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

摘要

The Western Ghats of peninsular India is a highly sensitive and threatened ecoregionof exceptional freshwater ichthyodiversity. The present study investigated the growth,mortality and stock characteristics of Hypselobarbus thomassi, an endemic cyprinidfish from the Parappar Reservoir of Western Ghats, on the basis of the length-frequencydata collected during the period from 2009 to 2011. The growth parametersof 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 atzero length (t_0) was calculated as −0.0485 year~(−1). The longevity (t_(max)) and growth performanceindex (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 E_(0.1) = 0.36, E_(0.5) = 0.28 and E_(max) = 0.42. The current explorationlevel (0.77) is higher than the optimum exploitation rate (E_(max) = 0.42), indicatingan overexploitation of the H. thomassi population. Accordingly, needed managementmeasures should include restrictions on fishing gear mesh sizes, reduced fishing effortand declaration of closed seasons and sanctuaries to protect this threatened species.