A study on fish eggs and larvae drifting in the Jirau reservoir, Brazilian Amazon

Jirau hydropower plant (Jirau HPP) is one of the largest scale run-of-river hydro-projects in the Madeira River, Brazilian Amazon. This project has attracted strong national and international attention, especially with respect to environmental issues, because the Madeira River supports a diverse fish species. Many of these are migratory species and impact the reproductive stocks of the fishes that live in the Amazon River. Numerical simulations to predict fish eggs and larvae drift have been scarce in hydropower plant studies in the Amazonian rivers. In this paper, we investigate the fish eggs and larvae drifting behavior in the backwater of the Jirau HPP. The model used simulates the fish eggs as passive particles, and adopts a second-order Lagrangian scheme coupled with a hydrodynamic model of SisBaHiA. The results obtained show that the transport of fish eggs in the Jirau reservoir is controlled mainly by hydrodynamic and the morphology of the run-of-river reservoir and that the fish eggs and larvae in the reservoir have a short residence time, and that the drift is continuing and unhindered. We observe, however, more studies are needed to have a whole understanding of eggs and larvae drifting in the Jirau reservoir.