title: Profiles of sex steroids, fecundity and spawning of a migratory characiform fish from the Paraguay-Paraná basin: a comparative study in a three-river system.
abstract: This study investigated for the first time the reproductive biology of Prochilodus lineatus in a system of rivers in southeastern Brasil, relating it to the role of tributary rivers in the reproductive success of this important commercial fish in the Upper Paraná River basin, where a cascade of hydroelectric dams were deployed. Specimens were caught bimonthly in three river sites: (S1) Grande River, downstream from the Porto Colômbia dam; (S2) Pardo River; and (S3) Mogi Guaçu River. Sex steroid plasma levels, fecundity, follicular atresia, oocyte diameter and gonadosomatic index (GSI) were compared among sites. In S1, fish exhibited changes in the reproductive parameters: lower GSI, oocyte diameter and fecundity and higher follicular atresia index, when compared to S2 and S3. Frequency of maturing fish was higher in S3 and spawning was only registered in S3. In sites S2 and S3, plasma concentrations of testosterone and 17β-estradiol in females and testosterone in males showed wide variations following gonadal maturation. Fish from S1 showed few significant variations in sex steroid concentrations throughout the gonadal cycle. These results indicate that P. lineatus does not reproduce in Grande River (S1), but probably uses the Pardo River (S2) as a migratory route towards the Mogi Guaçu River (S3) where they complete gonadal maturation and spawning. Our findings contribute for understanding the reproductive biology of P. lineatus and to highlight the importance of tributaries in impounded rivers as a favourable environment for migration and spawning of fish.
authors.affiliation: Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Belo Horizonte, MG, CEP: 30161-970, Brasil.
authors.forename: Violeta da Rocha
authors.initials: Vda R
authors.lastname: Perini
authors.forename: Alessandro Loureiro
authors.initials: AL
authors.lastname: Paschoalini
authors.forename: Cláudia Kelly Fernandes da
authors.initials: CK
authors.lastname: Cruz
authors.forename: Rita de Cássia Gimenes Alcântara de
authors.initials: Rde C
authors.lastname: Rocha
authors.forename: José Augusto
authors.initials: JA
authors.lastname: Senhorini
authors.forename: Dirceu Marzulo
authors.initials: DM
authors.lastname: Ribeiro
authors.forename: Paulo Sérgio
authors.initials: PS
authors.lastname: Formagio
authors.forename: Nilo
authors.initials: N
authors.lastname: Bazzoli
authors.forename: Elizete
authors.initials: E
authors.lastname: Rizzo
mesh_terms: D000818:Animals; D001938:Brazil; D060125:Characiformes / Q000097:blood* / Q000254:growth & development; D005260:Female; D005298:Fertility; D005496:Follicular Atresia; D012739:Gonadal Steroid Hormones / Q000097:blood*; D006066:Gonads / Q000254:growth & development; D008297:Male; D009865:Oocytes / Q000166:cytology; D012098:Reproduction; D045483:Rivers / Q000737:chemistry; D012741:Sexual Maturation
chemical_list: D012739:Gonadal Steroid Hormones