Blue whale recovery at South Georgia

18th March 2021

Photo credit: Russell Leaper

Blue whales were all-but wiped out from South Georgia waters by 20th century industrial whaling. For decades it seemed like they might be gone for good. But now they may finally be returning.

The island of South Georgia in the sub-Antarctic is known for its abundant wildlife. Until the start of 20th century industrial whaling in 1904, there were thousands of blue whales thronging the island’s waters, feeding on its plentiful Antarctic krill. But by the mid-1930s, over 40,000 had been killed by whaling operations around South Georgia alone, and the population had collapsed. Although whaling for blue whales was banned in the 1960s, decades of scientific surveys around South Georgia after that time found barely a trace of them. It was thought they might never return. But our more recent work at South Georgia suggests that might not be the case, and that given the right circumstances, even very heavily exploited populations such as blue whales do have a chance of recovery.

The whaling station at Grytviken, South Georgia as it is today. Photo credit: Russell Leaper

My involvement with blue whales at South Georgia began in 2017, when I was part of the ACE research expedition circumnavigating the Antarctic continent. Our team was deploying sonobuoys, which are underwater listening devices used to detect whale vocalisations. We’d been working with these for several years to track Antarctic blue whales and, as we approached South Georgia, that’s exactly what we heard. We were really heartened by being able to detect blue whale sounds in South Georgia waters. Could they be returning?

An Antarctic blue whale at South Georgia. Photo credit: Russell Leaper

When I returned to South Georgia in 2018 with the British Antarctic Survey, we heard even more blue whales, and saw some too. On our 2020 voyage, we saw 58 blue whales, detecting their vocalisations all around the island. These numbers obviously don’t even come close to how many blue whales and whales of other species used to be found around South Georgia pre-whaling. But what looks like the beginning of a recovery is really encouraging. It’s taken a long time; given that South Georgia was part of a hemisphere-wide near-extirpation of Antarctic blue whales, reducing them to 0.15% of their estimated pre-exploitation abundance, it’s maybe not a great surprise. But their extended local absence at South Georgia was particularly striking, and might have been due to a loss of cultural memory of the area as a foraging ground that is only now being rediscovered.

Blue whale recovery at South Georgia is a story of hope and, with South Georgia waters designated as a Marine Protected Area by the Government of South Georgia and the South Sandwich Islands, there’s optimism that continued research leading to effective management of the area can contribute to whale recovery in this unique and biodiverse area.

Welcome home: an Antarctic blue whale surfaces amongst seabirds at South Georgia. Photo credit: Amy Kennedy

Susannah Calderan

Susannah Calderan is an Honorary Research Fellow at the Scottish Association for Marine Science. She has worked with blue whales in every ocean basin, focusing on acoustic research and anthropogenic impacts.