A Fisheries and Oceans scientist says if people are seeing more tuna in Newfoundland waters, it's because there are.

"We're getting a lot of anecdotal information that tuna are actually showing up quite commonly around Newfoundland," DFO research scientist Gary Melvin said.

"It's a bit unusual, although in recent years there's been more and more."

People have been reporting sightings of the massive fish throughout the summer. Recently, a boater said a bluefin tuna swam and breached near his boat and put on quite a show for his family.

A Pilley's Island resident reported a tuna pod that has been hanging around in local waters for a week or so.

Melvin, who is based in St. Andrew's, New Brunswick, said there are a number of possible reasons people are seeing more tuna.

"One is related to the general distribution of the prey species: herring, mackerel and even some of the capelin when and where they're showing up. Bluefin tuna feed on these species and where they are generally the tuna will follow," he said in an interview with CBC Radio's Central Morning Show.

Melvin said a changing environment means warmer waters in the north.

"And also bluefin tuna is actually … increasing in abundance. There's two stocks of tuna, the eastern and western bluefin tuna stocks, and both have been showing positive signs of increases," he said.

"These species are highly migratory — they travel throughout the north Atlantic," he said.

As far as a more widespread tuna fishery, Melvin said most licences have been distributed throughout the region, including licences to Newfoundlanders.

If people come across a tuna while they're fishing, "they're not supposed to keep it, I believe," he said with a laugh.

"There was actually a video of someone from Corner Brook, they sent me, sitting on the wharf where the bluefin tuna broke right next to them. It was quite interesting, probably within 10 or 15 feet of the wharf," Melvin said.

"So they are common in the Gulf of St. Lawrence and they do occur around Newfoundland."