Topeka Shiner Monitoring in Minnesota: Year Five

This work represents the continuation of an ongoing project (Ceas & Anderson, 2004; Ceas & Monstad, 2005; Ceas & Monstad, 2006; Ceas & Plain, 2007) to monitor the presence/absence of Topeka shiners (Notropis topeka) within the federally designated critical habitat in Minnesota. These data comprise the fifth 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 a 10' x 5' eighth-inch mesh minnow seine. Topeka shiners were found at sixteen of the twenty 1-mile stream segments, and in fourteen of these sixteen stream segments Topeka shiners were found at the first site sampled. Off-channel habitats existed within only two of the 1-mile stream corridors (Topekas were found at both), and the shiners were generally found in well-developed in-channel pools or backwaters that appear to stay connected to the stream year-round. 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 further support to the conclusions drawn from the 2004-07 surveys: (a) The stream segments that did not produce Topeka shiners tend to be continuously flowing raceways/flowing waters; (b) A few of the 1-mile segments had good numbers of individuals and what appeared to be an abundance of suitable habitat; and (3) 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.