Poachers perpetrated a “genocide” against the fish population after laying an illegal net in the River Thames.

Warwick Salzer, who has lived and worked on the river for the past 20 years, found the 175 foot long net fixed by Teddington Lock.

He and two others noticed the net at about midday on October 22, marked with an empty bottle with a note in it, so those who came back to collect the bounty could perhaps have the excuse of saying they were intrigued by the note, thinks Mr Salzer.

It took the group 90 minutes to pull up the net and cut lose the fish, many of which had died.

The skipper at Fling Your Hook, based in Kingston, said there was more than 100 fish, mainly perch, and crabs caught.

He said: "We managed to save the majority of them.

"It was actually heart breaking. You can imagine the devastation that this has done.

"It has wiped out a decade of the economy in just a few hours. It's like genocide.

Surrey Comet:

"They [the people who set the net] will completely wipe out the Thames. It would shut me down [if poachers continued to set nets in the Thames].

"This is not something that can take years, it's something that can happen in months.”

Environment Agency officers came to retrieve the net and dead fish as evidence.

Today they are carrying out a boat patrol to look for more illegal traps or nets.

Surrey Comet:

Chris Hazelton, environment manager, said: "We are appealing to anyone who has seen any boats or vehicles operating in and around the weir-pool or any persons acting suspiciously to contact us on our incident hotline 0800 807060.

"We would also like to thank the angler who removed the net, as his actions will have undoubtedly saved more fish from being caught and killed."

The Environment Agency issued the appeal to help stop illegal trapping or nets and said it will increase patrols in the area.

People can face up to a £5,000 fine for setting traps and nets.