving – opening their cavernous mouths to let krill-laden seawater rush in.
We head slowly in the direction of the nearest blows and Natalia reaches for her crossbow.
The giant mammals build up chemical clues about their environment in their blubber – clues that Natalia plans to collect.
She picks up one of the crossbow bolts. On the business end, there is a 3cm metal tip that plucks a piece of skin and blubber from the whale’s body. A rubber stopper prevents the bolt from penetrating further: It grabs a sample, then bounces off the animal and floats in the water.
“It’s 3cm from an animal that’s 14m long – so it’s like a mosquito bite,” says Natalia. Sure enough, when her bolt takes a nick out of the body of a huge, female whale, the animal doesn’t flinch.
It’s a mother, side-by-side with her calf. She seems intrigued – circling our boat slowly, then gliding directly underneath. Her giant head and white pectoral fins – fringed with barnacles – are visible as she slowly floats beneath us.
“Hold on in case she comes up,” says Chris. But mother whale glides on, surfacing on the other side of us with a blow.
The calf is even more curious, raising its head out of the water. The young marine mammal seems to examine us; we’re a strange group of tiny, terrestrial mammals in a small, rubber boat. I can’t stop myself greeting the calf: “Hello, beautiful.”
Baby humpbacks spend a year nursing on their mothers’ rich milk. With a hungry, one-tonne newborn, calories are important.
“We need to find the most critical feeding habitats for whales, so we can protect them,” explains Chris.
The health of whales, he explains, shines a light on the health of the whole Antarctic ecosystem. And whales are physically necessary for a healthy ocean: Humpbacks eat krill, and krill eat microscopic plants that live in sea ice – plants that absorb planet-warming carbon as they grow. Whales then poop (in vast quantities) and fertilise the marine plants.
It’s a virtuous, productive cycle that climate change is disrupting. “These are natural processes we rely on for fresh air, food and clean water,” says Chris. “Places like this are important for all of us.”