
Sea Cages are in Bad Company
Here’s why salmon farming qualifies as a harmful industry
We all know a harmful industry when we see it.
It’s one that prioritizes corporate profit over environmental protection. It jeopardizes the health of its workers and sacrifices the wellbeing of their communities. It promotes the overconsumption of harmful substances and turns a blind eye to consumer protections.1, 2
It looks like the petroleum industry, the tobacco industry, the alcohol industry, fast fashion and gambling. It is also shaped like a sea cage.
Thousands of these underwater mesh enclosures litter our oceans, with significant environmental and social consequences, positioning aquaculture as a harm industry.3, 4
These sea cages allow waste, excess feed, chemicals and diseases to flow directly into surrounding marine environments, degrading water quality and harming wild fish populations. 5
Escaped farmed salmon can interbreed with wild salmon, weakening genetic diversity and threatening already fragile populations.6, 7, 8, 9
Additionally, sea cages are often established near coastal communities, impacting local fisheries, which depend on healthy ecosystems for their livelihoods.1, 5
While aquaculture companies often frame salmon farming as a boost to local economies, especially in rural and coastal areas, the full picture is less rosy. Sea cage farming can cause damage to other fisheries. For example, in 2013, aquaculture companies were charged with dumping large amounts of illegal chemical and pesticide sea lice treatments that killed nearby lobster populations in New Brunswick, Canada.10
In many communities, profits from open net-pen salmon aquaculture operations flow out to large multinational corporations, while the long-term economic risks—declining tourism, reduced wild fisheries, and degraded marine ecosystems—remain local.
The industry’s growth has been made possible through active repositioning of the governing body to simultaneously serve as regulator, investor, and development advocate for the private sector. Governments have redirected public resources and regulatory flexibility in order to create favorable conditions for private aquaculture companies. This is especially problematic when decisions are made based on economic interests alone.11
By prioritizing industrial production over ecological sustainability, the sea cage industry poses a serious threat to marine ecosystems, traditional fisheries and the communities that rely on them.12, 13, 14
In-text Citations:
- Burridge, Les & Weis, Judith & Cabello, Felipe & Pizarro, Jaime & Bostick, Katherine. (2010). Chemical use in salmon aquaculture: A review of current practices and possible environmental effects. Aquaculture. 306. 7-23. 10.1016/j.aquaculture.2010.05.020.
- Thorstad, E.B., et al. 2008. Incidence and impacts of escaped farmed Atlantic salmon Salmo salar in nature. NINA Special Report 36. 110 pp.
- Sandra, M.; Devriese, L.I.; De Raedemaecker, F.; Lonneville, B.; Lukic, I.; Altvater, S.; Compa Ferrer, M.; Deudero, S.; Torres Hansjosten, B.; Alomar Mascaró, C.; Gin, I.; Vale, M.; Zorgno, M.; Mata Lara, M. (2020). Knowledge wave on marine litter from aquaculture sources. D2.2 Aqua-Lit project. (Updated version). Flanders Marine Institute (VLIZ): Oostende. 136 pp.
- Skirtun M, Sandra M, Strietman WJ, van den Burg SWK, De Raedemaecker F, Devriese LI. Plastic pollution pathways from marine aquaculture practices and potential solutions for the North-East Atlantic region. Mar Pollut Bull. 2022 Jan;174:113178. doi: 10.1016/j.marpolbul.2021.113178. Epub 2021 Dec 2. PMID: 34864468.
- Page, F., Haigh, S., and O’Flaherty-Sproul, M. 2023. Potential Exposure Zones for Proposed Newfoundland Marine Finfish Salmon Aquaculture Sites: Initial First Order Triage Scoping Calculations and Consistency Comparisons. DFO Can. Sci. Advis. Sec. Res. Doc. 2023/071. iv + 80 p.
- McGinnity P, et al. 2003. Fitness reduction and potential extinction of wild populations of Atlantic salmon, Salmo salar, as a result of interactions with escaped farm salmon. Proc R Soc Lond B Biol Sci 270: 2443–2450.
- Bourret V, O’Reilly PT, Carr JW, Berg PR, Bernatchez L. 2011. Temporal change in genetic integrity suggests loss of local adaptation in a wild Atlantic salmon (Salmo salar) population following introgression by farmed escapees. Heredity, 106, 500–510.
- Bradbury IR, Duffy S, Lehnert SJ, Jóhannsson R, et al. 2020. Model-based evaluation of the genetic impacts of farm-escaped Atlantic salmon on wild populations. Aquacult Environ Interact, 12:45-59.
- Glover, K.A., Pertoldi, C., Besnier, F., Wennevik, V., Kent, M., and Skaala, Ø. 2013. Atlantic salmon populations invaded by farmed escapees: quantifying genetic introgression with a Bayesian approach and SNPs. BMC Genetics, 14:4.
- https://www.cbc.ca/news/canada/new-brunswick/aquaculture-company-on-the-hook-for-500k-for-pesticide-use-1.1317105
- https://www.sciencedirect.com/science/article/abs/pii/S0308597X16306777
- Karlsson, S., Diserud, O.H., Fiske, P., and Hindar, K. 2016. Widespread genetic introgression of escaped farmed Atlantic salmon in wild salmon populations. ICES Journal of Marine Science, 73(10), 2488–2498.
- Sylvester, E.V.A, B.F. Wringe, S.J. Duffy, L.C. Hamilton, I.A. Fleming, M.Castellani, P.Bentzen, I.R. Bradbury. 2019. Estimating the relative fitness of escaped farmed salmon offspring in the wild and modelling the consequences of invasion for wild population. Evolutionary Applications, 12(4): 705-717.
- Wringe, B.F., Jeffery, N.W., Stanley, R.R.E. et al. 2018. Extensive hybridization following a large escape of domesticated Atlantic salmon in the Northwest Atlantic. Commun Biol, 1, 108.
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