Topeka Shiner Monitoring in Minnesota: Year Seven

This work represents the continuation of an ongoing project to monitor the presence/absence of Topeka shiners (Notropis topeka) within the federally designated critical habitat in Minnesota (Ceas & Anderson, 2004; Ceas & Monstad, 2005; Ceas & Monstad, 2006; Ceas & Plain, 2007; Ceas & Larson, 2008; Ceas & Larson, 2009). These data comprise the seventh year of this population-monitoring project, which is designed to provide the DNR with a tool for detecting changes in the overall presence/absence of Topeka shiners within Minnesota. Following the protocol established in 2004, twenty 1-mile stream segments within the Rock and Big Sioux watersheds of southwestern Minnesota (Missouri River system) were selected randomly using an ArcView extension program. Based on known habitat preferences, aerial photos of the twenty stream segments were reviewed to identify the 10 most likely sampling sites within each stream segment. If off-channel habitats were present, then these were included as potential sample sites. A brief field reconnaissance of each stream segment allowed us to rank the ten sites within each segment according to which sites appeared most suitable for Topeka shiners, and sampling was conducted using small-mesh minnow seines. Topeka shiners were found at twelve of the twenty 1-mile stream segments, and in 6 of these 12 stream segments Topeka shiners were found at the first site sampled. Off-channel habitats existed within only four of the 1-mile stream corridors. The shiners were generally found in well-developed in-channel pools or backwaters that appear to stay connected to the stream year round; however, the two sites with the largest populations of shiners were both off-channel habitats. Compared to the previous six years of sampling very few Topeka shiners were found in 2010. Only two stream segments contained Topeka shiners in relatively large numbers. In the remaining ten segments that contained Topekas only one or two individuals were generally found, even after extensive seining efforts once the first individual was captured. The segments that were sampled in 2010 typically had very limited amounts of suitable or ideal habitat, and even the pools/backwaters that were present did not contain the extensive shallow waters in which Topeka shiners seem to be most commonly found in Minnesota. While the scope of this baseline project is limited and designed to conduct only straightforward presence/absence surveys for Topeka shiners in chosen stream segments, a few observations were noted. These observations lend continued support to the conclusions drawn from the 2004- 09 surveys: (a) The stream segments that did not produce Topeka shiners tend to be continuously-flowing raceways/flowing waters; (b) The two 1-mile segments that contained good habitat also had large numbers of individuals; and (b) The GIS cover of critical habitat/stream channels needs to be updated using current aerial imagery to account for changes in stream position due to the shifting stream channels.""