“…There is no easy solution, as indicated by recent studies (Reis et al, 2016;Pelicice et al, 2017Pelicice et al, , 2021. Dams cause multiple impacts that act synergistically to limit or prevent fish recruitment, including restrictions on upstream and downstream migration of adults and young (Pelicice, Pompeu & Agostinho, 2015), genetic isolation (Rosso et al, 2017;Baggio et al, 2018), the loss of critical habitats (Du et al, 2013), changes in environmental triggers and conditions (Dugan et al, 2010;Tamario et al, 2019), and anomalous behaviour in reservoirs and fishways (Hahn et al, 2020;Lopes et al, 2021;Silva et al, 2021). The conservation of migratory fish in degraded environments is a complex topic, requiring the maintenance of natural processes that take place at different temporal and spatial scales, such as migration, spawning, drift, growth and dispersal, and in a range of different environments and conditions (Pompeu, Agostinho & Pelicice, 2012;Lopes et al, 2018).…”