In a drastic attempt to protect rapidly dwindling stocks, it also announced restrictions on tackle that fishermen can use and said salmon net fisheries would be closed until June. The move has been prompted by plunging numbers in some of Britain's most celebrated salmon rivers.
An assessment in March showed catches in England and Wales in 1997 were among the worst on record, with the overall level of spawning well below that needed to maintain healthy sustainable fisheries.
In the River Wye in Wales, for example, which in recent decades has had an annual catch of about 3,500 fish, peaking at 7,000 in 1988, only 650 were caught last year.
The cause of the decline is uncertain: possibilities include over-fishing in rivers and at sea, and climate change altering the make-up of the oceanic feeding grounds of the mature fish.
Yesterday the agency announced new by-laws governing salmon fishing. They are aimed in particular at protecting "springers", larger fish that have spent several years at sea and which return to their native rivers to spawn early in the year.
From next year all salmon in all rivers caught up to 16 June must be released. Worm is banned as a bait before then, with only fly or spinner allowed. Hook type and size is to be strictly controlled, with no more than one barbless hook with a maximum gape of 8mm although, to give the tackle trade time to adjust, this restriction will be delayed until 2000. Net fishing for salmon is to be banned before 1 June.
"There is a clear consensus that stocks of early-run salmon are under threat everywhere and that there is a need to take action to arrest further decline," said the agency's head of fisheries, David Clarke. Earlier in the year the situation was thought to be so serious that the agency considered banning salmon fishing completely but it was a prospect seriously alarming to the considerable hotel and tourist industry that depends on salmon fishing.
Anne Voss Bark, owner of one of England's best-known fishing hotels, the Arundell Arms, at Lifton, Devon, said: "It would have put a lot of people out of business and out of work, not just the bailiffs, but the hotels and the bed-and- breakfasts and those who depend on the spending. This is less disastrous but it is still pretty draconian and it will certainly affect business."
In Scotland the great salmon rivers such as the Tweed and Dee, which have also suffered a serious decline, are managed by district salmon fishery boards. Some have voluntary catch-and- release agreements but the Scottish Office does not have the power to bring in mandatory restrictions.