LUNENBURG, N.S. -- A series of shark sightings in East Coast waters has some locals speculating the population is growing in the area, but a scientist says he has not seen any unusual activity.

A tour operator says he was taking a stag party on a tour off Nova Scotia's South shore on Saturday when the group saw a large shark jump straight out of the water three or four times.

Bill Flower, or "Cap't Bill" as he's known at Lunenburg Ocean Adventures, says the shark, spotted near Cross Island, looked to be about two-metres long, but he couldn't be sure whether it was a mako or a great white.

Flower says he has seen more sharks lately on his near-daily charters.

""I'm seeing more (sharks)," Flower said Sunday. "Not a lot, but ... I've never seen a mako breach unless it's on a hook before, and I saw one yesterday on a rough day and that was very unusual."

Last Sunday, a group of 22-year-olds filmed a shark hunting a pod of harbour porpoises in St. Margarets Bay near Hackett's Cove, N.S., while whale watching on a small inflatable boat.

One member of the group, Sean Potter, says he and friend pulled out a camera to film about a dozen porpoises, when some of them split off and "that's when the shark struck."

"We could not confirm (it was a shark) until we replayed the video, as it happened quite fast," Potter said in an online message Sunday. "We were excited to get a chance to see the shark hunting and catch it on film."

Warren Joyce, a researcher with the Department of Fisheries and Oceans in Halifax, said it looks like the porpoises might have been "a little shaken" from the encounter, but he suspects they escaped unscathed.

Joyce said the DFO is notified of shark sightings approximately 12 to 20 times every summer and there has not been a significant increase this year.

The researcher reckons about half of these reports may be false alarms inspired by the cultural fascination with sharks.

"The water is still a fairly foreign environment to us," Joyce said in an interview last week. "It's either a big fear to encounter sharks or a big excitement for folks. People that I've talked to, they seem interested whether they're scared to death of them or they find them really interesting animals."

Other sightings in Atlantic Canada this summer include a great white that was caught on camera cruising in the Bay of Fundy near St. Andrews, N.B. last week, and a shark that caused a stir in Liverpool, N.S., in July after gobbling mackerel straight off fishing hooks.

In New Melbourne, N.L., last month, a cod fisher hooked more than what he bargained for when he found the maw of a two-metre porbeagle shark at the other end of his handline.

In the United States, shark sightings have prompted authorities to close several beaches on the East Coast, including popular destinations in New England, New York and elsewhere.