Changes in fish species diversity and dominant species composition in the Yellow Sea

Species diversity of the Yellow Sea fish community in 1959, 1981, 1985 and 1986 was measured by means of several methods. An evenness index, E=log(e)(1/lambda)/log(e)S, was introduced to measure the fish community. The differences in diversity index in the Yellow Sea between seasons are due to fish migration, while the differences between years are attributed to the changes of species composition caused by overfishing and species interactions. The numbers of dominant, common and rare species of fish were calculated using Hill's diversity index. The dominant species in 1959 were all demersal fish, which were the major target for fisheries in the 1950s and 1960s. However, in the 1980s, pelagic fish took a very dominant position, especially small pelagic fish, which were the prey of large pelagic and bottom fish. This indicates that the depletion of most demersal fish and large size pelagic fish has resulted in the increase of small planktophagous pelagic fish in the Yellow Sea.