Harmless Giant Basking Sharks Reach Record In UK Waters

November 16, 2007

Release from: Environment Times

Sightings of Britain's biggest fish, the basking shark, have reached record numbers according to a report launched by the Marine Conservation Society (MCS).

MCS received 2,222 sightings of the giant sharks in 2006, representing a 70% increase over the year before (2005), which itself was a record high of 1,301. The new report describes the latest findings from the MCS Basking Shark Watch project, a 19-year public sightings scheme that boasts the UK's largest database of sightings of this 11 metre-long, plankton-eating giant.

Recent increases in sightings may indicate a greater number of basking sharks in UK seas, suggesting that populations could be recovering after eight years of legal protection within our inshore waters.

The basking shark (Cetorhinus maximus) is the largest shark that inhabits UK waters and is the second largest fish in the world after the whale shark. Basking sharks reach lengths of up to 11m and can weigh up to seven tonnes.

Like the whale shark, basking sharks are harmless plankton feeders, and are generally only seen in surface waters when they are feeding on plankton blooms.

Basking sharks have enormous mouths and can filter between 1,000 to 2,000 cubic metres of seawater every hour, the equivalent of an Olympic-sized swimming pool.

"After a ten-year campaign by MCS, basking sharks were afforded full protection in UK waters in 1998. Sightings have risen consistently since 2003, but never by the 70% increase we saw last year," said Angus Bloomfield, MCS Biodiversity Projects Officer.

"While these figures are a record of sightings rather than numbers of sharks, they are very encouraging and suggest that the population may be recovering as a result of protection."

Between 1987 and 2006, MCS received 10,284 sighting reports of 36,410 sharks through Basking Shark Watch from beach-goers, coastal walkers, sailors, surfers, fishermen and divers who recorded the sharks feeding, courting and even jumping clear out of the water (breaching).

2006 marked a return to form for Southwest England, the number one 'hotspot' for basking shark sightings between 1987 and 2002. From 2003 to 2005, Scotland overtook the Southwest, suggesting that basking shark distribution may be shifting north, possibly in response to climate change.

This may still be the case, as a wide range of other factors could produce the fluctuations shown in recent years, including changes in the abundance and distribution of basking sharks' plankton prey, and variable regional interest in the sightings scheme.

However, the vast majority of all MCS Basking Shark Watch sightings have consistently originated from three 'hotspot' regions: Southwest England, Scotland and the Isle of Man, which produced 40%, 32% and 24% of total sightings, respectively, in 2006. All other regions, when added together, made up only 4% of total 2006 sightings.

Thanks to the work of MCS and other organisations, basking sharks have received increasing legal protection in recent years. Firstly, within UK waters (out to 12 nautical miles) under the Wildlife and Countryside Act, in 1998; then under CITES, in 2002, leading to international regulation and monitoring of existing basking shark fisheries.

The most recent conservation success, in 2005, was the inclusion of basking sharks within the Bonn Convention on Migratory Species, which aims to protect vulnerable species within the waters of all signatory nations. In December 2006, this convention was supported by an amendment to European fisheries legislation, which made fishing for basking sharks illegal within EU waters, and worldwide for EU fishing vessels.

"This raft of conservation legislation is a tangible success of our basking shark work," concluded Angus Bloomfield, at MCS, "We owe a huge thank you to the thousands of people who have sent in their sighting reports. But the species is still endangered within the Northeast Atlantic.

"It is probably most threatened by accidental bycatch, vessel impacts, and harassment by members of the public, so we urge the public to continue reporting sightings - as well as any incidents of harassment, which should also be reported to the local police force."

The UK Government is committed to maintaining the current population of basking sharks in UK waters, but the actual size of the basking shark population using UK seas is not known. MCS is hoping to expand the Basking Shark Watch project to include effort-based counts, which could provide a better indication of shark numbers from year to year.