Regulating ‘fish out of place’: can policy mitigate the problem of farmed salmon escapes?

To develop sustainably, the ocean (blue) economy must balance the opportunities and impacts of the marine sector, ensuring that resources are used effectively without compromising the health of ecosystems. Aquaculture (fish farming) stands to play a core role in this growing economy by providing nutritious and low-carbon protein to meet global demand, and its sustainable development is a key objective in the EU’s common fisheries policy (CFP). This policy package aims to increase the productivity, resilience and sustainability of European fish markets while protecting marine ecosystems and continuing to push for climate neutrality in the sector (as per the European Green Deal).

In salmon aquaculture, one problem that must be addressed is the escape of farmed fish from open net-pens into the ocean. This occurs via both continuous low-level leakage and in larger numbers when pens collapse. It is driven by a mix of infrastructural, weather-related and human factors, say researchers behind a new study.

Escaped fish can negatively affect wild salmon by increasing competition, predation, transmission of disease and interbreeding. This may impact the longer-term fitness of wild fish and cause genetic introgression[1] – which has been found in wild Atlantic salmon populations known to be vulnerable to species hybridisation, say the researchers. Escapes can also trigger conflict between small-scale fishers and larger companies, as escaped fish remain the property of the aquaculture company.

Work in the early 2000s found that policies were insufficient to support sustainable development of aquaculture in the North Atlantic[2]. This new study builds on and updates this analysis, providing a detailed review and critical assessment of escape policies in 14 regions of salmon production around the world, including one EU country, Ireland. The insights are applicable to other types of aquaculture and other European countries too.

The analysis draws from diverse sources (government policy documents, non-governmental organisation reports and industry news articles) to assess the environmental impact and policy response to salmon escapes. The authors identify the top production regions for farmed salmon by volume, and their associated regulatory systems in 10 countries, using the FishStat database from the Food and Agriculture Organization (FAO) of the United Nations[3]. They look at regulation across five areas: the regulatory framework governing farmed fish escapes, the production requirements for aquaculture, reporting and recapture regulations, monitoring requirements, and sanctions or penalties in place for non-compliance.

Encouragingly, all 14 regions have specific measures in place to address escapes, reflecting that this remains an area of concern for regulators – although these measures do vary significantly in focus, scope and stringency. A notable development is the introduction of ‘codes of containment’ in many regions, regulations that govern escapes and the containment of salmon in ocean net-pens. This suggests that regulators are considering different tools to manage and limit escapes. Regulations not specifically aimed at fish escapes are also sometimes invoked, for example policies regulating environmental pollution or clean water.

Some level of fish escape is inevitable in open-net aquaculture, and so most frameworks aim to reduce escapes rather than eliminate them entirely. This constrains their effectiveness, say the researchers. Many regions have policies that are unlikely to significantly reduce the number or environmental impact of escapes, either due to lack of specificity, weak sanctions, a misplaced emphasis on monitoring or reporting over prevention, or provisions that allow companies to be absolved of responsibility. Some policies aim to reduce the number of escapes by requiring suitable nets and regular net maintenance, but do not address environmental impact post-escape through, for example, requirements on using triploid or sterile fish that cannot breed with wild fish. The study maps out existing policy measures based on these two priorities – reducing escapes and reducing environmental impact – offering insights into which combination of mechanisms may be most effective as part of a regulatory framework.

One country that has experienced significant escapes in previous decades, Chile, has responded by implementing a very strict regulatory system with substantial fines and company obligations. This is notable; most production regions do not have obligations or formal sanctions, and where these do exist, they vary significantly and remain disproportional to the ecological and socioeconomic risk of fish escapes, say the researchers. 

Chilean researchers have proposed an approach of co-management of fish escapes between stakeholders, such as governments, industry and anglers, to increase cooperation and chances of recapture, and to limit environmental impacts.

The authors also touched upon a perspective present in some industry circles: that ocean ecology and species, including wild salmon, have been irrevocably altered following many years of human activity, and there has been a view by some that escapes do not warrant significant concern. However, the authors concluded that this argument was not broadly supported either governmentally or scientifically, due to broader concerns around disease transmission and ecological change (not limited to genetic introgression). Escapes remain perceived as ‘fish out of place’.

https://doi.org/10.1016/j.marpol.2024.106572

Reference:

Jalili Kolavani, N. and Mather, C. (2025) Regulating a ‘fish out of place’: A global assessment of farmed salmon escape policies and frameworks. Marine Policy 173 (2025) 106572.

[1] Also known as backcrossing, this is where hybrid fish (in this case farmed) breed with (wild) fish from the original gene pool, changing the wild gene pool make-up over time with potentially negative effects. See: Bolstad, G.H., Karlsson, S., Hagen, I.J., Fiske, P., Urdal, K., Sægrov, H., Florø-Larsen, B., Sollien, V.P., Østborg, G., Diserud, O.H. and Jensen, A.J., 2021. Introgression from farmed escapees affects the full life cycle of wild Atlantic salmon. Science Advances, 7(52), p.eabj3397.

[2] R. Naylor, K. Hindar, I.A. Fleming, R. Goldburg, S. Williams, J. Volpe, et al.,

Fugitive salmon: assessing the risks of escaped fish from net-pen aquaculture,

Biosci. 55 (5) (2005) 427. Available from: https://academic.oup.com/bioscience/article/55/5/427-437/226100 

[3] https://www.fao.org/fishery/en/fishstat