Basking shark

© Chris Gotschalk

The basking shark (Cetorhinus maximus). 

This is one animal Melissa is definitely jealous her friends and officers in the UK get to dive with. They are the largest fish in British waters, reaching lengths up to 12 meters, and re-appear each spring and summer. They are second to only the whale shark (Rhincodon typus), and also a plankton-feeding shark species (the other two being the whale shark and megamouth shark).

So how can you identify these animals in their native habitat? 

Well, first, look for the largest fish there. Once found, if it’s a giant, grey-blue-green color with a pale underside and its mouth is gaping open, it’s probably a basking shark. A special characteristic is their nose- it’s funny shaped.

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© Unknown

They are slow swimmers, too, making them popular sharks to dive with. They swim kind of funny, too, moving their entire bodies from side to side.  

Overexploitation has reduced its populations to the point where some have disappeared; they are listed by the IUCN as Vulnerable (V). Once heavily targeted for their liver oil, meat and fins, these animals are now protected in all four Devolved Administrations. However, little is known about these animals, mainly because they spend most of their lives deep underwater. Plankton blooms occur in May-October along western UK, giving scientists a perfect opportunity to learn about these animals, seeing as these big lugs are ALL over those noms.

If you’re in the western coast of Scotland, or northern part of Ireland, they’ve been spotted there too, so keep an extra look out!

It is a cosmopolitan migratory species, found in all the world's temperate oceans. They are a migrating species, mainly following food sources, and are believed to overwinter in deep waters.

As filter feeders, their hundreds of little teeth are of little use. Instead, they use their gill rakers to filter through the water and their food. This includes anything from plankton to baby fish to fish eggs. 

Not much is known about basking sharks and their social lives, but they have been seen swimming alone, with a pair and in giant schools of up to 100 members. Limited information is also known about basking shark reproduction, as only one female carrying an embryo has ever been observed. It can be hypothesized that basking sharks reach sexual maturity relatively late, as many sharks. The widely accepted theory is that the basking shark is viviparous with yolk-sac. The gestation period is longer than 3 years, too. Females probably give birth to 1-2 live young, which are about 1.5-1.8 m (5-6 ft). 

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A school of basking sharks. © Tim Voorheis.

The conservation of these sharks is ever evolving:

• 1993 - It was reported that the global population of basking sharks had dropped by 80% since the 1950's.
• 1995 - A Barcelona Convention Protocol added the basking shark to its list of Threatened Species.
• 1997 - The U.S. National Marine Fisheries Service banned the fishing for basking sharks in US Federal Atlantic waters.
• April 1998 - The British Government moved to protect the basking shark under Appendix II of CITES (The Convention on International Trade in Endangered Species of flora and fauna). This request demanded that countries that traded basking shark keep detailed records, helping scientists in determining whether the fishery was sustainable or not.
• October 2000 - U.S. Departments of Commerce and Interior support  UK movement to protect basking sharks.
• November 2000 - AFS (American Fisheries Society) lists the population of basking sharks in the western Atlantic as conservation dependent (reduced but stabilized or recovering under a continuing conservation plan) and vulnerable in the eastern Pacific.
• Presently - The FAO (Food and Agricultural Organization of the United Nations) is planning to establish international shark fishery management strategies for a number of species, including the basking shark.
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The neat thing about these animals gaining more and more popularity is the science coming out of this! Organizations, like, Shark Trust, are helping gather public interest by allowing you to “adopt” a basking shark. The perfect holiday/birthday present for a fellow shark lover! 

do you love these gentle giants as much as we do?

glossary

• Cosmopolitan: Worldwide distribution.
• ​IUCN: International Union for Conservation of Nature.​
• Viviparous with yolk-sac: Also known as aplacental viviparous and previously known as ovoviviparous/ovoviviparity; it is the production of eggs that are fertilised and hatch inside the female shark but the embryos lack a placental connection to the oviduct or uterus and so do not feed off the mother.

say hello!

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