Journal of the Marine Biological Association of India

Biology, age, growth and population dynamics of threadfin bream Nemipterus japonicus

Volume 32 Issue 1&2

M. Samuel

Abstract

The family Nemipteridae forms aa important component of the demersal fish catches in the Arabian Gulf and especially in Kuwait. Three species of Nemipterus have been reported to occur in the Arabian Gulf, but only two species are known from Kuwait waters, Nemipterus japonicus sp and Nemipterus tolu. Single species assessment was carried out on N. japonicus which is one of the more important and abundant species in Kuwait's trawl fishery. 

Nemipterus sp. locally known as Bassi form 11-18% by weight in the by-catch category oflin&h landed by the Industrial trawlers in Kuwait. Nemipterus japonicus were collected from the Research Vessel trawl catches in Kuwaiti waters during 1979-1985. Age determinations were made on whole sagittal otoliths in young and on sections in older and bigger fish during 1984-1985. Growth curves were obtained from the age at length data. Growth parameters obtained for males and females were L 30.3 cm (TL), K. 0.542, 10.19 and L 26.5 cm (TL), K 0.595 to 0.03 respectively. Age varied from 0-6 years and length varied from 5-31 cm. The growth rate in males were faster than in females. The length-weight relationships for males and females were obtained and were significantly different at 1 % level. Condition factor (Kn) values for different months of the year for females were calculated and suggest that two spawning periods, March-May and September-October. Total mortality (Z) estimated from the age composition of the sample gave a value of 0.873 (P 0.001) and 0.802 (0.01 p 0.001) for 1984 and 1985. Natural mortality (Z) estimated by the method of Pauly (1980) was higher than total mortality (Z). No method applied so far, provided the estimates of F and M needed for accurate stocks assessment of N. japonicas.

Date : 31-12-1990