The effects of salinity on plasma levels of cortisol, glucose and sex steroids in Kutum (Rutilus frisii kutum)

The effects of salinity on reproduction and levels of cortisol, glucose and sex steroidsof Kutum were studied in three stages including pre-vitellogenesi, vitellogenesis andmaturation. The females caught from the Khoushkrood River were maturated inMarch, whereas the females held at salinity of < 0.5 ppt and 8-13 ppt had no ovulatedoocytes in their ovaries. In contrast, males were spermiated in captivity similar to that of wild specimens. The highest concentration of testosterone was observed inJanuary in wild specimens that was significantly higher than that of November andMarch specimens. There was no evidence of plasma T increase in fish held in either< 0.5 ppt or 8-13 ppt. Plasma cortisol levels were not significantly different betweenfemale kutum held in captivity and wild-caught fish in different months. Plasmaglucose concentration in wild-caught females was almost three times higher thancaptive female kutum in November. The results indicated that reproduction of kutumis somewhat affected by salinity.

کلیدواژه ها:

Kutum ، Sex steroids ، Salinity variation ، Captivity ، Caspian Sea