Experts believe a shortfin mako shark could be feeding off the Scottish borders and North Lincolnshire shoreline. More than 45 dead porpoises – five times the usual number – have been found along the North-East coast in the past two weeks, some with 12in bites on their torso. Decapitated seals have also been found, along with remnants of other large fish.
Experts say the size of the bites and number of kills would be consistent with a large mako shark in the area. It would not be unusual for mako sharks – which prefer cold water – to be found in the North Sea, but it is uncommon for one to stray close to the shoreline as they prefer deep waters.
It is believed cleaner water along the North-East coast as a result of conservation schemes has caused a massive increase in the natural porpoise population, which may have attracted the shark.
Zara D’Aronville, of the Blue Reef Aquarium, North Tyneside, said: ‘It is possible that mako sharks are in the water, but we will not know for sure what is happening until we get the autopsy results.
‘There is definitely an unusual amount of dead porpoises being washed up. Sharks are often spotted in the waters, but quite far off the coast. One could well have strayed closer to the shore looking for food and that could be the reason.’
Fishermen operating off the Sunderland coast reported the increase in dead porpoises. Staff from Sunderland Lifeboat Station were called to Seaham Beach in County Durham on Friday and Saturday after reports of attacks.
They found two dead porpoises, both showing signs of an attack by a large shark.
Ron Carroll, from the station, said: ‘The first porpoise had a chunk taken out the side of its head and neck. The bite mark was about 10in long.
‘On Saturday, the next porpoise had been bitten on the left side of the fin and its abdomen and this was about 12in across. It is very unusual to have this amount of dead marine life being washed up on shore.’
A spokesman for the Maritime and Coastguard Agency said: ‘We would advise all those using the water, including surfers, fishermen and divers, to be especially careful and vigilant.
‘There have been no reported sightings of this shark yet but we cannot rule out the possibility that one might be out there.’
The warnings come as marine biologists report growing numbers of exotic fish and marine creatures in British waters.
Global warming has pushed up water temperatures, resulting in regular sightings of the smooth hammerhead shark, which is not dangerous to humans. The once rarely- seen red mullet, black bream and cuttlefish are now being caught in fishermen’s nets as far north as the Isle of Man.
Japanese and Portuguese oysters – previously imported into Britain but unable to live in the cold water – have started to breed in British waters, as have the compass jellyfish and leathery sea squirt, which is originally from the Pacific.