Soluções construtivas e tecnologias amigáveis para peixes em hidrelétricas no Rio Tocantins com aplicabilidade ambiental

Abstract

The operation of hydroelectric power plants (HPPs) in the Tocantins River basin has led to recurring incidents of fish mortality, a significant environmental impact exacerbated by inadequate regulatory enforcement and the limited effectiveness of the state environmental agency, Naturatins, resulting in direct harm to local aquatic biodiversity. This study aimed to (1) examine fish-friendly technologies and solutions available in the scientific literature for mitigating the environmental impacts of hydropower projects; (2) investigate the existence and implementation of such technologies and design strategies in HPPs along the Tocantins River; and (3) identify the most appropriate alternatives based on the region’s ecological and hydrological characteristics. The findings highlight the potential of emerging technologies such as the Sensorfish and Gelfish monitoring systems, which provide real-time data on migratory behavior and hydraulic stressors affecting fish populations. Furthermore, fish-friendly turbine designs were identified, including the Archimedes Screw Turbine, suitable for low-head plants; the Alden Turbine, designed to reduce fish mortality in large-scale facilities; as well as modified Kaplan and Francis turbines, which feature structural adaptations to improve fish passage survival. Complementary mitigation measures were also analyzed, including Fish Passage Systems (FPS) such as ladders, elevators, nature-like fishways, and behavioral guidance systems that use sensory stimuli such as light and sound to direct fish toward safer migration routes. In the multiple-case study analysis, it was observed that, among the five hydroelectric plants examined along the Tocantins River, only the Peixe Angical and Lajeado plants were confirmed to have installed fish ladders; however, no technical data were found regarding their functionality or operational performance, underscoring the urgent need for systematic monitoring, technical validation, and site-specific application of these fish protection strategies.