Reproductive migration and probable spawning areas of Calophysus macropterus (Pisces: Pimelodidae) in the Amazon basin: a critical review with structured synthesis

Resumo

Abstract: We conducted a critical review and structured synthesis on the reproductive migration and probable spawning areas of Calophysus macropterus (Lichtenstein 1819) in the Amazon Basin, integrating multiple lines of evidence. Three hypotheses were compared: H1, spawning in the Andean foothills (600 – 200 masl.) with longitudinal migration; H2, mixed strategy with regional nuclei; H3, mainly local/lateral movements. Heuristic analysis showed convergent support for H1: (i) recurrent absence of mature females in the central Amazon lowlands, in contrast to several reports of females with ripe eggs in western Andes foothills tributaries; (ii) larval/juvenile peaks in rivers of the western Amazon such as the Marañón, Ucayali, and Beni/Madre de Dios at the end of the low water - beginning of the flood, compatible with upstream spawning and downstream drift; and (iii) eco-hydrological and geomorphological plausibility of the fluvial environments in the foothills, consistent with the flood pulse. Triangulation between independent lines and sensitivity analyses (alternative weightings and exclusion of low-quality studies) maintained the hierarchy H1>H2>H3. A four-phase migration model is proposed for C. macropterus. Information gaps remain, but all derived predictions are testable. In terms of management, the results reinforce the need to conserve Andes-Amazon connectivity and the functional integrity of the foothills, where reproductive bottlenecks can have downstream repercussions for C. macropterus and also for the large migratory catfish of the Pimelodidae family.