Biometric relations in Macrobrachium acanthurus Wiegmann, 1836 (Decapoda, palaemonidae) from Juréia’s Ecological Station í SP
Keywords:
freshwater shrimp, Macrobrachium acanthurus, biometric relationships, Juréia (SP)Abstract
Macrobrachium acanthurus samples were monthly collected in Rio Verde (Juréia-SP) during the period of September/1987 to August/1990, totalizing 159 males and 69 females. The relationships among the variables of individual measures of cephalothorax length (LCT), of abdomen (LAB), of telson (LTS), total weight (WT) and total length (LT) were statistically caIculated for each sex: LCT=0.459, LAB=0.403 LT, LTS=0.138 LT, WT=0.011 LT2.945 and WT = 0.011 LT 2.945 for males; LCT = 0.433 LT, LAB = 0.421 LT, LTS = 0.147 LT and WT= 0.013 LT2.792 for females. The values of angular coefficient obtained on weight / length relation characterized an allometric type relative growth, with males attaining more development. In the other biometric relationships this growth was of isometric type, with more participation of cephalothorax on relative size. The males quantity was always higher than females, with 2.3:1 of sex ratio. This predominance was fewer during the spring and summer.