Age, growth and maturity of brown stripe snapper Lutjanus vitta (Quoy& Gaimard, 1824) from southwest coast of India

Abstract

Growth, mortality, length-weight relationship, maturity and spawning of Lutjanus vitta were studied based on samples collected from 30 and 80 m depths along the southwest coast of India during October 1999 - December 2009. The von Bertalanffy growth equation was derived as L t = 32.5 (1-e-0.66 (t - 0.014)) during the year 2000; changes in these parameters during 2003-04 and 2007-08 are discussed in this paper. The lengthat-age was 12.3±1.36 cm, 18.9± 1.67 cm, 24.72± 1.58 cm, 28.9±0.98 cm and 31.5±0.94 cm in the I, II, III, IV and V year respectively. The annual natural, fishing and total mortality rates were 1.33, 0.85 and 2.18 respectively. The exploitation ratio (E) was 0.39, which indicates that this species is not under heavy fishing pressure. Recruitment was peak in March. Length-weight relationship was estimated for males and females, and later for the pooled data as W= 0.00000139 L 2.983. The relative condition factor (Kn) does not vary significantly among the size groups but the seasonal condition factor (K s) is comparatively lower in the smaller size group. Higher gonado-somatic index (GSI) was seen during August - December. The length-at-first maturity was 15.8 cm for female and 14.5 cm for male. During October and November, the one-year age group (12.5cm ( ) and 14 cm ( )) appeared in the spawning grounds and extended the spawning activity by performing batch fecundity. The relative fecundity ranged between 2,22,016 ± 28,543 and 5,21,482 ± 67,044 eggs/fish.