Squeezed in 3x more tightly than RSPCA standards

The amount of fish that can be kept together in a given volume is referred to as the stocking density.

The stocking density being proposed by Loch Long Salmon would be 48 (1kg) fish per cubic metre.

Compare that to RSPCA Assured farms, which is limited to 15 kilos per cubic metre. Or even to non-RSPCA Assured farms, where the maximum stocking density is between 20 and 25 kilos of salmon per cubic metre of water.

There is clear evidence that stocking density is an important factor in fish welfare, and that intensively reared fish can be subject to significant physical damage including skin lesions and fin erosion. Even at the stocking densities on existing farms, the Scottish Government Fish Health Inspectorate has found examples of horrific skin damage from fish rubbing against nets, as reported in The Ferret following a Freedom of Information request [1].

A scientific report by the Norwegian University of Science and Technology [2] states that "Many hypotheses have suggested that both fin erosion and body lesions can have a common cause: general water quality, superpopulation in the tanks…".

In their report "Closed Waters: The Welfare of Farmed Atlantic Salmon" [3], Compassion in World Farming explain that "Crowding is a stressful procedure that may cause lesions in fish and is a prime cause of poor welfare (Wall, 2000).  The main problem is a lack of sufficient oxygen in these densely packed conditions as well as elevated levels of ammonia.  The low oxygen levels can result in an increase in excitability, which in turn can lead to an even faster decrease in oxygen levels.  The increase in excitability can lead to damage to scales, skin ulceration, eye and snout damage and bruising (Wall, 2000).  Moreover, aggression between large and small fish is probably more frequent in the confined areas of crowding."

The developer’s requirement to drive profits for their investors will be to the total detriment of fish welfare. In the worst case it may lead to the same catastrophic disaster that befell the fish in Clayoquot Sound in Canada where, in the same type of farm proposed for Loch Linnhe, the fish died due to a lack of oxygen in their own urine after equipment failed.

References

[1] https://theferret.scot/

[2] https://ntnuopen.ntnu.no/ntnuxmlui/bitstream/handle/11250/245558/754713_FULLTEXT01.pdf?sequence=2&isAllowed=y

[3] https://www.ciwf.org.uk/media/3818650/closed-waters-welfare-of-farmed-atlantic-salmon.pdf