Assessment on the biomass of Scomber japonicus resources in the western East China Sea by length-structure VPA

Based on the data of fork length of Scomber japonicus caught in coastal waters of East China Sea and central southern Yellow Sea from May to December in 2007,and fisheries production statistics of East China Sea and Yellow Sea,the biomass of Scomber japonicus resources in the western East China Sea was evaluated by length-structure VPA method and its actual utilization structure and degree were analyzed.The results showed that the age structure of Scomber japonicus of the western East China Sea populations mainly were 0+ year fish (31.87%) and 1+ years fish (49.90%),the current annual resources was in number 3.68×109N and 39.55×104t in biomass,respectively.The fishery of Scomber japonicus was in the low to moderate degree,and maximum sustainable yield (MSY) is up to 24.08×104t.Catch of the year has exceeded MSY,and it can make the resource in a better state if fishing young fish is prohibited.By analyzing its utilization period and age structure of catches,it is suggested that the stock of Scomber japonicus in the western East China Sea could remain relatively steady,even though the annual yield had exceeded MSY.