Reproductive dynamics of Leporinus obtusidens captured downstream from an important hydropower Station in Brazil

Abstract

This study evaluated the reproductive dynamics and gonadal morphology of piaparas (Leporinus obtusidens) captured downstream from the Funil Hydroelectric Power Station. The 107 piaparas evaluated were captured monthly from Sep 2006 to Aug 2007. The data were stratified among the seasons to evaluate gonad maturation and the reproductive period was determined by assessing the gonadosomatic index, hepatosomatic index, abdominal fat index (AFI), weight:length ratio, condition factor and sexual proportion. The reproductive period lasted from winter to summer (Jul-Mar) in females and from spring to autumn (Sept-Jun) in males. AFI was high during and after the reproductive period in females and only during the reproductive period in males. The highest HIS values for males and females were obtained in spring and summer (Sept-Mar). The females observed did not spawn and showed follicular atresia. These characteristics suggest that L. obtusidens does not use the study area as a reproductive site and probably migrates for this purpose.Keywords: fish, reproduction, piracema, histology, gonad RESUMO Este estudo avaliou a dinâmica reprodutiva e a morfologia gonadal de piaparas (Leporinus obtusidens)

Comparative morphology of the oocyte surface and early development in four characiformes from the São Francisco River, Brazil

“…We studied four species with potential value for aquaculture: matrinxã Brycon orthotaenia , with a vulnerable conservation status in the IUCN red list of threatened species, dourado Salminus franciscanus with dramatically reduced populations in several regions of the river, curimatã‐pacu Prochilodus argenteus , one of the most abundant migratory species of the basin and piau‐verdadeiro Leporinus obtusidens , a widespread species in the La Plata and São Francisco basins that appears to have a relatively good conservation status when compared to other large migratory fishes (Carolsfeld et al, ; Sato and Sampaio, ; Reis and Lima, ). These four characiform fishes are single batch spawners, releasing a high number of nonadhesive eggs over a short reproductive period during the rainy season from October to February (Gonçalves et al, ; Arantes et al, ; Andrade et al, ; Freitas et al, ). Under hatchery conditions, these fish species respond positively to hormonal induction and fertilization (Arantes et al, ), however, the fingerlings production has been impaired by the egg quality and early larval development.…”