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

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 0.74 year and 2.66 year for C. striata and maximum were 0.93 year and 3.31 year 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 (3.98 cm), and the greatest was found for C. striata (16.96 cm). The minimum Lₒₚₜ was obtained as 3.78 cm TL for B. badis and maximum was 14.09 cm 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.