ASPECTOS REPRODUTIVOS DE Cichla piquiti (PERCIFORMES: CICHLIDAE) NO RESERVATÓRIO DA USINA HIDRELÉTRICA DE SERRA DA MESA, GOIÁS, BRASIL.

Abstract

The aim of this study was to analyze the aspects of reproductive biology of Cichla piquiti (Blue Peacock Bass) in the reservoir of the Hydroelectric Plant of Serra da Mesa, an environment where they occur naturally (Rio Tocantins, Goiás, Brazil) was characterized. 217 specimens were sampled, with 109 females and 108 males over an annual reproductive cycle (October 2012 to September 2013) with the use of artificial lures. Biometric fish and macro and microscopic classification of gonadal maturation data provided the basis for investigation of the following reproductive parameters: 1) the type of spawning for gonad morphology at each stage of development; 2) the reproductive period, through the time of gonadal maturation frequencies of gonadosomatic index (GSI) and condition factor (K1 and K2); 3) the existence of reproductive seasonality; 4) the size at first maturity (L50); 5) the size of which 100% of the population is able to play (L100); 6) the composition of the population in total length and sex ratio, and 7) the length-weight relationship of the specie. The results indicated parceled spawning and intense reproductive activity in all months of the year, with no reproductive seasonality. No differences in sex ratio over the year. There was sexual dimorphism in growth, with positive allometric growth of males and females negative allometric growth. Males had higher amplitudes in total length and weight than females, and sizes of first maturation (L50) higher than females, and 32 cm for males and 33.5 cm for females. The L100 was estimated at 33.4 cm for males and 34.2 cm for females. The variation in body condition represented by the allometric condition factor (K1) less somatic (K2), varied only for females, as well as variations of the gonadosomatic index (GSI) in different stages of gonadal development were significant only for females, both possibly due to the weight of the testes negligible when compared to the ovaries. There was no significant temporal variations in the IGS and K1 of males and females, possibly by mature individuals occur and emptied throughout the year. Variations in air temperature, accumulated rainfall and reservoir volume did not affect the reproductive activity, which may indicate reproductive success of Cichla piquiti in more variable environmental conditions. Still, continuous monitoring of the population would be needed as measures for management and preservation of the species in its original basin.