Reza Davoodi

Catch data of Penaeus semisulcatus were collected for three years (2009-2011) during the period of June to August to estimate the effect of depth variation on length frequency and catch rate (Kg h-1) of the species. No difference was observed between the shallow and deeper catch rate (ANOVA test, P > 0.05). However, the size composition of green tiger shrimp were affected by depth variation (Kolmogorov-Smirnov test, P < 0.05) and were positively correlated with depth (P < 0.05 and r = 0.140).The smaller individuals prefer shallow waters, indicating behaviour differences between the juveniles and adults of this species. The positive correlation between size of shrimp and water depth can be attributed to the behaviour predation.