In 2018, a multidisciplinary Antarctic expedition to study, among other things, the impacts of climate change on krill populations uncovered a heartening surprise about one of the crustacean’s prime predators: fin whales. Helicopters dispatched from aboard the research ship spied 100 groups of the cetaceans, while on-deck observers spotted groups of 50 and 70 near Elephant Island—about 550 miles southeast of Cape Horn. A return trip in 2019 revealed even larger gatherings of up to 150 in the same location.
The findings, published this week in the journal Scientific Reports, signal the whales’ return to their historic feeding grounds, and hint that the species—Earth’s second largest behind blue whales—are on the rebound after whalers hunted it to the brink. Similarly, the International Union for Conservation of Nature’s (IUCN) Red List‘s most-recent assessment of fin whale populations in 2018 moved the species’s status from Endangered to Vulnerable.
Seeing this volume of whales in the Southern Ocean has been unheard of for decades. Before a 1982 ban on commercial whaling, some 725,000 of the animals were killed for commercial purposes, knocking their totals down to less than two percent of their pre-whaling abundance. Today, the IUCN estimates their total population around 100,000.
Though this most-recent survey offers a small window onto the current count, the researchers’ estimates on the species abundance in the area are a hopeful sign. Their observations and calculations indicate that as many as 3,618 fin whales could be in the deneset area around Elephant Island alone. “Even if we still don’t know the total number of fin whales in the Antarctic, due to the lack of simultaneous observations, this could be a good sign that, nearly 50 years after the ban on commercial whaling, the fin whale population in the Antarctic is rebounding,” Bettina Meyer, a biologist at the Alfred Wegener Institute in German and co-author of the survey told Science Daily.
This latest survey confirms a trend lead author Helena Herr has been seeing in the region for nearly a decade. A 2013 trip to study minke whales led the ecologist from the Australian Marine Mammal Center to an unexpected gathering of fin whales as well, she recalled to The New York Times, and other research groups published similar findings in the past 12 years. But it was a 2016 sampling near Elephant Island that, according to this most-recent Scientific Reports paper, convinced Herr and her colleagues to do a more in-depth study.
Having fin whales feed in their historic haunts again could have benefits to the entire ecosystem. When the cetaceans munch on krill, they release iron as a waste product. Higher iron levels in the water can spur the growth of phytoplankton, which pull in carbon dioxide from the air. Marine scientists call this process the “whale pump.”
Though the fins’ rebound story is a strong sign that conservation efforts can work, whaling is far from the only stressor across whale populations. The animals face regular run-ins with both commercial and recreational boats, and can sometimes get entangled in fishing gear. Meanwhile, systemic issues like ocean noise and temperature shifts can mess with their movements and feeding patterns.