Population dynamics of wallago attu (Bloch and schneider 1801) (Osteichthyes, Siluridae) in three small rivers of Southern India

Abstract

The Asian sheat catfish, Wallago attu (Bloch and Schneider 1801) is a commercially important species harvested across tropical Asia owing to its high nutritional quality and consumer demand. Population dynamics and exploitation levels of W. attu based on catches from three small (< 245 km) river systems of southern India, revealed an asymptotic length (L∞) of 99.75 cm, growth coefficient (K) between 0.89 and 1.3 year-1, and total mortality rates between 2.23 and 3.36 year-1. In each river system, the exploitation rate (E) was greater than where the stock is reduced to half its virgin biomass (E50): Achenkovil (0.49 > 0.33); Pampa (0.51 > 0.30); Manimala (0.59 > 0.34), and close to the Emax (exploitation producing maximum relative yield per recruit of 0.58) in some, suggesting the immediate need for developing and implementing fishery management plans.