Red-horse Minnow, Notropis lutrensis (Baird and Girard, 1853), Leuciscus lutrensis Baird and Girard, 1853, Cyprinella lutrensis blairi (Hubbs, 1940).

Cyprinella lutrensis spawns over an extended period of time from spring into fall months, with a peak from early to mid-summer. Breeding season in Georgia is May through July, and in south central Oklahoma and central Texas it is from April to September (Farringer et al. 1979). Spawning may occur on riffles, on or near submerged objects, over vegetation beds, or in association with sunfish nests. Some individuals breed in two successive years, but very fewbreed in the same year they are hatched (Farringer et al. 1979). Females lay adhesive eggs in 5–19 clutches per reproductive season, ranging from approximately 400–700 eggs per batch and up to 16 batches per day (Gale 1986).

Adults typically school in midwater or near the surface. The species is thought to feed primarily on small invertebrates, plant matter and algae, and occasionally fish larvae (Laser and Carlander 1971). Red Shiners are forage fish and are consumed by various piscivores. In experimental units, Red Shiner survival was significantly negatively related to the abundance of Sunfish (Lepomis spp.) suggesting that predation can inhibit early stages of invasion by Red Shiners (Marsh-Matthews et al. 2011). Average life span of Red Shiner is 2–3 years in the wild (Herrington and DeVries 2008).

Potential pathway(s) of introduction: Released bait, Dispersed, Released aquarium.

The origin of most introduced Cyprinella lutrensis populations can be attributed to bait bucket releases. Koehn (1965) mentioned that the species has been introduced as a forage fish. The Red Shiner is also sold in the aquarium trade (Becker 1983; Etnier and Starnes 1993). They have been marketed in a pet shop under the name "rainbow dace" (Moore et al. 1976) and are currently available from online retailers (e.g., Amazon.com and various aquaculture stores). According to Dill and Cordone (1997), it was introduced into northern California as a forage fish, not as a bait minnow as suggested by Kimsey and Fisk (1964). The introduction of Red Shiner into the Yadkin drainage, North Carolina, was possibly the result of an aquarium release (Moore et al. 1976). Hubbs (1954) reported this species as established in the lower Colorado River basin by 1953. He attributed the source of the introduction to escapees from the Arizona Fish Farms in Ehrenburg, Arizona. There apparently has been more than one subspecies introduced into the southwestern United States. Hubbs (1954) also noted that Red Shiners found in the lower Colorado River basin were intergrades between the subspecies C. l. lutrensis and C. l. suavis. In contrast, Minckley (1973) reported that the Arizona specimens he examined more closely resembled the typical subspecies, C. l. lutrensis. Gilbert (1998) also referred it to the typical subspecies (C. l. lutrensis).

Initial introduction of Cyprinella lutrensis is often followed by its rapid population growth, dispersal, and aggressive colonization (e.g., Hubbs and Lagler 1958, Minckley and Deacon 1968, Minckley 1973). In some areas dispersal of introduced populations has been aided by the presence of irrigation ditches and canals (e.g., Jennings and Saiki 1990).

Great Lakes:
In contrast to Hubbs and Lagler's statement (1958), Becker (1983) found that there was no evidence to substantiate the presence of this species in lagoons of Lake Michigan at Chicago. Cyprinella lutrensis has not yet been recorded in any of the other Great Lakes.

The Red Shiner has created a tenet among some ecologists: where it appears, native fishes disappear (Stolzenburg 1992). Dill and Cordone (1997) called the Red Shiner the second most significant threat to the welfare of indigenous southwestern fishes, after the Western Mosquitofish (Gambusia affinis). Cyprinella lutrensis are very aggressive where introduced and have been associated with impacts on the indigenous fish populations through predation, competition, hybridization, and introduction of parasites.

Ruppert et al. (1993) suggested that establishment of Red Shiner in Yampa River and Green River immediately below their confluence in Dinosaur National Monument, Colorado has led to predation on vulnerable larvae of native populations of Razorback Sucker (Xyrauchen texanus) and Colorado Pikeminnow (Ptychocheilus lucius). This assumption was supported by a laboratory study that indicated that Red Shiner are a potential predator of Razorback Sucker larvae (Carpenter and Mueller 2008). In 2008, Schooley et al. (2008) found Razorback Sucker larvae in the guts of Red Shiners in Salt River and Sycamore Creek, Arizona.

The Red Shiner has also affected the distribution and abundance of native fishes. For example, populations in the Moapa and Virgin rivers, Nevada, have been implicated in the decline of the native fish of this region, including Spikedace (Meda fulgida), Woundfin (Plagopterus argentissimus), and Virgin River Chub (Gila seminuda) (Moyle 1976; Deacon 1988; U.S. Fish and Wildlife Service 1990). Members of this species may compete with and affect growth, condition, or survival of young Colorado Pikeminnow (Karp and Tyus 1990; Muth and Snyder 1995).

The Red Shiner may dilute the gene pools of native Cyprinella via hybridization (Mayden 1989; Burkhead and Huge 2002); studies have found that the Red Shiner is hybridizing with the Blacktail Shiner (Cyprinella venusta) in the Coosa River basin in Georgia and Alabama (Mettee et al. 1996, Burkhead and Huge 2002, Walters et al. 2008, Blum et al. 2010). The rate of hybridization between Red and Blacktail Shiners was higher due to increased premating social interactions in elevated turbidity (Glotzbecker et al. 2015).

The introduction of Red Shiner into Utah was probably how the Asian tapeworm entered the Virgin River; subsequent tapeworm infestation of Woundfin may be primarily responsible for the Woundfin's decline during the 1980s (Deacon 1988). The Red Shiner are one of the species that potentially introduced the Asian fish tapeworm (Bothriocephalus acheilognathi) to the Lower Colorado River (Choudhury et al. 2004). The introduction of Red Shiner to the Great Lakes may further the spread of Bothriocephalus acheilognathi within the basin (Marcogliese et al. 2016). Red Shiner are host to Pseudocapillaria tomentosa, a parasitic nematode that can cause inflammation and intestinal lesions in fish (Leis et al. 2016).

Introduced Red Shiner populations have contributed to the reduction of many fish populations and are known to dominate fish assemblages. For example, the introduced Redside Shiner (Richardsonius balteatus) declined when the Red Shiner became common in the Green River near the boundary of Dinosaur National Monument, Utah, in 1971 (Holden and Stalnaker 1975). In degraded streams in Georgia, introduced Red Shiners have become one of the most abundant species (Devivo and Freeman 1995). In a 1985-88 study of the Colorado and Green Rivers adjacent to Canyonlands National Park, introduced Red Shiners made up nearly 50% of the catch per unit effort (Valdez and Williams 1993).

There is little or no evidence to support that Cyprinella lutrensis has the potential for significant socio-economic impact if introduced to the Great Lakes.

No evidence has been found of Cyprinella lutrensis having any socio-economic impacts.

Cyprinella lutrensis has the potential for moderate beneficial impact if introduced to the Great Lakes.

Cyprinella lutrensis are a popular batifish (Dill and Cordone 1997). They are also sold in pet stores as an aquarium fish (Moore et al. 1976) and are currently available from online retailers (e.g., Amazon.com and various aquaculture stores). Cyprinella lutrensis has been introduced as forage fish in California (Kimsey and FIsk 1964) and would potentially act as a forage fish for piscivores in the Great Lakes but likely at the cost of species diversity.

Control

Biological

There are no known biological control methods for this species.

Physical

Electroshocking had no effect on total egg production by Red Shiners, but the interclutch time interval increased and the proportion of viable eggs decreased. Further, male weight and SL was significantly reduced (Stewart and Lutnesky 2014).

Chemical

Endocrine disrupting chemicals such as estradiol significantly reduced reproductive success of Red Shiner (McGree et al. 2010), but negative effects would likely include other non-target fish species. General piscicides (such as rotenone) may be used for control, but expect significant kill of non-target species.

Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.

Although hybridization with Blacktail Shiner has been reported in areas where Red Shiner are introduced, Higgens et al. (2015) found little evidence for hybridization (using both genetic and morphological data) in two river systems where both species are native and occur in sympatry.

Glotzbecker et al. (2016) examined cytochrome-b variation across the native and introduced range of Red Shiner, identifying four distinct regional genetic lineages; introduced populations in the western United States were founded by introductions from the midwest and western clades, whereas introductions in the eastern United States were solely derived from colonists from the mid-western clade.