SOME BIOLOGICAL CHARACTERISTICS OF LONGTAIL TUNA CAUGHT IN THE SEA WATERS OF KHANH HOA PROVINCE

Abstract

Based on date from length and weight measurements of 218 Longtail tuna samples in the seawaters of Khanh  Hoa province. Fork lenght range was from 31 to 49 cm, average 39.13 cm and 40 - 44 cm fork lenght group  comprised 39.45%. Weight range was form 550 to 2000 g, average  1090 g and 1250 - 1400 g weight group comprised 19.72%. The Lenght - Weight relationship equation, W = 0.000063L^2.7882, R² = 0.8436; the  growth parameters of the Von Bertalanffy equation, L_t = 51.98 (1 – e^-0.22t); the total lenght - fork lenght relation equation, L_t = 1.0439L_f + 1.149, R² = 0.9603. In this research period, 99.3% of both sex having gonads belonged to stage I and II (maturity). Degree of fullness of stomach was very poor - degree  of fullness 1, 2 and 3 comprised 87.01% and major species of preys found in stomach of Longtail tuna were major fish, squid and shrimp.