Revisits to Known Topeka Shiner Localities: further evidence of decline in Minnesota

Since 2004, the Minnesota Department of Natural Resources has monitored presence/absence of the federally endangered Topeka shiner (Notropis topeka) at randomly selected sites within the federally designated critical habitat. Throughout the first seven years of monitoring (2004-2010), Topeka shiners were present at an average of 76.4% of randomly selected sites, although surveyors in 2009 and 2010 noted an apparent decline in relative abundance at sites where the species was present. Monitoring surveys conducted in 2010, 2012 and 2013 found the lowest to date percentages of sites where the species was present (60%, 40%, and 30% respectively). This shift in prevalence motivated a second set of surveys in 2013 to revisit sites from recent monitoring surveys where the species was present in relatively high numbers. Results are presented for presence/absences surveys at 25 known Topeka shiner localities. Of 25 sites that were revisited in 2013, the species was present at 16 sites in low numbers relative to previous visits. Results from this and previous sampling efforts are indicative of a decline in prevalence of Topeka shiners in Minnesota. Standardization of catch effort at a set of permanent monitoring sites in addition to the annual randomized site selection within the critical habitat is recommended to further characterize Topeka shiner population dynamics in MN.