Wanton whales? For Nunavut belugas, size matters

Hunters near Sanikiluaq with a freshly-caught beluga. (PHOTO COURTESY OF STEVE FERGUSON)

LISA GREGOIRE

It’s unlikely you’ve ever seen two belugas “doing it” because it happens under water — and probably under ice — in remote Arctic waters.

Scientists can’t even agree on the time of year when belugas mate, let alone the rituals surrounding the act.

But how animals mate, where, how often and how successfully is key to helping wildlife scientists determine the health and adaptability of a species and that could potentially influence conservation plans and hunting quotas and identify the possible impacts of northern development.

In the absence of eye witness observation, University of Winnipeg PhD student Trish Kelley, under the direction of Steve Ferguson, a Department of Fisheries and Oceans marine biologist at Winnipeg’s Freshwater Institute, is studying the size and characteristics of beluga and narwhal sex organs to assemble clues about how they breed.

“We don’t have a good idea of what the mating system looks like so there is some theorizing,” Ferguson said, on the phone from Winnipeg.

Kelley is still completing her dissertation, but she and Ferguson presented preliminary findings of the study on a poster entitled “Size Matters: Mating Systems in Beluga and Narwhal,” at the April 2012 International Polar Year conference in Montreal.

You might wonder how this kind of research unfolds. Here’s a glimpse.

After thawing and examining hundreds of tissue samples donated to the institute over the years by hunters across Nunavut, Kelley discovered that when these whales reach sexual maturity, the relative size of the two species’ sex organs diverge.

The reproductive tract of the female beluga was proportionally longer than her narwhal counterparts, and the testes of the male beluga were proportionally larger than those from male narwhals.

It was surprising, Ferguson said, because the two mammals—the only members of the Monodontidae family—are closely related.

But based on these findings, the researchers believe belugas and narwhal have evolved different ways of mating.

Animal mating basically falls into two categories, Ferguson explained.

The first group includes animals who choose mates prior to intercourse. They can be monogamous, with a single mate, or polygynous—where dominant males sire the bulk of the offspring.

The second group includes animals in which mate selection occurs internally, after intercourse. These promiscuous animals have multiple partners and unique physical attributes to facilitate selective reproduction, Ferguson said.

Males usually have larger testes and penises to produce more sperm and deposit it closer to the uterus and females usually have longer reproductive tracts to ensure only the hardiest sperm arrive at their destination. That ample cavern might also serve as a battleground for sperm from competing mates.

These traits are designed to maximize the odds of strong offspring, Ferguson said.

In some promiscuous species, the female tract has “false passageways,” in the walls of the tissue that scientists speculate might be there to further test the fitness of sperm by leading weak ones astray. These passageways have been noted in orcas and Kelley also found them in bowhead whales.

In other species — fruit flies and mice, for instance — sperm work as a team: some are programmed as quarterbacks, hell-bent on reaching the egg, and others as blockers and deputies to help the quarterbacks get a touchdown.

As for narwhal, he and Kelley speculate that they are polygynous with males battling for sexual dominance. Their tusks might play a role in that battle, “but we really don’t know,” Ferguson added.

Promiscuous species tend to be more adaptable to changes in the environment, according to research, but they also have a higher rate of sexually transmitted viruses, Ferguson said. Polygynous species have a higher extinction risk.

The Freshwater Institute collects tissue samples of land and marine animals across Nunavut, and has done so for years, to facilitate research. The samples are logged and stored in multiple freezers at their Winnipeg location, Ferguson said.

Reproductive organs are always in demand because scientists often want to study animal DNA and procreation. They also collect a fair amount of blubber and muscle material, he said, to study contaminants stored there, and eyeballs, which scientists can use to gauge an animal’s age.

Over the years, the number of samples supplied by hunters has fluctuated, Ferguson explained, depending on whether communities, and individual hunters, support DFO’s work and whether there are strong local advocates to give instructions and encouragement.

“If hunters think their contribution might negatively influence their harvest, they are less co-operative,” Ferguson said. “We try to make the pitch that this will help in sustainable hunts because that is what we are after: sustainable hunting. But sometimes the support is there, and sometimes it’s not.”

Fisheries and Oceans compensates hunters with gas money when they contribute to the program, he said, but they don’t want to be seen as paying hunters to kill animals on their behalf so the fee is minimal. “There’s a fine line,” he said.

Periodically, when Ferguson hears about Nunavummuit visiting Winnipeg, he and his colleagues give them a tour of the institute so they can see how the animal parts are used and what they’re used for.

“That outreach really helps,” he said.