The largest Thresher shark ever recorded has been caught by a trawler off the Cornwall coast.
The 510 kg/1122 lb shark measured over 4.75 m/15'10" and was caught by a trawler fishing for squid and John Dory in the English Channel near Land's End peninsula.
Roger Nowell, the skipper of FV Imogen, spotted a shoal of scad near the bottom on his echo sounder and shot his trawl. The monster shark was among the haul.
Douglas Herdson, Information Officer at the National Marine Aquarium, told Practical Fishkeeping: "It was a female Common thresher, Alopias vulpinnis. Thresher sharks are one of the largest of the 28 types of sharks found in British waters.
"They are not common but are caught from time to time around our coasts, especially in the central Channel and off the coasts of Devon and Cornwall.
"When it was landed at Newlyn Fish Market it was found to weigh a monstrous 510 kg/1122 lb; making it one of the heaviest Thresher sharks ever caught anywhere in the world and the second giant from Cornish waters in a few weeks."
Herdson said that the world angling record Common thresher was a mere 348 kg, though larger ones have been caught possibly weighing up to 450 kg, and a related Bigeye thresher (Alopias superciliosus) weighing 433 kg/952 lb was caught on rod and line in Hawaii in March this year.
The female was very stout and may have been pregnant or feeding heavily to store energy in its liver.
Common thresher sharks have two to four young which are born at a size of around 150cm/5' and weigh around 6kg, says Herdson.
"Thresher sharks are easily recognised by their long tail, which is about the same length as their body. They have very sharp teeth but small mouths and are very unlikely to attack humans, as they normally prey on shoals of pilchards, herring and mackerel.
"They may fish in twos or threes, or on their own, but often use their tails to scare the fish into a tight shoal before attacking. A few years ago one was seen in Mevagissey Harbour, Cornwall, stunning a shoal of anchovies with its tail before feeding. The Newlyn fish seems to have gone into the trawl while busy hunting the horse mackerel.
"They are wonderful and fascinating fish and we have a small population around our coasts, mainly in the central and western Channel, but they are very vulnerable to fishing, taking a long time to grow and producing so few young at a time that they have difficulty replacing losses from the stock.
"For this reason most anglers no longer land the sharks they catch but attempt to release them again alive and unharmed, sometimes after attaching a marker tag for future identification.
"Several large threshers were caught and released by anglers this summer off the Isle of Wight and the Dorset Coast."