Pike anglers are backing Ramblers Scotland in their campaign against new camping by-laws proposed for Loch Lomond.
Park authorities claim tighter controls are needed to protect the Bonny, Bonny Banks from litter louts and vandals.
But the Pike Anglers Club of Great Britain (PAC) fears a ban would stop responsible anglers enjoying their sport around the loch shores.
It's worried similar by-laws could also stop visiting fishermen from bivvying up around lochs Tay, Tummel and Rannoch.
"The by-laws would deny us the right to enjoy the countryside, as our members have for generations," said PAC secretary Graham Slater. "It's wrong to punish the majority because a minority offend."
Trossachs National Park has announced a 12-week consultation on whether to stop "informal camping" along a 14-mile stretch of Lomond's eastern shore.
MSP Murdo Fraser is calling for similar bans to be imposed along the bans of lochs across Highland Perthshire. But the 2500-strong PAC says any bans would be contrary to the spirit of the Land Reform Act.
Its leaders have written to the Ramblers, expressing support for their campaign. They're also seeking urgent talks with National Park authorities.
"What these proposed by-laws fail to do is draw a line between the responsible behaviour of a group of anglers bivvied up around a loch, enjoying a pastime which is completely in tune with the philosphy of the National Park, and those who leave litter, light fires and behave like hooligans," said Fife-based Mr Slater.
"A blanket ban makes as much sense as banning driving because a minority of motorists speed, drink drive or cause crashes."
Loch Lomond is one of Scotlands most historically-important pike fisheries, which has been enjoyed by pike anglers from both sides of the border since Victorian times. Tommy Morgan's 47lbs 11oz pike, landed from the loch in 1945, still holds the Scottish record.
The largest pike ever to be found in the British Isles was discovered dead on its banks, near the River Endrick, in 1934. The head of this monster, estimated to weigh 70lbs, is now in Glasgow's Kelvington Museum.
Consultation over the by-law changes ends on May 3.
Click here for more on the consultation, and how to take part.
Click here for Scotsman story on how the proposed ban could spread.