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Expanding aquaculture in the Amazon could provide nutritional and economic benefits at a fraction of the environmental cost of cattle grazing, according to a in Nature Sustainability from Cornell researchers and colleagues in the U.S. and Brazil. Such expansion could also come with risks, especially the potential introduction of harmful non-native species, the paper finds.

"Cattle production is one of the most important drivers of deforestation in the Amazon," said Felipe Pacheco, an Eric & Wendy Schmidt AI in Science Postdoctoral Fellow in the Department of Ecology and Evolutionary Biology. "Aquaculture produces 10 times fewer greenhouse gas emissions and uses 20–100 times less land than cattle production. We think the expansion of aquaculture could be an important tool to advance food security and sustainability in the Amazon."

Cattle grazing is responsible for about 80% of the deforestation that has occurred in the Amazon over the past 30 years. The loss of forest land in one of the most biodiverse landscapes on Earth has led to , and widespread forest burning to clear land for cattle has now caused the Amazon rainforest to become a net carbon emitter, rather than a carbon sink.

Modern aquaculture in the Amazon began in the 1980s, and it has become the fastest-growing animal-sourced food system in the five Amazonian countries included in the new study (Bolivia, Brazil, Colombia, Ecuador and Peru). However, total aquaculture production still pales in comparison to beef: in 2021, Brazil produced 120 thousand tons of fish from aquaculture, but of beef.

Expansion of aquaculture, though more sustainable than cattle production, would come with significant challenges, the authors find. Particularly around the potential introduction of invasive species and in land-use change. Tilapia, for example, is not native to the Amazon but is farmed in some Amazonian countries; tilapia can outcompete native species and damage river ecosystems, harming biodiversity.

Some aquaculture systems can also cause harmful land-use changes, especially when ad hoc ponds are created along streams, said Alex Flecker, paper co-author and professor of ecology and evolutionary biology. Such setups block normal stream connectivity—especially problematic in impeding fish movement—and introduce excessive nutrients to waterways, he said.

The authors advocate for five key principles to enable sustainable expansion of aquaculture in the Amazon:

• Policies that incentivize placing aquaculture farms on already degraded land.
• Using diverse species in aquaculture ponds to improve sustainability and resource efficiency.
• Enhancing equitable benefits sharing among producers and distributors.
• Improving information flow to benefit producers, markets, policy development and environmental assessment.
• Improving producers' access to technology and financial resources.

"These are big challenges," Flecker said. "If aquaculture is done well, both from an environmental and a socioeconomic perspective, there are all kinds of potential benefits out there, but there are also really big challenges to get it right."

This research is part of a broader effort to address sustainability challenges in food production systems in the Amazon by integrating cutting-edge computational tools to track aquaculture expansion, Pacheco said. The study exemplifies the collaboration between ecologists and computer scientists in developing innovative solutions for environmental monitoring and resource management, he said.