Humpback Whales Have Recovered So Well, It's Changing Who Fathers the Calves

Commercial whaling pushed many of the world's great whales to the brink, slaughtering them by the hundreds of thousands until populations collapsed. The humpback whale was among the hardest hit. Now a study from the University of St Andrews, published in Current Biology in February 2026, offers an unusual and uplifting way to measure their recovery: the whales have rebounded so successfully that it is reshaping the social fabric of their breeding grounds.

Researchers analyzed nearly two decades of data from humpback whales that gather to breed in the waters around New Caledonia in the South Pacific, work carried out with the NGO Opération Cétacés. Because humpback mating has never been directly observed, the team used genetic testing to establish paternity and epigenetic "molecular clocks" to estimate the ages of individual whales from small skin samples — a clever workaround that let them reconstruct who was fathering calves and how that changed over time.

“The humpback whale was among the hardest hit.”

The pattern they found tells the story of recovery. In the earlier years, when the population was still thin after whaling, breeding groups were dominated by younger males, who fathered most of the calves simply because there were few older rivals around. As the population grew and developed a fuller, more natural age structure, older males increasingly won out — siring more calves than their younger competitors. Scientists suspect that years of practice perfecting their songs and competitive displays give mature males the edge.

"Male humpback whales likely need years to develop and perfect both their songs and their competitive strategies," said researcher Dr Ellen Garland. Her colleague Dr Franca Eichenberger noted that whaling's legacy reaches further than raw numbers: "the impacts extend beyond population size — they shape behavior, competition, and reproduction." That a population can recover enough for its elders to reclaim their natural role is, in itself, a quiet triumph. The humpbacks of New Caledonia are not just more numerous than they were — they are growing into a healthy, balanced society again, a living testament to what ending the hunt made possible.