Clinostomus elongatus (Kirtland, 1841)
Basis for Listing
The Redside Dace (Clinostomus elongatus) is restricted to the Cannon, Zumbro, and Root river systems in southeastern Minnesota (Eastern Broadleaf Forest Province). All of the Minnesota populations are isolated from one another and from other populations in Wisconsin and Illinois. Populations in the Root River system appear on the verge of extirpation, where the species has been found in only two streams since 1989. It has not been reported from Rush Creek since 1945, Pine Creek (1949), Trout Run (1972) and Shady Creek (1983). The Redside Dace is extirpated in Iowa, where it has not been reported since the late 1880s (Harlan et al. 1987).
Redside Dace have a peripheral and disjunct distribution in Minnesota, and populations, if lost, would have little chance of recolonization. The species is declining across its range. Furthermore, the potential impact of non-indigenous Brown Trout (Salmo trutta) predation has not been assessed (Lyons et al. 2000). These factors prompted listing the Redside Dace a special concern species in Minnesota in 2013.
The Redside Dace is a medium-sized minnow that averages 6.5 cm (2.6 in.) total length (TL). The largest individual reported in Minnesota was 10.4 cm (4.1 in.) (Hatch and Schmidt, in preparation). The mouth is large and upturned, with a pointed snout. The junction of the jaws extends to below the eye, and the tip of the lower jaw projects beyond the upper. The body is long and slender (laterally compressed). The back is green or blue-green, and the lower flanks have a broad orange to red stripe extending from the gill cover to, or beyond, the dorsal fin (Becker 1983). Breeding males exhibit a steel blue back, a yellow-gold stripe along each side, and bright red on the lower flanks (Page and Burr 2011).
The Redside Dace is a cool water species, preferring pools and small riffles of moderate gradient streams, 1-6 m (3.3-19.7 ft.) wide, with gravel substrates (Becker 1983).
Biology / Life History
The Redside Dace is an aerial insect feeder that will leap several centimeters into the air in pursuit of prey. The species reaches sexual maturity at age two and is a short period, late season spawner. In Minnesota, spawning occurs for about two weeks between mid-May and early June. At the end of the first growing season, young of the year range from 3.1-4.8 cm (1.2-1.9 in.) TL. Males leave overwintering pools for shallow riffles and gravel bars to spawn in Creek Chub (Semotilus atromaculatus) nests (Hatch et al. in preparation). In southwestern Wisconsin, Redside Dace were observed spawning in a Hornyhead Chub (Nocomis biguttatus) nest on May 4, 1998. Other spawning associates included Southern Redbelly Dace (Chrosomus erythrogaster) and Carmine Shiner (Notropis percobromus). In captivity, Redside Dace spawned at 20-22° C (68-72? F) over a pebble substrate, and offspring were sexually mature in two years (R. Katula, pers. comm.) and had a lifespan of 3-4 years (Hatch and Schmidt, in preparation).
Conservation / Management
Populations of Redside Dace appear stable in the Cannon and Zumbro river systems. However, in the Cannon, occurrences are almost solely confined to the Little Cannon River watershed, which has a barrier falls near its mouth making recolonization following a catastrophic event impossible. Clinostomus elongatus would benefit if barriers in the Cannon, Zumbro, and Root river systems could be minimized or mitagated. Additional research needs include a Minnesota life history study, determining the impact of Brown Trout predation, and habitat assessments for the purpose of future reintroductions in streams where apparent extirpations have occurred.
Conservation Efforts in Minnesota
The Little Cannon River receives some habitat protection from a DNR trout stream designation due to the non-indigenous Brown Trout and Rainbow Trout (Oncorhynchus mykiss) that occur in headwater reaches. Berendzen et al. (2008) received a MN DNR grant in 2006 to study the genetic variation of populations of this species in Minnesota. Results of the study revealed populations in Minnesota stream systems vary greatly and should be managed as separate genetic units (Berendzen et al. 2008). The recent inception of the Clean Water Legacy Program in Minnesota will eventually benefit the habitat and water quality of streams where the species occurs.