SCOTLAND’S booming salmon farming industry should not be allowed to expand any further without overhauling its environmental standards, an inquiry has found.

An in-depth probe by MSPs recommended handing regulators robust new powers to limit or close down production on farms where fishes regularly succumb to disease and infection.

It comes after campaigners warned salmon farming – which is worth more than £1 billion to Scotland’s economy – was turning the country’s seas into an “open sewer”.

But despite calling for tougher regulations, Holyrood’s Rural Economy and Connectivity Committee insisted there was “insufficient evidence” for a moratorium on new salmon farm development.

Only two MSPs, the Scottish Green’s John Finnie and Labour’s Colin Smyth, supported a temporary ban.

Scottish Tory MSP Edward Mountain, the committee’s convener, said the salmon farming industry offers “significant economic and social value to Scotland”.

He said: “There is a desire within the industry to grow. However, if this is to happen, it is essential that the serious challenges it faces such as the control of sea lice, lowering fish mortality rates and reducing the sector's impact on the environment are addressed as a priority.

"If the reputation of Scottish salmon as a premium product is to be maintained, Scotland's salmon farmers must demonstrate responsible and sustainable production methods.

“Importantly, the committee is strongly of the view that the status quo in terms of regulation and enforcement is not acceptable, and that we need to raise the bar in Scotland by setting enhanced and more effective standards.”

Salmon is Scotland’s biggest food export, but there are widespread concerns over sea lice, the spread of disease and the high mortality rate of farmed fish, as well as the impact of the sector on wild salmon.

MSPs have now made 65 recommendations to improve the industry, with their report insisting “maintaining the status quo in terms of the regulatory regime in Scotland is not an option”.

It raised concerns over “extremely high mortality rates” at some farms, and insisted no expansion should be permitted at sites which report high or significantly increased levels of fish deaths until these are addressed.

The inquiry also called for greater transparency over mortality rates and disease outbreaks, and recommended a review be carried out into the transportation and disposal of dead fish.

MSPs said they had “difficulty in understanding” how the farmed salmon sector can expand if the scourge of gill disease is not tackled, while also noting an effective way to deal with sea lice infestations had yet to be identified.

The issue of waste collection and removal, meanwhile, “needs to be addressed as a matter of urgency”.

Julie Hesketh-Laird, chief executive of the Scottish Salmon Producers Organisation, welcomed the report.

She said: “The Scottish salmon farming sector is at a critical phase of its development and the committee’s recommendation that regulation should be improved to keep pace with potential growth is encouraging.

“We produce the world’s most sought-after farmed salmon and are fully aware that, with that, comes the responsibility to ensure world-class fish welfare and environmental standards.”

She said the sector is already voluntarily reporting lice levels and working to improve fish health and welfare.