Abstract:Based on the data collected from bottom trawl in eight cruises by R/V “Beidou” in the central and southern Yellow Sea from 2000 to 2010 and historical data from 1985 to 1986, seasonal and annual variations in the growth, feeding habits, reproductive characteristics of small yellow croaker Larimichthys polyactis and the dynamics of its resource were analyzed. The results were as follows: the average body length and the dominant body length range in spring were higher than those in the other seasons, and showed a decreasing trend from 2000 to 2010 with narrower dominant body length spectra. The food composition of small yellow croaker greatly changed from 1985~1986 to 2000, but no significant changes were found from 2000 to 2010. Japanese anchovy Engraulis japonicus was the predominant diet in 1985~1986, accounting for 45.18% of the total weight of the diets, then was the small sized shrimps. In 2000 and 2010, Euphausia pacifica was the main diet, accounting for 47.28% and 37.20%, respectively, then were Crangon affinis and Leptochela gracilis. In addition, the proportion of Japanese anchovy in food composition increased from 4.67% in 2000 to 10.64% in 2010. The proportions of individuals with gonad development at stage Ⅱ in 2000s were less than those during 2007~2010. The mean catch of small yellow croaker was the highest in the 2000s (excluding summer), but the relative abundance gradually decreased since the 2000s. In addition, the distribution of small yellow croaker gradually migrated northward.The impacts of human activities and environment changes on fishery resource become more and more serious, thus the attribute of small yellow croaker population and its life history characteristics in the Yellow Sea greatly changed. So, variations in biological characteristics of small yellow croaker should be fully considered in fishery resource management and conservation.
