African Journal of Biotechnology

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Effect of weight on osmoregulation ability in Rutilus frisii kutum fingerlings

SA Hosseini, CR Saad, SA Hosseini, MS Bourani, HM Daud, SA Harmin


Experiments were conducted to study the downstream migratory behavior and effects of weight on osmoregulation ability of hatchery-reared Rutilus frisii kutum fingerlings during adaptation to the seawater. Accordingly, blood osmotic pressure regulation ability in kutum fingerlings with weights of 1, 3, 5 and 7 g in three different salinities, 13 ppt (Caspian Sea salinity), 7 ppt (estuarine area) and 0.3 ppt (freshwater) were assessed. The blood samples were collected before being transferred as control (freshwater) and after exposure to the sea and estuarine water in a period of up to 336 h by a pooling method. The results indicate that only 3, 5 and 7 g kutum are able to adapt to salinity of 7 and 13 ppt since they maintained the osmolarity. In 1 g kutum, the levels of osmotic pressure showed significantly higher values after 48 h until the end of the experiment compared to other weight groups and the respective control level (P<0.05). In conclusion, the results show that osmoregulation systems in 1 g fingerlings were not able to decrease the osmotic pressure. Therefore, they cannot be suggested as suitable sizes to be released into the brackish and marine environments.

Key words: Rutilus frisii kutum, osmotic pressure, salinity, weight, Caspian Sea.
AJOL African Journals Online