A new study published in the journal Nature Scientific Reports has documented large groups of southern fin whales (Balaenoptera physalus quoyi) in ancient feeding grounds in Antarctica for the first time since their hunting was restricted in 1976. During two expeditions in April 2018 and March 2019, the experts recorded 100 groups of fin whales with group sizes ranging from one to four individuals, and eight unusually large groups of up to 150 whales that seemed to be actively feeding.
During the nineteenth century, southern fin whales were extensively hunted, particularly around their feeding grounds in Antarctica and, by the time their hunting was banished in 1976, over 700,000 individuals had been killed. Now, their populations seem to be rebounding at an unprecedented rate.
“I’d never seen so many whales in one place before and was absolutely fascinated watching these massive groups feed,” said study co-author Bettina Meyer, a biologist at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI). “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.”
By modelling fin whale population densities in the Antarctic, the scientists predicted a population of 7,909 whales for the total survey area, with a density of 0.09 individuals per square kilometer, which significantly surpasses whale populations in other regions of the world. Moreover, in a noticeable hotspot around Elephant Island, the estimated fin whale abundance is even higher, with 3,618 individuals, or 0.21 per kilometer squared.
According to the researchers, this rebound in fin whale populations could enrich the Antarctic’s marine ecosystem through nutrient recycling from whale feeding and excrement, thus supporting the growth of phytoplankton and krill populations. “When the whale population grows, the animals recycle more nutrients, increasing the productivity of the Southern Ocean. This boosts the growth of algae, which for their part absorb carbon dioxide from the atmosphere through photosynthesis, reducing the atmospheric CO2 concentration,” Dr. Meyer concluded.