TY - JOUR AU - Olaya-Marin, Esther Julia AU - Lemus-Portillo, Ciromar AU - Echavarría Pedraza, Monika Cristina AU - Chaparro García, Oscar Andrés AU - Roa-Fuentes, Camilo Andrés AU - Salazar-Galán, Sergio AU - Barrios Peña, Miguel PY - 2022/01/24 Y2 - 2024/03/28 TI - Differences in body size and abundance of high Andean fishes, above and below the Neusa dam, Colombia JF - Revista de Biología Tropical JA - Rev. Biol. Trop. VL - 70 IS - 1 SE - Articles DO - 10.15517/rev.biol.trop..v70i1.49776 UR - https://revistas.ucr.ac.cr/index.php/rbt/article/view/49776 SP - 464–481 AB - <p><strong>Introduction: </strong>Tropical rivers are increasingly being affected by fragmentation and regulation; and, in Colombia, dams are known to endanger endemic fishes through, among others, limited migration and reduced availability of sediment-based feeding networks. However, knowledge of native ichthyofauna affected by dams in high Andean rivers is still incipient. <strong>Objective: </strong>To assess the effects of the Neusa dam on the ichthyofauna. <strong>Methods:</strong> We compared two rivers’ sections, one above and one below the dam with the Richter IHA System, we sampled three 100 m long transects in each section, every two months, between 2017 and 2019. The fishes were returned to the river after body measurements. <strong>Results:</strong> We collected 729 individuals from five families; <em>Trichomycterus bogotense</em> were smaller under the dam; <em>Oncorhynchus</em><em> mykiss</em> was smaller and less abundant; and there were no differences for <em>Grundulus</em><em> bogotensis</em> and <em>Eremophilus </em><em>mutisii</em>. Independently of climatic factors, <em>O. mykiss</em> and G. <em>bogotensis</em> were more abundant above the dam, and <em>E. mutisii</em> and <em>T. bogotense</em> under the dam. <strong>Conclusion:</strong> The five fish species differed in how the populations differed above and under the dam, suggesting that some are benefited by the dam, while others become smaller and less abundant.</p> ER -