Publicado el 7 April, 2021 / News

Research and proposals for the management of Chilean salmon farming in times of global and local emergencies

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The pandemic situation that we are experiencing at a global level and the latest red tide (harmful algal blooms, HAB) events that affect the salmon industry have been addressed by INCAR from various perspectives with the intention of contributing to science and relevant knowledge for public policies in Chile and global level for greater sustainability of aquaculture.
In November 2020, the Chilean Ministry of Environment launched the national  climate atlas platform, ARCLIM (https://arclim.mma.gob.cl/ ) where INCAR develops the climate change  risk maps for salmon farming and mussel farming. One of the modules describe risk maps for HABs affecting salmon farming (https://arclim.mma.gob.cl/atlas/view/acuicultura_f_salmon_fan/ ) generated by a gradual reduction in rainfall, especially in northern Patagonia. The risk analysis considers the climate component as a threat but also includes some elements that make the system more susceptible to being affected, for example, the accumulated production or harvested  biomass  in the last decade in each neighborhood or ACS (salmon farming concession groupings) . In other words, those neighborhoods where there has been a greater biomass of farmed  salmon have loaded more nutrients to the ecosystem and this is always a risk factor for eutrophication, facilitation or triggering  algal blooms, oxygen reduction, etc. The current HAB event apparently due to Heterosigma akashiwo especially affecting the Comau fjord (ACS 17A) has undoubtedly been generated by the extreme and prolonged drought that we are experiencing, but we cannot rule out the role of additional nutrients in the ecosystem where salmon farming takes place. In addition, this is a neighborhood with a high concentration of production, which in the risk model is equivalent to high exposure, “you can lose a lot if something bad happens.” In other words, it is a perfect storm.
We could also mention that as a result of a joint effort of several Chilean centers and scientists led by INCAR and with the support of WWF-Chile, a proposal for an ecosystem approach to the assessment of salmon farming environmental performance was presented in January 2020 (https: //www.incar .cl / wp-content / uploads / 2021/01 / Revista.pdf). In this document, through scientific analysis we recommended to increase efforts towards the evaluation of the ecosystems that host salmon farming, with a risk approach leading to preventive measures. The preliminary assessment shows some water bodies including Estuary and Seno Reloncavi, Comau fjord in the Los lagos  region, and Cupquelan,  Quitralco, Puyuhuapi  fjords in Aysen region with higher levels of eutrophication risk. In the risk analysis, this is influenced by the higher biomass being farmed and accumulated (harvested), lower water circulation (equivalent to higher retention) artes  and the presence of hypoxic zones (low oxygen) below the 50 m depth in these water bodies. This information has been provided by IFOP’s CHONOS oceanographic program.  Coincidently, within the last week massive salmon mortalities have been also reported in Aysen region due to oxygen declines and possible HABs, mainly in ACSs in the aforementioned fjords, thus supporting our projections.
The proposal for the management of salmon farming with an ecosystem approach underscore the need for a permanent evaluation and monitoring of the environmental condition of water bodies (this is beyond farms) that host salmon farming leading to preventive measures adequately communicated. Other risk reduction measures must be considered, including the reduction of salmon production in those ecosystems mentioned.
It is necessary to review the spatial distribution of salmon farming and establish maximum allowed production in accordance with risk levels for both, the activity and for the ecosystem. It is necessary to consider the far side effects paying special attention to the carrying capacity of water bodies. This can be initially guided by oceanographic and productive evaluations as mentioned.
Our recent publication on the vulnerability of salmon farming to COVID also alludes to the components of risk for the industry and for the socio-ecological system and highlights the need for a strategic review of production and its distribution in the sea (https://authors.elsevier.com/a/1cqsT_,iw2HLG1).
The mentioned activities and products are generated to fulfil our main missions as a FONDAP center, “contributing with science of excellence to the priority development areas of the country ”.