Nov. 19 (UPI) -- After being nearly completely wiped out by whalers, new research suggests Antarctic blue whales have returned to the sub-Antarctic island of South Georgia.
Researchers were able to confirm the dramatic comeback with the help of documented sightings, photographs and underwater sound recordings collected over the last three decades.
Scientists detailed the discovery in a new paper, published Thursday in the journal Endangered Species Research.
Blue whales were abundant off the coast of South Georgia, but between 1904 and 1971, the industrial whaling industry killed 42,698 whales.
Between 1998 and 2018, whaling surveys turned up only a single sighting.
However, in February, scientists documented 58 blue whale sightings and recorded dozens of blue whale calls.
"The continued absence of blue whales at South Georgia has been seen as an iconic example of a population that was locally exploited beyond the point where it could recover," lead study author Susannah Calderan said in a news release.
"But over the past few years we've been working at South Georgia, we have become quite optimistic about the numbers of blue whales seen and heard around the island, which hadn't been happening until very recently," said Calderan, a researcher at the Scottish Association for Marine Science.
In addition to relying on their own visual and sonic observations, scientists surveyed blue whale sightings by sailors and tourist ship passengers reported to the South Georgia Museum.
Over the last few years, the museum has also fielded photographs of blue whales snapped by seafarers.
So far, 41 blue whales in South Georgia have been photo-identified between 2011 and 2020. None of the South Georgia whales matched the profiles of the 517 whales in the Antarctic blue whale photographic catalogue.
"We don't quite know why it has taken the blue whales so long to come back," Calderan said. "It may be that so many of them were killed at South Georgia that there was a loss of cultural memory in the population that the area was a foraging ground, and that it is only now being rediscovered."
Conducting whale surveys in South Georgia, where the seas are often rough and the weather unforgiving, is difficult work, researchers said. But for conservationists, knowing where blue whales are is essential the task of safeguarding the species.
"This is an exciting discovery and a really positive step forward for conservation of the Antarctic blue whale," said study co-author Jennifer Jackson, researcher with the British Antarctic Survey.
"With South Georgia waters designated as a Marine Protected Area by the Government of South Georgia and the South Sandwich Islands, we hope that these increased numbers of blue whales are a sign of things to come and that our research can continue to contribute to effective management of the area," said Jackson, a researcher with the British Antarctic Survey.