State institutions publish data for medication used on open-pen salmon farms

Based on Norwegian usage (see reference below), 6,597kg formaldehyde would be required to treat surface infections in the freshwater stage for the projected production of 200,000 tonnes of farmed salmon in the Falkland Islands.
According to the Norwegian Institute of Public Health, 53,105kg of formaldehyde were used in 2023 in Norway as agents for surface infections in freshwater farmed fish.
Norwegian Institute of Public Health
Based on Norwegian usage (see reference below) 195,155kg of hydrogen peroxide would be needed as sea lice treatments for the projected production of 200,000 tonnes of farmed salmon in Falklands waters.
According to the Norwegian Directorate of Fisheries Statistic Booklet 2023, Norwegian salmon production required 1,571,000 kg of hydrogen peroxide in 2023.

Based on figures from the Scottish Environment Protection Agency, approximately 8000 tonnes of hydrogen peroxide were discharged into Scottish waters per annum to produce 200,000 tonnes of farmed salmon – which is the projected potential production Unity Marine Ltd suggests for Falklands waters. Reference

The pesticides azamethiphos and emamectin benzoate are regularly used as sea lice treatments at salmon farms in the Faroe Islands. Reference

"‘The Marine Research Institute has pointed out in comments to the Fish Disease Committee and the Food and Veterinary Authority that the institute expresses its concerns about the effects of these drugs [chemical sea lice treatments] on wild animals – especially crustaceans – in fjords where the drugs are used. It is also pointed out that these wild animals are important in the fjord food web,’ says Rakel Guðmundsdóttir, PhD in Biology and expert at the Marine Research Institute in environmental issues of aquaculture and project manager for the fjord carrying capacity assessment.” Reference

“Although emamectin is assessed to have a low effect, the knowledge is weak, and many treatments will increase uncertainty and thus the risk. The use of deltamethrin and flubenzurons [also anti-lousing agents] in the summer provides a high probability of severe effects on non-target species; increased use of these delousing agents will lead to increased risk.”
Risk report Norwegian fish farming 2024 published by the Norwegian Institute of Marine Research
“Hydrogen peroxide is highly damaging to kelp and shrimp; with impacts on the latter occurring up to 1km away from a treated salmon farm.” Reference
“Finally, it is emphasised that the lack of knowledge in the form of limited monitoring data and research means that we can say little about possible effects of, for example, nutrients, particulate organic material, copper, or delousing agents from fish farming on vulnerable habitats such as mearl beds, eelgrass beds, and kelp forests.”
Risk report Norwegian fish farming 2024 published by the Norwegian Institute of Marine Research

Tonnes of medication are used on open-pen salmon farms