Experimental analysis of reintroduction strategies to conserve the vulnerable plains topminnow Fundulus sciadicus in Nebraska

Abstract

Plains topminnow Fundulus sciadicus are endemic to the Great Plains (USA), and because of declines in their geographic range and local abundance, are granted protection throughout their native range. Experimental reintroductions were conducted to improve conservation techniques and enhance the long-term outlook for plains topminnow persistence in Nebraska. Reintroductions were attempted at 17 extirpated stream reaches using low and high founder densities (no. of fish per suitable area) and during 2 seasons (spring and fall) to identify successful techniques for future conservation efforts. Reintroduced populations were sampled monthly (excluding winter) for 2 yr to monitor population persistence. Repeated presence-absence data was used to estimate persistence probabilities (1 - extinction probability), which we used to compare reintroduction strategy treatments. Plains topminnow were recaptured at 76% of reintroduction locations (1456 total individuals) and reproduction was observed at 35% of those sites. Catch rates at reintroduction sites varied substantially (range: 0 to 30.78 ind. per 100 m). The influence of season and founder density were minimal. Population persistence was more likely at sites stocked in fall at higher densities; however, wide confidence intervals suggest that individual site characteristics may more strongly influence population persistence. Similar population outcomes regardless of reintroduction strategy provide managers flexibility when making conservation decisions.