Celestino, L.F., Sanz-Ronda, F.J., Miranda, L.E., M.C. Makrakis, J.H. Pinheiro Dias, and S. Makrakis. 2020. Bidirectional connectivity via fish ladders in a large Neotropical river: response to a comment. River Research and Applications 36:1377-1381. https://doi.org/10.1002/rra.3687
In a recent article we applied electronic tags to the fish Prochilodus lineatus to document how a fishway connected aquatic habitats downstream and upstream of a major dam. Moreover, given that tagged fish remained upstream or downstream for periods extending months and years before returning to the fishway, and that observed patterns of passage were consistent with seasonal migratory cycles, and building on existing literature, we speculated that the fishway allows fish access to spawning habitats upstream and feeding habitats downstream. Our interpretation of the movement data provoked several comments from Pelicice, Pompeu, & Agostinho (2020) and they set various reasons by which, in their opinion, some of our conclusions may be mistaken. Their critique is threefold. First, they argue that the percentage of fish attracted into the fishway is too low to consider the fishway an effective link between the reservoir and the river downstream. We counter that without estimates of population size it is impossible to judge if 28% passage is limited; possibly absolute numbers may still be enough to maintain a viable population. Second, they assert that because receivers were located only in the fishway, it is unknown if fish that used the fishway remained near the dam, or if they continued on their migration. We counter with a brief literature review that documents P. lineatus migrating through reservoirs and spawning in tributaries. Third, they advocate for a broader conservation perspective and for additional research. We had already expressed in the article that fishways are only a temporary fix and that we support their use only as an element of a broader environmental management package. We agree with the need for more research but argue that procrastinating on conservation action may not be wise because we don’t know if the research will be done, how long it will take, or what is the cost of waiting. We do thank Pelicice et al. (2020) for their interest and comments on our article.