جستجوی مقالات مرتبط با کلیدواژه "polarization index" در نشریات گروه "زیست شناسی"

Availability of brood fish with high quality is one of the main aspects in sturgeon rehabilitation programs. The present study was conducted to compare different biological parameters and reproduction indices in 397 of Persian sturgeon broodstocks caught in the Sefidroud River and the Caspian Sea using beach seine and gillnets. A total of 74 Persian sturgeon broodstocks were caught in the Sefidroud River, and in the sea 199 spawners were collected using beach seine and 124 collected using gillnets. Results obtained showed that the minimum mean weight (26.5 ± 5.1 kg) recorded belonged to fish caught in beach seine whereas maximum mean weight (30.0 ± 4.0 kg) recorded belonged to fish caught in the river which were significantly different (P<0.05). No significant differences were detected in the weight of gonad from different groups of broodstocks (P>0.05). The highest polarization index (PI) (10.6 ± 2.6) in broodstocks belonged to the groups caught in beach seine and minimum PI values (6.6 ± 0.9) were observed in broodstocks caught in the river (P<0.05). Highest fertilization rate (92.2 ± 3.3 %) belonged to broodstocks caught in the river which was significantly higher than broodstocks collected from the sea (75.1 ± 4.8 %) (P<0.05). It is evident from the results obtained that higher values for reproduction indices were recorded in broodstocks caught in the river. Therefore, it is suggested that in order to improve artificial breeding programs in hatcheries and also to increase fertilization rate and survival rates of eggs and larvae, more attempts should be made to facilitate the migration of these spawners into the Sefidroud.