Sightings of two largest whale species offers fresh survival hope

By Stephen Beech

Increased sightings of the world's two largest whale species offers fresh hope for the future of the endangered ocean giants, say scientists.

More than 40 years since the end of commercial whaling, new research reveals a recent increase in sightings of blue and fin whales in the southeastern Atlantic.

Researchers compiled more than 60 years of confirmed sightings and strandings from Namibia and South Africa's west coast.

Although overall numbers remain low, the findings showed sightings of both species have increased markedly in recent years — with 95% of observations recorded since 2012.

Study lead author Bridget James said: "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.

"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."

The study, published in the African Journal of Marine Science, focused on Antarctic blue whales and fin whales, both heavily targeted during the industrial whaling era.

Between 1913 and 1978, an estimated 350,000 blue whales and 725,000 fin whales were killed, causing dramatic global population declines.

Today, Antarctic blue whales are still listed as "critically endangered" by the International Union for the Conservation of Nature (IUCN) Red List.

Their population is currently estimated at around 3% of the pre-whaling numbers, increasing slowly at about 5% and 8% per year.

Fin whales are currently classified as "vulnerable" — with populations thought to have recovered to more than 30% of historical levels and growing at around 4% to 5% annually.

But, despite the signs of improvement, researchers say both species remain difficult to study as they roam vast distances and spend much of their lives in remote Antarctic waters.

Data from migration routes and potential breeding grounds — including the southeastern Atlantic — has been particularly limited.

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James, from the University of Cape Town, South Africa, said: "Historic whaling data suggests that the southeast Atlantic may once have been an important nursery area for both blue and fin whales.

"But until now, we have had very little consolidated information on their more recent presence in this region."

To address the gap, the research team compiled verified sightings and strandings recorded between 1964 and March 2025, focusing on the Benguela upwelling ecosystem — a nutrient-rich region off Namibia and the west coast of South Africa — to better understand trends in presence and seasonality.

Blue whales were recorded infrequently, with 12 sightings, one stranding and five additional published records.

Fin whales were encountered more often, with 76 sightings and six strandings documented.

Blue whales were most often seen between late spring and autumn, while fin whales appeared to occur year-round.

Study co-author Simon Elwen, from Stellenbosch University, South Africa, said: "As populations slowly rebuild, we would expect to see these whales begin reoccupying parts of their historical range.

"The increase in sightings and strandings is consistent with this gradual recovery, although increased offshore observation efforts may also contribute."

The researchers cautioned that recovery does not mean threats have disappeared.

They say large whales remain at risk from ship strikes, entanglement in fishing gear, underwater noise, pollution and climate-driven changes in ocean ecosystems.

James said: "Signs of a return to the south-east Atlantic do not signal full recovery for blue and fin whales, and these populations have a long way to go to reach their historic numbers."

Elwen added: "They point to resilience — but it should be emphasized that both species remain vulnerable to modern human pressures, and highlight that even with more than 50 years of recovery since the end of commercial whaling, we could only compile 12 records of blue whales off our coast."

The researchers recommend expanding passive acoustic monitoring, increasing trained observer coverage in commercial sectors, and incorporating whale distribution data into marine spatial planning to safeguard the slow but important recovery.