Basking Shark Factsheet

Cetorhinus maximus

Basking sharks have long been summer visitors to the shores of the UK. Sometimes reaching over ten metres in length and up to seven tonnes in weight, they are the largest wild animal regularly found in Britain's waters. Sometimes, on calm days, the nose, dorsal fin and tail fin are all visible at the same time, breaking the surface of the water, as the sharks feed in sheltered bays and off headlands.

Despite their massive size, these are gentle giants which pose no direct threat to man.  In fact, basking sharks have only minute teeth, and live on tiny zooplankton which they filter out with modified gill rakers from vast quantities of sea water passing through their enormous mouths.

Basking sharks are found in temperate oceans throughout the world, usually during the summer months. They normally arrive off the Cornwall coast in April, with the highest numbers appearing in May and June. Occasionally, large schools of over a hundred sharks have been sighted, sometimes very close to popular beaches, providing a fantastic spectacle for watchers ashore and afloat.

It is thought that basking sharks come into our inshore waters not just to feed but to find partners to mate with. The young are born live, at about 1.5-2m in length, and newborn sharks of this size are seen from time to time, although the average size of sharks recorded in recent years has been around five metres.

Recent studies involving satellite tracking of individual basking sharks have shown that most of them move into deep water and continue foraging for plankton, often out on the Continental Shelf break. Very rarely are basking sharks sighted at the surface in the winter, and equally rarely they have been caught in nets by trawlers operating in deeper waters.

Much remains unknown about these fascinating but enigmatic creatures, which make their annual visits to the waters of our western seaboard all the more interesting and valuable for visitors and researchers alike.

Facts about basking sharks

1. The basking shark (Cetorhinus maximus) is the second largest fish in the world, after the Indo-Pacific whale shark (Rhincodon typus).
2. They may reach 12m in length, and weigh up to 7 tonnes.
3. They may take 12-20 years to reach sexual maturity.
4. Gestation may take 18 months - 3 years.
5. Females give birth to 5-6 live young (pups) at a time.
6. Pups are believed to be 1.5m at birth.
7. They feed only on tiny zooplankton.
8. Basking sharks are found in most temperate waters of the world.
9. Basking sharks appear in the waters around the western coasts of Britain each spring from May onwards.
10. The basking shark is the biggest wild animal to regularly visit Britain.
11. Basking sharks have been known to live up to 50 years.