WILDLIFE native to the region is being driven out by unwanted pet fish dumped in the region's ponds and waterways.

To tackle the problem, environment and conservation experts have, quite literally, adopted shock tactics.

Using a method of capture known as electric fishing, The Environment Agency is able to move the invaders to sites were they can do no harm.

A rod connected to a generator is used to send an electric pulse into the water, stunning the fish so they float to the surface.

The fish are collected from the water and moved to a tank to be checked before being introduced to a suitable site.

As the electric field is carefully managed, the stunned fish quickly recover.

Recently, the Agency teamed up with Sedgefield Borough Council to move more than 100 fish from a pond in Newton Aycliffe, County Durham.

There the endangered great crested newt, common newts and frogs were in decline because dumped fish were preying on their spawn.

Among the catch were dozens of large roach, rud, carp and even exotic koi and shubunkin goldfish.

Countryside officer Tammy Moris-Hale said: "Volunteers who manage Aycliffe Nature Park noticed the number of newts and frogs dropping dramatically over the past year or two.

"Perhaps people who could no longer look after their pet fish thought they were doing the best thing, and we think some were put there on purpose for angling.

"But there were far too many big fish in there eating spawn and they really do damage the natural environment.

"The electric fishing was fascinating and very successful, so hopefully now this valuable pond can recover."

Fisheries technical specialist, Phil Rippon, said: "There is a fine balance of species in our ponds and waterways, and anything which is introduced, whether it is native or not, can have a serious impact.

"Fish can prey on species such as newts and frogs and may dominate an ecosystem at the expense of other animals. Fish introduced from other waters can also spread disease to resident fish stocks."

Mr Rippon warned it was illegal to introduce fish to inland waters, other than garden ponds and aquaria, without written consent from the Environment Agency.

He said: "We would urge everyone to heed this, and help us to help the environment.