A giant bluefin tuna found dead off a Cornish beach has been taken to the Penryn campus of Exeter University for testing, but just how rare are these sought after fish?
The discoverey by a group of women out kayacking has caused massive media attention and raised a lot of questions. How rare are blue fin tuna and why was it found in Cornish waters? Why did it die and where has it been taken?
Claire Wallerstein, a volunteer for Cornwall Wildlife Trust’s Marine Strandings Network was alerted on Saturday, July 12 to record the 2.19 metre Atlantic blue fin tuna washed into shallow water on Kingsands beach on Cornwall’s Rame Peninsula.
Matt Slater, marine awareness officer for Cornwall Wildlife Trust said: "Bluefin tuna are one of the world’s most incredible creatures – built for speed they can travel thousands of miles each year and were regularly found in our waters and in the North Sea. They supported a fishery consisting of 200 boats between 1950 and 1960.
"Bluefin are highly prized for sushi and with each fish being worth hundreds of thousands of pounds fishing levels are still high and this species has been brought to the verge of extinction in the last 50 years.
"Large scale global overfishing has resulted in a collapse of their stocks, resulting in a 90 per cent decline in Atlantic bluefin tuna stocks since 1970’s.
"They can travel as fast as 62 miles per hour and never stop swimming as they rely on ram ventilation to keep their blood oxygenated. Most fish are cold blooded but bluefin tuna are able to regulate their internal body temperature to ensure their muscles operate at maximum efficiency.
"Bluefin tuna are extremely streamlined and are predatory animals which feed on smaller fish such as herring, sardine and mackerel. They can live for up to 40 years and are the largest of the tuna family, growing to a massive 4.5 meters in length and weighing up to 680kg – nearly three quarters of a tonne.
Matt Slater has an old photo of a fisherman with a blue fin tuna which was caught at the entrance to the Helford estuary in 1910 by the famous local artist Powder Thurburn.
Powder Thurburn at Frenchmans Creek with a bluefin tuna
Although highly valuable, bluefin tuna are a long lived species and have been found to accumulate high levels of toxins such as mercury and PCBs within their flesh. The fish has been taken to the University of Exeter’s Environmental Sustainability Institute at Penryn where it is hoped it will be used for toxicology research and for educational purposes.
This Atlantic bluefin’s exact cause of death is a mystery. Its stomach was empty and there are no other signs that could suggest how it died – maybe the post mortem will reveal more?
A total of 26 records of tuna being found in our waters have been made to the Environmental Records Centre for Cornwall and the Isles of Scilly since the late 1800’s.
"We hope this is a good sign and one day blue fin tuna will once again be a common sight around our coasts", said Matt.
Cornwall Wildlife Trust urge the public to continue to report what they see when at sea and to record stranded animals found on beaches. The Trust has a 24 hour manned hotline for marine strandings that you can ring 0345 2012626. To record sightings of live animals visit www.orks.org.uk.