After commercial whaling nearly erased them, blue and fin whales are slowly reclaiming the southeast Atlantic

Nearly 50 years after the end of commercial whaling, new research shows a recent surge in sightings of blue and fin whales in the southeast Atlantic. These findings, appearing in the African Journal of Marine Science, analyze over 60 years of whale sightings and strandings from the coasts of Namibia and South Africa. Despite the fact that overall populations remain small, the number of sightings has skyrocketed in the past decade—nearly 95% of those observations have been made since 2012.

Lead researcher Dr. Bridget James from the University of Cape Town explains that these results strongly indicate that blue and fin whales are gradually recovering from the catastrophic effects of 20th century commercial whaling, which nearly drove them to extinction. Blue whales, targeted heavily during the industrial whaling era, are now listed as Critically Endangered with an estimated population of just 3% of their pre-whaling numbers.

Fin whales, classified as Vulnerable, have shown signs of recovery, with populations thought to have rebounded to more than 30% of historical levels.

Blue whales were recorded in the southeastern Atlantic infrequently, with 12 sightings, one stranding and five additional published records over the study period. Fin whales, on the other hand, were encountered more frequently, with 76 sightings and six strandings documented. Sightings of blue whales tend to occur between late spring and autumn, while fin whales appear to be present year-round.

The study emphasizes that while the recovery is evident, it does not suggest that these species are fully recovered. Both blue and fin whales still face numerous threats, including ship strikes, entanglement in fishing gear, underwater noise pollution, pollution, and climate changes that are altering ocean ecosystems. Dr. James and Dr. Simon Elwen, co-author from the University of Stellenbosch, caution that these sightings must be viewed in the context of ongoing human pressures and the need for continued protection and monitoring.

While the study provides valuable evidence of slow recovery, the authors stress that even with more than 50 years since the end of commercial whaling, there are still only a handful of confirmed records of blue whales off the coast of South Africa. They call for more systematic scientific monitoring and mitigation measures to safeguard these iconic species, including expanding passive acoustic monitoring, increasing coverage by trained observers on commercial vessels, and integrating whale distribution data into marine spatial planning.