Investigations on age, growth and mortality parameters of Ailia coila (Hamilton, 1822) (Siluriformes: Ailiidae) from Brahmaputra river system of Assam, India

Abstract

The present study deals with the detailed investigation on population dynamics of the near-threatened catfish Ailia coila
(Hamilton, 1822), which inhabits the Brahmaputra River of India and forms an important component of freshwater inland
fishery, providing nutritional and financial security to the local community. A total of 1034 individuals were collected by
weekly sampling from the Uzanbazar and Dhubri landing centres of this river system from September 2013 to April 2014.
The estimated asymptotic length (L∞), growth coefficient (K) and age at zero length (t0) of A. coila were 268 mm, 0.87 yr-1
and t0 = 0.000028 years respectively. Estimated total mortality (Z), natural mortality (M) and fishing mortality coefficient
(F) were 5.76, 1.63 and 4.13 yr-1 respectively. Using von Bertalanffy growth formula (VBGF) the length attained at the end
of first, second and third years of life were estimated at 156, 221 and 248 mm, respectively. The von Bertalanffy growth
equation of this fish can be written as Lt = 268 {1-e-0.87(t+0.000027866)}. The exploitation ratio (U) and exploitation rate (E) and
M/K ratio were estimated at 0.71, 0.72 and 1.87, respectively.

Keywords: Ailia coila, Asymptotic length, Fishing mortality, Growth co-efficient, M/K ratio