Publicado el 28 March, 2024 / News

Permanent assessment and care of the health of marine ecosystems where salmon farming takes place is key to demonstrate the sustainability of the sector

Currently, any economic activity that wants to contribute to the country’s progress towards the Sustainable Development Goals (SDGs), must ensure its environmental, economic, and social sustainability and it is especially important for salmon farming because the activity (the fattening part) takes place in the marine environment, a national asset of public use, and administered by the state.

The possible environmental impacts of intensive salmon farming are several[1], including salmonid escapes (which are exotic species and all potentially invasive), the use of antibiotics and pesticides, nutrient inputs to the water column and sediments with potential risk of local and larger scale eutrophication, negative interactions with marine mammals, among others. The most complex aspect is that these problems affect the relationship between salmon farming and broad sectors of the community and citizens in general, who see the activity as a source of negative externalities without an effective management.

On the other hand, this industry has advanced significantly in the last decade in innovation and improvements in production and environmental performance. It is estimated that more than 90 % of the innovation that has been carried out in global aquaculture comes from the salmon farming sector. At the AQUASUR fair that took place in Puerto Montt these days, with an estimated attendance of more than 22 thousand people, we saw some of the most innovative technological advances in food production at a global level, advances that should undoubtedly contribute to sustainability.

However, innovation and technological advances are not enough to ensure production and development without tipping the equilibrium of natural ecosystems. It is necessary to promote and improve public policies that support permanent environmental monitoring at the scale of ecosystems and ensure that they remain healthy and can support the production of farmed salmon, and this must be done based on clear, accessible, and transparent scientific information.  An ecosystem integrated monitoring system would be an important advance towards the social acceptance of salmon farming, to the extent that its outputs and information are communicated in a timely manner and the management of the sector responds effectively to such assessment.

As an example, recent innovations such as the use of micro-nanobubbles and other mechanisms to ensure the removal of organic waste and oxygenation of the bottom under farming cages are becoming very popular. Such innovations respond, in part, to a recent regulation that requires salmon farms to avoid or reduce, as appropriate, the deposit of organic waste at the bellow the farming area. This seems to be an excellent idea to minimize impacts on benthic ecosystems; however, there is insufficient scientific support to show the effects of these mechanisms at the farm scale, nor at the ecosystem scale. Indeed, bubble systems and other micro-oxygenation mechanisms would facilitate the dispersion of organic matter beyond the boundaries of the concessions and the transformation and availability of dissolved nutrients in the receiving water body. This highlights the fact that each farm requires ecosystem services that go far beyond the area of its concession, in this case to disperse organic matter and nutrients dissolved in the receiving water body. This confirms a common mistake to assure that the marine area used by salmon farming in southern Chile is only the sum of the area corresponding to the active concessions. The problem is that we do not know if these nutrient outputs that are dispersed by the mentioned mechanisms are integrated in a balanced way to the ecosystems normal functioning,  for example increasing their productivity, or if they cause damage and to what degree, by cumulative effect, a dilemma that becomes more crucial in the face of climate change[2], particularly when organic matter could be accumulating, far beyond cages, in the deepest parts of fjords and channels.

On the other hand, regarding the risks from the use of antibiotics, the industry has made a great effort to reduce the use per ton of salmon produced; however, from the perspective of ecosystems, what is important is the total amount that enters and the processing and dilution capacity of these. The effects at this scale are still unknown, although there are some research progresses.

Yet there are advances that promise to reduce the use of antibiotics and pesticides, for example, by increasing the production of Coho salmon, which allows reducing the monoculture of Atlantic salmon, should lower, to certain extent, the sanitary risks and, therefore, the use of these products, a great advance!  Unfortunately, the solutions are not perfect, as Coho salmon present greater environmental risks from escapes. In extensive comparative risk reviews, we have shown that there are watersheds and ecosystems more susceptible to be colonized for the reproduction of these species, for example, south of Aisén and in Magallanes. Therefore, it is necessary to implement permanent monitoring systems to identify the presence of these species at an early stage and ensure their eradication. Here again a clear definition and position of the government and society is needed, since it is contradictory to protect exotic species for the benefit of recreational fishing, which generates local social benefits, while at the same time fighting them as invasive species.

Clearly, salmon farming should continue to provide employment and development, hopefully in a more equitable way and with positive local effects, but within the ecological and social capacities of the ecosystems. Therefore, it is urgent to increase research efforts and funding associated with integrated permanent monitoring systems (including oceanographic, biological, and considering  key biodiversity variables) of the health of the main water bodies that support the sector. This is necessary to establish a secondary standard or system based on ecological indicators (traffic light system) to regulate maximum production at this scale. Simultaneous monitoring of marine protected areas is also necessary, in this case to compare with those being used by salmon farming.  In this way we will be able to promote more effective conservation of biodiversity and ecosystem services, while giving more confidence to society and the productive sector itself. A system of this type will possibly allow to disregard or confirm some myths about the impacts of the activity and should also facilitate the shared use, circular economy, and associativity of the users of these ecosystems, for example, through a multi-trophic spatial integration of crops (e.g. salmon-mussels-seaweed) and artisanal fisheries.

The Interdisciplinary Center for Aquaculture Research (INCAR) has made an initial proposal and roadmap to establish a traffic light system[3], and we continue research to offer a more specific technical proposal that we hope will be a relevant contribution to the future Aquaculture Law. Undoubtedly, in the medium to long term it is also necessary to establish and improve a system of integrated evaluation of socio-economic benefits vs. externalities to decide on the presence and magnitude of salmon farming and other productive activities at local, regional, etc. scales, fed with the best science and quality information and with responsible citizen participation, through processes promoted by the government.

Making balanced progress towards the achievement of the SDGs, seeking a balance between poverty reduction with local development and biodiversity conservation, is one of the most relevant challenges facing all human societies today. This is what we must address in transparent, honest, constructive, and collaborative spaces, thinking about the present and the future we want as a society and as a healthy planet.  The announced preparation of a new specific Aquaculture Law by the government offers a tremendous challenge and an opportunity to do better, which we cannot miss.


Dr Doris Soto

Principal Scientist

Interdisciplinary Center for Aquaculture Research