- How many cages are there, and how many fish are in the cages when at maximum?
There are 18 pens permitted however the pens are not always all stocked with fish – for instance there are currently only 11 pens stocked. We follow the RSPCA welfare standards which have been developed to follow good practice in the care and welfare of commercially farmed Atlantic salmon at all stages of their lives. The maximum stocking density set by the standard is 8kg per cubic metre of water. Dependent on production inputs fish numbers can vary but are generally around 90,000 – 100,000 per pen.
- How long is the cycle from arrival to departure? – i.e., until they are big enough to have to be moved on.
Commonly, the cycle lasts from June to December, on occasion we have been stocked to February depending on the overall production needs of Mowi so approx. 6 – 8 months a year.
- How long is the fallow period between the fish leaving and a new cycle starting?
4 – 6 months depending on production.
- Do all of the cages follow the same cycle at the same time?
Yes, all pens follow same cycle.
- What are the elements of the feedstuff?
We tailor our feed ingredients throughout a salmon’s lifecycle to ensure we are meeting the nutritional needs of our fish. Generally, fish feed includes about 20% fish meal and fish oil, 20% vegetable oil, 20% wheat, 15% soya, and the remainder a mix of beans, peas, corn and vitamin supplements that includes astaxanthin (a naturally produced antioxidant). For full information see – Mowi’s 2021 Annual Report page 68. Link – Mowi_Annual_Report_2021.pdf
- Which medicines are used and what is an average quantity per cycle per cage?
As per our SEPA licence the site is permitted to use veterinary approved medicines containing Bronopol, Chloramine-T and Formaldehyde-based solutions. The limits and controls on use of medicines are set by SEPA to ensure environmental standards are maintained thus protecting water quality and ecology, and all use is audited by SEPA. For an example, formaldehyde, which is a naturally occurring compound in many biological systems, breakdowns rapidly in freshwater to harmless by-products. We are presently undertaking a scientific monitoring study examining the environmental fate and behaviour of formaldehyde solutions which is confirming the rapid breakdown of the product and compliance with environmental standards. Medicinal treatments are only carried out if there is a fish health reason and under veterinary supervision and often growth cycles can complete without the need for treatments. During 2022 the site has carried out six site treatments with Bronopol (10 litres is used per pen) and with Formaldehyde solution (50 litres is used per pen) to treat infections such as saprolegnia, a naturally occurring fungal infection found in wild fish in freshwater loch environments. Quantities of medicines used at our Loch Ness site are reported to SEPA on a quarterly basis, as per the standard reporting requirements in place for all fish farms.
- What other chemicals are used and what is an average quantity per cycle per cage?
SEPA permits a range of licensed substances such as anaesthetics, disinfectants, and detergents to be used at fish farms. As these substances are low in use and have very low environmental risk there are no specific controls or limits set regarding their use. Substances are used only if needed and more commonly applied at a site level as opposed to pen level, e.g. disinfectant footbaths used for site biosecurity or anaesthetics used to safely immobilise fish so they can be handled more easily during health checks. Quantities used are generally very low, as an example disinfectant use <15 litres per year.
- What is the cage cleaning regime, and is this when they are empty and what chemicals are used for this cleaning?
The site has a defined cleaning schedule, and this is carried out during fallow periods following guidance from Marine Scotland. Products used for cleaning and disinfection – Fat Solve and AquaDes – are on SEPA’s approved list for use at fish farms.
Best regards
Stephen
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Stephen MacIntyre
Head of Environment
Mowi Scotland Limited