It was recorded in the icy waters of Bristol Bay, Alaska (United States). Florida Atlantic University revealed a fact about beluga whales (Delphinapterus leucas). They survive in the long term through a surprising strategy: Alaskan belugas exchange partners.
It is published in 'Frontiers in Marine Science'. Beluga whales live in a world that is difficult for scientists to observe. Very little was known about how they choose a mate, compete for mates, or raise their young in the wild. For 13 years, researchers collected genetic samples from 623 beluga whales in Bristol Bay. This population is made up of about 2,000 whales. It is largely isolated, with little or no admixture with other populations.
Great longevity
They wanted to determine if Bristol Bay belugas were polygynous (that is, when one male mates with several females). Or polyandrous (that is, when a female mates with several males). The study reveals that this population of belugas practices highly strategic mating: a polygynandrous system. Both males and females mate with multiple partners over several years.
Variability in reproductive success among individuals is moderate, rather than dominated by a few. This partner change gives rise to many half-siblings and few full-blood siblings. Reduces the risk of inbreeding and contributes to maintaining genetic diversity despite the small size and isolation of the population.
This would explain their incredible longevity: belugas can live perhaps 100 years or more. Instead of competing intensely in a single season, males appear to play the long game. They extend their reproductive efforts over many years. It seems to be a 'take your time, there are plenty of fish in the sea' strategy.”
Changing to stay
Females also change partners frequently from one breeding season to the next. It is a form of risk management, allowing females to avoid mating with low-quality males. Increases the probability of having healthy and genetically diverse offspring.
Alaskan belugas exchange partners to survive. Understanding these dynamics is essential for conservation. If only a few males father the majority of calves, the effective population size is greatly reduced compared to the actual number of whales present.
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