Life-history traits variation of Lutjanus malabaricus (Bloch & Schneider, 1801) in the waters off Northern Vietnam

Lutjanus malabaricus represents a widely distributed and intensively exploited snapper species. The present article is the first attempt to describe the life-history traits of L. malabaricus in Vietnamese waters and estimate their variability. The fish were collected at the landing sites of Nghe An and Ha Tinh provinces from June 2020 to May 2021. The standard length of fish ranged from 10 to 74 cm, weight varied between 18.53 and 8972.89 g, age ranged from 1 to 17 years and all three parameters were subjected to a significant seasonal variation. A similar seasonal pattern was observed in the variation of maturity and gonadosomatic index. We assume that the observed variation of the stock structure is the result of spawning migrations when large fish migrate inshore from the foraging grounds. Growth and weight gain of fish were described via the von Bertalanffy function, constants of the equations were as follows: L∞ = 76.2, K = −0.077, t0 = −2.26 in males and L∞ = 56.9, K = −0.176, t0 = −0.48 in females; W∞ = 6498, K = −0.100, t0 = −1.96 in males and W∞ = 8317, K = −0.100, t0 = −1.31 in females. The growth constants of the North Vietnamese stock of L. malabaricus are similar to the ones of the North-eastern Australian stock. A general tendency for the reduction of the growth rate and asymptotic size from equatorial waters to higher latitudes was observed.