Biological aspects of the Ganges River sprat Corica soborna (Clupeidae) in the Mathabhanga River (SW Bangladesh)
The present study describes some biological parameters, including sex ratio, length-frequency distributions, size at sexual maturity, fecundity as well as length-weight (LWR) and length-length (LLR) relationship of the Ganges River sprat Corica soborna (Hamilton, 1822) (Clupeidae), an important target species for small scale fisheries in the Mathabhanga River in Bangladesh. A total of 135 specimens ranging from 30.6-48.9 mm TL (total length) and 0.22-1.20 g BW (body weight) were analysed. Sampling was done using traditional basket traps and funnel bag nets between January and December 2004. The sex-ratio showed no significant differences from expected value of 1:1 (χ2 = 0.07, p > 0.05). The size at sexual maturity (TL50) for C. soborna females was estimated to be 44.4 mm TL and the mean fecundity of the sampled population was 1,280 ± 870 eggs, ranging from 420 to 3,240. The allometric coefficient b values of the LWR indicated isometric growth (~3.0) for both males and females (2.946 and 2.968, respectively). The LLR analysis between TL and fork length (FL) showed a highly significant correlation in both sexes (r2 > 0.911, p < 0.001). The data presented in this study would be useful for the sustainable management of the Ganges River sprat fishery in the Mathabhanga River in Bangladesh and neighbouring countries.