Morpholine Imprinting and Homing Behavior of Kutum (Rutilus firisi kutum) in the Caspian Sea

The effect of Kutum (Rutilus firisi kutum) stock enhancement for homing behavior and imprinting with morpholine were studied during 2004 to 2008. This species is a migratory anadromous fish, spawning in rivers in March–April. It has a group synchronous and single spawning behavior. Total of 15,930 Tagged (ABC Tags) specimens of Kutum fingerlings were released into the Khoshkroud river estuary (South part of the Caspian Sea). Kutums were treated with synthetic amine based odorant morpholine (C4H9NO) with different concentrations (5x10-2.5x10-5 and 5x10-7 mg/lit) to enhance imprinting of natural river odors and promote homing behavior. To find the best time of exposing at various developmental stages, Kutums were treated with 5x10-5 mg/lit morpholine in yolk sack, active larvae, 2-3 g. fingerlings and 4-5 g. fingerling stages. Results revealed that significant differences (P < 0.001) existed between kutum homing rate exposed to 5x10-5 mg/lit (0.5 %) with other treatments i.e. 5x10-7، (0.16%) and 5x10-2 (0.1%) as well as with control (0.02 %),during the experimental period. Total Return rate was 0.32%. Results showed significant differences (P < 0.001) between kutum return (homing) rate in active fry stage (1 %) compared to other stages, i.e., yolk sac fry (0.23%), 2-3- g fingerling (0.23%), 4-5 g. fingerling (0.26%) and control (0.13%) during the tree years of experimental period. There were significant differences in sex ratio [M (1.42): F (1)] in recaptured kutums in khoshkrud river (x2=6.4 ?= 0.05 df= 1). Average recapturing rate was greater (6.7 %) than the average recapturing rate for the 5 year period of 2000 to 2004 (5%). As such, it is suggested that revealed that morpholine could be used for return rate enhancing of kutum .Results reviled the role of morpholine as an pheromone like substance for enhancing migratory behavior of Kutum (Rutilus firisi kutum) fish.