Growth and survival rate of Acipenser stellatus fish in different salinities of the Caspian Sea

Due to the drought and water shortage of rivers in the Southern basin of the Caspian Sea, especially during the release of these fish and illegal fishing of juveniles in the river, to increase the survival rate, it is better to release these fish in the river or directly into the sea. Acipenser stellatus were examined in different weights with four treatments of ۰.۵-۰, ۰.۵-۰, ۴-۹ and ۹-۱۳ salinity per thousand (ppt) and each treatment in three replications. The experiment was performed for a period of one month along with feeding with live food, preferably Daphnia, Gamarus, Nereis worm with a saturation of ۶ times per day. The water was exchanged and uneaten feed siphoned each day. Daily losses were collected and recorded during the period. The results showed that the percentage of survival in salinities of ۰.۵-۰ and ۴-۵ g/l was significantly higher than salinity of ۴-۹ and ۹-۱۳ g/l in the weight range of ۰.۵-۱ g. It was ۰ g (df=۳, F=۶۸.۸۰۰, P=۰.۰۰۰). Also, the percentage of survival in salinities of ۰.۵-۰ and ۴-۹ g/l was significantly higher than the salinity of ۱۳-۹ g/l in the weight range of ۱-۳ g (df=۳, F=۷.۵۵۸, P=۰.۰۱۰). Survival percentage in salinities of ۰.۵-۰ and ۰.۵-۴ g/l was significantly higher than salinity levels of ۴-۹ and ۱۳-۹ g/l for weight of ۳-۵ g (df=۳, F=۸.۹۳۳ P=۰.۰۰۶). Survival percentage in different salinities in the weight range of ۵-۱۰ g showed a significant difference (df=۳, F=۶۸.۸۰۰, P=۰.۰۰۰). According to the results, it is suggested that juvenile Acipenser stellatus are first released in the estuary at salinity below weight range of ۸ g/l and enter to the sea after adapting to salinity.

Keywords:

Growth , survival rate , Acipenser stellatus , salinity , Caspian Sea