Lythrurus umbratilis (Girard, 1856)
Basis for Listing
The Redfin Shiner (Lythrurus umbratilis) is a peripheral species at the northern edge of its range and is restricted to the Cedar, Zumbro, Root and Upper Iowa river systems in southeastern Minnesota (Paleozoic Plateau Section and Oak Savanna Subsection). However, the species has not been collected from the Upper Iowa system since 1966. In the Root system, there are no records from Spring Valley Creek since 1938, Trout Run since 1945, and Bear, Carey, Rabbit, and Robinson creeks since the early 1980s (Hatch et al. in preparation). Survey data suggest a definite decline in both distribution and abundance of Redfin Shiners, with recent collections of only one or two individuals per site, except when sampling during spawning. In Wisconsin, the Redfin Shiner has been listed threatened since 1979 (WI DNR 2013).
While the Redfin Shiner can tolerate some turbidity, their preferred stream habitat is under increasing pressure from human activities, such as farming and residential development. Because of their reduced distribution and abundance in the state as well as the potential for further negative impacts to their stream habitat, the Redfin Shiner was designated a species of special concern in 2013.
The Redfin Shiner is a medium-sized minnow that is typically 3.5-6.5 cm (1.4-2.6 in.) total length, with a maximum of 8.5 cm (3.3 in.). Distinguishing characteristics include round lateral line scales, straight lateral line, 10-12 anal fin rays, a dark blotch at the frontal base of the dorsal fin, a terminal mouth without barbels, and a body flattened side to side (laterally compressed). Nuptial males exhibit intense colors from bluish black on the back to bluish silver on the sides. Fins are red to orange, and the membranes of the upper portion of the dorsal fin are black. Small breeding tubercles develop on the head, back, flanks, and sometimes the leading edge of fins (Lyons et al. 2006).
Redfin Shiners prefer pools in low gradient turbid streams that are 12.1-24.0 m (39.7-78.7 ft.) wide and contain substrates of silt, gravel, or rubble (Becker 1983).
Biology / Life History
Most Redfin Shiners reach sexual maturity during their second or third summer of life. In the Upper Midwest, the spawning period can last from late May to mid-August. However, the species is a nest associate so the actual onset and duration is likely synchronized with the lowest spawning temperatures of local sunfish species (Lepomis spp.) populations. Embryos reared in a lab hatched in 7-10 days and were synchronized with the hatching of Green Sunfish (Lepomis cyanellus) embryos (Hatch et al. in preparation). Redfin Shiners typically live to two years old.
Conservation / Management
Populations of Redfin Shiners appear stable in the Zumbro and Cedar river systems, where life history studies need to be conducted. In the Root River system, habitat and water quality assessments are needed to compare historic localities with extant populations. If suitable habitats are identified, reintroductions should be attempted and monitored for established populations. Stream surveys of Beaver Creek and the Little Iowa and Upper Iowa rivers (upstream of Chester, Iowa) are necessary to confirm the species is extirpated in this system.
Conservation Efforts in Minnesota
Berendzen et al. (2008) received a DNR State Wildlife Grant in 2006 to study the genetic variation of Redfin Shiner populations in Minnesota. The results of the analyses indicate that this is a widespread population and that there is no genetic distinctiveness within southeastern Minnesota. Conservation efforts should focus on maintaining the genetic diversity within this species and manage all populations as a single genetic unit (Berendzen et al. 2008). The recent inception of the Clean Water Legacy Program in Minnesota will eventually benefit the water quality of streams where the species occurs.
References and Additional Information
Becker, G. C. 1983. The fishes of Wisconsin. University of Wisconsin Press, Madison, Wisconsin. 1052 pp.
Berendzen, P. B., J. F. Dugan, and J. J. Feltz. 2008. Establishing conservation units and population genetic parameters of fishes of greatest conservation need distributed in southeast Minnesota. Final report for the State Wildlife Grants Program, Minnesota Department of Natural Resources. 44 pp.
Coffin, B., and L. Pfannmuller, editors. 1988. Minnesota's endangered flora and fauna. University of Minnesota Press, Minneapolis. 473 pp.
Eddy, S., and J. C. Underhill. 1974. Northern fishes, with special reference to the Upper Mississippi Valley. Third edition. University of Minnesota Press, Minneapolis, Minnesota. 414 pp.
Harlan, J. R., E. B. Speaker, and J. Mayhew. 1987. Iowa fish and fishing. Iowa Conservation Commission, Des Moines, Iowa. 323 pp.
Hatch, J. T., and K. P. Schmidt. Redfin Shiner Lythrurus umbratilis (Girard, 1856). In J. T. Hatch, G. L. Phillips, K. P. Schmidt, M. C. McInerny, and J. C. Underhill, editors. The Fishes of Minnesota (in preparation).
NatureServe. 2013. NatureServe Explorer: an online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington Virginia. <http://www.natureserve.org/explorer>. Accessed 30 April 2013.
Phillips, G, L. American Eel Anguilla rostrata (Lesueur, 1817). In J. T. Hatch, G. L. Phillips, K. P. Schmidt, and M. McInerny, editors. The Fishes of Minnesota (in preparation).
Schmidt, K. P. 1991. Stream survey results for the Slender Madtom (Noturus exilis), Crystal Darter (Ammocrypta asprella) and Bluntnose Darter (Etheostoma chlorosomum) in southeastern Minnesota. Final report submitted to the Natural Heritage and Nongame Research Program, Minnesota Department of Natural Resources. 12 pp.+ appendices.
Schmidt, K. P. 2000. Stream survey results for the Gravel Chub (Erimystax x-punctatus), Slender Madtom (Noturus exilis), and Bluntnose Darter (Etheostoma chlorosomum) in southeastern Minnesota. Final report submitted to the Minnesota Department of Natural Resources. 14 pp + figures.
University of Wisconsin Sea Grant Institute. 2013. Wisconsin fish indentification [web application]. University of Wisconsin Sea Grant Institute, Madison. <http://www.seagrant.wisc.edu/home/Default.aspx?tabid=604>.
Wisconsin Department of Natural Resources. 2013.. Wisconsin's endangered and threatened species list [web page]. Wisconsin Department of Natural Resources, Madison. <http://dnr.wi.gov/topic/endangeredresources/etlist.html>. Accessed 09 May 2013.