According to the theoretical model proposed by Santos (1972), the analysis of the "maturation curve" which relates ovaries mean weight and the female total length shows results concerning the type and periodicity of the spawn, total length at the begining of the spawns, fecundity and the female growth curve. Since the model is so simple and it gives a great amount of biological informations, we thought on applying it to some data analysed by the traditional way to verify the fitness of the obtained results. It was done on population I of Micropogonias furnieri (Vazzoler, 1971), a well known species concerning the life history and behavior. The analysis showed that the obtained results depend totally on how the data are grouped in length classes and does not agree with the previous knowledge about the species. It is clear that the application of the model to species which does not have secure informations obtained by traditional way, may lead to erroneous conclusions about the different aspects analysed, having serious limitations concerning its efficiency.
