Brazil’s Amazonas and Rondônia states – River communities along the Madeira River grapple with vanishing fish stocks years after the Santo Antônio hydroelectric dam reshaped the waterway.
A Stunning 90% Decline Grips the Madeira
A Stunning 90% Decline Grips the Madeira (Image Credits: Imgs.mongabay.com)
Fish populations in some locations dropped by as much as 90%, according to research grounded in local knowledge. Construction of the dam began in 2008, with operations starting in 2012. This infrastructure curtailed the river’s natural currents, vital for fish migration and spawning.
Riverine residents once relied on daily hauls for food and income. Today, traditional fishing grounds lie barren, compelling longer journeys and higher costs. The upstream Jirau dam, operational since 2013, compounded these pressures across 65 species.
Fishers’ Stories Reveal Daily Struggles
“Fish need currents to navigate. They don’t need still water, they need moving water. And the Madeira River stopped flowing,” fisher Raimundo Nonato dos Santos shared from Lago Puruzinho community. Species like pirarucu vanished from local waters, turning routine catches into rarities.
In Paraíso Grande, smallholder Maria Delci Barros de Morais described her sons’ futile investments in gear and ice. “After the power plants, the fish disappeared,” she noted. Indigenous leader Adriano Karipuna reported shifts from half-ton hauls in 30 minutes to mere handfuls after hours of effort in the Karipuna Territory.
Groundbreaking Study Born from Collaboration
Researchers from the Federal University of Amazonas partnered with over 120 fishers for a 2023 analysis. They compared daily landing data from 2009-2010 before full dam impacts with 2018-2019 records at Humaitá Fishing Colony.
The effort employed the TSBCAMPA method, capturing details on locations, times, costs, and species. Findings highlighted altered capture dynamics, with new grounds emerging amid losses in areas like Sossego, Trapicho, Lago do Caiarí, and Santa Júlia. Lead author Igor Lourenço emphasized shifts in spatial-temporal patterns over sheer volume drops.
An interactive dashboard now tracks ongoing data to inform management.
Ecological Shifts and Community Toll
Milky waters lingered for months post-dam, harming habitats. Orders like Characiformes and Siluriformes suffered reduced catches in former hotspots. Fishers adapted to 25 new sites, but communities faced protein shortages, turning to processed foods and facing health concerns.
The Santo Antônio reservoir covers over 54,600 hectares, yet operator Axia claims minimal hydrological interference and ongoing monitoring. Fishers pursue compensation through a pending lawsuit, backed by these findings.
Key affected species include:
- pirarucu (Arapaima gigas)
- tambaqui (Colossoma macropomum)
- pirapitinga (Piaractus brachypomus)
- Fish stocks fell up to 90% in impacted zones, disrupting livelihoods.
- Dam-altered flows changed fishing patterns, forcing adaptations.
- Collaborative monitoring offers hope for future policies and redress.
This crisis pits clean energy ambitions against Amazon biodiversity. Ongoing data collection could guide restoration efforts and fair compensation. What do you think about hydropower’s role in conservation? Tell us in the comments.
