Growth of the blue mackerel Scomber scombrus in Tunisia using the otolith microstructure

Abstract

This paper studies the age and the growth of male and female of the Tunisian blue mackerel Scomber scombrus during 2004–2006. The age was determined by interpreting and counting daily increments on the otoliths sagitta of 320 individuals sampled from landings caught by different gears specially by purse seine. The parameters of the Von Bertalanffy growth curve were estimated for sexes combined: Lf = 31.46(1 − e−0.228 (t+3.034)) (L∞ = 31.46 cm, k = 0.228 per year, t0 = −3.034 years); for male Lf = 27.43(1 − e−0.422 (t+1.747)) (L∞ = 27.43 cm, k = 0.422 per year, t0 = −1.747 years) and for female Lf = 31.70(1 − e−0.227 (t+2.196)) (L∞ = 31.70 cm, k = 0.227 per year, t0 = −2.916 years) for the whole study period. The difference between the growth of male and female is not significant. The relationship between length and weight shows a length growth faster than of the weight with parameters of the equation Wt = a*Lb; a = 9.89*10−5 and b = 2.37 for the sexes combined.