Nearly 2M metric tons of wild fish used to feed Norwegian farmed salmon annually

Environmental and Ecological Impacts of Farmed Salmon

• Many see marine fish-farming as ecological “scorched earth”: parasites and disease from dense open-net pens spread to wild salmon, weakening or collapsing local runs (e.g., BC, Norway).
• Waste feed and excrement accumulate under cages, shifting biodiversity toward pollution-tolerant invertebrates and degrading surrounding waters; nearby wild fish can become abnormally fat and off-tasting from eating pellets.
• Use of small “forage” fish as feed is criticized as turning edible wild fish (e.g., sardines, mackerel) into less-tasty farmed salmon, and hollowing out local food security in poorer regions.
• Some argue certain small species are ecologically problematic and that fishmeal refines “low-value” biomass into higher-value food; others counter that this ignores food-web disruption.

Efficiency and Numbers Debate

• The report’s claim that ~2M tons of wild fish produce less mass of farmed salmon triggers skepticism about methodology and wording.
• Several note that all animal farming is thermodynamically inefficient (more biomass in than out); the real issue is using directly-edible fish as feed rather than inedible inputs.
• Others question whether the small fish used are truly “edible quality,” with conflicting assertions and some data (in other languages) that many are indeed desirable food fish.

Impacts on Wild Salmon and Coastal Communities

• Open-net farms are blamed for sea lice and disease burdens on migrating wild salmon; some regions report wild stocks rebounding after farm closures.
• Local pollution and visual impacts (e.g., bays fouled with scum) fuel opposition where farms were politically approved despite poor flushing conditions.
• There are concerns about seafood fraud: farmed fish sold as wild, especially in restaurants.

Proposed Solutions and Alternatives

• Suggested policy tools: larger no-fishing zones, territorial limits with enforced quotas, and global sustainable catch caps—though enforcement (especially against distant-water fleets) is seen as politically difficult.
• Technical alternatives include land-based/inland salmon farms and replacing fishmeal with insect meal or GMO/algæ-based oils, but these face cost, availability, and consumer-perception barriers.

Broader Food-System and Diet Discussion

• A large subthread argues that individual diet (less meat, more plant protein like soy/legumes) is among the most impactful personal climate actions.
• There is tension between cultural attachment to meat/fish, moral arguments, and calls to price in externalities rather than rely on voluntary behavior change.