Population dynamics of fish species in a marine ecosystem: A case study in the Bohai Sea, China

Abstract

There were rapid shifts of the dominant species in the Bohai Sea from the 1950s to the 1990s, with large-sized, high-valued species (e.g., Small Yellow Croaker Larimichthys polyactis and Largehead Hairtail Trichiurus lepturus) being replaced by small-sized, low-valued species (e.g., Japanese Anchovy Engraulis japonicus and Hairfin Anchovy Setipinna taty). From the 1990s to the present, the Small Yellow Croaker and some of the smallsized species (Hairfin Anchovy and Dotted Gizzard Shad Konosirus punctatus) have become the dominant species. The food web is now simple, with species from relatively low trophic levels controlling the energy flow within the fishery ecosystem. Along with the shift in community structure, the abundance of dominant species changed, the diversity of fish species and species number density decreased, and interannual and seasonal variations in species number density were found. Fish abundance had a decreasing trend and fish interannual and seasonal distribution greatly changed. Variation in the sizes of the ecological niches of the dominant species regulated the succession of the fish community, and the alteration of ecological niches caused changes in the fishery community.