Fin whales as far as the eye could see, hundreds upon hundreds of them, shrouding the horizon in clouds of their breath. Near Antarctica in January 2022, passengers and crew aboard the National Geographic Endurance stumbled upon this magical sight, unobserved since industrial whaling drove the species to near extinction.

“What greeted us as we sailed north of Coronation Island last year was beyond belief: a horizon filled with whale spouts,” says Conor Ryan, a zoologist and resident naturalist aboard the cruise ship, which is operated by Lindblad Expeditions.

“Once we got closer, the sound of blowing from the whales was continuous and all around us, as was condensing whale breath in the air, which required regular cleaning of our camera lenses and sunglasses,” Ryan said by email.

(Watch the massive pod of whales on YouTube.)

Somewhere between 830 and 1,153 fin whales, along with a handful of humpback and blue whales, had gathered to gorge themselves on a dense patch of krill off Coronation Island, which lies north of the Antarctic Peninsula. (Get a rare underwater look at Antarctica’s whales.)

Scientists at Stanford University who analyzed photos and videos of this event say this massive gathering of baleen whales may be the largest seen since industrial whaling ended in the late 20th century. Previously, the largest recorded gathering of fin whales was a mere 300 animals.

“A little more than a hundred years ago, seeing something like this probably wouldn’t have been that uncommon, says Matthew Savoca, a marine ecologist at Stanford and co-author of a new study on the event, published today in the journal Ecology.

Weighing in at 80 tons, fin whales are second in size only to blue whales. Around one million of these colossal cetaceans once plied the world’s oceans, but a century of whaling reduced their numbers by roughly 98 percent. The International Union for Conservation of Nature lists the species as vulnerable to extinction, though increasing in number.

The incredible sighting makes Savoca, a National Geographic Explorer, optimistic about the recovery of fin whales in the Southern Ocean, he says. At the same time, he’s also concerned: One of the threats to fin whales is ship strikes and entanglement in fishing gear, and the whales were spotted amid several industrial krill fishing vessels.

Krill fishing concerns

“It’s great that the fin whales are back, and that more and more people get to witness that,” says Helena Herr, marine mammal ecologist at the Center of Natural History of the University of Hamburg in Germany.

Herr, who has conducted extensive research on whales in the Southern Ocean, says whales often congregate off Coronation Island because its surrounding waters are rich in Antarctic krill.

Tiny crustaceans called krill, seen here feeding on phytoplankton, form the base of the ocean’s food web.  
PHOTOGRAPH BY PAUL NICKLEN, NAT GEO IMAGE COLLECTION

These tiny crustaceans form the base of the food web in the Southern Ocean as favorite prey for penguins, whales, and squid. People also have an appetite for krill and remove hundreds of thousands of tons of them from the Southern Ocean each year for use in dietary supplements and food for farmed fish. (Read how life in Antarctica relies on a shrinking supply of krill.)

The elation Ryan and the cruise ship tourists felt at seeing so many fin whales was “somewhat tarnished when we realized that the fishing vessels were actually trawling through the whale aggregation,” he says. “This was quite shocking to witness.”

Ryan, who is also a co-author on the new paper, and others warn in the study that as whale numbers rise, so will harmful run-ins with the krill fishing industry—unless more actions are taken.

For instance, the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), which regulates krill fishing in the Southern Ocean, should take the safety and nutritional requirements of whales into account, Savoca says.

Additionally, the commission needs to enforce existing rules, says Herr. “There are rules that krill fishing should not be carried out in close proximity to whales or any other feeding animals. This study showed us that at least these four vessels do not adhere to this rule,” she says.

According to Savoca, how we manage Antarctic krill fisheries over the next decade will determine if gatherings like the one seen in January 2022 become common—or simply a fluke.