Schizothorax richardsonii is an important genera of Schizothoracine group and is considered as important food fish of Peer Panjal region in North West-Himalaya, India. Schizothoracids represent the most dominant group of fish fauna in the snow-fed rivers of Poonch among which S. richardsonii has a vital role in commercial fishery. Although lot of work on the various aspects of reproductive biology of the group inhabiting in both lotic and lentic water bodies have been reported in the past from this region, however, detailed knowledge about reproductive biology of S. richardsonii from any geographical regions has not been reported yet. Therefore, the present study aims to characterize the reproductive biology of S. richardsonii inhabiting in river Poonch.
Monthly sampling was carried out from four different sites and a total of 125 specimens were collected. The specimens were transported to the laboratory for further analysis. Total length was measured using vernier caliper, while as body weight was recorded using digital electronic balance. Sex ratio was calculated on monthly basis and the results were analyzed by a χ2 test (1:1; P ? 0.05). For gonad collection, ventral side of the fish was cut and opened from the anterior end and gonads were carefully detached from other visceral organs and cleaned. Gonadosomatic index (GSI) was calculated by standard formula. Number of eggs and oocyte diameter were also recorded. Maturity stages and reproductive seasonality were determined by visual observation of gonads as well as by examination of monthly changes occurred in GSI. Fecundity was estimated for 24 mature females following the gravimetric method. Relationships between absolute fecundity and total length, total body weight and ovary weight were determined by using standard formula.
The results showed that GSI increased from May onwards and attained a peak in the month of October both for (8.23 ± 2.04) males and (12.42 ± 4.10) females and thereafter again an increase in GSI was recorded from January to March, indicating that fish had two spawning seasons with a peak in October and another short peak period was noted in the month of March. Based on the GSI and visual analysis six maturity stages were identified which showed that fish spawns twice in a year. Minimum ova diameter was recorded in the month of April (0.21 ± 0.09), while highest was estimated in the month of October (2.12 ± 0.80 mm). Fecundity was recorded in the range from minimum 2012.6 (TL = 17.8 cm) to maximum 5213.7 (TL = 39.2 cm). Regression analysis was used to determine the relationship between fecundity and total length (TL), fecundity and total body weight (BW) and fecundity and ovary weight (OW). Fecundity were correlated positively with TL (Log F = 97.65+683.1 log TL; r2 = 0.524), BW (Log F = 9.530+226.2 log BW; r2 = 0.328) and OW (Log F = 67.35+1866 OW; r2 = 0.478). During the study period different physico-chemical parameters were also recorded.