Age and growth of moonfish, Mene maculata from mouth of theBeibu Gulf, South China Sea

Abstract

Fish age and growth are key biological parameters for the assessment of fisheries resources.By the purse seiners and trawlers catch sampling,a total of 1 025 individuals of moonfish,Mene maculata were collected monthly in the mouth of the Beibu Gulf,South China Sea from August 2010 to May 2011.The samples ranged from 83 to 256 mm with fork length(FL).By biological measurement and age identification of 292(female: 148,male: 144) pieces of vertebrae section,the age and growth of M.maculata were studied.Results showed that the annuli was composited of opaque wide band and transparent narrow band which indicated they were formed once a year,from August to October by monthly changes in the Marginal Growth Increment(MGI).Moreover,the Gonadosomatic index(GSI) designated that the time of reproduction period and formed annuli were similar.Both the GSI and the pelagic water temperature peaked from August to October,which indicated the close relationship of M.maculata spawned periods and pelagic water temperature.Age was determined by reading annuli on vertebrae,and the estimated age ranges from 0+ to 5+ years for female and from 0+ to 4+ years for male.The females and males moonfish showed similar ages structure and growth patterns,and the body weight and fork length data fitted the function W=6×10?5L2.8415(n=1025,r2=0.94,P0.05).The fork length and age data fitted the von Bertalanffy growth function Lt=334.85[1?e?0.17(t+0.92)].It can be safely concluded that moonfish grows faster before age three,and then slows down.