In the Amazon region, a high global value conservation area, the production of farmed fish requires much less land than cattle farms and provides low-carbon source of protein when compared to beef. Overall, aquaculture in the Amazon region has not developed to the extent that it has outside the Amazon River watershed, where exotic tilapia is the most farmed species. In the Brazilian Amazonian region, the farming of tilapia is not allowed or not encouraged due to its high risk as an invasive species. While the aquaculture of native species, especially characins, offers an opportunity with lower potential impacts on local biodiversity, the farming of these species tends to be less efficient than the farming of tilapia, making them less competitive as an option for farmers.
Here we used a semi quantitative approach to evaluate risks for freshwater fish biodiversity associated with aquaculture in Brazilian Amazonia districts (“Estados”). The objective being to explore risk components and ways that those risks might be minimized, as well as exploring opportunities for farming of native species vs tilapia farming and other human perturbations that are threatening fish biodiversity. Here we defined risk as a function of hazard, sensitivity, and exposure. Hazard (or potential harm) was estimated from the current production of farmed fish normalized by the area of the district. Sensitivity included characteristics of the ecosystems that make them more susceptible to negative outcomes associated with aquaculture such as a high rate of deforestation already affecting aquatic ecosystems, and large urban and suburban developments. Exposure refers to the extent of biodiversity that can be lost due to aquaculture and was represented by a simple account of fish species richness and endangered species per watershed area for each district.
Our analysis suggests that native fish farming could generate comparatively higher risks in Tocantins, Rondônia, and Acre but for different reasons. Risks in Tocantins and Acre are related to a high exposure, as fish richness per area of the watershed in these states is very large. Rondônia by contrast has elevated risk because fish farming per watershed area, is larger. However, if aquaculture in these states were to proceed and was to be very well managed, it could provide food and alternative livelihoods with little negative impacts in those same states – and could perhaps help to reduce deforestation as livelihoods are diverted towards aquaculture. Thus, this approach provides a multidisciplinary framework to understand and compare risks component and could contribute to design pathways and additional opportunities for sustainable native species farming in the region.