Qualitative and quantitative study of sturgeon fingerlings from the time of production up to their release

The main objective of the present study was to collect information to improve artificial breeding operations in sturgeon in the Shadid Beheshti and Yousefpour hatcheries. This investigation addressed four aspects including recording normatives of sturgeon breeding control and examination of earthen ponds, control of the hygienic state of sturgeon fingerlings and the quantitative control of fingerling release of various sturgeon species. The study of normatives in sturgeon brood fish commenced on 9 March 2001 simultaneously with the breeding season for the species Huso huso and terminated on 4 June 2001. Totally 226 brood fish were examined in this study that included 148 Acipenser presicus (82 female brood fish used for artificial breeding, 9 female brood fish used for caviar production and 57 male brood fish), 62 Acipenser stellatus (15 female brood fish used for artificial breeding, 21 female brood fish used for caviar production and 26 male brood fish), 13 Acipenser nudiventris (12 female brood fish and 1 male brood fish ) and 3 female H.huso. The average body length recorded in A. persicus breeders used for artificial breeding was 174.03 cm and the average body weight before the removal of eggs was 28.64 kg. The average weight of eggs was 4.93 kg with an average of 54.8 eggs per gram egg. The condition factor recorded for these breeders was 0.73 and the average age was 18.5 years. The breeders responded to breeding at an average period of 436.4 ؛t. The GV in these breeders ranged from 14- 49 and the average fertilization rate was 88.2%. A. persicus breeders that were used in caviar production had an average length of 173.9cm with an average weight of 28.06kg. The total average weight of eggs in these breeders was 5.31 Kg with an average of 54 eggs per gram egg. The average germinal vesicle in these breeders was recorded as 8.7. These breeders showed an average age of 19.2 years and an average condition factor of 0.71. Average length in male A. persicus breeders was 48.9 cm and average condition factor was 0.61. In A. stellatus breeders the average body length was recorded as 145.6 cm and the average body weight was 11 kg. The average weight of eggs was 1.7 kg with an average of 92.2 eggs per gram egg. The conditicn factor recorded for these breeders was 0.49 and the average age was 12.9 years. The breeders responded to breeding at an average period of 427.3 ؛t. The GV in these breeders ranged from 7.8 to 15.2 and the average fertilization rate was 55.5%. A. persicus breeders that were used in caviar production showed an average length of 147.1cm and an average weight of 10.7 kg. The total average weight of eggs in these factor (0.21) were poor. A. nudiventris showed poor growth rate (3.07) and average condition factor (0.39). In this study 2547755 fingerlings were harvested from 29 earthen ponds(4 hac each) at the Late Yousefpour hatchery and released in to the Sefidrud River of which 2252459 fingerlings(88.4%) belonged to A. persicus with an average weight of 4.1g and an average length of 10.2cm, 183378 fingerlings(7.2%) belonged to A. stellatus with an average weight of 5.6 g and average length of 13.1 cm, 105299 fingerlings (4.14%) belonged to A. nudiventris with an average weight of 5.8 g and an average length of 10.6 cm and 6619 fingerlings (0.26%) belonged to H. huso with an average weight of 29.4 g and an average length of 20.2 cm. Of the total number of fingerlings released, 59.3% of A. persicus, 82.6% of A. stellatus, 77.2% of A. nudiventris and 100% of H. huso belonged to the 3 g weight class. Survival rate recorded was 30.8% for A. persicus, 62.1% for A. stellatus, 13.8% for A. nudiventris and 5.8% for H. huso. In is evident from the results obtained that growth rate (2.86) for A. persicus was poor while condition factor (0.37) for this species was at an average level. Growth rate (3.33) and condition factor (0.23) for A. stellatus were poor. A. nudiventris showed poor growth rate (3.08) and average condition factor (0.44), whereas H. huso showed poor growth rate (3.8) and condition factor (0.32). Significant difference was seen in A. persicus fingerlings released from the two hatcheries in the 3 g weight class regarding weight, length, growth rate, condition factor and percentage of release (P0.05). However A. persicus fingerling weighing 3 g released from the Shahid Beheshti hatchery were in a better state regarding growth rate and condition factor in comparison with those of the same species released from the Yousefpour hatchery. It may thus be concluded that A. persicus fingerlings reared in the Shahid Beheshti hatchery showed better growth and survival rates and reached a higher average weight in a shorter period of time.