Reproductive pattern and maturity phases of indigenous Kunar snowtrout Schizothorax labiatus inhabiting Vishav Stream in Kashmir Himalaya, India
2022
Arafat, Mohammad Yasir | Bakhtiyar, Yahya
The controlled breeding program of Schizothorax labiatus requires in-depth knowledge of its reproductive features, which were studied for 2 years (October 2017 to September 2019). The study revealed four maturity phases in S. labiatus differing morphologically as well as histologically. Overall gonadosomatic index (GSI) followed the same trend in both the sexes (p>0.05; t-test), but a significant difference in GSI was observed in March with females having a higher GSI than males (p<0.05; t-test). The peak values of GSI in both sexes were observed during April and May with an abrupt decrease in June. The minimum ova diameter (0.3 mm) showed high frequency during the regressing phase, whereas the maximum ova diameter (2.4 mm) showed high frequency during the spawning capable phase. Absolute and relative fecundity ranged from 2754±1388 to 13465±7508 ova and 14±10 to 45±12 ova/g body weight, respectively. Absolute fecundity showed a highly significant positive correlation (p<0.01) with ovary weight as compared to ovary length, total length, and the total weight of the fish. Length at first maturity (Lₘ) for males and females was estimated to be 23.6 cm and 27.6 cm, respectively, indicating that males mature earlier than females. GSI of both sexes was found to increase significantly with the water temperature from December to April (rₛ = 1.0 for males and rₛ = 0.9 for females; p<0.05). The unimodal distribution of oocytes revealed that all oocytes are released in a short period (total spawner) from the late spring to summer season.
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