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

Recent studies have shown that the Topeka shiner was once a common, wide-ranging species in the small prairie streams of portions of Minnesota, South Dakota, Nebraska, Kansas, Missouri, and Iowa. The species has experienced a widespread decline throughout its historic range, and is now listed by the U.S. Fish and Wildlife Service (USFWS) as endangered. This study was undertaken as a pilot project to conduct baseline presence/absence surveys for Topeka shiners within the federally proposed critical habitat in Minnesota. These data will comprise the initial 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 were selected using an ArcView extension program. Based on known habitat preferences, aerial photos of the 20 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 4' (or, depending on stream size, a 25' x 4') eighth-inch mesh minnow seine. Topeka shiners were found at 17 of the 20 1-mile stream segments, and in 11 of these 17 stream segments Topeka shiners were found at the first site sampled. Few true off-channel habitats existed within the 20 1-mile stream corridors, but 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 baseline pilot-year project was limited and designed to conduct only straightforward presence/absence surveys for Topeka shiners in 20 1-mile stream segments. Even so, a few of observations were noted: (a) The three stream segments that did not produce Topeka shiners were all very small headwaters with narrow down-cut channels and almost continuous 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 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.