How to behave around basking sharks

Where are some of the best spots to see basking sharks, and would they ever attack a surfer or a dog who's swimming?

Basking Sharks: The Irish Basking Shark Group

Basking sharks are widely distributed across the world’s oceans, but Irish waters are a hotspot for this seafaring species. And they have been showing up on social media a lot too lately as hikers, paddleboarders, and kayakers are thrilled to see and share footage of these amazing creatures. 

But these wild creatures are still endangered and the experts want to ensure they aren't disturbed. The Irish Basking Shark Group has some facts for wildlife fans.

How many basking sharks are there in Irish waters now?

It is very hard to determine the number of sharks in Ireland because they are so migratory. For example, visual tagging efforts by Dr Simon Berrow, Dr Emmett Johnston, and our group, have shown that some, but not all, individuals return to Ireland annually. More data is required to address this definitively, and it is something that many folks are currently working on. Some studies estimate that Ireland may host a population as big as several hundred sharks, but that number varies widely.

Underwater video image from Irish Basking Shark Group

Do they live here all year?

Basking sharks migrate worldwide, and are capable of traversing entire ocean basins. We aren’t completely sure what drives their movement patterns, but we know that conditions related to temperature and plankton abundance are likely very important. Recent evidence also suggests that Ireland offers an important mating ground for this species. The most common behaviors we observe in Irish waters are feeding and interacting, following each other around, and breaching, so we suspect they come to Ireland seasonally to feed on plankton and also to mate, the latter happening later in the summer/early fall. During the winter, they tend to disappear from Irish waters, and studies have shown that some stay in the Northeast Atlantic while others go across the Atlantic Ocean or down to the coast of Africa. It is likely that they are in deeper waters during this time, if they stay in Ireland at all.

How big do they get?

8 meters

Do they have any predators?

Their biggest 'predators' are humans, who can cause unintentional harm when sharks are caught in nets or are struck by ships.

What do they eat?

They eat zooplankton (microscopic animals). They have a favorite food and prefer Calanus copepods. They filter seawater through their gills and catch the zooplankton.

Would they ever attack or hurt a human or a dog who's swimming — even by mistaking a surfer or paddleboarder for a seal etc?

Many people think that all sharks are dangerous. However, though they may be intimidating based on their size, basking sharks are filter feeders. They will not attack people, and it is exceedingly rare that anyone is injured by a basking shark. But, people should be aware that they do have a habit of breaching (jumping out of the water). That’s a big shark you don’t want landing on you.

Or what about if they have a young basking shark with them?

Sharks do not practice parental care, and we very rarely see young individuals. However, be sure to keep a safe distance from groups of sharks, as they may be participating in important feeding/courtship rituals, and we don’t want to disturb them.

Are they ever interested in looking at or engaging with humans?

Basking sharks are still considered predators, even if they are at the top of a very small food chain (phytoplankton, zooplankton, shark). Though they will often dive if startled, they can also be unafraid of recreational water users and may approach them. We have an established code of conduct that shows how to interact with them safely. In cases where you are approached, you should simply remain still and allow the shark to pass. Do not follow or touch them, because it may interrupt important behaviors, like feeding or mating.

Basking Shark Code of Conduct: The Irish Basking Shark Group

Where are some of the best spots for seeing basking sharks?

Recently, basking sharks have been observed in hotspot locations all along the west coast of Ireland, including Achill Island, Malin Head, and near Courtmacsherry. We recommend that people view the sharks from a distance. In sunny conditions and on calm days, the sharks can be easily sighted from land, as they come in quite close to feed. We also recommend people on the water are extra cautious of the sharks under these conditions, because the sharks are prone to ship strikes while feeding at the surface.

If I see some would it be ok to get my kayak or paddleboard and visit them?

We have an established code of conduct designed to minimise disturbance. We understand that these are fascinating animals and it is easy to want to interact with them. However, close proximity to humans interrupts critical behaviors, so we recommend keeping a distance. If you are in the water and the sharks are around, please go into neutral (if on a boat), and if on a kayak/paddleboard, remain still and allow the sharks to approach you.

Basking Shark

Why do we need a code of conduct for basking sharks?

Basking sharks are endangered, so disruptions to their feeding or reproductive habits can have devasting consequences. Like many wild animals, they can be spooked if approached.

How about photographing / videoing them — is there any issue with either of these?

Video/photography is fine and encouraged, as long as you do not aggressively chase/pursue the shark and remain a safe distance. We also encourage you to share the videos with us and file a sightings report here.

Anything else I should know?

Basking sharks are considered globally endangered, and were the first fish to be protected as wildlife under the Wildlife Act by Ireland this past year. Ireland remains one of the only locations worldwide where these animals can be consistently observed, and we are excited to see global and local attention drawn to this unique resource in Irish waters!

• Dr Alexandra McInturf is co-coordinator of the Irish Basking Shark Group (IBSG).

• Chelsea Gray is a researcher and science communicator with the IBSG.