STUDIES ON GONADOSOMATIC INDEX AND FECUNDITY OF STRIPED SNAKEHEAD (Channa striatus) IN NATURAL WATER OF SYLHET

Abstract

The research was conducted to determine the breeding season of striped snakehead Channa striatus based on gonadosomatic index, hepatosomatic index, fecundity, length-weight relationship, body weightfecundity

relationship and gonad weight-fecundity relationship. The objectives were evaluated through sampling for six consecutive months from April to September, 2014 and samples were collected from local natural water resources in Sylhet. During study, the range of mean values of length and weight of female fish were recorded as 31.03±.70 to 36.64±3.04 cm and 264.31±11.74 to 410.03±75.87 g, respectively. The highest mean GSI was 5.10±0.81 for female and 0.74±0.21 for male also showing the gonadal development reached its peak in June. Hepatosomatic index implies energy storage for reproduction. Lower somatic condition during the spawning season gives an indication that the somatic growth is limited due to the development of gonads. The highest mean HSI was 0.81±0.05 in the month of September and lowest mean value 0.67±0.17 was recorded in the month of June for female. In case of HSI in male, the highest mean value was recorded in the month of April 0.84±0.03 and lowest value was shown in the month of June 0.62±0.01. The GSI value was found to be inversely related with the HSI during the study period, which indicates transformation of energy into ovary in form of vittelogenine. The fecundity was found to range from 6,158 to 22,783 eggs, where the maximum fecundity 22,783 was observed in June. Fecundity bears stronger relationship with gonad weight and body weight. The regression equation for gonad weight and fecundity, body weight and fecundity was estimated as F=844.3 GW+3092 (r =0.875) and F= 63.88 BW-9678 (r 2 =0.501), respectively. The relationship between fecundity and gonad weight was significant and the correlation coefficient between fecundity and body weight was also significant and provided a positive correlation. The relationship of body length and weight of female was found BW=23.40 BL–456.8 (r²=0.872) and male was found BW=28.93 BL-675.6 (r 2 =0.921), which was showed significant correlation. The monthly values of GSI indicated that the main breeding season of C. striatus was observed in the month of May to July where the peak breeding occurred in June in the natural habitat of Sylhet. 2