The species Prochilodus lineatus, with great commercial relevance in the rivers Grande, Pardo and Mogi-Guaçu, is characterized by the formation of great shoals which are capable of developing wide migratory displacements. Current assay evaluates, by means of the morphometric characteristics and age, whether the curimbatás (P. lineatus) of different migratory and resident stocks form a single population, with interactivities among the sub-populations during the 'piracema' period (reproduction migration). A completely randomized plot with a 4 x 2 factorial scheme, with four stocks (one resident and three migratory) as factors and two genders (male and female), with thirty replicates, was employed, with each fish taken as an experimental unit. An 80.19% variation for the first principal component and an 8.09% variation for the second principal component were reported as provided by the ten morphometric variables of resident and migratory stocks. The resident stock had the highest rate for the whole morphometric variables. There was superposition of individual scores of the same characteristics among the migratory stocks. Significant predominance of males was observed among resident stocks and migratory stocks I and II. Morphometric similarity verified among the migratory stocks showed a single population, with small inter-population variations.
fish age; reproductive migration; analysis of main components
