The size of the tiger shark pulled out of Bermuda’s waters this week came as no surprise to a team of island researchers who have been tracking them for years.

The 11ft fish, caught as part of the Robinson’s Marina Fishing tournament on Sunday, caused onlookers to stop and stare.

But sharks in Bermuda, though increasingly rare, are not uncommon.

Tiger sharks are seasonal visitors to the island, with the largest numbers found on Challenger and Argus Banks between July and October.

They rarely come inshore and you are unlikely to encounter one unless you are out on the banks deep-sea fishing.

Their habits, migratory patterns and even their numbers remain something of a mystery.

But scientists say they are crucial to marine ecosystems.

The Bermuda Shark Project has been tagging and tracking sharks in the island’s waters in a bid to answer key questions about the fish, which has existed since the days of the dinosaurs.

Ten sharks were tagged last year.

With funding from the Guy Harvey Research Institute and the support of Rhode Island University, 10 more will be tagged this year. Filmmaker Choy Aming made a movie about the project, A Tiger’s Tale, that premiered at the Bermuda Film Festival.

He said the latest tracking data showed the sharks are heading back in the general direction of Bermuda, having spent the winter in the Caribbean.

He added: “It looks like we may have stumbled across the first evidence of a tiger shark migration in the Atlantic.”

Mr. Aming said it is not a “Bermuda migration” as many of the sharks, tagged here last year, are still hundreds of miles away from the island.

But while some travelled as far afield as Puerto Rico, all are now heading north. The Bermuda Shark Project monitors their progress with satellite tags that send an electronic signal every time the shark breaks the surface.

The team, which includes vet and fisherman Neil Burnie, has secured funding to tag 10 more sharks this summer.

The aim of the project is to “de-monster” sharks and foster knowledge and understanding. The team hopes their research will get support for protecting tiger sharks and sharks in general.