Biometry, sexual maturity, natural mortality and fecundity of endangered halfbeak Dermogenys pusilla (Zenarchopteridae) from the Ganges River in northwestern Bangladesh
1548-1555The present study express the biometry, including length-weight relationships (LWRs) using 12 equations, length-length relationships (LLRs) using 15 equations, condition factors (allometric, KA; Fultonʹs, KF; relative, KR; and relative weight, WR), form factor (a3.0), first sexual maturity (Lm), natural mortality (MW) and fecundity (FT) of Dermogenys pusilla from the Ganges River, northwestern Bangladesh. A sum of 75 individuals was hardly collected using cast net and gill net during July 2013 to June 2014. In our study total length ranged from 6.6–16.1 cm for male and 7.5-15.6 cm for female and fin formula was- dorsal, D. 12 (4/8); pectoral, P1. 11 (2/9); pelvic, P2. 6 (1/5); anal, A. 13-14 (2-3/11-12) and caudal C. 18-20 (4/14-16). All LWRs were highly significant (P r2, BW vs. FL was the best fitted model among 12 equations for both sexes. The analysis of covariance (ANCOVA) revealed significant differences between males and females for LWRs (P P r2 values ≥ 0.940. According to highest value of r2, LLR by TL vs. FL was the best suited model among 15 equations for both genders. Based on Pearson correlation values, KF was highly correlated with BW and TL; thus KF can be used for the wellbeing of this species in the Ganges River. The a3.0 was 0.0025 for male and 0.0024 for female. The Lm was 9.70 cm TL for male and 9.40 cm TL for female. Also, the MW was 1.13, 1.41 year-1 for males and females respectively, and the fecundity was ranged from 620-1544 (mean ± SD = 1125 ± 248). Therefore, the findings of this study would be very effective for sustainable conservation of this endangered species in the Ganges River and surrounding ecosystem
