Is Salmon Farming a 'Dead Loss'?

Salmon farming is one of Scotland's largest sources of revenue (bringing in about £2bn per year). The 'Dead Loss' report by the Just Economics group suggests, however, that this activity has substantial costs for marine life (https://www.theguardian.com/environment/2021/feb/11/global-salmon-farming-harming-marine-life-and-costing-billions-in-damage). The report notes that fish mortality, in Scottish salmon farms, increased from 3% in 2002 to almost 13.5% in 2019. Most of the deaths were linked ectoparasitic sea lice infestations. Salmon that are not killed by sea lice in the farms can still be damaged by these pests. The salmon farms can also act as sources of parasitic infestation for wild fish. The 'Dead Loss' report also notes that 20% of wild fish are actually caught to make fishmeal and fish oil. This results in over-fishing in some parts of the world (e.g. sardine stocks around Africa). The report claims that 70% of this fishmeal and fish oil is used to feed salmon in the fish farms. The balance sheet, looking at profits versus environmental costs, seems progressively more shaky.