Estimation of life history parameters of the Gangetic leaffish, Nandus nandus from southern coastal waters of Bangladesh: Implications for sustainable management

The Nandus nandus (Hamilton, 1822) is a highly prized food fish that possesses significant nutritional and commercial worth. Bangladesh, India, Pakistan, Malaysia, Myanmar, Thailand and Viet Nam are the countries where it is endemic. The IUCN Bangladesh has classified this species as near endangered due to its current progressive decline. Hence, immediate actions are necessary to efficiently manage the fishery in this country. To address this issue, a comprehensive understanding of its life history parameters is required. This study aimed to examine the growth characteristics, recruitment length, sexual maturity, mortality, exploitation rate, and maximum sustainable production of N. nandus in Bangladesh's southern coastal waters. Samples were taken every month from January through December of 2021. Our study indicates that N. nandus grows in an isometric manner. The estimated asymptomatic length of this species is 18.0 cm in total length (TL), growing at a rate of 1.30 year−1. The growth performance index of this species was determined to be 2.62, and the projected lifespan was calculated to be 2.31 years. The initial length at recruitment was measured to be 9.5 cm TL, whie the size at first sexual maturity was recorded to be 9.4 cm TL. With the contributions of the natural mortality rate (2.26 year−1) and the fishing mortality rate (1.86 year−1) the total mortality rate was found to be 4.12 year−1. The exploitation rate, determined to be 0.45, surpasses the upper limit of sustainable yield criteria set at 0.37. Therefore, it is imperative to implement strategies to avoid excessive fishing and guarantee the long-term control of N. nandus populations.