The Environment Agency is responsible for guarding against the pollution of water in Britain. It issues fishing licences to anglers and carries out a Government edict to promote angling.
They report that angling has contributed to the decline of wild trout.
"There has also been an increase in the artificial stocking of rivers with both hatchery-reared brown and rainbow trout. This has been in response to declines in wild trout, probably due to a combination of habitat damage and heavy fishing pressure. Therefore, wild trout populations are becoming ... rarer."