Sea-bed monitoring under Scottish salmon farms reveals breaches of Environmental Quality Standards at nearly one in five fish farms for residues of sea-lice treatments toxic to lobster, crabs and prawns.
Information obtained under Freedom of Information by the Salmon & Trout Association Scotland (S&TAS) from the Scottish Environment Protection Agency (SEPA) shows that toxic pollution is carrying on unabated despite the requirement to meet set environmental protection standards.
Nearly one in five results reported to SEPA from fish-farms using Slice – emamectin benzoate for sea-lice treatment - show samples in excess of Environmental Quality Standards designed to protect wild flora and fauna from the toxic effects of sea-lice chemicals.
Data from 146 fish-farms which used Slice between January 2011 and September 2012 were obtained by the S&TAS.
At 28 of those farms (19.1%), Environmental Quality Standards were breached. The list of the 28 farm concerned is given in the Annex below this article. The results are broadly in line with an earlier study by the S&TAS based on data obtained under FoI and covering 2005 to 2010.
At that time, the Environment Minister responsible, Stewart Stevenson MSP, stated that: ‘should an EQS for sea louse chemicals be breached following the use and discharge of the substances to treat sea-lice at fish farms, SEPA would take various steps to rectify the situation – for example, through a variation of licence conditions limiting the further release of these substances until residue levels reduced to below those identified safe levels.’
Matters do not however appear to be improving and, to date, the S&TAS is unaware of SEPA varying the conditions of any fish-farm licence to reduce chemical residues in line with the then Minister’s assurance – which has never been revoked.
The Marine Harvest position
15 of the 28 fish-farms with samples in breach of Environmental Quality Standards for Slice are operated by Marine Harvest (Scotland) Limited.
Although Marine Harvest is the biggest operator in Scotland of salmon farms and is shortlisted for the Stewardship Award at tonight’s Crown Estate sponsored Marine Aquaculture Awards 2013, this is a higher than expected number of breaches from Marine Harvest farms.
The S&TAS queried this ratio with SEPA who replied that: ‘the results are unlikely to be impacted by an artefact of the reporting or recording process’. [Ed: this trouble with plain English appears to mean that there is nothing in the reporting process that would skew the results against one salmon farmer.]
The reasons for the apparent problem associated with Marine Harvest fish farms are not known but one possibility might be that efforts being made by the company to reduce on-farm sea-lice numbers are having the unwelcome consequence of increasing the likelihood of breaches of chemical residue Environmental Quality Standards in sea lochs.
This is the Catch 22 of open cage intensive aquaculture.
Heavy sea lice infestation to which the dense populations in the the cages are very prone, presents a serious demonstrable threat to the sustainability of wild salmon and trout fisheries. Free swimming sea lice around the cages – often in waters through which migrating salmonids must travel – are a danger to adults but fatal to the vulnerable juveniles on which the futures of the fisheries depend.
But if the cage populations are treated with Slice drenching to keep the sea lice under control in the interests of wild fish, the sea bed residues in excess of the set standards threaten wild crustaceans, which are particularly susceptible to Slice, and therefore also to lobster, crab and creel fishermen operating in the loch systems where salmon farms are using emamectin benzoate.
The value of closed containment salmon farming
Hughie Campbell-Adamson, Chair of the S&TAS, identifies the issue and suggest the only feasible solution, saying:
‘What this shows is that not only is SEPA yet to get control of the chemical residue issue, but the apparent issue at Marine Harvest farms, which of course is yet to be bottomed out, could be due to efforts being made to control sea-lice on the farmed fish.
‘If it does turn out to be the case that efforts to control sea-lice are having a negative effect elsewhere, it may be impossible in practice to adequately control sea-lice on very high tonnage fish farms, down to a level which does not cause an unacceptable parasitic load on wild fish, while at the same time avoiding a threat to wild crustaceans, such as lobster, prawn and crab, upon which many inshore fishermen rely for their livelihoods.
‘The answer is clear. Again, the S&TAS would urge both Marine Harvest and the Scottish Government to start the move towards closed containment of all salmon farming.’
Not for the first time, it would appear that the Scottish Environmental Protection Agency has a serious case to answer for its neglect of the responsibilities on which its existence is assumed to rest.
Note: The list of salmon farms in breach of Environmental Quality Standards in sea-bed residues of mamectin benzoate is here: Annex.