So many basking sharks have already been spotted in British waters that experts are declaring this the best start to shark season in living memory.

A wildlife tour group reported sighting 19 basking sharks up to 25 feet in length last weekend as the eight-tonne travellers begin to arrive off the south west coast.

The animals, which travel to temperate waters and can stay in British regions until October, have been growing in numbers year on year according to The Shark Trust. A total of 266 Basking Shark sightings were reported to the Trust last year as it hopes for an even higher number in 2014.

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“To see so many this early has been an absolute honour and it is exciting to consider what the rest of the season may hold for us,” said Captain Keith Leeves, a veteran skipper with AK Wildlife Cruises, told the Western Morning News.

“We have been blown away with the size of the sharks too, with several sharks being over 20 feet long, which is something truly special to behold! This has been one of the best starts to a shark season in living memory.”

Crew Member Billy Burton said: “Guests have been absolutely blown away by the sightings they have had. There is something awe-inspiring about seeing a 25-foot shark approach you, mouth wide open.”

The cruise company has raised concerns about basking sharks, the second biggest fish behind whale sharks, after spotting a number of sharks with chunks missing from their fins. It said the most likely cause for the damage was encounters with boats navigated by negligent skippers and holidaymakers. AK stressed the importance of following the guidelines from the Shark Trust when around the animals.

The swelling numbers led Penzance-based operator Marine Discovery to urge people to be more cautious than normal when on the water around the south west coast.

A spokesman said: “At this time of year basking sharks can be found feeding off the Cornish coast and it’s fantastic to see them. However it is important to remember that they need to be approached carefully so as not to disturb their natural behaviour, this feeding time is a crucial part of their yearly cycle.

“If a shark thrashes its tail and dives or stops feeding and dives then it is likely you have disturbed it. If this happens learn from the mistake and try not to repeat it.”

Exeter University student Tom Whitlock said he saw four basking sharks, one of three plankton-eating sharks alongside the whale and megamouth sharks, on a recent cruise trip along the coast.

Basking sharks became a protected species in 1998 meaning they cannot be targeted, retained or disturbed in British waters.

A spokesperson for the Shark Trust said: “It may come as a surprise to many, but sharks are a natural part of UK marine fauna; whether native or vagrant, over 30 species of shark, as well as over 16 species of skate and ray, can be found in British waters. However, shark, skate and ray numbers have dropped dramatically in our waters due to the impact of poorly managed fisheries.

“Sightings of sharks are mainly reported in summer months when more people are out on the water and should be treated as a privilege rather than a point of concern. Sharks make an easy target for dramatic headlines but it remains far more dangerous to drive to the beach than to swim in our seas.”

British sharks

At least 21 species of shark are resident inhabitants and commonly found around the coasts of Britain all year round, including the Smallspotted Catshark, Porbeagle Shark and Basking Shark, according to The Shark Trust.

Its website says: “Blue Sharks and Shortfin Mako Sharks are seasonal visitors, appearing in British waters in summer during their trans-Atlantic migrations. A few species, Smooth Hammerhead and Frilled Shark may be vagrants, occurring infrequently off the British coast, with their main distribution ranges being outside British waters. At least 11 shark species, including the Portuguese Dogfish, Black Dogfish, Kitefin Shark and Gulper Sharks are only found in deep water.”