Survival out there in the deep blue is hard, and aquatic life often has to improvise to endure the watery wilderness. Researchers say the belugas of Bristol Bay have done just that.
Dr. Greg O’Corry Crowe is a research professor at Florida Atlantic University. His team published an article on the reproductive success of beluga whales in the journal Frontiers in Marine Science. The study was released this January and was the culmination of 13 years of inspecting beluga whale genetics in Bristol Bay.
O’Corry Crowe worked with a team of scientists, local subsistence hunters, and the Alaska Department of Fish and Game to study the mating system of belugas all from tiny tissue samples.
“We use either a crossbow or a jab stick to get close enough, and then just take a little skin plug,” he said. “And from that skin plug, you can do a whole lot of research.”
In the past, researchers had predicted that belugas were a polygynous species—meaning that large males compete for females and often have a number of partners, much like gorillas. It seemed to be a straightforward assumption, given the size of males and how common polygyny is in nature.
“But when we did the genetics, what we found is that some males were more successful than others, but we didn't have an extreme case of polygyny,” said O’Corry Crowe. “We didn't seem to find these animals that were dominating all the offspring and that were being produced.”
Instead, they discovered that belugas have a polygynandrous mating system—where males and females share partners in order to “spread out” their reproductive efforts.
“And we think part of it is that it's probably quite difficult for a male beluga to defend multiple females in a marine environment,” he said. “And it's also interesting that belugas live a very long time, and so we think beluga males play the long game—if you're not successful this year, there’s always next year.”
O’Corry Crowe says this prevents inbreeding and is essential to the betterment of their species.
“We think this constant mate switching by both sexes helps actually maintain genetic diversity even in the face of small population size, so it's kind of an encouraging element to their reproductive biology,” O’Corry Crowe said.
If a pod of belugas loses that genetic diversity, all sorts of issues arise. Scientists call this genetic drift, which can hinder a species from adapting to new or changing environments. But that is precisely what this unique mating system is fighting against. While the social groups of belugas do contain some family, they’re mostly populated by unrelated members.
“It's like belugas like to hang out with their friends and acquaintances as much as with their families,” he said.
O’Corry Crowe expects that polygynandry may be much more common among marine mammals than we think. He says overall, the study is a testament to how nature always finds a way to live on, no matter the situation.
“I think it's a good reminder to everybody that nature has inherent resilience,” O’Corry Crowe stated. “You just have to give it a break, you just have to take your foot off its neck and it'll come back.”
He says he expects to be working with belugas for the rest of his life, as there’s still much more to uncover. He also feels this study is a perfect example of how western science and indigenous knowledge can complement each other, and of the power of partnering with local communities to make such discoveries.
