Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Belo Horizonte, MG, CEP: 30161-970, Brasil.
Fish Physiol Biochem. 2013 Dec;39(6):1473-84. doi: 10.1007/s10695-013-9800-z. Epub 2013 Apr 25.
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.
本研究首次调查了东南巴西北部河流系统中 Prochilodus lineatus 的生殖生物学，将其与支流在巴拉那河上游重要商业鱼类生殖成功中的作用相关联，该流域部署了一系列水电大坝。每隔两个月在三个河流地点（S1）大格兰德河（位于波多科洛比亚大坝下游）、（S2）帕多河和（S3）莫吉瓜苏河捕获标本。比较了各地点的性类固醇血浆水平、生殖力、卵泡闭锁、卵母细胞直径和性腺指数（GSI）。在 S1，与 S2 和 S3 相比，鱼类的生殖参数发生了变化：GSI、卵母细胞直径和生殖力降低，卵泡闭锁指数升高。S3 中成熟鱼类的频率更高，仅在 S3 中记录到产卵。在 S2 和 S3 中，雌鱼的睾酮和 17β-雌二醇以及雄鱼的睾酮的血浆浓度在性腺成熟后表现出广泛的变化。S1 中的鱼类在整个性腺周期中类固醇浓度的变化很少有显著变化。这些结果表明，P. lineatus 不在大格兰德河（S1）繁殖，但可能将帕多河（S2）用作迁移到莫吉瓜苏河（S3）的途径，在那里它们完成性腺成熟和产卵。我们的研究结果有助于了解 P. lineatus 的生殖生物学，并强调支流在蓄水河流中的重要性，因为它们是鱼类迁移和产卵的有利环境。
