A preliminary study on fishery biology of main commercial fishes surveyed from the bottom trawl fisheries in the East China Sea

On the basis of the bottom trawl fishery resources investigation in the East China Sea in 1997~2000,this paper analyzed the fishery biological characteristics of 18 species of main commercial fishes.Parameters,such as von-Bertalanffy growth parameters,total mortality,natural mortality,fishing mortality and exploitation rates,were estimated by length-based methods.The results showed that,miniaturization occurred in most of the fishes,and the exploitation rates of 15 species were excessively high.Among those fishes,4 species,whose exploitation rates were more than 0.8,were in high over exploitation;7 species,whose rates ranged from 0.7 to 0.8,were in middle over exploitation;and the other 4 species ranged from 0.5 to 0.7 were in lower over exploitation.In order to sustainable utilization of fishery resources,effective protection and management measures should be taken.