Anglers have said they are being unfairly penalised by proposed rules designed to reverse the decline of salmon and sea trout in Welsh rivers.
Wales’ environmental watchdog has begun a consultation on how to increase stocks, including plans for new bylaws such as making anglers put back fish.
But the Angling Trust said the real problem was agricultural pollution.
Natural Resources Wales (NRW) said it needed to protect salmon stocks because they were in “very bad condition”.
Fish stocks are assessed annually and 21 of 23 salmon rivers are at risk of not meeting target numbers, while 21 of 33 sea trout rivers were described as vulnerable.
Angling Trust chief executive Mark Lloyd said he was glad NRW was investigating the reducing number of salmon in Welsh rivers.
But he added he was against restricting anglers by asking them to throw back fish for the next 10 years.
“We’ve been talking about the problem in salmon stocks for a number of years,” he said.
“The need is for urgent action to tackle the underlying problem, which is pollution, particularly from agriculture but also forestry and sewage.
“Anglers are killing a few hundred fish across Wales. But many thousands of fish are being killed with slurry and sediment and pesticides off fields.”
Mr Lloyd said anglers volunteered to help maintain river banks and habitats, adding Wales “can’t afford to lose that army of people who look after our rivers”.
“It is like trying to control organised crime by regulating pickpockets,” he told the BBC.
“If anglers are overregulated, they’ll just go abroad to fish or fish in England where there are voluntary restrictions.”
Fisheries are worth about £150m to the economy each year and support about 1,500 jobs.
NRW said salmon and sea trout were “vital” to rural Wales and helped “support economies”.
“We have to guarantee their wellbeing in the future,” said Peter Gough, NRW principal fisheries advisor.
“We need to protect the really important spawning resources of salmon and sea trout. The stocks are in very bad condition.”
In 2014, it urged anglers to release more of the fish they caught to conserve stocks but has now taken that advice a step further.
Other proposals for people fishing with nets and rods include maximum catch sizes and restricting what bait is used.