Abstract: Fish age and growth are the important biological parameters for the assessment of fishery resources. With the help of purse seiners, 262 individuals of skipjack tuna (Katsuwonus pelamis) were sampled from western and central Pacific Ocean in October 2007-January 2008. The measurements in situ showed that the fork length of the samples ranged from 278 to 746 mm, and their body mass ranged from 345 to 9905 g. The first dorsal spine of each individual was collected for age identification and growth parameters estimation. The relationship between fork length (L,mm) and body mass (M,g) was expressed as M=3.612×10^-6L^{3. 278} （R²=0.9782）,and no significant difference was found for the males and females (F=2.002,P>0.05). A comparison with Akaike information criterion (AIC) suggested that among power regression equation, linear regression equation, and exponential regression equation, linear regression equation was most suitable for describing the relationship between fork length and spine radius (AIC=2257.4). The mean back-calculated fork lengths of K. pelamis with the ages of 1-5 estimated by FraserLee’s method were 398.4, 494.2, 555.4, 636.8, and 728.8 mm, respectively. Residual analyses indicated that there was no significant difference in the growth of male and female K. pelamis (F=0.670;df=182;P>0.05). The sex-combined von Bertalanffy growth equation of K. pelamis was L_t=706.51(1-e^{-0.64(t+0.037)}).

Key words: western and central Pacific Ocean, purse seine, Katsuwonus pelamis, age, growth, dorsal spine, Brassica campestris, winter rapeseed, safety wintering, division, economic benefit.