Resumo
Taunayia bifasciata (Eigenmann & Norris, 1900) is a small catfish that inhabits headwater streams of the Tietê and Paraíba do Sul river basins, southeastern Brazil, being restricted to the Atlantic rain forest. The species is found on lists of threatened species of Brazil and the state of São Paulo. Despite that, there is no literature information about the biology of the species. In the present study we endeavored to collect data on the biology of T. bifasciata. A total of 37 specimens were captured in two streams, Piracuama and Oliveiras. Of those, 22 were females, 14 were males and 1 specimen was immature. Adults with mature gonads were captured in all samples excepting the last, suggesting that T. bifasciata has a long reproductive season. The average fecundity was 319 oocytes/female (range 173-504), with diameters ranging from 0.183 to 2.135 mm. Seven different food items were found in the stomach contents of our subjects. Terrestrial insects and immature Plecoptera were the most frequent and most important food items in the diet of T. bifasciata
Resumo
Taunayia bifasciata (Eigenmann & Norris, 1900) is a small catfish that inhabits headwater streams of the Tietê and Paraíba do Sul river basins, southeastern Brazil, being restricted to the Atlantic rain forest. The species is found on lists of threatened species of Brazil and the state of São Paulo. Despite that, there is no literature information about the biology of the species. In the present study we endeavored to collect data on the biology of T. bifasciata. A total of 37 specimens were captured in two streams, Piracuama and Oliveiras. Of those, 22 were females, 14 were males and 1 specimen was immature. Adults with mature gonads were captured in all samples excepting the last, suggesting that T. bifasciata has a long reproductive season. The average fecundity was 319 oocytes/female (range 173-504), with diameters ranging from 0.183 to 2.135 mm. Seven different food items were found in the stomach contents of our subjects. Terrestrial insects and immature Plecoptera were the most frequent and most important food items in the diet of T. bifasciata
Resumo
Taunayia bifasciata (Eigenmann & Norris, 1900) is a small catfish that inhabits headwater streams of the Tietê and Paraíba do Sul river basins, southeastern Brazil, being restricted to the Atlantic rain forest. The species is found on lists of threatened species of Brazil and the state of São Paulo. Despite that, there is no literature information about the biology of the species. In the present study we endeavored to collect data on the biology of T. bifasciata. A total of 37 specimens were captured in two streams, Piracuama and Oliveiras. Of those, 22 were females, 14 were males and 1 specimen was immature. Adults with mature gonads were captured in all samples excepting the last, suggesting that T. bifasciata has a long reproductive season. The average fecundity was 319 oocytes/female (range 173-504), with diameters ranging from 0.183 to 2.135 mm. Seven different food items were found in the stomach contents of our subjects. Terrestrial insects and immature Plecoptera were the most frequent and most important food items in the diet of T. bifasciata
Resumo
In low-order streams, the high and variable water flow rates offer both advantages and disadvantages to the life cycle of fishes. Even closely related species living in similar habitats can show differences in life history patterns. Based on oocyte-size distributions, C. lauroi was classified into the fractional spawning type, and C. alipioi into the total spawning type. The absolute fecundity of C. lauroi ranged from 1,313 to 2,925 oocytes; in C. alipioi the absolute fecundity ranged from 2,213 to 25,550 oocytes. The nonparametric Spearman correlation test showed statistical significance between the gonadosomatic index and fecundity for both species. The growth parameters, natural mortality rate and survival rate for females of C. lauroi were: K = 0.68 yr-1, Loo = 8.7 cm, tmax = 4.4 years, M = 1.62 yr-1, S = 19.79%, and for males: K = 0.78 yr-1, Loo = 6.9 cm, tmax = 3.8 years, M = 1.89 yr-1, S = 15.11%. The growth parameters, natural mortality rate and survival rate for females of C. alipioi were: K = 0.90 yr-1, Loo= 12.2 cm, tmax = 3.3 years, M = 1.81 yr-1, S = 16.37%, and for males: K = 0.76 yr-1, Loo = 10.1 cm, tmax = 3.9 years, M = 1.71 yr-1, S = 18.10%.
Em riachos de pequena ordem, o alto e variável fluxo de água oferece tanto vantagens como desvantagens para o ciclo de vida de peixes. Mesmo espécies próximas que vivem em habitats semelhantes podem apresentar diferentes em seus padrões de ciclo de vida. Com base na distribuição de tamanho de ovócitos, C. lauroi foi classificada no tipo de desova parcelada, e C. alipioi no tipo de desova total. A fecundidade absoluta de C. lauroi variou de 1.313 a 2.925 ovócitos; em C. alipioi, a fecundidade absoluta variou de 2.213 a 25.550 ovócitos. A prova não-paramétrica de correlação de Spearman mostrou haver significância entre a relação gonadossomática e a fecundidade para ambas as espécies. Os parâmetros de crescimento, a taxa de mortalidade natural e a taxa de sobrevivência para fêmeas de C. lauroi foram: K = 0,68 ano-1, Loo = 8,7 cm, tmax = 4,4 anos, M = 1,62 ano-1, S = 19,79%, e para machos: K = 0,78 ano-1, Loo = 6,9 cm, tmax = 3,8 anos, M = 1,89 ano-1, S = 15,11%. Os parâmetros de crescimento, a taxa de mortalidade natural e a taxa de sobrevivência para fêmeas de C. alipioi foram: K = 0,90 ano-1, Loo = 12,2 cm, tmax = 3,3 anos, M = 1,81 ano-1, S = 16,37%, e para machos: K = 0,76 ano-1, Loo = 10,1 cm, tmax = 3,9 anos, M = 1,71 ano-1, S = 18,10%.
Resumo
In low-order streams, the high and variable water flow rates offer both advantages and disadvantages to the life cycle of fishes. Even closely related species living in similar habitats can show differences in life history patterns. Based on oocyte-size distributions, C. lauroi was classified into the fractional spawning type, and C. alipioi into the total spawning type. The absolute fecundity of C. lauroi ranged from 1,313 to 2,925 oocytes; in C. alipioi the absolute fecundity ranged from 2,213 to 25,550 oocytes. The nonparametric Spearman correlation test showed statistical significance between the gonadosomatic index and fecundity for both species. The growth parameters, natural mortality rate and survival rate for females of C. lauroi were: K = 0.68 yr-1, Loo = 8.7 cm, tmax = 4.4 years, M = 1.62 yr-1, S = 19.79%, and for males: K = 0.78 yr-1, Loo = 6.9 cm, tmax = 3.8 years, M = 1.89 yr-1, S = 15.11%. The growth parameters, natural mortality rate and survival rate for females of C. alipioi were: K = 0.90 yr-1, Loo= 12.2 cm, tmax = 3.3 years, M = 1.81 yr-1, S = 16.37%, and for males: K = 0.76 yr-1, Loo = 10.1 cm, tmax = 3.9 years, M = 1.71 yr-1, S = 18.10%.
Em riachos de pequena ordem, o alto e variável fluxo de água oferece tanto vantagens como desvantagens para o ciclo de vida de peixes. Mesmo espécies próximas que vivem em habitats semelhantes podem apresentar diferentes em seus padrões de ciclo de vida. Com base na distribuição de tamanho de ovócitos, C. lauroi foi classificada no tipo de desova parcelada, e C. alipioi no tipo de desova total. A fecundidade absoluta de C. lauroi variou de 1.313 a 2.925 ovócitos; em C. alipioi, a fecundidade absoluta variou de 2.213 a 25.550 ovócitos. A prova não-paramétrica de correlação de Spearman mostrou haver significância entre a relação gonadossomática e a fecundidade para ambas as espécies. Os parâmetros de crescimento, a taxa de mortalidade natural e a taxa de sobrevivência para fêmeas de C. lauroi foram: K = 0,68 ano-1, Loo = 8,7 cm, tmax = 4,4 anos, M = 1,62 ano-1, S = 19,79%, e para machos: K = 0,78 ano-1, Loo = 6,9 cm, tmax = 3,8 anos, M = 1,89 ano-1, S = 15,11%. Os parâmetros de crescimento, a taxa de mortalidade natural e a taxa de sobrevivência para fêmeas de C. alipioi foram: K = 0,90 ano-1, Loo = 12,2 cm, tmax = 3,3 anos, M = 1,81 ano-1, S = 16,37%, e para machos: K = 0,76 ano-1, Loo = 10,1 cm, tmax = 3,9 anos, M = 1,71 ano-1, S = 18,10%.