Brrrrr…British Sharks: Where do they go in Winter?
Contrary to popular belief, sharks are indeed present around the coasts of Britain. In fact, we have over 40 species! Including some of the fastest, rarest, largest and most highly migratory in the world!
At least 21 of these 40 species live in British waters all year round. Including when the waters drop into single digits! These include smallspotted catsharks, tope, smoothhounds and spurdog. Not forgetting a host of British skate and rays too, such as the Thornback, Spotted and Undulate Rays. As well as the 21 resident sharks, there are at least 11 deep-water shark species. Including the Portuguese Dogfish, Black Dogfish, Kitefin Shark and Gulper Shark.
But some sharks are only seen in the summer months, when the sun comes out and the water warms up. Then you may be lucky enough to spot the world’s second largest fish. The filter-feeding Basking Shark! Often seen basking in the sun (thus its name) and feasting on plankton. Basking Shark season tends to be May-October, and there are a few hotspots around the British Isles where you’ll most likely spot them. Find out more by visiting our Basking Shark Project webpage.
Other seasonal visitors include the Blue Shark and Shortfin Mako. The Shortfin Mako is the fastest shark on record. They can reach speeds of up to 30mph, enabling them to catch fast-swimming prey such as tuna and swordfish.
Where do they go in Winter?
The vast majority of sharks, excluding those in the Lamnidae family (the mackerel sharks, eg White Shark, Mako, Porbeagle and Basking Shark) are cold blooded or ectothermic. This means that their body temperature is highly dependent on their environment. So, in winter, when the temperature drops, their metabolism and activity levels slow down. In order to remain speedy and hunt efficiently, they must undertake seasonal migrations to warmer waters. Other reasons for their migrations include for reproduction or to follow their prey as that moves too.
Blue Sharks are one of the most migratory sharks. They can travel over 5,700 miles (9,200km) in a single trip. At the end of summer, they start an annual migration that takes them to the other side of the Atlantic, where they can be found along the eastern coast of the USA and Caribbean Islands.
Thresher Sharks and Mako Sharks are also oceanic sharks, traversing the high seas to find food. They are only seen off our shores in the UK when their favourite prey is here too. In Summer. They follow their food source to deeper or warmer waters during the coldest months.
Basking Sharks are rarely seen at the surface in the winter months, and it was once suggested that they might hibernate. But now, thanks to satellite tagging, we know that they spend their time in deeper water, feeding on deep-water plankton. We also know that they are likely “regionally endothermic”, meaning that they are able to keep some part of their bodies at a higher temperature than the surrounding environment. A recent study showed that in fact, Basking Sharks may have a higher thermal tolerance than we had previously suspected – this is likely due to their regional endothermy. The study showed their behaviour to be highly dependent on their surroundings: the bathymetry, prey availability, or even bioluminescence. This behavioural plasticity (ability to be flexible) might mean that Basking Sharks are better able to adapt to the ever-growing list of climate-driven changes in the world.
Sadly, scientists consider over 50% of British sharks to be Threatened with extinction. Species such as the Angelshark and the Flapper Skate are now Critically Endangered. At the Shark Trust, we work globally to improve the conservation status of sharks, skates and rays. Advocating for policy changes. And generating collective action to support our goals.
Find out what you can do to help by visiting the Shark Trust website
