Life history Traits of the Threatened Freshwater Fish Cirrhinus reba (Hamilton 1822) (Cypriniformes: Cyprinidae) in the Ganges River, Northwestern Bangladesh (Ciri Sejarah Kehidupan Ikan Air Tawar Terancam Cirrhinus reba (Hamilton 1822) (Cypriniformes: Cyprinidae) di Sungai Ganges, Barat Laut Bangla
The threatened Reba carp, Cirrhinus reba is a freshwater fish species found in ponds, rivers, canals and tanks of Bangladesh, India, Myanmar, Nepal and Pakistan. The present study describes the first complete and inclusive description of life history traits including sex ratio, length frequency distributions (LFD) length weight relationships (LWR) condition factors (Allometric, K A Fulton's, K F Relative condition, K R Relative weight, W R form factor (a 3.0 and size at first sexual maturity of C. reba in the Ganges River, NW Bangladesh. Sampling was done using traditional fishing gears including cast net, square lift net and conical trap from April 2011 to March 2012. The total length TL) fork length (FL) and standard length (SL) were measured to the nearest 0.01 cm using digital slide calipers and total body weight (BW) was measured using an electronic balance with 0.01 g accuracy. The LWR was calculated using the expression: W= a L b where W is the BW, L the TL. The size at first sexual maturity of C. reba was estimated using the empirical equation by Binohlan and Froese (2009) for male and female, separately. A total of 250 specimens ranging from 8.00 cm 23.40 cm TL and 4.30 g 200 g BW were analyzed in this study. The overall sex ratio did not differ significantly from the expected value of 1:1 kh 2 3.38, p 3.00) in male and female and there was significant differences in the intercepts ancova, p< 0.001) and in the slopes (ancova, p< 0.001) between the sexes. In addition, the Mann Whitney U test showed significant differences in the Fulton's condition factor between male and female (p< 0.001) The one sample t test showed that the mean W R (actual mean 99.50) did not differ from 100 for male (p= 0.523) and female (p= 0.197) in this study, indicating the habitat was still in good condition for C. reba. Moreover, the size at sexual maturity of male and female C. reba were estimated as 11.50 cm TL and 13.50 cm TL, respectively. The results of this study would be useful for the sustainable conservation of this threatened carp fishery in Bangladesh and also neighboring countries.