Every summer, one of the ocean’s most elegant predators visits British waters. The Blue Shark. This species is a seasonal visitor to our waters, undertaking huge trans-Atlantic migrations of up to 6,000 miles each year as they follow seasonal changes in water temperature and prey movement. These epic migrations make them some of the Ocean’s most impressive long-distance travellers.

Blue Sharks spend most of their lives far from shore. However during the warmer months (generally July – October), they will travel into the waters off Southwest England and South Wales, where they feed primarily on squid and small fish. Their streamlined shape and huge paddle-like pectoral fins allow them to cruise through the open sea, and their distinctive metallic blue colouration above and white underside offers them countershading.

Blue Sharks are incredibly inquisitive. This curiosity makes them a favourite among wildlife tour operators in Cornwall, Devon, and Pembrokeshire, who offer swim-with excursions. Many of the operators in these regions have contributed to a series of workshops run by MARECO, with support from the Shark Trust, to develop a Code of Conduct for snorkelling with Blue Sharks. These excursions are carefully managed to minimise disturbance, while giving visitors the chance to see these beautiful sharks in their natural environment.

 

An unforgettable day at sea.

In early July, Cat and Caroline took the opportunity to head offshore with Plymouth Marine Safari for a snorkel with these incredible sharks - and it certainly didn’t disappoint! Having motored out from Plymouth for nearly 2 hours, while spotting Common Dolphins and plenty of seabirds along the way, we reached the site and the engine was switched off. A chum slick* was put into the water to tempt any passing sharks to come closer and investigate. With six highly developed senses, including an exceptional sense of smell, Blue Sharks are adept at detecting food sources. As such, we didn’t have to wait long, and within 15 minutes (while the onboard safety briefing was still happening) we had our first shark appear!

Blue Sharks are known to segregate by size and sex, and the individuals encountered in British waters are generally females. Throughout the trip, we had at least seven individuals visit us, gliding around the boat and curiously approaching the snorkellers.

Armed with an Insta360 camera, we got some footage of Blues as they swam by the boat and trialled it while we were in the water – though they become very inquisitive with the camera and tend to bump it a lot, so it didn’t stay in for long! This camera films in 8k resolution and we think this must send their electroreception into overdrive. Caroline has been working through her dive connections around the world to film footage of different species occupying different habitats to develop the virtual reality (VR) experience we use during outreach events, as well as developing an immersive 360◦ experience. These experiences are designed to showcase the fantastic diversity of sharks and how they use different habitats (seagrass, mangroves, open ocean etc.) and help people experience the underwater world without getting wet – so watch this space for updates on this exciting project!

We spent around three hours in the water, with these unforgettable encounters highlighting just how graceful and curious Blue Sharks are. Experiences like these remind us how fortunate we are to have such remarkable wildlife visiting British waters each summer - and why conservation and effective management measures are vital in safeguarding their future.

 

*Blue Shark provisioning statement developed in collaboration with MARECO and the Shark Trust:

Blue sharks are highly mobile, wide-ranging oceanic predators that spend much of their lives in the open ocean. These factors mean that chance encounters at sea by members of the public and wildlife tourism operators can be unpredictable. To facilitate viewing opportunities and in-water interactions, UK operators use fish-based chum (a mixture of natural fish products) to create a scent trail in the water. This may attract sharks that are present in the wider area and can elicit investigative behaviour.

The use of chum in shark tourism is often a topic of discussion. In UK waters, swim-with experiences are generally dependent on the use of scent trails however actively feeding the sharks is discouraged - a Code of Conduct has been developed to support safe and responsible interactions. Available evidence indicates that encounters involve transient animals rather than animals associated with a particular site. To reduce the likelihood of repeated exposure at any one location, UK operators generally conduct interactions with sharks for a limited time (typically a few hours) and regularly rotate between sites.

Wildlife viewing operations are conducted in a manner intended to minimise disturbance while providing opportunity to engage the public, support research efforts and build appreciation for shark conservation and management efforts.