Seasonal Shifts in Diet Composition of Great Cormorants Phalacrocorax carbo sinensis foraging at a Shallow Eutrophic Inland Lake

[摘要] ThedietofGreatCormorantsPhalacrocoraxcarbosinensisatLakeDümmer,ashalloweutrophiclakeof1240hainLowerSaxony(Germany)wasanalysedbycollecting562regurgitatedpelletsoveraperiodofoneyear.Pelletscontainedstructuresof10,645fishesbelongingto15species.Substantialdifferenceswerefoundinfrequency,compositionandsizeofpreyfishspecies.Pikeperch,Ruffe,RoachandPerchaccountedforthelargestseasonaldifferencesinthediet.Duringlateautumnandwinterthedietwasdominatedbysmall-sizedcyprinidsandRuffe.InspringGreatCormorantsprimarilyforagedonlarger-sizedcyprinids.Young-of-the-yearpercids,dominatedbyPikeperch,weretheprimarypreyduringsummer.Weestimatedthatatleast32.6tons(26.3kg/ha)oftotalfishbiomasswasremovedbyCormorants,ofwhichonethird(10.8tons)consistedofPikeperch.81%ofthePikeperchbiomasswasremovedinAugust—September,indicatingthattheGreatCormorantisanimportantpredatorofjuvenilePikeperchatLakeDümmer.OurfindingshighlighttheneedofextensivedietanalysesinallseasonstoobtainacomprehensivepictureoftheimpactofCormorantpredationonfishstocks.Snapshotsofthedietsampledovershort-timeperiodsmaybemisleadingandinadequateforlocalmanagement.

[学科分类] 动物科学

[关键词] Biomass Removal