The effects of salinity on reproductive performance and plasma levels of sex steroids in Caspian kutum Rutilus frisii kutum |
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| Authors: | Ali Bani Ali Haghi Vayghan MirGhasem NaserAlavi |
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| Institution: | 1. Department of Biology, Faculty of Science, University of Guilan, Rasht, Iran;2. Department of Fisheries, Faculty of Fisheries and Environment, Gorgan University of Agricultural Science and Natural Resources, Gorgan, Iran |
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| Abstract: | Sexually mature kutum, Rutilus frisii kutum, captured from its natural habits, the Caspian Sea and the Khoushkrood River, reared at 0.5 g L?1 and 8–13 g L?1 for approximately 1 year in experimental condition, for assessing the effect of salinity on reproduction. Plasma concentrations of sex steroid hormones (17β‐estradiol, testosterone and 17α‐hydroxyprogestrone) were measured in the three stages of gametogenesis. Female kutum held at <0.5 g L?1 or 8–13 g L?1 had no ovulated oocytes in their ovaries. In contrast, males held in captivity were spermiated, similar to their wild counterparts. The average sperm volume of males held at <0.5 g L?1 (2.36 ± 0.46 mL) was lower than males held at 8–13 g L?1 (3.65 ± 0.73 mL) at the end of the experimental period. The highest concentration of testosterone was observed in mid‐gametogenesis in wild fish that was significantly higher than the concentration seen in fish held in either <0.5 g L?1 or 8–13 g L?1. Female kutum showed suppressed steroid hormones in captivity, resulting in failure in the gonad development. However, male kutum adapt well to captivity and showed synchrony in steroid hormone variations with the wild fish, resulting in the testicular development. Results of this study also indicate that salinity plays a minor, but vital, role in reproduction of kutum, a factor that needs to be considered for keeping broodstock of brackish water fish species like kutum. |
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| Keywords: | sex steroids salinity hormone cyprinid Caspian Sea |
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