|
|
:
|
Due to the drought and water shortage of rivers in the southern basin of the Caspian Sea, especially during the release of juveniles Acipenser stellatus and illegal fishing of these fish in the river, to increase the survival rate, it is better to release these fish in the river or directly into the Sea. Four weight groups of 0.5-1, 1-3, 3-5 and 5-10 g of juvenile Acipenser stellatus in four treatments of 0-0.5, 0.5-4, 4-9 and 9-13 salinity per thousand (g/l) and each treatment in three replications. The experiment was performed for a period of one month along with feeding with live food, preferably Daphne, Gamarus, Nereis worm with a saturation of 6 servings per day and water change. Daily losses were collected and recorded during the period. The results showed that growth indices (weight gain (WG), percentage of daily weight gain (ADG), specific growth rate (SGR), daily growth (GR), obesity coefficient (CF) and survival rate (Survival Rate) in different salinity there was no statistically significant difference in each of the weight groups. the percentage of survival in salinities of 0-0.5 and 4-5 g/l was significantly higher than salinity of 4-9 and 9-13 g/l in the weight range of 0.5-1 g. It was 0 g (df = 3, F = 68.800, P = 0.000). Also, the percentage of survival in salinities of 0-0.5 and 4-9 g / l was significantly higher than the salinity of 9-13 g/l in the weight range of 1-3 g (df = 3, F = 7.558, P = 0.010). Survival rate in salinities of 0-0.5 and 0.5-4 g/l was significantly higher than salinity levels of 4-9 and 9-13 g/l for weight of 3-5 g (df = 3, F = 8.933 P = 0.006). Survival rate in different salinities in the weight range of 5-10 g showed a significant difference (df = 3, F = 68.800, P = 0.000). According to the results, it is suggested that juvenile Acipenser stellatus first released in the estuary at salinity below range of 8 g/l and then enter to the Caspian Sea after adapting to salinity.
|