Tipo de desova e fecundidade do tambiú Astyanax bimaculatus Linnaeus, 1758 (Pisces, Characiformes, Characidae), na Represa de Ibitinga, Estado de São Paulo, Brasil

Abstract

Durante o período de junho de 1989 a maio de 1990 foram estudadas, para determinação da fecundidade, 39 fêmeas maduras de Astyanax bimaculatus, na Represa de Ibitinga, (21°46'S e 48°59'W), Estado de São Paulo. Observou-se, mediante a amostra de 368 fêmeas, que a desova para essa espécie é descontínua, periódica, anual com prevalência no bimestre dezembro/janeiro. A fecundidade média foi de 12276 ± 8483 ovócitos, com limites de variação entre 1189 e 43005. Relacionou-se a fecundidade com o comprimento total, peso total, peso corporal e peso gonadal, sendo este último o melhor indicador da fecundidade para a espécie.

Condition factor in nine species of fish of the Characidae family in the upper Paraná River floodplain, Brazil

“…Results similar to those of the present authors were obtained for Astyanax schubarti by Rodrigues et al (1995). Since the species has its highest condition factor in December-January, it has been suggested that specimens develop and prepare for reproduction during this period.…”

“…Results shown in Fig. 5 are not so clear on this point when compared with those of Rodrigues et al (1995), which may be explained if one considers that the population is essentially composed of juveniles (only 3.2% of sampled individuals with lengths greater than those of L 50 ).…”

Reproductive biology ofChromidotilapia guntheri(Sauvage, 1882) (Cichlidae, Perciformes) in four coastal rivers (Ehania, Noé, Soumié and Eholié) of Côte d’Ivoire in West Africa

“…The sex ratio varies considerably among fish species. Examples of such variation in the tropical species were reported by Giamas et al (1984), and Goulart and Verani (1992), who found higher frequency of males, whereas Rodrigues et al (1989a) observed higher frequency of females. Rodrigues et al (1989b) and Andrian et al (1992) reported a sex ratio of 1:1.…”

Population structure, condition factor and reproductive period of Astyanax paranae (Eigenmann, 1914) (Osteichthyes: Characidae) in a small and old Brazilian Reservoir

“…They reveal either the biological attributes (weight, length, gonadal maturity and others) or the species relationship to the environmental conditions (Wootton, 1999). The sex ratio varies considerably among the fishes species and examples of such variation in the tropical species can be found in Giamas et al (1984), Goulart and Verani (1992), (higher frequency of the males); Rodrigues et al (1989b), Andrian et al (1992) (sex ratio of 1:1); Rodrigues et al (1989a) (higher frequency of the females). The weight-length relationship is frequently used in the fishery assessment to predict the weight from the length, to estimate the fishes condition and to infer the fishes growth pattern (Bagenal and Tesch, 1978;Ney, 1993;Morey et al, 2003).…”