Partitioning of food resources among three sympatric scorpionfish (Scorpaeniformes) in coastal waters of the northern Yellow Sea

The partitioning of food resources among three abundant co-occurring reef-associated scorpionfish, Hexagrammos agrammus, Hexagrammos otakii and Sebastes schlegelii, was determined on an artificial reef zone in nearshore and offshore coastal waters of northern China, using stomach content and stable isotope analyses (delta C-13 and delta N-15). The three species consumed similar prey items, mainly a variety of crustaceans, teleosts, polychaetes and macroalgae, but the proportions of the items differed among species. The dietary composition of all three scorpionfish differed significantly in nearshore waters, but not between H. otakii and S. schlegelii in offshore waters, where both species fed predominantly on carideans, penaeids and brachyurans. The delta C-13 values varied significantly among the three scorpionfish in nearshore waters, and tended towards significance (P=0.053) between H. otakii and S. schlegelii in offshore waters, suggesting that they partition food resources. Bayesian mixing models further confirmed that all scorpionfish were generalist carnivorous and that the main food sources were assimilated in different proportions. In the nearshore waters, resource partitioning occurs among the three scorpionfish, reducing the potential for competition and the feeding ecology implies that they have dietary plasticity, which facilitates their coexistence and maintains local benthic fish community stability.