CLIMATE AND HABITAT FACTORS RELATED TO A LOCALIZED EXTIRPATION OF GIZZARD SHAD (DOROSOMA CEPEDIANUM)

Gizzard shad are a riverine species commonly transplanted into manmade reservoir systems to provide prey for predatory game fish. Thermally limited, the range of their native distribution extends into the midwestern Great Plains. Following the harsh winter conditions of 2000-2001, numerous incidents of extensive gizzard shad die-offs were reported in eastern Nebraska during spring ice-out. In an effort to determine the breadth and extent of mortality, statewide fish population surveys conducted between 1994 and 2004 were examined, and it was found that gizzard shad were extirpated from seven flood-control reservoirs in a localized area of eastern Nebraska. Meteorological data confirmed that extreme cold and windy conditions were prevalent in the area during early December 2000, and may have been correlated to this unique extirpation event. Hydrologic connection to groundwater and wind sheltering may have protected smaller waterbodies from extirpation.