Abstract

ARAYA, Patricia; HIRT, Lourdes  and  FLORES, Silvia. Reproductive biology and growth of Pimelodus clarias maculatus (Lac. 1803) (Pisces, Pimelodidae) in the influence area of Yacyretá dam. Ecol. austral [online]. 2003, vol.13, n.1, pp.83-95. ISSN 1667-782X.

We analyzed growth and reproductive dynamics of Pimelodus clarias maculatus (Lac. 1803) in the influence area of Yacyretá dam, Paraná River, Argentina. This species is of a relative economic importance and is frequently captured in this river. Samples were collected between 1990 and 1997 from experimental fisheries using gill nets of different mesh sizes. Three different gonadal stages were recognized: pre-vitellogenesis, vitellogenesis and post-spawning. The reproductive period spanned from August to March. Maximum gonadal activity was recorded from October to March, in coincidence with the annual maximum hydrometric level (over 3 m). We observed a positive correlation between the gonadal somatic and both hydrometric level and temperature. Spawning was not continuous and ovocyte development was synchronic in more than two groups of ovocites. Standard length at first maturity was 190 mm. Absolute mean fecundity was 97000 ovocytes per female. Ages 1 to 7 were recognized using growth marks of dorsal spines. The most frequent age was 4 for males and 5 for females. Mean standard length at ages 3, 4 and 5 was greater for females. The b parameter of the length-weight relationship was less than 3, suggesting a negative allometric growth for both sexes.

Keywords : Reproduction; Dam; Age; Growth.

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