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Lukáš Poledník, Kateřina Poledníková, Andreas Kranz, Aleš Toman
Časopis
Lynx, n.s. (Praha)
Rok vydání
Diet of the Eurasian otter was studied using the analysis of 2701 spraints collected along banks of 40 ponds in Českomoravská vrchovina (Bohemian-Moravian Highlands) in 2003–2004. Fish dominated the diet (80%, expressed as the relative number of individuals), with 19 different species identifi ed. The proportion of fi sh in the diet varied signifi cantly at different ponds, ranging from 25% to 100%. Amphibians (frogs, toads and occasionally newts) made up the second most important prey group with 13%. Crayfi sh were only locally important, reaching 4% of prey consumed. Other prey groups such as insects, birds, mammals and reptiles occurred rather sporadically. The common carp was the most important fi sh species in the diet (24%), refl ecting the fact that the ponds are primarily used for its production. However, its proportion in the diet at ponds with stocked carp varied signifi cantly from 2% to 91% of prey consumed. Other fi sh species regularly found in the diet were perch (11%) and tench (9%). Roach, sunbleak, morroco, gudgeon, stone loach and grass carp were locally important. Other fi sh species were taken rather occasionally. The diet varied among ponds concerning both the number of fi sh species consumed and their proportion in the diet. Commercial fi sh species made up 35% in the warm period and 42% in the cold period. When the diet composition was expressed in biomass values, the proportion of carp, and consequently of commercial fi sh showed considerable differences compared to their relative abundance in the diet: 69% vs. 24% in the case of carp, and 70% vs. 35% in commercial fi sh, respectively. Proportion of commercial fi sh may be reduced signifi cantly when alternative prey (non-commercial fi sh species, frogs, crayfi sh) is available.