Investigation of the changes in length, weight, gender and caviar production and also CPUE of Persian sturgeon in the southern coast in theGolestan Province (2009-2012)

This research was carried out at the southern part of the the Caspian Sea coast from 2009 to 2012. Samples collected at the same time with wild broodstocks transferring from fishing station to the Shahid Marjani sturgeon hatchery in order to artificial propagation and stocks restoration activities. A total of 742 fish were studied which 416 numbers were female and 326 of male. From theses fish, 17659 kg meat and 562057 kg caviar produced. The highest and lowest frequency distrbution of fish in 2009 and in 2012 was 35.12% and 20.17% repespctively. The results showed that fork length ranges from of 50 to 218 cm during 2009-2011. The mean fork length of the Persian sturgeon caught on the southern coast of the Caspian Sea was 153.7±18.8 cm in 2009, 123.4±20.1 cm in 2012 where a decreasing trend observed. Minimum and maximum fork length was 123.44 cm and 154.35 cm respectively with a mean standard division ±18.8 and also minimum and maximum weight were respectively, 41 and 75 kg, with mean standard division ± 9.27 kg. The ratio of male to female was 1 to 1.3 and the matured females were in the fourth stage of sexual maturity. During the four years, a total of 2060.56 kg of caviar was produced in the Golestan province and this amount reached from 699.92 kg in 2009 to 379.59 kg in year 2012. In 2009, more than 78.51% of caviar graded as grade 1 and 16.29% as grade 2 caviar and also 5.18 % of them as grade 3 and compress caviar. But in 2012, more than 66.66% of them graded as grade 1 caviar, 23.8% grade 2 and 9.52% as grade 3.