Anglers have renewed verbal hostilities against fish farming calling on ministers to impose an immediate moratorium on the industry expanding further.

The move comes amid new claims there is growing evidence that Highland salmon river stocks are suffering.

Representatives of one of the most popular sporting pastimes in Scotland, have long pointed an accusing finger at the industry which produces the country's number one food export, for its impact on wild salmon stocks.

Now Salmon and Trout Conservation Scotland (S&TCS) claims the Scottish Government’s own newly published classification of the country’s salmon rivers puts all those in the West Highlands and Inner Hebrides, in the worst-performing category.

This includes important river systems such as the Awe and the Lochy. It means stocks are not reaching what are known as ‘conservation limits’, a measure of the overall health of the population, the S&TCS says.

Its director Andrew Graham-Stewart, said: “This new analysis by Marine Scotland should ring alarm bells. Fisheries’ scientists have long warned of the impact of sea lice and escapes emanating from salmon farms.”

He said the fact that no single river within salmon farming’s heartland on the west coast had a sufficient stock of wild salmon for any sustainable fishing, could not be a coincidence.

“Regrettably, Scottish Government has until now habitually downplayed studies by third parties, but we believe it cannot ignore its own fisheries scientists’ analysis. The contrast between western Scotland and the rest of the country is clear to see and the only major or substantive distinction between the east and west coasts is, of course, the presence of salmon farming in the west. We call on the Scottish Government to halt any further growth in salmon farming until the industry can definitively prove itself to be environmentally sustainable.”

Roger Brook, Chairman of the Argyll District Salmon Fishery Board, agreed: “Marine Scotland’s analysis must call into question Scottish Ministers’ repeated claims that salmon farming, as it is currently practised, is inherently sustainable. While the majority of east, and north coast rivers are ‘category one’, indicating that wild salmon populations are reasonably healthy, all the rivers in the West Highlands and Inner Hebrides are designated as ‘category three’, indicating that they are in very poor health."

He said on the one hand Scottish Government was claiming that salmon farming was sustainable, whilst on the other hand it was categorising all wild fisheries in salmon farming areas as unsustainable.

But the Scottish Government pointed out that the grade three areas also covered significant parts of Scotland where no salmon farming takes place.

A spokeswoman said it was working to preserve wild salmon populations, with measures including spring conservation, introduced earlier this year and the proposed salmon kill licence, which would come into operation for the 2016 season.

“Any application for a new salmon farming development requires a detailed assessment of any potential impacts by the relevant local authority. We are working with Scotland’s salmon farming industry and representatives of the wild salmon sector on an ambitious programme of research which will explore any potential risk to wild salmon from sea lice, which will help inform Scottish Government policy in relation to supporting both sustainable growth in aquaculture and conserving important wild salmon stocks.”

Scott Landsburgh, chief executive of Scottish Salmon Producers Organisation, said it was of course, regrettable that the status of these rivers was so poor, but added.

"The industry’s joint working with wild fisheries organisations has shown a productive and co-operative relationship looking at restoration and restocking projects. Work has focused on the importance of maintaining and improving river habitats and encouraging catch and release rather than depleting the river populations. "

He said the technical expertise and facilities of the fish-farming industry had also helped with a restocking programme of the River Lochy, as part of a wider five year project to assist 14 different rivers in Lochaber.

Martin Jaffa of the fish-farming consultancy Callander McDowell said west coast rivers were generally very short and a handful of fish could make a difference to the calculations. The much longer rivers of the east had much greater stock "and thus the maths allows a much greater margin for error."