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Tanked up fish taste freedom

Thousands of fish, which have been living in large tanks at a water treatment works for most of their lives, were transferred back to the River Thames at the begining of the fishing season.

A complex operation took place to remove the fish from the water treatment plant at Walton, Surrey,  Species including roach, perch, eels, bream, minnows and bleak have been moved to the river.  They were drawn into the tanks some years ago as eggs or baby fish and have been unable to swim back into the natural river course because they have grown too big to swim through the pumps.  Species have been able to survive for so long in the water tanks, which are at the first stage of the treatment process, by feeding on algae and invertebrates.

Six members of the our  fisheries team have been working in partnership with Thames Water staff to remove them using Seine nets, which act like a fence to encircle groups of fish.  Fish were transferred to oxygenated transport tanks in a vehicle before being placed back into the nearby river.

George Gerring, fisheries technical specialist, said: “I’ve never seen anything quite like this – shoals of specimen fish ideal for restocking back into the river where they belong.  ”It has been a complex operation to rescue them but well worth the effort – Thames anglers are going to be delighted!”

Thames Water is carrying out essential maintenance work on the tanks as part of the Walton Service Delivery Project and used this opportunity to perform the restocking.  Each of the two tanks is around six metres deep.

Ignacio Pont Lezica, a Thames Water project construction engineer at Walton, said: "This was a fantastic opportunity to capture and release the fish back to their natural environment. “It has been a brilliant joint effort between the Environment Agency, Thames Water and our contractors Black and Veatch."