Diet of the Great Cormorant (Phalacrocorax carbo Sinensis) at the Juodkrantė Colony, Lithuania

Abstract

Substantial population increases in the Great Cormorant (Phalacrocorax carbo sinensis) in Lithuania since the mid 1980s have given rise to complaints by fishermen and fish farmers that the stocks of fish that they target or cultivate are being depleted. In order to test the veracity of these claims, we investigated the dietary composition of the Great Cormorant breeding colony at Juodkrantė on the Curonian Spit, Lithuania, through the analysis of 220 pellets, collected during the breeding seasons in 2005–2007. At least 25 fish taxa were identified in the sample, but only three dominated by both abundance (82.9%) and biomass (73.6%), namely Ruffe (Gymnocephalus cernuus), Perch (Perca fluviatilis) and Roach (Rutilus rutilus). The mean total length of fish prey caught was 9.5 cm and the mean weight was 16.8 g. Commercial fish species comprised a large proportion of the Great Cormorant diet (83% by biomass), predominately small, low commercial value fish, mostly Roach. Despite the proximity of the Baltic Sea ...