The basking shark, scientific name Cetorhinus maximus, Manx name Gobbag vooar (big mouth) is the second largest fish in the world and we, in the Isle of Man, are fortunate enough to have a large number of them coming through our coastal waters from mid May to the beginning of September.

They are named basking sharks because of their habit of ‘basking’ at the surface of the water. They feed by filtering out plankton from the water in a similar manner to whales. Despite their huge size they are completely harmless to man. Unlike bony fish that can produce millions of young in a year basking sharks are viviparous (live bearing) and therefore breed exceedingly slowly. They are, therefore, very vulnerable to over-exploitation.

Many scientific papers mourn the fact that little is known about these gentle giants. This isn’t completely true as this website draws on 37 scientific reports about basking sharks and there are many more. Drs Matthews and Harrison carried out some remarkable dissections in 1947 and their scientific papers remain the classical works on basking shark anatomy[17,18]. Until recently there were large knowledge gaps about what basking sharks did in the winter but currently Dr Sims’ team at Plymouth Marine laboratory[24-31] and researchers working in New Zealand [10] are well on the way to remedying this situation. Dr Colin Speedie [33] is working with the European Basking Shark Photo-Identification Project (EBSPiP) to try to understand how far individual basking sharks move. This work is complimentary to Dr Sims teams tagging work. No one is sure where the females have their young. Hopefully the resurgence in interest about basking sharks will encourage funding to help solve the remaining mysteries surrounding these wonderful fish.


Basking sharks are, like all sharks, part of the family of fishes known as elasmobranches. The skeleton of elasmobranch fish is made of cartilage, a material not unlike the hard gristle found around mammalian joints. This might be partially calcified, as it is in the basking sharks backbone but not to the same extent as in the bony fish (teleosts). The scientific classification of sharks is a little controversial. Rather surprisingly the harmless, plankton-eating basking shark is in the same ‘family’, the Lamniformes, as the great white shark! However, the basking shark is in a genus of its’ own, the Cetorhinidae.

Geographical distribution

Basking sharks have a worldwide distribution in cool temperate seas of temperature 8-14°C, being found in the Pacific, Atlantic and Indian Oceans. It has only once been found in warm tropical water (off Florida) and this was probably a sick stray. They are mentioned in the scientific literature as being sighted in waters off Britain and Ireland, Florida, California, Japan, Norway, New Zealand, Canada and Novia Scotia.

Basking sharks are the


biggest fish in the world

Newborn basking sharks of

1.5 - 2 m

are seen in manx waters

We are commited to: raising public awareness and research into basking sharks.

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