DETERMINATION OF STAGES SEX MATURITY OF Rutilus frisii kutum Kamenskii, 1901 IN CASPIAN SEA BY BIOLOGICAL INDEXES

Caspian sea as a unique habitat has accommodated Rutilus frisii kutum for as long as the course of history but has undergone extreme ecological & managerial disturbances over the recent centuries which has in turn, borough about dire consequences including a the formation of a potentially fragile ecosystem. In fact various researches undertaken a this issue has shown that the specter of such ominous changes in ecosystem & the living resources of the Caspian Sea loom near. The present study aims at investigating the sexual & biological aspects of fish &their sex organs in Rutilus f. Kutum along the southern coasts of the Caspian Sea. For this reason, the fish and gonad samples of Rutilus f. kutum migrating to rivers & estuaries were collected & analyzed through sampling procedure based on fish gonad. Upon treating the samples with Bouin & the related preparations, (I.e. extraction of water, making from the sample them transparent, molding & doing them based on H&E method), , whereas Peterson correlation coefficient was applied for toxic variables. The results of the analysis shows the sampled fish with average length of (34958) mm weighing 564334) are percentage45 of male & percentage54.4 male. The sexual maturity rate, as specified by the six stages analysis me Thad of Johnson’s (Johnson’s, 1970) in dictated the position of female in the stages: IV & V during March, April & June. 32% of female fish were in stage V & %68 in stage IV in March whereas the percentages of female fish in April was %87 in the stage V followed by %94 in the stage V during June.

Caspian sea, Rutilus frisii kutum, ecosystem, sexual maturity, female fish