Basking shark ©Alex Mustard/2020VISION

Basking shark

Scientific name: Cetorhinus maximus

This gentle giant is the largest shark in UK seas, reaching up to 11m in length. There's no need to fear them though, they only eat plankton!

Species information

Statistics

Length: up to 12m
Weight: up to 6 tonnes
Average Lifespan: unknown, thought to be around 50 years

Conservation status

The North East Atlantic population are classed as Endangered on the IUCN Red List. They are listed under CITES Appendix II and classified as a Priority Species under the UK Post-2010 Biodiversity Framework. Protected in the UK under the Wildlife and Countryside Act.

When to see

May to September

About

The basking shark is the second largest fish in our oceans - its relative the whale shark being the biggest. Despite their size, basking sharks only feed on zooplankton which they filter out of the water, swimming slowly back and forth with their enormous mouths wide open. They are most commonly seen in the summer, when they arrive in British waters. Courtship behaviour has been seen off the Isle of Man - so perhaps they arrive here to breed! For your best chance of spotting them, visit Cornwall, the Isle of Man and the Inner Hebrides. They can be seen from cliffs, but your best chance is to take a boat trip with a reputable wildlife watching company.

How to identify

The large, black, triangular dorsal fin moves slowly through the water, with the tail tip and bulbous snout often visible above the waves too. The basking shark has a massive, grey body and swims with its cavernous mouth agape.

Distribution

Found all around our coasts, but most frequently sited around the south-west of England, Wales, Isle of Man and west coast of Scotland.

Habitats

Marine

Did you know?

The basking shark may be huge but we still know very little about this elusive giant. Satellite tracking has shown that they can migrate long distances in the winter, with some showing up off the Azores and even Newfoundland. However, some fishermen have reported seeing them in midwinter in the UK and they sometimes wash up dead in the winter after storms.

How people can help

Report your basking shark sightings to your local Wildlife Trust. If you meet them out on the water, give basking sharks plenty of space. If in a boat, maintain a distance of 100m and remember that for every shark at the surface, there may be many more feeding below. If they suddenly appear closer than this, switch the engine to neutral to avoid propellor injuries. If you spot one whilst on a jetski, maintain a distance of at least 100m and do not approach any closer. Jetskis will stress the sharks and contact would cause serious injury to the shark and potentially even the rider. If in a kayak or on a SUP, remain calm and quiet and maintain a safe distance. Never paddle directly at a shark or across its path. Remember that sharks can be unpredictable - be extra careful if they have been seen breaching, they might well do it again! If swimming with the sharks, stay in a group and remain at least 4m from each shark. You should never touch the shark. The Wildlife Trusts are working with fishermen, researchers, politicians and local people towards a vision of 'Living Seas', where marine wildlife thrives. Do your bit for our Living Seas by supporting your local Wildlife Trust or check out our Action pages.