Fishermen on the whole love nature and have come to be known as the guardians of our river banks but introducing yet another fish predator into an already crowded water system certainly raised a few eyebrows.

First zander came on the scene, then we have cormorants that have devastated some fenland drains and with otters now also competing for fish stocks along the drains and, if recent sightings are correct, the River Nene, then I think many will agree the balance has now been tipped firmly in the favour of fish eating creatures.

To be fair it must be a wonderful sight to see otters in the wild, but long term I do feel we are heading for a vast reduction in fish stocks.

The re-introduction of otters has not been without its own problems. The irresponsible and illegal setting of crayfish traps is leading to an increased number of otter deaths across East Anglia.

The Environment Agency has investigated four separate incidents in Cambridgeshire and Buckinghamshire where six dead otters have been found drowned in crayfish traps.

Otters are a protected species so killing them is illegal and could lead to a fine of up to £5,000 or imprisonment for up to six months.

Andy Sadler from the Environment Agency's Fisheries and Biodiversity Team said: "A lot of work has been carried out to encourage otters in the county and numbers are now recovering. To find them needlessly killed is very disappointing, especially when people trapping crayfish can take simple measures to stop it happening."

Anyone setting a crayfish trap must have consent from the Environment Agency and the owner of the river bank where they want to set the trap. If a trap is allowed, it must conform to strict size dimensions and some designs need to be fitted with an otter guard to stop otters getting into them. Some traps can also unintentionally trap water voles, another rare British mammal.

Ruth Hawksley of the Wildlife Trust who has been closely involved with the project to help otter numbers recover said: " Otters are well adapted for life in the water so drowning is a particularly slow and cruel death for them. We urge anyone who is using crayfish traps to do so legally and to fit an otter guard where necessary."

Environment Agency wildlife officer Rachael McFarlane said: "We only licence traps of the correct design, and where they are placed in appropriate locations.

"The trap we found recently had too large an entrance which allowed the otter to enter when attracted either by the bait or a fish in the trap.

"Once it had entered the trap it could not escape and sadly drowned."

Not all traps are illegal - the Environment Agency licenses crayfish trapping for monitoring for scientific purposes and eel trapping. If you see a crayfish or eel trap that does not have a tag visible please do not move it but contact the Environment Agency immediately on 0800 807060.