HALIFAX -- Hilton is back in Nova Scotia waters -- a return ocean researchers say could reveal an uncharted great white shark mating site in the North Atlantic.

The celebrity shark, who stole the hearts of people in Nova Scotia last year with a charming, mischievous Twitter feed, returned to the area after a winter sojourn down south.

Hilton announced late Sunday on Twitter that he was enjoying waters off the southern tip of the province, prompting an official with the research group Ocearch in South Carolina to tweet that it's "the big moment we've been waiting for."

"His presence there could reveal another mating site in the North Atlantic."

Chris Fischer, founding chairman of Ocearch, called the return of the 600-kilogram tagged shark to Nova Scotia "a eureka moment"

"He spent the entire mating season last year around the Mahone Bay region, and we wanted to see if it's a fluke or not," Fischer said in an interview from Nantucket, Mass.

"Lo and behold, boom, Hilton arrived there last night."

Hilton swam right past the Nantucket and Cape Cod area -- a known mating ground -- appearing to confirm researchers' belief that there is second mating site in the region.

The shark timed his arrival with TV's popular week-long shark programming.

Hilton posted one of his typically cheery messages, saying, "Oh yeah, kickin off.SharkWeek in Nova Scotia! Thrilled to be back!"

Some of his 36,000 followers immediately chimed in online to welcome Hilton back.

One said, "Welcome back, buddy!! We've been eagerly awaiting your arrival!" while another said, "I was just wondering where you were. Thanks for checking in."

Hilton first appeared on Nova Scotia's south shore last August, charming locals with a wry Twitter feed chronicling his movements.

The almost four-metre-long male shark had been tagged by the research group Ocearch in South Carolina.

This year, the research group has launched a contest for a chance to tag along on a Nova Scotia shark expedition. The winner will receive a trip for two to Nova Scotia and will get to watch researchers catch, tag, and release great white sharks.

They'll also get to name a shark.

The expedition was planned based on Hilton's movements in Nova Scotia's waters last summer.

"We committed to bringing a ship up there last fall, which costs us about half a million dollars, based on his data last year," Fischer said. "For him to confirm that this early in the season makes it feel a little bit less like a gamble."

The research organization hopes to tag some mature females and track them to a birthing site.

"In theory, 18 months later they could show us where the Canadian white shark pups are born," he said. "That's the holy grail of the science because where they're born, the babies are at the most vulnerable phase of their lives."

Ocearch has worked hard to "undo everything 'Jaws' did" and help people understand that "without these sharks there are no fish sandwiches," Fischer said.

"They prevent the second-tier predators from exploding in numbers and foraging in an unrestricted way, which would wipe out the food chain below it and all the fish and shellfish we want to eat get wiped out."