Classification and other UK sharks

• The basking shark (Cetorhinus maximus) is a member of the lamnid family of sharks which includes the notorious great white shark (Carcharodon carcharius), the salmon shark (Lamna ditropis), porbeagle (Lamna nasus), shortfin mako (Isurus oxyrinchus), and longfin mako (Lamna paucus). Of the lamnid sharks, only the shortfin mako, porbeagle and basking shark are native to UK waters. Other pelagic (open-water) sharks native to UK waters are the blue shark (Prionace glauca) and thresher shark (Alopias vulpinus). The Shark Trust have a useful guide to all 21 UK shark species.

Size

• The basking shark is the largest wild animal to regularly visit the UK and is the second biggest fish in the world, after the whaleshark (Rhincodon typus). They can reach 11m (36 ft) in length and weigh up to 7 tonnes.  That's approximately the size of a double-decker bus!

Food

• Despite their enormous size they do not pose a threat to humans, as they have tiny teeth and filter-feed on small copepod zooplankton. The only other planktivorous shark in the world is the megamouth shark (Megachasma pelagios)
• In order to take in enough food they must filter approximately 2000 cubic meters of water an hour - this is equivalent to an Olympic-size swimming pool of water!

Biology

• It can take 12-20 years for a basking shark to reach maturity.
• Even then, females give berth (to live young) only once in four years.
• Gestation may take 18 months to 3 years and a litter is thought to consist of 5-6 pups.
• This life history makes the basking shark population extremely vulnerable to any threats (see below).

Threats

• The basking shark has been a targeted fishery in the past, when it was hunted primarily for liver oil.  Because of its biology (see section above), basking sharks are extremely vulnerable to fishing pressure, and all fisheries around the UK and Ireland have collapsed in the past.
• The greatest threat facing the basking shark today is the high market price the fins fetch on the Asian market. These fins not only end up in shark fin soup but are also displayed in people's homes as status symbols.
• Bycatch in fishing nets may be a serious threat.  We don't know the scale of this problem.
• Harassment by vessels including speedboats, jetskiiers and even wildlife watching operators, is a growing concern in UK waters.  MCS has received a number of such reports during 2006.  Please follow the Basking Shark Code of Conduct or use a WiSe Scheme accredited operator.

Protection

• It is illegal to kill, injure or to recklessly disturb basking sharks in British waters under Section 5 of the Wildlife and Countryside Act 1981. Any person committing such an offence could face up to 6 months in prison.
• The basking shark recently received increased international protection with a listing on CITES (Convention on International Trade in Endangered Species) Appendix II ensuring that its international trade is carefully monitored. It remains unprotected in Northern Ireland and the Republic of Ireland.

Conservation

• The Marine Conservation Society (MCS) is a member of the Basking Shark Species Action Plan steering group and has collected sightings data since 1987.
• Please report all basking shark sightings to MCS. Click here to use the online form.
• If you have taken a photo, it might be useful to the European Basking Shark Photo-Identification Project (EBSPiP).