Studies on the growth and reproductive biology of Schizothorax curvifrons (Heckel, 1838) in River Jhelum, Kashmir
Shah, Tasaduq H.
2015
M.Sc
During the present study on the growth and reproductive biology of Schizothorax curvifrons in River Jhelum, various morphometric characters, length-weight relationship, histology of gonads, growth parameters (L∞ and K), fecundity, sex ratio, gonadosomatic index and Length at first maturity was investigated. A total of 298 specimens of S. curvifrons were studied during May 2013 to April 2014. The total length of the specimen ranged from 140 mm to 446 mm with the corresponding weight being 71 gm and 442 gm respectively. Correlation coefficient (r) of morphometric characters was highest for total length and standard length (0.94%) and lowest for total length and head length (0.72%). The length weight relationship was recorded separately for both males and females. The regression equation for males was expressed as Log W = -3.9323 + 2.5863 Log L (R2 = 0.746) and for females as Log W = -4.1708 + 2.6852 Log L (R2 = 0.745). The length weight equation for pooled data was Log W = -3.9975 + 2.6138 Log L (R2 = 0.7962). The ‘b’ value of 2.6138 obtained for the pooled data was found to be significantly different from 3 indicating negative allometric growth in the fish. Maximum (gonadosomatic index) GSI values were recorded around spawning season i.e. March and April with peak values of 6.5 in males and 12.0 in females. The absolute fecundity varied from 4762 to 17196 eggs and relative fecundity from 23 to 76 ova. The average absolute fecundity recorded was 9764 where as average relative fecundity was 43 per gram body weight. The average sex ratio (Male: Female) varied from 1:0.20 in May to 1:0.59 in November. The average sex ratio for the entire period of study was 1:0.40 (Male: Female) indicating a significant dominance of males. The estimated condition factor (K) of S. curvifrons varied from 0.62 (July) to 0.86 (June) in case of females and 0.64 (July) to 0.87 (June) in case of males. The length at first maturity (L50) for females of S. curvifrons was estimated as 252 mm. The annual ovarian cycle consists of five stages viz. (i) Immature Phase (ii) Preparatory Phase (iii) Maturing Phase (iv) Ripe/Spawning Phase and (v) Spent Phase. The annual testicular cycle has also been divided into five stages (i) Early Immature Phase (Resting Phase) (ii) Late Immature Phase (iii) Maturing Phase (iv) Mature Phase and (v) Spent Phase. Growth was obtained at monthly intervals and the regression of Lt+1 on Lt were used for the calculation of ‘L∞’ (asymptotic length) and ‘K’ (growth coefficient). The estimated values of ‘L∞’ and ‘K’ by modal progression method were found to be 493 mm and 0.091 month-1 respectively. The value of to estimated by VBGF plot was found to be 0.007529 years.
en
SKUAST Kashmir
Studies on the growth and reproductive biology of Schizothorax curvifrons (Heckel, 1838) in River Jhelum, Kashmir
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Studies on the growth and reproductive biology of Schizothorax curvifrons (Heckel, 1838) in River Jhelum, Kashmir
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