1 September 2009

A young basking shark, which stranded on a beach in west Cornwall in early August has been the first of its kind in England to be examined by veterinary pathologists. At over four metres long, the fish was so huge it wouldn't fit on the examination table and was too heavy to be weighed on their scales.

The male shark washed ashore at Sennen Cove and was reported to Cornwall Wildlife Trust's Marine Strandings Network. Joanna Osborn, who was on duty that day, took the call and asked local volunteer Rory Goodall if he could go down to the beach to record the animal. Rory was unable to see any obvious cause of death and he found that, unusually, the specimen was very fresh in comparison to other basking sharks the Marine Strandings Network had recorded previously in Cornwall. It was, therefore, a prime candidate for a post-mortem examination.

"Usually the basking sharks we've recorded are very decomposed" said Joanna Osborn, "so we realised that this was a fantastic opportunity to learn more about this amazing fish which we see so often here in the summer, but about which so little is known."

"I checked with our partners at the Institute of Zoology, who are studying basking sharks as well as other marine species under the collaborative UK Cetacean Strandings Investigation Programme, and they were really pleased that we might have one to examine."

"Normally a team of Network volunteers would be mustered to lift an animal onto a trailer" added Rory, "but as you can imagine, we don't have the equipment or manpower to move a shark, even one this small! So we were very grateful to Sue Nicholls from Cornwall Council, who agreed that their Beach Management Team would transport the shark to the Veterinary Laboratories Agency (VLA) in Truro where it could be examined."

Sue and her team were delighted to help and said, "We're very pleased to work with Cornwall Wildlife Trust and delighted that we were able to assist with the removal and transportation of this shark to enable a post-mortem to take place."

James Barnett, veterinary pathologist at the VLA conducted the examination and concluded, "This young male basking shark was in reasonable body condition and there was evidence that it had fed recently. It appeared to have a gastritis, as the stomach lining was inflamed. There was some damage to the gill slits, which could mean that it stranded alive. But there was no obvious reason for its death, although we're still waiting for other test results to come through. It was a very rare opportunity for us, and a first for Cornwall."

Basking sharks are the second largest fish in the world and are frequently seen around the coast of Cornwall, feeding on zooplankton as they cruise gracefully through the water. They can filter 6,000 litres of water through their gills every hour and grow up to 11 metres long.

Cornwall Wildlife Trust recently joined forces with Seawatch SW to establish its first effort-based basking shark monitoring project, sponsored by British International Helicopters. The aims of the project were to provide a greater understanding of basking shark distribution and behaviour and to encourage people to report live and dead basking sharks.

The Trust welcomes reports of any stranded sharks, or other marine animals on the beach, to its Marine Strandings Hotline on 0845 201 2626. As sharks decompose quickly, the public are urged to call right away.