These Byelaws: (a) require every person who is licensed pursuant to byelaws made under the Fisheries Act (Northern Ireland) 1966 to fish for wild salmon and sea trout to affix a gill tag to every wild salmon or sea trout captured and retained by him (Byelaw 3); (b) provide for the issue of gill tags to such persons (Byelaw 4); (c) provide for the removal of a tag which is affixed to a wild salmon or sea trout only in specified circumstances (Byelaw 5(1)(a) and (5)); (d) prohibit the affixing of