According to the treasure hunting company Odyssey Marine Exploration, fishing trawlers are destroying wrecks by snagging them with nets and cables, dragging objects and gradually tearing the ships apart.

An example of the damage trawlers can cause is the wreck of HMS Victory, a British warship sunk in the English Channel in 1744. Trawling nets and cables have become entangled around cannon and ballast blocks, and three of the ship’s bronze cannons have been displaced. One of them, a 42-pound (19 kg) cannon weighing 4 tonnes, has been dragged 55 metres (180 feet) and flipped upside down. Two other cannon recovered by Odyssey Marine Exploration last year show fresh scratches from trawls and damage caused by friction from nets or cables.

“We know trawlers work the Victory site because one almost ran us down while we were there,” says Tom Dettweiler, senior project manager of Odyssey Marine Exploration.

“It turns out that Victory is right in the middle of the heaviest trawling area in the Western Channel,” says Greg Stemm, chief executive of the company. “We were shocked and surprised by the degree of damage we found in the Channel, he continues. “When we got into this business, like everyone else we thought that beyond 50 or 60 metres, below the reach of divers, we’d find pristine shipwrecks. We thought we’d be finding rainforest, but instead found an industrial site criss-crossed by bulldozers and trucks.”

While surveying 4,725 sq miles (12,300 sq km) of the western Channel, Odyssey Marine Exploration found 267 wrecks, of which 112 showed evidence of being damaged by bottom trawlers. That is over 40 percent.

The English Channel has been a busy area for at least three and half millennia and was thought to be littered with wrecks. In these fairly cold waters, wooden ships tend to stay intact for much longer periods of time than they would in warm tropical regions. Strangely enough, Odyssey Marine Exploration found no more than three pre-1800 wrecks when surveying the area using modern technology sensitive enough to disclose a single amphora. According to historic estimations, at least 1,500 ships have been lost in these waters so finding no more than three pre-1800 wrecks calls for further investigation.

Odyssey Marine Exploration blames bottom trawlers for the lack of wrecks. “The conclusion and fear is that the vast majority of pre-1800 sites have already been completely obliterated by the deep-sea fishing industry,” says Sean Kingsley, of Wreck Watch International, the author of the Odyssey report.

Odyssey Marine Exploration is the world’s only publicly-listed shipwreck exploration company and critics argue that these American treasure hunters are overstating the damage for their own gain.

“You have to ask why Odyssey is doing such a study,” said Robert Yorke, chairman of the Joint Nautical Archaeology Policy Committee. “They want to pressurise the UK Government to allow them to get at the wreck . . . the Victory hasn’t disappeared since 1744; it’s not going to disappear tomorrow.”

The Ministry of Defence has jurisdiction over warships’ remains and it has asked English Heritage for an assessment of the threats to the site. English Heritage has a policy of leaving shipwrecks untouched on the seabed unless a definite risk can be shown.

Sarpa salpa, a fish species capable of causing long-lasting hallucinatory experiences in humans, has been caught far north of its normal range. Normally found in the warm waters of the Mediterranean and off the African west coast, Sarpa salpa is an unusual guest in northern Europe. Only three previous recordings exist from British waters, with the third being from 1983 when a single specimen was caught off the Channel Islands.

The most recent specimen of this mind altering Sparidae was caught six miles south of Polperro, Cornwall, by fisherman Andy Giles. When Giles found the strange looking creature entangled in his net he brought it back to shore to have it identified.

Picture by by Sam and Ian

“We were trawling for lemon sole but hauled up the net at the end of the day and almost immediately saw this striped fish”, Giles said. “I had never seen one before so brought it back for experts to have a look at it. But now I realise what it was – and the crazy effects it can have – perhaps I should have taken it into town to sell to some clubbers.”

Instead of selling it to clubbers, Giles could also have brought it home to the dinner table – without much risk of having any mind altering experiences. Within its native range, Sarpa salpa, commonly known as Salema porgy, is a popular food fish and suffering from hallucinations after ordering a plate of Salema in a Mediterranean restaurant is very rare.

According to marine experts, Sarpa salpa has to feed on a certain types of plankton in order to become hallucinogen. In 2006, two men were hospitalized in southern France after eating Sarpa salpa who evidently had feasted on vast amounts of psychedelic plankton before being caught.

“Plankton has very minute amounts of poison and fish that eat a great deal of it can develop this poisoning”, says Oliver Crimmen, fish curator at the Natural History Museum. Sarpa salpa are a popular fish to eat in the Mediterranean and I think the 2006 incident was a rare event.”

So, why can urge a Sarpa salpa to leave the pleasant waters of Africa and head for chilly Britain? According to James Wright, senior biologist at the National Marine Aquarium in Plymouth, the fish may simply have tagged along when some other species decided to head north, but it may also be possible that the species is on the rise in northern Europe.

“These are a fairly common fish off Tenerife, Malta and Cyprus but it is very rare to get them this far north. It could be a single fish that was shoaling with a different species, says Wright. But it could be that there are more of them in our waters.”