Some characteristics and short-term preservation of spermatozoa of Deccan mahseer, Tor khudree (Sykes)

Over the years, the natural stocks of Tor khudree (Cyprinidae) have depleted due to anthropogenic activities and hence it is considered a threatened species in India. Several in situ and ex situ conservation strategies have been suggested for the revival of T. khudree stocks. The total volume of milt obtained from hormone-injected (gonadotropin-releasing hormone analogue+domperidone) T. khudree were significantly higher (six to seven times) than that of uninjected fish. The total number of spermatozoa per fish was also higher in injected fish (6.5 x 10(8)-7.6 x 10(8)) than that obtained from uninjected counterparts (1.3 x 10(8)-1.8 x 10(8)). On the contrary, the spermatozoa density and spermatocrit were found to be lower in injected fish than that of the controls. Spermatozoa density and spermatocrit ranged between 4.1 x 10(8)-4.4 x 10(8) spermatozoa mL(-1) and 38.1-39.4%, respectively, in injected fish, whereas the figures fluctuated between 6.0 x 10(8)-7.8 x 10(8) spermatozoa mL(-1) and 61.5-63.1%, respectively, in uninjected fish. However, there was no significant difference in the spermatozoa motility rates between experimental and control fish. Different spermatozoa-activating media revealed no significant difference in spermatozoa motility between hormone-injected and uninjected mahseers. But motility duration was the longest with NaCl+urea (190-193 s) and the shortest with tap water (50-55 s) in the experimental and control groups. Short-term preservation of the spermatozoa of T. khudree indicated that spermatozoa stored at 4 degrees C had higher motility rates than those preserved at room temperature either in the presence or absence of oxygen.