This study investigated the relationship between the seasonal flow of the Madeira River with fish production and the effects of hydroelectric plants.
The installation and operation of the Santo Antônio and Jirau hydroelectric plants in Rondônia has resulted in irreversible changes to the Madeira River, one of the main tributaries of the Amazon River. The doctoral thesis of the biologist Maria Alice Leite Lima, recently defended at the Federal University of Rondônia (UNIR), explored these changes in regard to seasonal flows and fish populations.
The Madeira River is more than three thousand kilometers in length.
Lima’s dissertation, titled “The history of the ecosystem and fishery resources the Madeira River basin as it faces the implementation of hydroelectric dams “, aimed to analyze the effects of hydroelectric dams on the food interactions of the river species, while evaluating the influence of the hydrological level as it was altered by the dams, the fisheries catch, and the price of the fish to the final consumer.
Dr. Lima, who partners with the civil society organization Ação Ecológica Guaporé – Ecoporé, carried out data collection from 2009 to 2013, in addition to data provided by the Fishermen’s Colony Tenente Santana Z- 1 from 1990 to 2014. Her research demonstrated that the natural variations of the hydrological level strongly influences the life cycle of the most important species for commercialization. Consequently, artisanal fishing of the Madeira River is now irreversibly altered by the impacts of hydroelectric dams due to their impacts on Amazonian fish stocks, especially large migratory catfishes. These results, published in Ecohydrology, pointed out that the variation of the river level is fundamental in the structuring of fishing catch patterns, as Maria Alice explains: “The construction of dams, besides modifying the natural dynamics of ecosystems, directly affects the human populations which depend on fish stocks as a source of income and/or subsistence.” Lima’s dissertation was supervised by Dr. Carolina Rodrigues da Costa Doria from Federal University of Rondônia, Dr. Ronaldo Angelini from Federal University of Rio Grande do Norte (UFRN) and Dr. David Kaplan from University of Florida. Her research, the first of its kind in Brazil, used quantitative ecosystem models to analyze the fish stock and fishing economy to understand the impact of large hydroelectric dams on Amazonian rivers.
“We also identified changes in the price and quantity of the main fish species over 25 years, which allowed us to evaluate the effects caused by the construction of hydroelectric plants,” said Dr. Lima. This novel analysis showed a significant drop in artisanal fishery production, especially since 2009, while fish market prices increased approximately 50% (excluding inflation in the period). For catfish, which were a valuable source of income for riverine people the pattern is even more worrying, since in addition to the drastic reduction in catch and the increased prices, the dams impact their life cycle, since they use the Madeira River as migratory route for breeding.
According to the Dr. Lima, several studies have highlighted the challenges for management and evaluation of fish stocks and different models have been proposed. “The lack of data on inland fisheries makes it difficult to understand the effect of environmental changes on different processes, fisheries, and species. But thanks to the information from the Fishermen’s Colony, we have managed to overcome this challenge. ” The analyzes presented in her dissertation also support the idea that long-term fisheries monitoring is fundamental for understanding the changes that have occurred in fishing in relation to different impacts, despite the limitation of some fishing data. In addition, they can serve as a basis for understanding the changes in fisheries resulting from the recent construction of the Santo Antônio and Jirau dams in the Madeira River basin. According to Dr. Carolina Doria, the results collected from the research contribute directly to the orientation of public policies and the establishment of previous, consistent, and standardized studies in future hydroelectric projects in the Amazon. “In addition, it also helps to guide the application of this approach, which can predict impacts generated at ecosystem scale in aquatic environments.”
By Natália Lima