Bristol Bay, Alaska – A new study reveals that Alaska’s beluga whales use a surprising strategy to survive in a small, isolated population. Over 13 years, researchers studied 623 belugas and found that both males and females mate with multiple partners over several years.

Scientists observed the whales’ social groupings and collected genetic samples to determine who fathers which calves and how these strategies affect genetic diversity and inbreeding. The results show a polygynandrous system, where multiple mating partners create many half-siblings and few full-siblings. This reduces inbreeding and helps preserve genetic diversity despite the population’s small size.

“What makes this study so thrilling is that it upends our long-standing assumptions about this Arctic species,” said Greg O’Corry-Crowe, Ph.D., senior author and National Geographic Explorer. He explained that males, though larger than females, only moderately dominate reproduction in any given season, spreading reproductive efforts over many years.

Females also show strategic behavior, switching mates between breeding seasons to avoid low-quality partners and increase the chance of healthy, genetically diverse calves. “It’s a striking reminder that female choice can be just as influential in shaping reproductive success as the often-highlighted battles of male-male competition,” O’Corry-Crowe said.

Older mothers had more surviving calves, showing that experience and mate choice boost reproductive success. Most adults had only a few offspring at a time, reflecting slow female reproduction and low annual male reproductive output.

Researchers say understanding these mating strategies is crucial for conservation, as they maintain genetic health, reduce inbreeding, and buffer the population against environmental change. Indigenous communities in Bristol Bay assisted in the research, blending traditional knowledge with scientific methods to help protect belugas in a changing Arctic.

Podcast: Play in new window | Download