THE Scottish Government has come under fire for “grossly inflating” the number of wild salmon in rivers and giving the fish farming industry licence to expand.

Fisheries experts say that Government scientists have over-estimated salmon populations in some rivers by 10 times. They are demanding that the estimates – and their related conservation measures – be revised.

They fear that fish farmers could seize on the exaggerated numbers to justify plans to double the size of their business by 2030. Anglers blame pests and diseases from salmon farms for decimating wild stocks, though this is disputed by the industry.

Government scientists have recently come up with new, higher estimates of wild salmon numbers. This resulted in the conservation rules for 57 west coast rivers being relaxed, enabling more fish to be taken.

But an expert report commissioned by Salmon & Trout Conservation Scotland has concluded that the estimates are flawed. They should be treated with “considerable caution”, warned Professor Colin Adams from the University of Glasgow.

“There is little doubt that the assumptions and simplifications used combined with a lack of empirical data are resulting in estimates of salmon abundances which differ significantly from the reality in a number of rivers,” concluded his report.

A fish counter in the River Morar in the west Highlands shows an annual count of 500 salmon, a third of the Government’s estimate. A survey using snorkels by the Argyll Fisheries Trust found 30 adult salmon in a river that the Government reckoned had 1,500 annually.

“When we compare our survey data of several Argyll rivers with the Marine Scotland Science (MSS) salmon abundance estimates, we conclude that MSS has overestimated the number of salmon present by up to a factor of 10,” said Craig MacIntyre, director of the Argyll Fisheries Trust.

“Grossly inflating salmon numbers risks setting back local conservation efforts, such as catch and release, as well as misleading local authorities and regulators when they are making decisions about aquaculture expansion.”

Bill Whyte, chairman of the Wester Ross Area Salmon Fishery Board, said: “The highly questionable re-categorisation of many of our rivers will serve as a green light for the salmon farming industry to push for unjustifiable expansion.”

The Scottish Government accepted that it might need to alter some of its estimates. Consultation had “identified several areas where new data can be incorporated to iron out inconsistencies in river gradings, particularly with respect to the west coast of Scotland”, said a spokesman.

“Conservation assessments are based on the best available data using internationally recognised methodologies. We have been working closely with local fisheries biologists to identify and use all appropriate information and have an on-going programme of work to refine grading processes and produce new data.”