Diet of the great cormorant (Phalacrocorax carbo L. 1758) at two Greek colonies VASILIOS LIORDOS and VASSILIS GOUTNER Department of Zoology, School of Biology, Aristotle University, GR-54124 Thessaloniki, Greece Abstract The diet and commercial value of prey of the great cormorant (Phalacrocorax carbo L. 1758) were studied at two Greek colonies: the Axios Delta and the lake Mikri Prespa, through the analysis of regurgitated pellets. A variety of fish taxa were found in the samples, but only one or two dominated in the great cormorant’s diet. Prussian carp (Carassius gibelio) dominated in the Axios Delta, whereas pumpkinseed (Lepomis gibbosus) and Prussian carp were the most important in the lake Mikri Prespa. Differences in diet found between the areas are probably due to differences in prey species richness and diversity. Fish of high commercial value contributed in low proportions to the great cormorant’s diet. The small overlap between the bird’s diet and the valuable prey suggests minimal competition with fisheries.   < back .