Investigations on the age, growth and mortality parameters of Kawakawa, Euthynnus affinis (Cantor, 1849) from the North west coast of India

Abstract

Kawakawa, Euthynnus affinis contributes to the tune of 35,466 tonnes forming 1% to the total marine fish landings of India. Investigations on growth and mortality were of this species carried out based on the length frequency data during 2008-2012. The length-weight relationship for the pooled samples were derived for intercept a=0.0286, slope b=2.857 and coefficient of determination r2=0.917. The values obtained for growth parameters of L∞ was 67.86 cm, for growth coefficient (K) 0.70 and for to -0.26y-1. The natural, total and fishing mortalities recorded as 0.86, 1.48 and 0.62 y-1,respectively. The exploitation ratio (F/Z) was observed as 0.42. The M/K ratio was estimated at 1.23. The average fork length of 46 cm and weight of 2024 g were estimated in the samples collected. The length at the end of 1st year to 5th year was observed to be 33, 52, 64, 70 and 75 cm, respectively. The fishing mortality derived in this study is more than the optimum and limit value indicated the sign of overexploitation.

Keywords

• asymptotic length, mortality, exploitation ratio, length at age.