Suddenly, the magnificent basking shark is once again appearing back in UK seas. The Marine Conservation Society (MCS) has just received the first three sightings reports for 2007, occurring on 22nd March, in Cardigan Bay, West Wales; on 24th March, near Douglas on the Isle of Man; and most recently, on 7th April, near Falmouth in Cornwall. Basking shark numbers will increase dramatically over the next few months, and there is every chance you might spot one from a beach, cliff top, boat or surfboard. The Marine Conservation Society (MCS) is appealing to everyone to report their sightings of these wonderful and endangered creatures, the largest wild animal to regularly visit the UK.
The basking shark (Cetorhinus maximus) is the second largest fish in the world (after the whale shark, which occurs only in tropical waters), reaching up to eleven metres in length and weighing up to seven tonnes. They are easily identified when feeding, swimming slowly with huge mouths agape to filter the plankton which blooms at the sea’s surface during the warmer months. This means they are often seen with their nose, dorsal fin and tail all protruding above the surface. They are also easily identified by their large, somewhat floppy, triangular dorsal fin, and five huge gill slits on each side.
The basking sharks’ surface-feeding behaviour, large size and slow swimming speed makes them extremely vulnerable to collision with vessels, accidental bycatch in fishing nets and disturbance. Like most shark species, their life history makes the population itself extremely vulnerable if at all depleted by these impacts (they are slow growing, mature late and produce few young). To make matters worse, we know very little about the population size, and the basking shark is listed as ‘endangered’ in the NE Atlantic.
The MCS Basking Shark Watch project has collected information on public sightings of basking sharks since 1987, and the database now contains over 10,000 sightings records. 2006 was a record year, with over 2000 sightings, up from 1296 in 2005, itself a record year. The survey has identified ‘hotspots’ for sightings, including the West Country (particularly Cornwall), Isle of Man (IOM) and West Coast of Scotland. Sighting numbers generally peak in June for the West Country and Channel Islands, July for the Isle Of Man, and August for Scotland, suggesting a possible migration of sharks from South to North. Very few sharks are seen between the months of October and March, which had previously been linked with migration to deeper waters for ‘hibernation’. However, recent tagging studies have shown the sharks carry on feeding in deeper waters around the coasts of France, England, Wales, Ireland, Northern Ireland and Scotland. They have been recorded travelling significant distances (up to 3,400km) and feeding at depths in excess of 750m.
Angus Bloomfield, Biodiversity Projects Officer at MCS, said “Public sightings records, collected and analysed by MCS, make a vital contribution to our very limited knowledge of the population distribution over time and space, enabling us to provide better management and protection for this magnificent yet vulnerable animal. This data was pivotal to the successful inclusion of basking sharks in the Bonn Convention on Migratory Species (CMS) in 2005, which has since resulted in European countries banning landing and trade in the species. So please send us your sightings reports – they really do make a difference!”
Sightings should be reported online at www.mcsuk.org, by phoning MCS on 01989 566017, or by filling in freepost report cards, available to order from MCS. Marine turtle and jellyfish sightings should also be reported to MCS. Posters promoting the sighting schemes, as well as ID-guides and summary reports are also available free of charge.
Raising public awareness of basking sharks in our waters is not without its drawbacks, as the species is now suffering from its new status as a tourist attraction. Naive but deliberate disturbance from a curious public is an increasing threat. MCS has received numerous reports of sharks being surrounded by speedboats, or approached far too close. Collisions with boats are not unusual, as a feeding shark will not necessarily take evasive action. But even without a collision, it is illegal to disturb a basking shark in this way (under Schedule 5 of the Wildlife and Countryside Act). Please report such incidents to us, at MCS, and also to the local police force’s Wildlife Liason Officer (every force has one). Observe the basking shark Code of Conduct (available from MCS) and use a WiSe-accredited operator (www.wisescheme.org) for any organised marine wildlife watching trips.