Deep in the South Atlantic Ocean lies the island of South Georgia. The waters surrounding the island were once abundant with Antarctic Blue whales, but that all changed when the industrial whaling industry established itself on the island in 1904.

Records show some 42,698 of these blue whales were slaughtered there, and although most of these killings happened before the mid-1930s, the whaling industry continued on there until the early 1970s—more than a decade after blue whales were protected by international law. That the waters around South Georgia fell silent after having once been a hotspot for blue whales is a tragic story, but there is reason for hope.

This year, a research expedition conducted by an international team resulted in 58 blue whale sightings and numerous acoustic detections. That is particularly good news considering that between 1998 and 2018, only a single blue whale was sighted in the waters surrounding South Georgia. The sudden uptick in sightings raises hopes that the critically endangered mammal, which is the largest and loudest animal on the planet, is finally recovering five decades after whaling was banned.

“We don’t quite know why it has taken the blue whales so long to come back,” said Susannah Calderan, of the Scottish Association for Marine Science and the lead author of a study in the journal Endangered Species Research. “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.”

Blue whales aren’t the only marine animals that are showing signs of a comeback in the region. Since 2013, scientists have regularly reported seeing large groups of humpback whales in South Georgia waters, confirming their return to this historical center of whaling.