Biologia reprodutiva de Astyanax henseli (Teleostei, Characidae) do curso superior do Rio dos Sinos, RS, Brasil

Abstract

ABSTRACT. Reproductive biology of Astyanax henseli (Teleostei, Characidae) in the upper Rio dos Sinos, RS, Brazil. This study describes the reproductive biology of a population of Astyanax henseli Melo & Buckup, 2006 from the upper Rio dos Sinos, Caraá, Rio Grande do Sul, Brazil. A total of 336 specimens was analyzed, comprising 169 males, 154 females and 13 individuals of undetermined sex. The reproductive season lasted approximately five months, from August to December, gonadossomatic index (GSI) peaked of in October, corresponding to the end of winter and the spring in the southern hemisphere. No correlation was found between the GSI and abiotic factors (temperature, rainfall and photoperiod). However, these factors may trigger gonad maturation. Also, no correlation was observed between biotic variables, such as stomach repletion index (RI) and hepatosomatic index (HSI), and GSI. Despite that, high RI values during the reproductive period may indicate that A. henseli maintains its feeding activity throughout the reproductive months, while low HSI values during the peak of GSI suggest a higher energy expenditure of the liver during this period. The sex ratio in the population was 1:1 for the total number of individuals sampled, among different classes of length, and among the different months of the year. The size at first gonadal maturation was 69 mm for males and 60 mm for females. The absolute fecundity mean was 3,038 oocytes and the relative fecundity mean was 0.13 oocytes mg -1 . The oocyte development indicated that A. henseli is a total spawner. KEYWORDS.Reproductive period, small size characid, gonadosomatic index, fecundity, first gonadal maturation. RESUMO. No presente estudo é descrita a biologia reprodutiva de uma população de Astyanax henseli PALAVRAS-CHAVE.Período reprodutivo, caracídeo de pequeno porte, índice gonadossomático, fecundidade, primeira maturação gonadal.

Ovarian development and the reproductive profile of Astyanax altiparanae (Teleostei, Characidae) over one year: Applications in fish farming

“…As reported in the literature on Astyanax species, there is some variation in the duration of the reproductive period [36]. However, similar to the current findings, most studies on this genus report seasonal reproduction in spring and summer in the Southern Hemisphere (from September to March), with durations ranging from four to six months [19,27,33,38e42].…”

“…The same reproductive period was observed by Viana et al [19] in a study on A. altiparanae, as well as in studies on A. scabripinnis [24,27,33] and A. paranae [26,35]. The reproductive period of A. henseli was found to be shorter d from August to December [36], and A. bimaculatus exhibited continuous reproductive activity throughout the year, though with reduced gonadal activity from May to July [37].…”

Population structure and reproductive biology of Loricariichthys melanocheilus Reis & Pereira, 2000 (Siluriformes: Loricariidae) in the rio Ibicuí, Brazil

“…This reinforces the idea that there is an accumulation of reserves for reproductive activity. Similar results were found for Loricariichthys platymetopon and Rhinelepis aspera (Agostinho et al, 1990;Querol et al, 2002), and also for Characiformes, such as Leporinus copelandii Steindachner, 1875 (Costa et al, 2005), Steindachnerina insculpta (Fernández & Yépez, 1948) (Ribeiro et al, 2007), Astyanax henseli de Melo & Buckup, 2006(Dala-Corte & Azevedo, 2010, among others. According to Svedäng & Wickström (1997), in the case of females, the decrease in HSI during the maturation period is mainly due to the depletion of liver reserves as a result of depletion of glycogen and lipids in hepatocytes, where the synthesis of vitellogenin (Mommsen & Korsgaard, 2008) and transfer to oocytes take place.…”

“…Seasonal reproductive cycles may be strongly influenced by biotic factors such as food availability and competition, and abiotic factors such as variations in temperature, photoperiod and rainfall (Dala-Corte & Azevedo, 2010). In tropical regions of Brazil, where the level of the rivers determines the availability of habitat and food, rainfall seems to be the factor that most influences the reproductive cycles of fish (Vazzoler et al, 1997;Agostinho et al, 2004;Bailly et al, 2008;Freitas et al, 2011).…”

Life history traits of Characidium pterostictum (Characiformes, Crenuchidae) along the longitudinal gradient of a Neotropical river in southern Brazil

“…Other studies have also found absence of relationship between GSI with RI and HSI (e.g. Lampert et al, 2004;Dala-Corte & Azevedo, 2010). A possible explanation for this result is that food availability may be abundant throughout all the months of year for C. pterostictum in the studied sites.…”