Researchers have documented the largest reported super-group of humpback whales in the Scotia Sea, with an estimated 710 animals gathering near Clerke Rocks, off South Georgia.
The whales were observed on 30 November 2025 from the expedition ship National Geographic Endurance. They were feeding inside a designated krill no-take zone - an area where commercial krill fishing is prohibited to help protect the marine predators that depend on this vital food source.
The encounter took place in challenging conditions, with strong winds, rough seas and limited visibility. Researchers photographed and filmed the gathering, using the whales’ visible blows to estimate how many animals were present.
Their analysis produced a best estimate of 710 humpback whales, with a likely range of between 620 and 820. A further 75 to 100 humpbacks were seen farther south later that evening.
The scale of the gathering was difficult to judge by eye. Estimates made by 12 experienced observers were between 36% and 53% lower than the figure produced through photographic analysis. This demonstrates the challenge of accurately counting large groups of whales, particularly in poor weather.
The finding has particular historical resonance. South Georgia was once at the centre of the commercial whaling industry. More than 26,000 humpback whales were killed there, most of them between 1904 and 1916. By the mid-1950s, the western South Atlantic population may have fallen to just 450 animals.
Today, that population is estimated at around 25,000 and is considered close to recovery.
In 1908, whaling pioneer Carl Anton Larsen recorded seeing “masses of humpbacks” at Clerke Rocks. The new observation, made 117 years later in almost the same location, provides an evocative glimpse of what these waters may have looked like before industrial whaling.
The whales appeared to be feeding on Antarctic krill. South Georgia’s shelf waters are an important feeding habitat, and local krill concentrations support whales, seals, penguins and other seabirds.
However, scientists caution that a single observation cannot prove that the no-take zone caused this exceptional gathering. Continued research will be needed to establish whether protections such as fishing closures are delivering measurable, long-term benefits for whales.
The recovery of humpback whales is an extraordinary conservation success, but it also creates new responsibilities. As whale numbers increase, fisheries management must ensure that they have access to sufficient prey - particularly in feeding hotspots where large numbers may gather.
This spectacular super-group shows what recovery can look like. Protecting the habitats and food sources these whales depend upon will help ensure that such gatherings become an enduring feature of a restored Southern Ocean.
ORCA’s work is global and evidence-led. Every sighting collected by our citizen scientists strengthens the case for protection - influencing decision-makers and shaping conservation worldwide.