Life-history traits of ten commercially important small indigenous fish species (SIFS) in the Oxbow lake (Southwestern Bangladesh): key for sound management

Abstract

For the first time, we revealed the life-history traits including growth pattern (length-weight relationships, LWRs), condition factors, form factor (a3.0), first sexual maturity (Lm), age at first sexual maturity (tm), life span (tmax), natural mortality (Mw), asymptotic length (L∞), and optimum catchable length (Lopt) of ten commercially important small indigenous fish species (SIFS) in the Oxbow lake (Baor), southwestern regions of Bangladesh. A total of 1651 specimens were sampled during January to December 2020 with traditional fishing gears including seine nets, gill nets, and lift nets. Individual total length (TL) and body weight (BW) were measured by digital slide calipers and digital balance, respectively. To calculate the Lm, empirical maximum length-based model was considered, and Lopt was calculated based on L∞. The TL vs. BW relationship indicated positive allometric growth for Chanda nama (Hamilton 1822), Channa punctata (Bloch 1793), Channa striata (Bloch 1793), Lepidocephalichthys guntea (Hamilton 1822), Macrognathus pancalus (Hamilton 1822), and Puntius sophore (Hamilton 1822), but negative allometric growth for Badis badis (Hamilton 1822), Gudusia chapra (Hamilton 1822), Glossogobius giuris (Hamilton 1822), and Hyporhamphus limbatus (Valenciennes, 1847). All r2 values exceed 0.910 that indicated all LWRs were highly significant (P < 0.001). According to Spearman correlation test, Fulton's condition factor (KF) vs. BW was highly correlated (P < 0.001), indicating better well-being for these species. Moreover, a3.0 indicates B. badis, C. punctata, C. striata, G. giuris, H. limbatus, L. guntea were elongated; C. nama, P. sophore, were short and deep; G. chapra was fusiform, and M. pancalus was eel-like body shape respectively. The minimum tm and tmax were obtained as 0.74year and 2.66year for C. striata and maximum were 0.93year and 3.31year for B. badis, respectively. This study provided information on tm and tmax for ten SIFS that is globally absent. From empirical models, the smallest mean value of Lm was found for B. badis (3.98cm), and the greatest was found for C. striata (16.96cm). The minimum Lopt was obtained as 3.78cm TL for B. badis and maximum was 14.09cm TL for C. punctata. The minimum Mw was documented as 1.39 for B. badis and maximum was 1.73 for C. striata. The output of this research will be helpful for developing sustainable management policies and protection of SIFS through the application of mesh size based on Lm and Lopt in the Oxbow lakes, Bangladesh and neighboring countries.