Scientists are hopeful that blue and fin whale populations in the southeast Atlantic are finally recovering more than 40 years after they were devastated by commercial whaling.
Researchers looked at more than 60 years of data (May 1964 to March 2025) on sightings and strandings of Antarctic blue whales (Balaenoptera musculus intermedia) and southern fin whale (Balaenoptera physalus quoyi) off the coasts of Namibia and South Africa.
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They found that sightings of both species have significantly increased, indicating that the whales are finally starting to recover from the impact of commercial whaling. The findings are published in the African Journal of Marine Science.
Commercial whaling was banned globally more than 40 years ago. But, before it ended, it almost wiped out several whale populations around the world. Around 350,000 blue whales and 725,000 fin whales are thought to have been killed by commercial whaling between 1913 and 1978.
Numbers are only now starting to nudge up.
“Although the total number of sightings of each subspecies was relatively low, sightings appear to be steadily increasing as these whale populations recover, with 95 percent of the observations recorded since 2012,” write the authors in the paper.
This gives experts hope that whales may be starting to bounce back.
“Our results provide important evidence that these giants of the ocean are slowly recovering from the devastating impact of 20th century commercial whaling, which pushed them to the brink of extinction,” says lead author Bridget James, from the Centre for Statistics in Ecology, Environment and Conservation at the University of Cape Town, in a statement.
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“Sightings remain rare, but they are becoming more frequent than in previous decades – and with sustained protection, there is reason to believe this recovery can continue,” she adds.
These enormous animals – the two biggest whales on the planet – are still under serious threat. The IUCN Red List categorises blue whales as endangered (Antarctic blue whales are critically endangered) and fin whales as vulnerable.
Studying these ocean wanderers is a challenge as they swim epic distances and are often far from the sight of humans. To try to get a clearer picture, the researchers look through more than 60 years of data.
“Blue whales were sparse, with 12 sightings, 1 stranding and 5 published records, whereas fin whales were seen more frequently, with 76 sightings and 6 strandings,” they write in the study.
Seeing more blue and fin whales in these waters is promising but there could be other reasons for the boost in sightings – such as more eyes on the water.
“As populations slowly rebuild, we would expect to see these whales begin reoccupying parts of their historical range,” says co-author Simon Elwen, director of Sea Search and research associate at the Department of BotZoo, University of Stellenbosch.
“The increase in sightings and strandings is consistent with this gradual recovery, although increased offshore observation efforts may also contribute.”
Even if populations are starting to rebound, it’s too soon to celebrate. Whales are still threatened by human activities such as overfishing, entanglement, ship strikes, noise and chemical pollution and warming waters.
“These populations have a long way to go to reach their historic numbers,” says James.
Top image: a blue whale at the sea's surface. Credit: Wirestock/Getty Images
