As the damage being caused to wild salmon and sea trout in Scotland continues, the Salmon & Trout Association (Scotland) (S&TA(S)) has analysed aggregated sea lice data published by the Scottish Salmon Producers Organisation (SSPO), in its first two quarterly sea lice reports (see links in Note 2).

In June 2013 over one third of salmon farms (47 farms) on the Scottish mainland and in the Hebrides were in areas where average sea-lice numbers exceeded the industry’s own limit for sea lice. In each of the previous five months at least one quarter (35 farms) were in this category.

In three key fish-farming areas, the SSPO’s ‘averaged data’ showed sea lice numbers in excess of the industry’s own limits for sea lice for every month from January to June 2013:

  • ‘Inchard to Kirkaig North’ - eight active salmon farms, all run by Loch Duart Limited, the self-styled “sustainable salmon company”. Between February and April the average monthly lice count on Loch Duart farms was more than three times the industry’s own threshold and never went below twice that threshold in any month.
  • ‘Kennart to Gruinard’ - seven farms operated by two companies, Wester Ross Fisheries Limited and Scottish Sea Farms Limited. Between February and June the average monthly lice count on farms in this area ranged between four to more than nine times the industry’s own threshold
  • ‘Isle of Harris’ - 12 fish-farms operated by three different companies including The Scottish Salmon Company and Marine Harvest (Scotland) Limited. Between February and June the average monthly lice count on farms in this area was at times more than five times the industry’s own threshold..

Hugh Campbell Adamson, Chairman of S&TA(S), said:

“The SSPO reports confirm that, in at least three key fish-farming regions of Scotland, sea lice numbers are out of control and consequently the fish-farm companies are failing to protect wild fish from the devastating effects of the release of vast numbers of juvenile parasitic sea lice into west coast sea lochs.

We have a simple question for the SSPO. Why have companies such as Wester Ross Fisheries and Loch Duart not been expelled from SSPO membership when they fail so consistently and dramatically to keep sea lice numbers within the limits they have signed up to? If the SSPO’s Code of Good Practice on sea lice is to retain any credibility, then surely serial offenders like Wester Ross Fisheries and Loch Duart should be excluded from the salmon farmers’ trade organisation”.

Guy Linley-Adams, Solicitor to the S&TA(S) Aquaculture Campaign said:

“In light of the appalling sea-lice numbers that companies such as Wester Ross Fisheries Limited and Loch Duart Limited have been reporting, we would ask Paul Wheelhouse MSP, Minister for the Environment in the Scottish Government, what he intends to do about this.

Specifically, when is the Minister going to introduce statutory controls on on-farm sea lice numbers to protect juvenile wild fish from picking up lethal infestations in the sea-lochs?

The SSPO’s reports also expose just how wrong Scottish Government was when it refused earlier this year, against the better advice of all west coast local authorities, all wild fish groups and its own Scottish Environment Protection Agency (see Note 7), to include a requirement in the Aquaculture and Fisheries Bill for all fish-farms to publish weekly sea lice count data by law. The supposed confidential interests of the fish-farmers were allowed to trump the public right to know what is being released by the salmon-farmers into the wider environment potentially causing huge damage to wild fish conservation.

However, the Scottish Government still has the power under the Aquaculture Act 2007 to order the publication of farm-specific data and we call upon them now to use that power”.

Why are sea lice on fish-farms such a threat to wild salmonids?

The negative impact of sea lice, produced in huge numbers by fish-farms, on wild salmonids (salmon and sea-trout) is widely accepted by fisheries scientists including the Scottish Government’s own Marine Scotland Science (see Note 7).

In Ireland, the Government of Ireland’s agency, Inland Fisheries Ireland, is crystal clear as to where the problem lies (see Note 8):

“The presence of salmon farms has been shown to significantly increase the level of sea lice infestation in sea trout in Ireland, Scotland and Norway. These lice infestations have been shown to follow the development of marine salmon aquaculture….studies from Ireland, Scotland and Norway have shown that in bays where salmon farming takes place the vast majority of sea lice originate from salmon farms……”

Most recently, a new paper published in 2013 by a group of fisheries experts from Norway, Canada and Scotland re-analyses data from various Irish studies and shows that the impact of sea lice on wild salmon causes a very high loss (34%) of those returning to Irish rivers (see Note 9).

Most importantly, there is clear evidence that both wild salmon and sea trout are in decline in Scotland’s ‘aquaculture zone’, whereas, generally, populations have stabilized on the east and north coasts where there is no fish-farming (see Note 10).


  1. Just what is the problem with sea lice? Adult wild salmon are perfectly adapted to coping with a few sea lice. Background levels of these parasites occur naturally in the sea. However the advent of salmon farming, particularly in fjordic sea lochs, has led to a fundamental change in the density and occurrence of sea lice in parts of the coastal waters of the west Highlands and Islands. Even one or two mature female sea lice per fish within a set of cages housing hundreds of thousands of farmed salmon amounts to a rampant breeding reservoir pumping literally billions of mobile juvenile sea lice out into the local marine environment. The consequences when wild salmon and sea trout smolts, the metamorphosing fragile skin of which is not adapted to cope with more than the odd louse, migrate from local rivers into this “sea lice soup” are devastating.

    A burden in excess of 13 pre-adult sea lice is known to compromise severely the survival of juvenile migratory salmonids. Lice feed by grazing on the surface of the fish and eating the mucous and skin. Large numbers of lice soon cause the loss of fins, severe scarring, secondary infections and, in time, death. Quite literally, the fish are eaten alive. Badly infested salmon smolts disappear out to sea, never to be seen again. In contrast afflicted sea trout smolts remain within the locality and they, together with the impact of the deadly burdens they carry, are more easily monitored through sweep net operations.
  2. The first SSPO report giving aggregated sea lice data from fish-farms covering 30 regions of Scotland over January to March 2013 is available at:
    The second SSPO report covering April to June is available at:
  3. Wester Ross Fisheries Limited’s farms in Loch Broom and little Loch Broom have a poor track record of controlling their sea lice numbers.
    Fish Health Inspectorate reports of inspections conducted at WRF’s farm at Ardmair in Loch Kanaird on 10th November 2009, 15th June 2011, 2nd August 2011 and 25th July 2012, at WRF’s farm in Loch Broom at Corry on 21st March 2011 and 6th June 2011 and in Little Loch Broom at Ardessie on 7th June 2011, 2nd August 2011 and 16th May 2013 all recorded that sea-lice levels of the farmed fish were not below the suggested adult female sea lice threshold in the industry’s own Code of Good Practice during the period that records were inspected.
  4. The Scottish Sea Farm’s farm at Tanera was inspected by the Fish Health Inspectorate on 12th February 2013. The inspection recorded high gravid numbers (adult female lice with eggs) on the farmed fish. Sea-lice levels on the farmed fish were not below the suggested adult female sea lice threshold in the industry’s own Code of Good Practice during the period that records were inspected, despite the presence on the farm of 42,000 wrasse ‘cleaner fish’.
  5. Currently, the fish-farm companies are only required under the Record Keeping Order to collect and record weekly sea-lice count data at each of their farms (including the number of adult female lice found per farmed fish, which is a surrogate measure for the production of juvenile lice). They are not required by law to publish this data, nor submit it to the Scottish Government’s Fish Health Inspectorate (FHI).
  6. Referring to a proposal to require the publication of farm-specific sea lice data, Douglas Sinclair of SEPA told the Scottish Parliament’s Rural Affairs Climate Change and Environment Committee that this is “one of the few areas in the Scottish environment in which someone can be doing something that can significantly impact on someone else’s interests and there is no public access to what is going on … if someone lives downwind of smoking chimneys on a factory and they want to find out what is in the smoke, they can find out from us—from the published record. Fish farming in Scotland is the one omission. For all sorts of reasons, it ought to be sorted out and the information ought to be published.” Official Report, Rural Affairs, Climate Change and Environment Committee, 5 December 2012; c 1431.
  7. Marine Scotland Science (2013) Summary of information relating to impacts of sea lice from fish farms on Scottish sea trout and salmon - 4th April 2013 – see Note that Marine Scotland Science acknowledges that compliance with the thresholds within the Code of Good Practice is not necessarily sufficient to ensure that juvenile sea lice emanating from the fish farms do not damage wild fish.
    See also S&TA (2013) Recent research and findings on the impact of salmon aquaculture on wild salmonids – see
  8. Inland Fisheries Ireland (2013) Factsheet on the Impact of Salmon Farms on Wild Salmon and Sea Trout Stocks.
  9. M Krkosek, C W Revie, B Finstad and C D Todd (2013) Comment on Jackson et al. ”Impact of Lepeophtheirus salmonis infestations on migrating Atlantic salmon, Salmo salar L., smolts at eight locations in Ireland with an analysis of lice-induced marine mortality” - Journal of Fish Diseases.