Determinants of the presence of conflict bird and mammal species at pond fisheries in western Poland

Abstract

The presence of piscivorous vertebrates at fish farms often ignites conflicts over fish resources managed by humans. This study investigates the factors affecting the presence of conflict vertebrates at fish ponds. A telephone survey in western Poland in 2012–2013 examined 104 fish ponds. Six species were most often observed at fish farms: European otter Lutra lutra (87 % at farms), grey heron Ardea cinerea (83 %), great cormorant Phalacrocorax carbo (67 %), great egret Ardea alba (42 %), Eurasian beaver Castor fiber (37 %) and American mink Neovison vison (31 %). American mink, Eurasian beaver, great egret and grey heron were more often present at carp ponds. Eurasian beaver, European otter and great cormorant were present more often at larger ponds. Latitude significantly affected the occurrence of great egrets (more frequent in the south). European otter and American mink were present more often at ponds supplied by river water. Ponds supplied by river water may provide both species opportunity to enter imperceptibly to farms, with no need to exit water. Methods of pond protection and proximity of buildings to farms did not significantly affect the presence of conflict species. The data from this study concerning the presence of piscivores at ponds may serve as base for more comprehensive studies investigating the impact of these species on fish farming practices as well as for comparative and experimental studies on the effectiveness of various mitigation measures. Regular surveys of species occurring at ponds may be a tool of monitoring invasive species as well as species increasing its range.