Fish Ladder at the Baguari Dam, Doce River, Brazil: Analysis of Passage Metrics to Evaluate Post-Construction Issues

Fish passage is an important management tool to minimize hydropower impacts on fisheries. However, passage provisions are often installed without specific criteria in Brazil, with consequences for fish conservation. Collection of data from existing fish passage deployments can help define new operational rules and influence designs for future hydro facilities. Accordingly, the fish ladder at Baguari Dam was evaluated regarding fish temporal distribution, attraction, and ascension. Fish were collected downstream of the dam and inside the ladder from 2010-2011. Seasonal variation in abundance and richness was recorded with higher numbers of migratory fish collected during reproductive seasons (Kruskall-Wallis, p = 0.04 and p = 0.05). Furthermore, higher concentrations of migratory non-native and non-migratory species were recorded for the spill bay (Wilcoxon, p = 0.009 and p = 0.006) compared to the tailrace and ladder. Results indicate low efficiency/attraction by the ladder and suggest operations only during the reproductive season. More precise evaluation tools (e.g. radiotelemetry or PIT tags) must be used to better understand the efficiency and/or limits of the Baguari ladder during critical migration seasons. Results will have important fisheries management implications for energy production and environmental agency sectors in designing new fish passage facilities in Brazil and beyond.