Food partitioning by flatfishes on a herring spawning ground

Inter- and intraspecific dietary variations and diet overlap patterns of plaice ( Pleuronectes platessa L.), dab ( Limanda limanda L.), lemon sole ( Microstomus kitt Walbaum) and long rough dab ( Hippoglossoides platessoides Fabricius) from a coastal bank off Norway were analysed. Sandeel ( Ammodytes marinus Raitt) was the dominant prey in terms of weight of both plaice and dab, while polychaetes were the most common prey of lemon sole. The long rough dab, which tended to occur in deeper waters than the other species, fed mainly on crustaceans and echinoderms. In March-April, when the Norwegian spring-spawning herring stock uses the bank as spawning ground, herring eggs were consumed by lemon sole and to a lesser extent the plaice and dab. There were indications of partitioning of food resources among the co-occurring species, but also extensive diet overlap when feeding on sandeel and herring eggs that were probably very abundant.