The report was co-published this week by the Salmon and Trout Conservation and animal campaign charity OneKind.
Over the course of 12 months Tescos and Sainsburys supermarkets, stocked with Scottish farmed salmon, were monitored against publicly available data about their origins by the two charities.
They found that much of the stocked salmon comes from open cage farms, which have reported raised levels of sea lice parasites and disease, significant premature mortalities and “unsatisfactory” levels of marine pollution, all of which are putting Scotland’s wild fish and local ecosystems at risk.
An unsatisfactory classification is defined by the Scottish Environment Protection Agency (SEPA) as emissions on a scale that is beyond the “assimilative capacity of the local environment” relating to “impacts on benthic fauna or sediment chemistry, unacceptable in- feed medicine residues concentrations, or a combination of these parameters”.
According to SEPA’s latest environmental monitoring survey for 2017, the status of Scotland’s salmon farms receiving an unsatisfactory rating surged by almost 10 percentage points from around 12 to 21% between 2017 and 2018.
The charities’ report also notes that emissions of parasites from sea lice infestations incubated by salmon farms in Scotland doubled when the month of April 2018 was comparted with the month of April 2019. The increase of 0.25 to 0.49 on adult female sea lice represented an increase of 96% and continues to push wild Atlantic salmon populations “to the brink of extinction”, the report notes.
However, over the longer-term the rolling average shows that the sector has more than halved sea lice populations in its stocks since 2015.
Sea lice are small parasites that occur naturally in the sea around Scotland eating the skin of salmon. But due to the intensification of caged salmon farming, lice can multiply in exponential numbers as one farm can hold between 200,000 to 2 million salmon at any one time, threatening wild fish populations, according to the report.
One farm recorded an almost 33% premature mortality rate. Overall, the rate of premature stock deaths on salmon farms has increased fourfold in fifteen years on Scottish salmon farms, the report states.
Other supermarkets could not be analysed because only a handful of products with farm origin labelling are available on supermarket shelves, the report notes.
Terry A’Hearn, the chief executive of the Scottish Environment Protection Agency, said that it was working closely with the Scottish Government, Marine Scotland and Scottish salmon farmers.
He said: “Following over twenty-two months of work, more science and more listening to stakeholders than ever before, on 1 June SEPA launched a new firm, evidence-based regulatory framework which further strengthens the protection of the marine environment.
“The framework makes clear our shared aspirations that the industry reach and maintain full compliance with Scotland’s environmental protection laws and outlines our commitment to supporting those investing in innovation and moving beyond compliance.
“We’re pleased with the ongoing progress being made, which we expect to be reflected in our 2018 compliance assessment report to be published in January.”
To read the report in full click here