Fishery and population dynamics of Asian leaf fish Nandus nandus (Hamilton, 1822) for sustainable management implications: Insights from West Bengal, India

The Asian leaf fish Nandus nandus (Hamilton, 1822), a crucial small indigenous freshwater species of the Nandidae family, plays a pivotal role in supporting the livelihoods of fishers reliant on subsistence and marginal fisheries across India and neighbouring countries. There is only limited quantitative data on its exploitable status. Length frequency based growth and mortality dynamics of this species was studied from monthly samples collected from the wetlands of West Bengal during 2020-2021. Parameters of the length-weight relationship (a = 0.00892, b =3.244 and r2 =0.9364) indicated positive allometric growth. The von Bertalanffy growth parameters werew estimated as L∞ = 18.38 cm TL and K = 1.2 y-1. Mortality estimation indicated total mortality Z = 2.89 y-1, with natural mortality M = 2.33 y-1 and fishing mortality F = 0.56 y-1. The growth performance index (ϕ`) was 2.69. Length at capture (Lc50) was determined to be 14.3 cm TL, with current exploitation rate (Ecur) of 0.19, underscoring an opportunity to enhance fishing efforts and reduce natural mortality. Beverton and Holt yield per recruitment analysis indicated maximum exploitation rate (Emax) of 0.41. With E 0.1 at 0.35 and Ecur at 0.19, it is evident that the species is underexploited and there is scope to increase the effort to achieve maximum economic yield. Keywords: Exploitation rate, Recruitment dynamics, Sustainable fisheries management, Wetland fisheries