A study on the physical and biochemical characteristics of semen of Tor putitora- an endangered fish species in Himalayan Water

Tor putitora is distributed in the entire northeast Himalayan region. The declining population of Tor putitora in natural waters has major concern to its fishery. The knowledge of semen characteristics is helpful in the selection of good quality semen for artificial fertilization thus have a role in fishery development. The current study aimed to determine the physical and biochemical composition of seminal plasma of Tor putitora.

The semen samples were collected by stripping the ripe male brooders procured from the natural habitat. The sperm motility, sperm density, spermatocrit value and osmolality were determined for physical characteristics of semen. Haemocytometric method was used for sperm density. The seminal plasma was separated by centrifugation for the determination of ionic and organic component of semen through atomic absorption spectrometer.

The semen of T. putitora has shown species-specific features of sperm density (1.712 ± 0.18 * 10⁹ ml⁻¹), spermatocrit (62.96 ± 2.63%) and sperm motility duration (48.16 ± 1.68 s). The Na²+ (102.06 ± 5.115 mM l^J) and K+ (51.66 ± 3.205 mM l ^−l) are predominating ions among the other inorganic constituents (Ca²+: 1.38 ± 0.304 mg dl⁻¹, Mg²+: 0.86 ± 0.261 mg l⁻\ phosphate: 4.00 ± 1.102 mg dl⁻¹, Cu²+: 0.004 ± 0.001 mg I⁻¹ and Zn²+: 0.062 ± 0.005 mg I⁻¹) of the seminal plasma. The organic constituents of seminal plasma contained - Glucose: 9.6 ± 0.678 mg dl⁻¹, Cholesterol: 21.0 ± 1.049 mg dl⁻¹, Triglycerides: 11.0 ± 0.316 mg dl⁻¹, Urea: 12.6 ± 1.7206 mg dl⁻¹ and Uric acid: 0.5 ± 0.10 mg dl⁻¹. The Osmolality (256.8 ± 31.940 mOsmol kg⁻¹), pH (7.34 ± 0.04) and ionic composition of semen seem to be the most important factor responsible for inhibition or activation of sperm motility. A high significant positive relationship (r=0.807, P<0.01) was found between sperm density and spermatocrit suggests the use of regression equation for quick and reliable estimation of sperm concentration in Tor putitora. The study is helpful in the selection of high-quality male spawners and provides baseline information for the development of extenders and dilutants for the preservation of viable semen.