Population dynamics of Hypselobarbus thomassi (Day 1874), an endemic cyprinid fish from a tropical reservoir of Southern Western Ghats, India

Abstract

AbstractThe Western Ghats of peninsular India is a highly sensitive and threatened ecoregion of exceptional freshwater ichthyodiversity. The present study investigated the growth, mortality and stock characteristics of Hypselobarbus thomassi, an endemic cyprinid fish from the Parappar Reservoir of Western Ghats, on the basis of the length‐frequency data collected during the period from 2009 to 2011. The growth parameters of this species were estimated using the FiSAT program, and the asymptotic length (L∞) and growth constant (K) being 476.79 mm and 0.39 year−1, respectively. The age at zero length (t0) was calculated as −0.0485 year−1. The longevity (tmax) and growth performance index (ϕ) were reported as 7.69 years and 2.95. The estimated total mortality (Z), natural mortality (M) and fishing mortality (F) were 1.65, 0.38 and 1.27 year−1, respectively. The relative yield per recruit (Y/R) analysis revealed the exploitation rate (E) at different levels as E0.1 = 0.36, E0.5 = 0.28 and Emax = 0.42. The current exploration level (0.77) is higher than the optimum exploitation rate (Emax = 0.42), indicating an overexploitation of the H. thomassi population. Accordingly, needed management measures should include restrictions on fishing gear mesh sizes, reduced fishing effort and declaration of closed seasons and sanctuaries to protect this threatened species.