Effects of active protection of the endangered fish lake minnow, Eupallasella (Rhynchocypris) percnurus (Pallas, 1814), on its occurrence in Mazowieckie Voivodeship in Poland

Mazowieckie Voivodeship was the first region in Poland to widely apply fish translocations for the active protection of the lake minnow, Eupallasella (Rhynchocypris) percnurus, a species of the family Leuciscidae at serious risk of extinction. These efforts began in 2002 and concluded in 2018, during which time over 21,000 juvenile fish from aquaculture were translocated to 13 water bodies. As a result, five new viable populations were established with the use of 17,000 fish. Three of these were confirmed to be viable in 2024, and one other probably also still exists. The failure of all the other translocations were habitat loss from drying up or population extinction caused by introductions of predatory fish species. The three or four new lake minnow populations contribute considerably to the present status of this species in the voivodeship, because the total number of all sites in 2024 did not exceed seven. These new populations also play a notable role in Poland, as there are likely not more than 80 lake minnow sites at present.