Fishery, Growth, and Mortality of Threatened Asian Sunfish, Horabagrus brachysoma (Gu¨nther 1864) in Five Rivers of Western Ghats Hotspot, India

Community-based data monitoring (CBM) systems play a vital role in small-scale inland fisheries, offering valuable insights into the catch patterns of various fish species over extended periods. This study adopted a participatory approach to investigate the fishery, demography, and exploitation patterns of the 'Vulnerable' Catfish (Horabagrus brachysoma) in five river systems within the Western Ghats biodiversity hotspot of India. The catches of this species from various landing centres across the Western Ghats' rivers varied between 0.73 t to 3.15 t annually. These fish typically measured between 11.00 and 41.10 cm in Total Length (TL) and weighed between 26.00 g to 470.00 g in Total Weight (TW). Analysis of annual length frequency data provided by local fishers, the estimated growth parameters of H. brachysoma are estimated as; asymptotic length (L∞) between 316.05 and 421.05 mm, growth coefficient (K) between 0.58 yr -¹ and 1.10 yr -¹ from different rivers. The total mortality (Z) was calculated to range between 1.25 yr -¹ and 2.91 yr -¹ while the fishing mortality (F) was estimated between 0.62 yr -¹ and 2.09 yr -¹. The estimated fishing mortality rate of H. brachysoma in the Periyar River, at 2.09 yr -¹, is alarmingly high and among the highest recorded for this species. The calculated exploitation rate (E) ranging from 0.49 to 0.72 yr -¹ exceeds the anticipated optimum exploitation levels (0.5). This suggests that the populations of H. brachysoma in the river systems of the Western Ghats are experiencing overexploitation. Various conservation measures such as fishing closures during spawning seasons, restrictions on mesh sizes, non-fishing zones and quota systems should be implemented.