Results of a Pilot Monitoring Project for Topeka Shiners in Southwestern Minnesota: Year Two

This work represents the continuation of a long-term surveying project (Ceas & Anderson, 2004) to conduct baseline presence/absence surveys for Topeka shiners within the federally proposed critical habitat in Minnesota. These data will comprise the second year of an ongoing population-monitoring project designed to provide the DNR with a tool for detecting changes in the overall presence/absence of Topeka shiners within Minnesota. Twenty random stream segments within the Rock and Big Sioux watersheds of southwestern Minnesota (Missouri River system) were selected using an ArcView extension program. By chance one of these stream segments was a resurvey a 2004 stream segment. 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 always 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 ten of these sixteen stream segments Topeka shiners were found at the first site sampled. Few true off channel habitats existed within the twenty 1-mile stream corridors, and the shiners were generally found in well-developed in-channel pools or backwaters that appear to stay connected to the stream year-round. The scope of this project was limited and designed to conduct only straightforward presence/absence surveys for Topeka shiners chosen stream segments. Even so, a few of observations were noted. These observations are essentially the same as witnessed during the 2004 sampling: (a) The stream segments that did not produce Topeka shiners were all small headwaters with narrow down-cut channels and almost continuous raceways/flowing waters, and the few off-channel pools were artificial farm ponds that appeared to have steeply-sloped banks; (b) A few of the 1-mile segments had good numbers of individuals and what appeared to be an abundance of suitable habitat, and may warrant a closer look for future habitat enhancement/landowner involvement projects; 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 ever-changing stream channels.