A great white shark named Helena, who scientists hope can help unveil one of the prevailing mysteries of her kind, has returned to frigid Newfoundland waters from her winter home in the Gulf of Mexico, a group of scientists say.

A team of marine biologists from Ocearch, an organization that collects data on sharks, first caught and tagged Helena in 2019. 

Helena was just four metres long back then, recalls chief scientist Bob Hueter. 

"She's gone on quite a trek since we tagged her," Hueter said, adding the shark has travelled over 20,000 kilometres around the Atlantic Ocean.

"This is her second trip up to the Grand Banks area.… She really seems to like it there in the summer time."

The region off Newfoundland's south coast, he explained, offers bountiful feeding grounds to great whites, who put up with the icy temperatures to take advantage of large fish stocks. The team has observed pregnant sharks in the area who use the summer months to bulk up and prepare to give birth.

Hueter suspects Helena's not yet old enough to mate, but could be feeding voraciously to prepare to give birth to pups next spring, likely off the coast of the northeast United States.

Watching her movements on Ocearch's public tracking platform, he says, will give his team clues to a mystery not yet solved by researchers.

"The one piece that's really eluded the biologists is, where exactly are they mating," Hueter said. Ocearch's cadre of tagged sharks, who regularly ping back their locations to the team, haven't yet revealed how members of the species go about getting pregnant — but sustained population numbers tell the team they are, indeed, doing it somewhere.

As of Friday, Helena seemed to be swimming around just east of St. John's.

"That's about as far north as they like it," Hueter said. Later in the season, she may return to the Gulf of Mexico, or winter off the Carolinas, before joining other sharks in Canadian waters next year.

The areas off Nova Scotia are particularly teeming with the animals, Hueter adds. His team has embarked on several expeditions in Atlantic Canada, hauling sharks onto a specialized hydraulic platform for up to 20 minutes at a time to take measurements and samples, before affixing a tagging device and releasing them.