Algunos aspectos biológicos de Bryconamericus iheringii (Ostariophysi: Characidae) en dos arroyos de la alta cuenca del río Samborombón, Argentina

Abstract

Some aspects of biology of Bryconamericus Iheringii (Ostariophysi: Characidae) in two streams in the high basin of the Samborombón river, Argentina. This study analyzed the following aspects of the Bryconamericus iheringii population structure: abundance patterns, condition factor, male-female sex ratio, relation between weight and length, and reproductive period. Samples were made monthly from May 2004 to April 2005 using small trawling nets, in the Manantiales and El Portugués streams. � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �The highest values of biomass for the Manantiales stream corresponded to May, July and March, the highest values of biomass for El Portugués stream were for May, September and March. In the Manantiales stream, both for males and females, the set of individuals < 25 mm Lst dominated during the spring. Individuals included among the 26-40 mm Lst predominated in the warmer months, while those between 41-60 mm Lst abounded at the end of the summer, autumn and winter. In the Portuguese stream, individuals males < 25 mm Lst, were present in the summer, the rest of the year was dominated by sizes between 26-40 mm Lst during the warmer months. Sizes between 41-60 mm Lst dominated in colder months. The relationship between the sexes differed significantly from the 1:1 reason with predominance of females in almost every month. Higher values of K factor were recorded at the end of the spring and summer for both streams. This species has a slightly allometric growth and differences between males and females in this factor may be due to the greater size of females. The largest number of females in maturation and mature was observed in the months of August, September and November in both streams and during the post-spawning period in February-May in the Manantiales stream and in March-May in the Portuguese stream. This would indicate that the spawning period would be between the months of August and November.