Composition of food and niche overlap of three Sciaenidae species in Haizhou Bay

Based on the data collected from bottom trawl surveys in Haizhou Bay in 2011 and 2013, the food composition and differences in trophic and spatial niche of Johnius belangerii, Larimichthys polyactis and Collichthys lucidus were studied by means of multivariate statistical analysis and niche overlap coefficient. The results showed that J. belangerii was a kind of benthic predator, mainly feeding on shrimp, amphipoda and polychaetes. L. polyactis belonged to the benthic and swimming predator, mainly feeding upon fish, shrimp, cephalopod and euphausiacea, C. lucidus belonged to the benthic and zooplankton predator, mainly feeding on shrimp, acetes, euphausiacea and mysidacea. Among the three Sciaenidae species, their trophic niche widths were relatively close, with the trophic niche width (2.69) and spatial niche width (2.78) of the L. polyactis being the highest. J. belangerii had the lowest values of trophic niche width (2.59) and C. lucidus had the highest spatial niche width value (2.42). The trophic niche overlap between the three Sciaenidae species was between 0.24 and 0.46, with J. belangerii and C. lucidus having the highest trophic niche overlap value (0.46). Their spatial niche overlap value was between 0.19 and 0.30, indicating that there was little spatial overlap among the three species, which alleviated the food competition. Their trophic-spatial niche overlap index was between 0.05 to 0.11, with J. belangerii and C. lucidus having the highest trophic–spatial niche overlap value (0.11). These species can reduce their interspecific competition by changing their food composition and space distribution.