SEPA issues new reports on marine sediment chemical levels

date24 April 2013

The Scottish Environment Protection Agency (SEPA) has today (24 April 2013) published the results of surveys showing the levels of certain chemicals, used in fish farming, present in Scotland's marine sediments.

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'The Occurrence of Chemical Residues in Sediments' covers a variety of areas of the West Coast, and Western and Northern Isles, over four documents (from 2010 to 2012) which can be viewed on SEPA's website.

A total of 792 analyses were performed on samples from the seabed as part of SEPA's surveillance monitoring programmes, from 2010 to 2012, in order to establish the presence of chemicals in marine sediments.

Over 78% of the analyses returned no detectable residues. Of the 170 analyses returning positive values, 98 (58%) were within the environmental standards set by SEPA.

Douglas Sinclair, SEPA's fish farming expert, said:

We are pleased that the majority of analyses returned no detectable residues, and that the reports show a low incidence of positive results overall. This indicates that the regulatory framework used by SEPA provides protection for the environment.

"There are however some areas where positive values, including results above our environmental standards, are more prevalent. These sites will be subject to further investigation by SEPA.

"This is important research and will be used to inform our work in this area in the coming years. The reports enable us to identify the poorest performing operations and direct work and resources to improve any areas of concern."

The areas surveyed were:

  • 2010 – Firth of Lorne, Loch Spelve, Loch Fyne
  • 2011 – Orkney, West Shetland, East Shetland
  • 2012 – Loch Shell, Loch Erisort, Loch Roag, Loch a Chairn Bhain

Results of the analyses showed that the samples contained only residues of chemicals used in legally authorised medicines. The chemicals are found in products formulated to treat sea louse infestations at salmon farms as set out below:

  • Teflubenzuron is used in a sea louse medicine, Calicide.
  • Emamectin benzoate is the active ingredient in the sea louse medicine Slice.
  • Cypermethrin is found in the sea louse medicine known as Excis.
  • Deltamethrin is the active ingredient in the sea louse medicine AMX.


Notes to editors


  2010 2011 2012
Areas visited Firth of Lorne. Loch Spelve and Loch Fyne                   Orkney and Shetland                                              Loch Shell, Loch Roag, Loch Erisort and Loch a Chairn Bhain
Total analyses undertaken                            108 324 360