Análisis de progresión modal de Bryconamericus iheringii (Boulenger, 1887) en la laguna Lacombe, provincia de Buenos Aires

The small silver characin, Bryconamericus iheringii, is an important species in the fish community structure because among the accompanying species of the silver side, Odontesthes bonariensis, it is most density important and has a planctophagous regime which partially overlaps with that of this atherinid as well. The objective of this paper is to describe the individual growth, analyzing size structure and using modal progression analysis as first stage for its demographic appraisal. The catches were carried out with a beach seine net (opening of the mesh in the bag 10 mm) between October of 1997 and October of 1998. The application of modal progression method is hindered by the wide seasonally oscillating growth and by capturability. The obtained parameters for the Lacombe population, assuming the interpretation of two annual cohorts (Sendra & Freyre for Chascomús shallow lake) but fitting the generalized Pauly’s seasonal model of von Bertalanffy, compared with those obtained by the scale they would be close by. However the interpretation of a single annual cohort is more compatible with the lepidologic interpretation.