
Unveiling the conditions inside salmon farms
The high environmental costs of sea cages
If consumers could see inside sea cages, there would be an outcry over the condition of farmed salmon. What they would witness are densely packed pens teeming with stressed, injured, and often dying fish.
Hidden from public view, sea cages are overcrowded and filthy – not to mention deadly.
According to a recent study in Nature, 865 million salmon died between 2012 and 2022 in salmon farms off the coasts of Norway, Canada, the U.K., Chile, Australia and New Zealand – countries that produced more than 92% of the world’s farmed salmon in 2021.1
These deaths weren’t random – they were driven by systemic failures across the industry. Cramped conditions, aggressive disease outbreaks, and poor environmental management continue to plague the sector. These deaths are a testament to the serious welfare concerns for farmed Atlantic salmon. They struggle to survive in overcrowded conditions that only encourage the uncontrolled spread of diseases, parasites and viruses.2, 3, 4
The dense stocking of fish in a confined space also creates an ideal environment for sea lice to proliferate exponentially, feeding on the skin of live salmon, with these parasites growing to unnaturally large sizes and causing severe injuries to the salmon.5 Viral outbreaks and bacterial infections spread rapidly in such conditions, further driving death rates skyward.6
Waste products from these operations – including feces, uneaten food pellets, and chemical treatments – are generally left unchecked in the waters beneath and around the cages. This sludge can be rich in antibiotics, pesticides, and anti-parasitic drugs, which are routinely added to the feed or directly administered into the water. This waste accumulates in the surrounding water, harming the health of the fish and nearby marine ecosystems.7, 8
The reality inside open net-pen salmon farms is grim – and largely invisible to the public eye. With millions of fish dying each year due to overcrowding, parasite infestations, and polluted environments, it’s clear that the welfare of farmed Atlantic salmon is being sacrificed for profit. Until there is meaningful transparency and a shift toward more responsible practices, the true cost of farmed salmon will continue to be paid not at the checkout counter, but in the suffering of the animals we never see.
In-text Citations:
- Singh, G. G., Sajid, Z., & Mather, C. (2024). Quantitative analysis of mass mortality events in salmon aquaculture shows increasing scale of fish loss events around the world. Scientific Reports, 14. https://doi.org/10.1038/s41598-024-54033-9
- Krkošek, M. (2010). Host density thresholds and disease control for fisheries and aquaculture. Aquaculture Environment Interactions, 1, 21–31. https://doi.org/10.3354/aei0004
- Lafferty, K. D., Harvell, C. D., Conrad, J. M., Friedman, C. S., Kent, M. L., Kuris, A. M., Powell, E. N., Rondeau, D., & Saksida, S. M. (2015). Infectious diseases affect marine fisheries and aquaculture economics. Annual Review of Marine Science, 7, 471–496. https://doi.org/10.1146/annurev-marine-010814-015646
- Salama, N. K. G., & Murray, A. G. (2011). Farm size as a factor in hydrodynamic transmission of pathogens in aquaculture fish production. Aquaculture Environment Interactions, 2, 61–74. https://doi.org/10.3354/aei00030
- Kent, M. L. (2000). Marine netpen farming leads to infections with some unusual parasites. International Journal for Parasitology, 30(3), 321–326. https://doi.org/10.1016/S0020-7519(00)00018-7
- Kennedy, D. A., Kurath, G., Brito, I. L., Purcell, M. K., Read, A. F., Winton, J. R., & Wargo, A. R. (2016). Potential drivers of virulence evolution in aquaculture. Evolutionary Applications, 9(3), 344–354. https://doi.org/10.1111/eva.12342
- Ortiz-Severín, J., Hodar, C., Stuardo, C., Aguado-Norese, C., Maza, F., González, M., Cambiazo, V. (2024). Impact of salmon farming in the antibiotic resistance and structure of marine bacterial communities from surface seawater of a northern Patagonian area of Chile. Biological Research, 57(1). https://doi.org/10.1186/s40659-024-00556-4
- CBC. (2013, April 26). Aquaculture company on the hook for $500K for pesticide use. https://www.cbc.ca/news/canada/new-brunswick/aquaculture-company-on-the-hook-for-500k-for-pesticide-use-1.1317105
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