Thousands of native fish are to be released into a County Durham river to increase stocks in the region.
Around 3,000 grayling are being brought to the River Browney, to further aid its recovery from urban pollution.
The aim is also to boost stocks in the River Wear into which the Browney discharges and improve prospects for anglers in the region.
The release is taking place at three locations between Lanchester and Durham on Monday.
Phil Rippon, the Environment Agency's fisheries specialist, said: "Grayling is native to the River Wear and we want to see their numbers increase in that part of the catchment.
"Because the Browney is now healthier and its water quality has improved, the stream is the ideal place to release the fish and give it a new lease of life."
Anglers in the region are also being called on to keep a log of their fishing during the season to help the Environment Agency monitor coarse fish populations.
The information from the log books will help officers understand the extent of fishing in the area, and the size and types of fish populations.