Diet composition and food selectivity of 0-group herring (Clupea harengusL.) and sprat (Sprattus sprattus(L.)) in the northern Baltic Sea

Diet composition and prey selectivity of the major Baltic Sea zooplanktivores, 0-group herring (Clupea harengus) and sprat (Sprattus sprattus), were studied in a coastal area. Diets were dominated by zooplankton, mainly cladocerans (Bosmina longispina maritima and Pleopsis polyphemoides) and copepods (Acartia spp. and Eurytemora affinis hirundoides/Temora longicornis). There were differences in order of the prey selected by the two different 0-group predators (fish hatched during the sampling year) when analysing each species separately. The general order of prey preference for herring was Acartia > Eurytemora>cladocerans>Pseudocalanus minutus>copepod nauplii and for sprat Eurytemora>cladocerans>Acartia>Pseudocalanus>copepod nauplii. As they grew 0-group clupeoids selected larger prey; the greatest preference was shown for intermediate sized prey (0.7–1.0 mm in cephalothorax length).