DNA study uncovers surprising mate-switching strategy helping isolated Alaska belugas avoid inbreeding

Beluga whales in Alaska's Bristol Bay seem to avoid inbreeding in a surprisingly effective way by changing mates over time.

That pattern is giving researchers one of their clearest views yet into how a small, isolated population can stay genetically healthy, according to ScienceDaily.

What happened?

Over 13 years, researchers tracked 623 beluga whales through a DNA study based on small tissue samples.

Florida Atlantic University scientists worked with the Alaska Department of Fish and Game and Bristol Bay Alaska Native subsistence hunters to gather the samples.

Studying belugas in the wild has long been difficult because they spend much of their lives beneath Arctic waters and sea ice.

"We still know very little about beluga whales, despite their immense popularity," lead author Greg O'Corry-Crowe said, per ScienceDaily. "The primary reason for this is the difficulty of studying a species that lives beneath the waves in the cold and often frozen north. But this is the challenge that makes discovery, when it happens, more exciting."

Before seeing the results, researchers expected a sharp breeding hierarchy, with most calves being fathered by a relatively small number of dominant males.

Instead, the DNA evidence showed that both males and females had calves with more than one partner over the years.

Many calves that had siblings turned out to share only one parent, meaning they were half-siblings rather than full siblings, a mate-switching pattern scientists had not fully expected.

Why does it matter?

The finding may also explain another surprise: This beluga population, though only about 2,000 animals, showed strong genetic diversity and comparatively little sign of inbreeding.

"A leading concern for small populations is that they tend to lose genetic diversity faster than large populations and the risks of inbreeding are higher," O'Corry-Crowe explained. "We expected to find low diversity and high inbreeding, but we found something quite different. The mating system may explain this surprising finding."

Strong genetic diversity can help animal populations better withstand disease, environmental shifts, and other pressures, supporting the Arctic ecosystem that coastal communities rely on.

The study drew on long-term conservation research rooted in local knowledge and community collaboration, especially in Bristol Bay, where wildlife health is closely tied to culture, food systems, and regional stability.

What are people saying?

The researchers said the findings challenge old assumptions about beluga social behavior.

"Beluga males were indeed polygynous but, surprisingly, only moderately so," O'Corry-Crowe said, per ScienceDaily. "The three-dimensional aquatic environment likely limits a male's ability to successfully court or corral multiple females."

He added that female belugas may also be improving their reproductive odds through the same pattern.

"The female story is just as fascinating. The genetic profiling revealed that female belugas regularly switch mates across breeding seasons, also over a long reproductive life. This could be a bet-hedging strategy to limit the risk of mating with low-quality males," O'Corry-Crowe said. "... To me, the differences in sexual dimorphism among populations of beluga whales could indicate that mating systems also vary, and this is something we are currently working on."

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