Reproduction of the duck catfish Ageneiosus ucayalensis in a ria river system.
A total of 1006 duck catfish Ageneiosus ucayalensis were collected from a ria river system of eastern Amazonia, of which 733 were females and 273 males, a sex ratio 2·69:1. Condition factors of males were higher than those of females and size at first sexual maturity (L50) was 12·8 cm for females and 11·8 cm for males. The relative frequency of mature specimens and gonad condition indices indicate that the breeding season is short and coincides with the rainy season.
Graduate Programme in Zoology, Universidade Federal do Pará-Museu Paraense Emílio Goeldi, Rua Augusto Corrêa, N° 1, Bairro Guamá, CEP: 66075-110, Belém, Pará, Brazil.
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Oliveira
Developmental Biology and Immunohistochemistry Laboratory, Instituto Ciências Biológicas, Universidade Federal do Pará, Rua Augusto Corrêa, 01 - Guamá, 66075-110, Belém, Pará, Brazil.
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Ferreira
Cellular Ultrastructure Laboratory, Instituto Ciências Biológicas, Universidade Federal do Pará, Rua Augusto Corrêa, 01 - Guamá, 66075-110, Belém, Pará, Brazil.
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Rocha
Ecology and Conservation Laboratory - Ichthyology, Instituto de Ciências Biológicas, Universidade Federal do Pará, Rua Augusto Corrêa, 01 - Guamá, 66075-110, Belém, Pará, Brazil.
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Montag
D000818:Animals; D001938:Brazil; D002397:Catfishes / Q000502:physiology*; D005260:Female; D008297:Male; D012098:Reproduction; D045483:Rivers; D012621:Seasons; D012741:Sexual Maturation / Q000502:physiology
Amazonia; catfish; drowned rivers; high rainfall; seasonal spawning