Anglers asked to report fish with blue markings

The Environment Agency released 1,000 fish with blue marks into the River Lea

Anglers should report any fish caught that have blue markings, the Environment Agency (EA) said.

In November, it released 1,000 "tattooed" juvenile barbel into the River Lea at Kings Weir near Turnford, Hertfordshire, and Fishers Green in Waltham Abbey, Essex.

The fish were given a blue dye mark between their pectoral fins as part of a project to track barbel populations in the river. This method of marking fish was used in different global projects and was not believed to be harmful.

EA fisheries team leader Richard Tyler said: "We've responded to concerns of anglers about declining fish stocks, including barbel, and this project will give us some good data to monitor barbel populations."

King's Weir is one of the locations where fish were released

The barbel were sourced from the agency's National Coarse Fish Rearing Unit, which is funded by rod licence income.

Mr Tyler added: "The work will also help anglers, and ourselves, increase our knowledge of fish populations in the river, growth rate and just how far up and downstream the barbel migrate.

"It will give us great information on how well they are thriving."

People who have caught one of the marked fish have been asked to send a photo, location, size and weight of the fish to EA via email.