Biological insights into the vulnerable<i> Hyporhamphus xanthopterus</i> from Vembanad Lake: Fishery trends and growth parameters

This study examined the fishery characteristics, length-weight relationship (LWR), and condition factor of Hyporhamphus xanthopterus (Valenciennes, 1847), T from Kumarakam region of Vembanad Lake, Kerala, during 2020-2021. This investigation provides the first sex-wise analysis of length–weight relationships (LWR) and season-wise evaluation of condition factor (Kn) for H. xanthopterus population. A total of 657 specimens (304 males and 353 females) were caught employing 18 mm mesh sized gillnets, and measured for total length (TL) and total weight (TW) to estimate growth patterns using the allometric model. Males exhibited isometric growth (b=3.004) (R2 =0.94), while females displayed slightly negative allometric growth (b=2.857) and R2=0.96. When all the individuals are pooled, the estimated growth exponent b was 2.918 (R2=0.96). Seasonal analysis of condition factor indicated statistically significant variation, with higher Kn values observed in both males and females during Season 3 (post-monsoon), likely reflecting ecological influences such as food availability, reproductive activity, and environmental stress. These findings highlight distinct sex-specific growth patterns and seasonal physiological shifts, offering valuable insights into the biology and ecological adaptation of H. xanthopterus. The baseline data provided here can inform future research, resource management strategies, and biodiversity conservation efforts targeting H. xanthopterus and the broader aquatic ecosystem of Vembanad Lake. Keywords: Condition factor, Conservation, Length-weight relationship, Management, Ramsar site