Beschreibung:
<jats:p>The diets of two non‐commercial flatfish species (solenette <jats:italic>Buglossidium luteum</jats:italic> and scaldfish <jats:italic>Arnoglossu</jats:italic>s <jats:italic>laterna</jats:italic>) and two commercial flatfish species (dab <jats:italic>Limanda limanda</jats:italic> and plaice <jats:italic>Pleuronectes platessa</jats:italic>) were compared in a study area in the German Bight (southern North Sea) to investigate prey‐resource partitioning between these species. The diets of <jats:italic>A. laterna</jats:italic> and <jats:italic>B. luteum</jats:italic> mainly comprised crustaceans (harpacticoids, amphipods, cumaceans and decapods), whereas the diet of <jats:italic>L. limanda</jats:italic> and <jats:italic>P. platessa</jats:italic> consisted mainly of polychaetes. The Schoener index, calculated for different fish size classes between these flatfish species, showed a biologically significant diet overlap between small‐sized <jats:italic>L. limanda</jats:italic> and <jats:italic>P. platessa</jats:italic> and <jats:italic>B. luteum</jats:italic> and <jats:italic>A. laterna</jats:italic>, using similar prey resources of smaller prey (<jats:italic>e.g.</jats:italic> amphipods, harpacticoids and juvenile bivalves). In contrast, with increasing body size, a change in the diet of <jats:italic>L. limanda</jats:italic> and <jats:italic>P. platessa</jats:italic> towards larger prey occurred (<jats:italic>e.g.</jats:italic> polychaetes and decapods), resulting in low diet overlap values with <jats:italic>B. luteum</jats:italic> and <jats:italic>A. laterna</jats:italic>. Due to these size‐related differences in resource use, it is assumed that there is reduced interspecific competition for prey between larger <jats:italic>L. limanda</jats:italic> and <jats:italic>P. platessa</jats:italic> and both non‐commercial flatfishes, probably facilitating resource partitioning within the same area. In contrast, smaller <jats:italic>L. limanda</jats:italic> and <jats:italic>P. platessa</jats:italic> may compete directly for the same prey resources with <jats:italic>B. luteum</jats:italic> and <jats:italic>A. laterna.</jats:italic> Furthermore, prey availability of most important prey items of the studied flatfishes was relatively low in the study area. Therefore, increasing abundances of <jats:italic>B. luteum</jats:italic> and <jats:italic>A. laterna</jats:italic> in the southern North Sea since the late 1980s, owing to fishing effects and climate change, might affect the population dynamics of <jats:italic>L. limanda</jats:italic> and <jats:italic>P. platessa</jats:italic>.</jats:p>