By Jonathan Amos
BBC Science Correspondent

Publishedduration2 hours agoimage copyrightAmy Kennedyimage captionAn Antarctic blue whale surfaces off South Georgia

The resurgence of blue whales around the island of South Georgia is real and has probably been under way for a little while now, say scientists.

When a survey was conducted at the British Overseas Territory earlier this year, 58 of the animals were seen.

That was described as "astonishing" at the time because there had been so few sightings previously.

But a reassessment of 30 years of observational data suggests this bumper crowd of blues was no anomaly.