Comparing some biological characteristics of two sturgeons species, Persian sturgeon (Acipenser persicus Borodin, ۱۸۹۷) and Russian sturgeon (A. gueldenstaedtii Brandt & Ratzeburg, ۱۸۳۳) in the Caspian Sea

The objective of this study was to compare the biological parameters such as length, weight, age, caviar production indices, caviar/weight, condition factor and sex ratio of Persian sturgeon (Acipenser persicus Borodin, ۱۸۹۷) and Russian sturgeon (A. gueldenstaedtii Brandt & Ratzeburg, ۱۸۳۳) in the Caspian Sea during ۱۹۹۰-۲۰۱۴. All these characteristics (except condition factor) of Persian sturgeon were greater than the Russian sturgeon. In the long period, annually average (±SD) fork length ranged from ۱۲۹.۳ (±۱۱.۸۷) to ۱۴۰.۹ (±۱۵.۹۹) cm for Russian sturgeon and ۱۴۵.۷ (±۱۷.۶۱) to ۱۵۷.۴ (±۱۹.۳۱) cm for the Persian sturgeon. The annually caviar harvest for the Russian sturgeon ranged from ۳.۸۶ (±۱.۰۵) to ۵.۰۲ (±۱.۸۲) kg with a caviar/weight ratio were ranged from ۱۶.۹ (±۴.۱۲) to ۲۰.۱% (±۵.۱۲), while comparatively for the Persian sturgeon was greater and ranged from ۴.۸۴ (±۱.۶۲) and ۷.۰۴ (±۲.۵۸) kg with a caviar/weight ratio of ۱۶.۲ (±۳.۹۹) to ۲۱.۱% (±۵.۲۰). The age of both species ranged between ۶ to ۴۰ years but the modal age of Russian sturgeon was less than Persian sturgeon. The male:female sex ratio of Russian and Persian sturgeons were ۰.۲۳:۱ and ۰.۵۷:۱, respectively. The sex ratio of Russian sturgeon was significantly different from sex ratio of Persian sturgeon (p<۰.۰۰۱). The condition factor of Russian and Persian sturgeons were ۰.۹۲ (±۰.۱۶) and ۰.۷۴ (±۰.۱۳), respectively. Moreover, results of the MANOVA revealed significant differences in population structure of two species (p<۰.۰۰۱). Therefore, different conservation and management activities need for these two valuable sturgeons in the Caspian Sea.

Keywords:

Acipenser persicus , Acipenser gueldenstaedtii , Age , Length , Weight , Sex , Caspian Sea