Adult tuna can weigh more than 500 kilograms. (CP)

Prince Edward Island tourism operators could make big money offering people a chance to swim with tuna, says an American author and professor.

Carl Safina, who teaches at Stony Brook University, was in P.E.I. this fall filming a documentary with a Nova Scotia film crew. While on the Island he swam with a group of tuna off of North Lake.

Safina said being in the water gave him a different sense of the giant fish, which typically weigh in at between 200 and 500 kilograms.

"I think it would really change people's relationship with these fish in a way that is similar to what people do on coral reefs. There are a lot of fish on coral reefs. But the big money is in letting people dive on reefs and letting them just see how the fish really are," said Safina.

"There's an opportunity in P.E.I., and maybe even in parts of New Brunswick, to actually get in the water with these really, really amazing giant fish."

Tuna swim would be expensive

Ross Keus took Safina out to the waters off North Lake on his boat The Neptuna.

Keus wanted to show Safina and his film crew that there are plenty of fish in the area and that the hook and line method is the best way to catch the fish. Safina has been lobbying to have the Atlantic bluefin tuna named an endangered species.

Keus doesn't expect swimming with tuna as a tourist attraction will take off any time soon.

"There's the issue with the liability insurance," he said.

There is a lot of activity on the water when there are tuna in the area, said Keus. There is a commercial tuna fishery with hook and line, a tag and release program, and the herring fishery.

"Divers could get caught in nets, and if there happens to be a person fighting a tuna on a hook and line, the line is zipping tight and it could cut through you quite easily," he said.

Keus said if this idea was to ever take off it would cost about $5,000 per person to swim with the tuna in order to cover insurance costs.