Environmental Assessment (Scotland) Act 2005 Aquaculture and Fisheries Bill Consultation Document Environmental Report February 2012

This Environmental Report sets out the results of the assessment of the possible environmental effects of provisions in the Aquaculture and Fisheries Bill.


Current Situation

11.1 A total of 113 escape incidents from finfish aquaculture farms were reported to Marine Scotland between May 2002 (when reporting began) and December 2011 [51] . Over this period, almost 2 million Atlantic salmon were reported as having escaped to the marine environment, as well as approximately 280,000 other species of farmed fish (halibut, cod, charr and trout). Incident numbers for all farmed species have generally declined, from 25 incidents in 2006 to 12 incidents in 2010.

11.2 These incidents typically involve the escape of juvenile or adult fish from freshwater or sea cages [27] . Between March 2002 and October 2009, the following causes of escapes were identified:

  • a hole in the net (57%;78 incidents);
  • cage and mooring failures (16%;22 incidents);
  • fish handling incidents (5%; 7 incidents);
  • nets under water (4%; 6 incidents);
  • screen failure (4%; 6 incidents); and
  • other causes (14%) [52] .

11.3 For Atlantic salmon, these incidents are largely the result of equipment failures, with fish primarily escaping due to structural failures of containment equipment and through holes in the cage nets [67] . Storm events have proved to be a major cause of escapes and damage to farm equipment, and these events can result in the release of large numbers of fish compared with other incidents. In January 2005, five salmon farm escape incidents were reported during one large storm event, resulting in a total escape of 633,334 fish. Escapes during this one storm accounted for 25% of the escape incidents in 2005, while making up over 72% of the escaped salmon numbers for that year. In December 2011, severe storms led to the loss of approximately 370,000 adult farmed Atlantic salmon in two separate incidents involving the loss of a grid of 12 cages and a separate single cage in Shetland. The incidents are currently being investigated.

11.4 Escaped salmonids are known to disperse over large geographic areas, often moving with the currents [53] , and mixing, migrating and breeding with wild salmonid populations in inland rivers [54] . The number of escaped farm salmonids that successfully spawn is not known, although studies have indicated that there is wide variation in reproductive success for both escaped males and females [55] . Findings of studies conducted in North America [56] and Norway [57] suggest that inter-breeding between farmed escapees and wild salmonid populations can result in significant alteration of the genetic integrity of native salmon populations, with possible loss of adaptation to wild conditions.


11.5 The proposed provision includes powers for Scottish Ministers to require finfish farms to use equipment that conforms to a Scottish Technical Standard.

Potential Effects

11.6 The Improved Containment Working Group, established in September 2009 under the auspices of the Ministerial Group on Aquaculture, is making significant progress on a range of actions to improve containment. Other work in this area includes significant investment by the salmon farming industry in new equipment and Marine Scotland Science's containment inspection regime. Taken together, this effort, along with increased awareness of containment issues, has led to the lowest reported fish farm escapes in 2010 since statutory reporting began in May 2002.

11.7 The CoGP sets out recommendations on containment and notes that installations and holding facilities should be suitable for the purpose. Through the Improved Containment Group, industry has agreed to a Scottish Technical Standard for fish farm equipment. Preliminary work on developing a draft standard is well underway.

11.8 The proposed provision would make compliance with the forthcoming Scottish Technical Standard a statutory requirement. It therefore has the potential to reduce escape incidents, and hence further reduce the numbers of farmed salmon entering the marine environment. This measure would reduce the risk of competition, displacement and inter-breeding between escaped farmed salmonids and wild salmonids, and would therefore be of benefit to wild salmonids.


11.9 As no significant negative effects from these provisions have been identified, no mitigation measures are required. Given the high-level nature of the provisions, enhancement measures have not been proposed at this stage of the Bill's development.

Effects of Continuing the Status Quo

11.10 Continuing the current situation would result in the continuing risk that escapes of farmed salmonids would continue to occur, which would have adverse implications for wild salmonid populations.


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