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.

Impact of a large dam on reproduction of a non-migratory teleost species, Acestrorhynchus lacustris (Characiformes: Acestrorhynchidae)

“…In an integrated analysis of the results, our data showed that unlike migratory species (Arantes et al, 2010;Perini et al, 2013), the non-migratory species A. lacustris, maintain their reproductive activity even in environments with lower temperature, dissolved oxygen and flow, suggesting a greater tolerance for environmental changes than migratory fish. However, even though it is considered a more resistant species, these alterations in the physical and chemical parameters of water reflected the decrease in the reproductive fitness of this species, fact that may influence in a worse health status of the offspring and affect the maintenance and conservation of this species in the São Francisco River.…”

“…In order to determine the batch fecundity, samples from the middle region of 20 mature females from each section Abujanra et al, 2009;Olden and Naiman, 2010;Paschoalini et al, 2013;Perini et al, 2013). It is known that alterations in the temperature and hydrological dynamics of rivers can negatively affect the reproductive activity and other biological processes of several freshwater fish with long-term deleterious effects in the aquatic community (Arenzon et al, 2002).…”

Atresia of ovarian follicles in fishes, and implications and uses in aquaculture and fisheries

“…For instance, the deviation or damming of watercourses by the construction of dams alters the local ecological balance and causes changes in the chemical-physical parameters (mainly temperature and dissolved oxygen concentration). These affect the reproductive biology of the inhabiting fish species, by reducing sex steroid concentrations, inducing extensive follicular atresia and decreasing fecundity (Agostinho et al, 1993;Arantes et al, 2010Arantes et al, , 2011Perini et al, 2013;Sato et al, 2005;Thomé et al, 2012). Low dissolved oxygen concentration also characterizes the so-called coastal "dead zones," that is hypoxic zones mainly occurring in the northern hemisphere and originating from the combined action of natural phenomena such as upwelling and anthropogenic fertilization of marine systems by excess nitrogen (Diaz & Rosenberg, 2008).…”

Evaluation of the reproductive parameters of female neotropical migratory fish from a lotic and lentic environment of a dammed river

“…Approximately two thirds of the world's rivers are obstructed by more than 845,000 dams (Fuggle 2000). In addition to the physical barrier to fish migration, river damming for hydroelectric power generation can cause changes in sediment transport and water quality, as well as thermal and hydrodynamic changes that modify the community structure and composition N o n -c o m m e r c i a l u s e o n l y Evaluation of fish from a dammed river of ichthyofauna species (Arantes et al 2010;Perini et al 2013;Freedman et al 2014).…”