Dilution and dispersion

Sir, My letter in the Banner last week has prompted a number of questions about other fish farms in the Clyde. What quantities of waste is discharged into the entire Clyde Estuary by salmon companies? Does any other company use simple dilution and dispersion rather than treatment to dispose of industrial wastes?

The Firth of Clyde ‘hosted’ 17 farms in 2016, the last reported number, with a total of 23,780 tonnes of maximum biomass licenced. Of these farms 15 are owned and operated by The Scottish Salmon Company (SSC) in Loch Fyne, Loch Striven, Kyles of Bute and Lamlash Bay; two, in North and South Carradale in Kilbrannan Sound, are owned and operated by Marine Harvest licensed for 2,500 tonnes each, so a total of 5,000 tonnes biomass. So SSC has licenses for 18,780 tonnes of salmon biomass in the Clyde alone. For further information on other fish farms owned by SSC see www.aquaculture.scotland.gov.uk.

Whilst individual farms vary in licenced biomass the total content from the present 17 farms of discharges into the Firth of Clyde and its sea lochs for the years 2014, 2015, and 2016 approximate to the following:

*38 tonnes of total copper from feed and nets.

*4 tonnes of zinc from feed.

*1,539 tonnes of nitrogen as ammonia and urea.

*212 tonnes of phosphorus as phosphate.

*4,939 tonnes of total organic carbon

It is surely time to look carefully at bioaccumulation of wastes and effects of treatment chemicals used in aquaculture on the ecosystem.

Now, there are also plans to discharge Isle of Arran distillery waste into Kilbrannan Sound. Again the principle of using dilution and dispersion to dispose of industrial wastes was rejected a number of decades ago when it was realised that so-called assimilation by the natural environment in this way is invariably accompanied by a detrimental cost paid by all of us in society through damage to very ecosystems that we are ultimately dependent upon.

The report submitted, in support of an application for the right to discharge, states that the chemical oxygen demand (COD) organic content in the effluent is to be around 1.9 tonnes/ day and this is equated in sewage COD content terms to a community population of 9,729 people, a not insignificant quantity, greater indeed than Arran’s population. The discharge pipe is to be located by the roadside in one of the most beautiful stretches of the west coast of Arran north of Thunderguy and south of Catacol.

On land, almost all industries with waste to treat do so within their boundaries or pay water companies for treatment as a service. Farmers, particularly livestock farmers and, increasingly, intensive units, also are having to contain and treat their wastes.

It is ironic that recently I read that Rough Guides announced Scotland is the most beautiful country in the world. Not so beneath the waves of the Clyde or sea lochs around the west of Scotland – or is beauty only in the eyes of the beholder?

Yours,

Dr Sally Campbell Lamlash