During the 1970s the survival of otters was threatened by a loss of habitats and they were rare in most parts of Britain.
But this native species was brought back from the brink of extinction and numbers have recovered largely as a result of conservation work and improved water quality.
There are now thought to be otters in every county in England.
Some believe their recovery has been so successful that there are too many otters and native fish are under threat.
Angler John Wilson thinks there is a need for more controls on otters in rivers across some areas including Norfolk.
David Whiteley looks to the argument for controlling otter numbers in rivers where fish stocks are threatened.
Inside Out is broadcast on Monday, 30 September on BBC One East at 19:30 BST and nationwide thereafter on the iPlayer.