Longnose dace (Rhinichthys cataractae) are not listed as a species of special concern, endangered, threatened, or regionally extirpated in any of the following conservation lists: IUCN Red List, CITES appendices, or the United States Endangered Species Act.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
Longnose dace are potential prey species for fish-eating birds, such as herons, and predatory stream fishes including many salmonid species (Brazo, Liston, and Anderson, 1978).
Known Predators:
Anti-predator Adaptations: cryptic
Longnose dace are typically dark olive-brown with a lighter yellow-tan venter (Page and Burr, 1991). A dark lateral stripe, present in juveniles, fades as the fish matures. This is a good distinguishing characteristic between longnose dace and their close relatives, blacknose dace (Rhinichthys atratulus), which maintain their dark lateral stripe throughout their lifetime (Page and Burr, 1991). Other identifying characteristics include a sub-terminal mouth with a fleshy snout projecting far beyond the mouth. A small barbel is also present near the corner of the mouth (Goldstein and Simon, 1999). Total length is largely based on local habitat conditions; adults are usually 60 to 90 mm in length (Sigler and Miller, 1963) and reported maximum sizes are around 160 mm for stream dwelling individuals, slightly larger for lake-dwelling longnose dace (Page and Burr, 1991; Brazo, Liston, and Anderson, 1978). Longnose dace have been reported to get up to 225 mm in total length (Gerald 1966).
Range length: 60 to 225 mm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: female larger
Longnose dace have a maximum reported lifespan of 5 years, but lifespan is typically only 3 years for male individuals (Reed and Moulton, 1973; Brazo, Liston, and Anderson, 1978).
Range lifespan
Status: wild: 3 to 5 years.
Average lifespan
Status: wild: 3 years.
Typical lifespan
Status: wild: 2 to 3 for males, 4 to 5 for females years.
Average lifespan
Status: wild: 3 years.
Populations of longnose dace use different niches based on local habitat conditions. Different habitat availability as well as the presence or absence of competing species drives populations into different patterns of niche use. Longnose dace are found in fast-flowing, cold water. Most populations are found in stream riffles. When in lakes, they are typically in the turbulent surge zone less than 10 m deep, where outflow from a river mixes with lake water (Brazo, Liston, and Anderson, 1978). Another characteristic of longnose dace habitat is rocky or gravel substrate (McPhail and Lindsey, 1970; Cooper, 1980). Brazo et al. (1978) reported similar substrate preferences in lake-dwelling populations, where longnose dace prefer gravel substrates over sandy habitats. Streams they inhabit tend to be small creeks and rivers with shallow pools as well as an abundance of fast-flowing riffles; similar to "trout streams" (Reed, 1959). Young longnose dace are found in shallow pools for the first four months following hatching (Reed 1959). Pools are also used by adults in the absence of competing species (Edwards, Li, and Schreck, 1983).
Range depth: <1 to 10 m.
Average depth: <1 m.
Habitat Regions: temperate ; freshwater
Aquatic Biomes: benthic ; lakes and ponds; rivers and streams
Longnose dace (Rhinichthys cataractae) have the widest geographic distribution of any member of the Cyprinidae family (Jenkins and Burkhead, 1994). The distribution spans much of North America, ranging from the Atlantic coast to the Pacific Ocean and from northern Mexico to the Arctic Circle in northern Canada.
Biogeographic Regions: nearctic (Introduced , Native )
Longnose dace are primarily nocturnal feeders (Brazo, Liston, and Anderson, 1978). This nocturnal foraging strategy is different from most cyprinids, but Rhinichthys cataractae is well adapted for this method (Beers and Culp, 1990). Longnose dace have dark-adapted vision for night foraging. Beers and Culp (1990) studied how changes in light intensity changed foraging efficiency when predators were removed. All factors indicative of foraging ability were greatest under low light conditions, such as around dusk. However, most foraging occurs at night where they are slightly less efficient. Therefore, this nocturnal strategy is thought to be a combination of minimizing predation risks while still increasing efficiency in low-light conditions (Beers and Culp, 1990).
Longnose dace are well adapted for feeding on bottom dwelling insects (Gerald, 1966). At night, they use benthic-rooting behavior; it is thought they locate prey by olfaction using their barbels to probe into the substrate (Beers and Culp, 1990). Brazo et al. (1978) determined through stomach analysis that longnose dace depend primarily on invertebrates as their primary food source. As in previous studies, their invertebrate diet consisted of midges, black flies, and mayflies (Reed 1959) as well as leaf hoppers, aphids, and small cicadas. Small, juvenile longnose dace feed primarily on algae and diatoms until they were large enough to consume the same diets as adults. Larger adults shifted their diet toward larger terrestrial insects as well as fish eggs from other Cyprinidae (Brazo, Liston, and Anderson, 1978).
Animal Foods: fish; eggs; insects; zooplankton
Plant Foods: algae; phytoplankton
Primary Diet: carnivore (Insectivore )
Rhinichthys cataractae is a wide-ranging freshwater minnow that is an important part of the food chain in many stream habitats. One of the important functions these fish provide are consuming terrestrial insects, bringing them into the aquatic food chain. Longnose dace are a potential prey species to predatory stream fishes including many salmonid species. This is especially believed to occur when alewives (Alosa pseudoharengus) undergo substantial population crashes (Brazo, Liston, and Anderson, 1978).
Longnose dace are also hosts to 13 parasitic species, including individuals from 6 larger taxonomic groups: 1 monogenean fluke, 2 flukes, 2 cestode species, 4 nematodes, 1 spiny-headed worm, and 3 protozoan species) (Muzzall, Whelan, and Taylor, 1992).
Commensal/Parasitic Species:
Direct anthropogenic interactions are minimal with longnose dace, but in some areas they are used as bait for fishing (Scott and Crossman, 1998).
Positive Impacts: research and education
There are no known negative affects of Rhinichthys cataractae on humans.
After fertilization, eggs develop for 3 to 4 days before hatching into protolarva. During this time, the head and tail separate from the yolk sac and the circulatory system begins to develop, as does the spinal cord. Pelagic protolarvae continue to develop, pigmentation begins, and early fin development occurs. By the 9th day after hatching, the sac is absorbed and the larvae are now considered mesolarvae. Fin rays become more defined and pigmentation continues to accumulate. As Rhinichthys cataractae metalarvae develop into juveniles, fin buds develop, the fish takes on the morphology of a juvenile (including an elongated fleshy snout), and pigmentation accumulation is completed (Fuiman and Loos, 1977; Cooper, 1980).
Juvenile longnose dace (Rhinichthys cataractae) continue to grow and develop in streams. Most longnose dace mature at age 2. A small percentage of adults are mature at age 1. This percentage increases slightly in lake-dwelling populations, where growth and maturation is accelerated (Brazo, Liston, and Anderson, 1978). Age 1 spawners are predominantly males, indicating possible shorter maturation times for males than females (Brazo, Liston, and Anderson, 1978). Mature individuals, both male and female, are approximately 75 mm in total length at the time of maturation (Roberts and Grossman, 2001). Females generally become the dominant sex and typically grow larger than males by age 3 (Gerald, 1966).
Development - Life Cycle: metamorphosis ; indeterminate growth
Detailed information on Rhinichthys cataractae communication and perception is not available.
Communication Channels: visual ; tactile ; chemical
Perception Channels: visual ; tactile ; acoustic ; vibrations ; chemical
Adult longnose dace are polygynandrous (promiscuous) because both mature males and females have multiple spawning partners. Males are territorial and breed with many females who visit their habitat (Bartnik, 1970). Female longnose dace are capable of spawning 6 or more times during their breeding season and will breed with multiple males during this time (Roberts and Grossman, 2001).
Mating System: polygynandrous (promiscuous)
Some longnose dace are capable of reproducing at age 1, all are mature by age 2 (Roberts and Grossman, 2001; Brazo, Liston, and Anderson, 1978). Mature individuals, both male and female, are approximately 75 mm in total length. While spawning typically occurs only in one year, females are capable of producing 6 or more clutches per year. Total potential fecundity ranged from 1155 to 2534 eggs for females in stream dwelling populations (Roberts and Grossman, 2001) and from 870 to 9,953 eggs per female in Lake Michigan populations (Brazo et al., 1978). Longnose dace larvae hatched 3 to 4 days after fertilization occurred; with an mean length of 5.9 mm (Fuiman and Loos, 1977; Cooper, 1980). Information on mass at the time of hatching was not available. Spawning typically occurs in summer but timing is dependent on latitude and water temperature (Edwards, Li, and Schreck, 1983). Typical spawning season takes place in late June and early July (Brazo, Liston, and Anderson, 1978) but occurs as early as late May (Reed, 1959) and as late as August (McPhail and Lindsey 1970). Peak spawning typically occurs at water temperatures between 14° and 19° C (Brazo, Liston, and Anderson, 1978).
Breeding interval: Female longnose dace are capable of having 6 or more clutches per year but typically only spawn for 1 season.
Breeding season: Longnose dace reproduce between May and July.
Range number of offspring: 1155 to 2534.
Average number of offspring: 1832.
Range gestation period: 3 to 4 days.
Range time to independence: 3 to 4 days.
Range age at sexual or reproductive maturity (female): 1 to 2 years.
Average age at sexual or reproductive maturity (female): 2 years.
Range age at sexual or reproductive maturity (male): 1 to 2 years.
Average age at sexual or reproductive maturity (male): 2 years.
Key Reproductive Features: semelparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); oviparous
In stream and lake-dwelling populations, spawning occurs over gravel. Male longnose dace construct a small nest in the pebbles where eggs are deposited (McPhail and Lindsey, 1970). Males are territorial and defend their spawning habitat, which is visited by multiple females (Brazo, Liston, and Anderson, 1978). After spawning, little or no parental care is given the eggs. They are are categorized as benthic spawners who broadcast their eggs over gravel. The eggs are not hidden (Helfman, Collette, and Facey, 1997). Embryos temporarily adhere to the gravel for 7 to 10 days and then the hatched fry become pelagic (McPhail and Lindsey, 1970; Cooper, 1980).
Parental Investment: no parental involvement; pre-fertilization (Provisioning, Protecting: Male)
The longnose dace (Rhinichthys cataractae) is a freshwater minnow native to North America. Rhinicthys means snout fish (reference to the long snout) and cataractae means of the cataract (first taken from Niagara Falls). Longnose dace are small, typically less than 100 mm and characterized by their fleshy snout that protrudes past the mouth. They are well adapted for living on the bottom of fast-flowing streams among stones. Longnose dace eat algae and aquatic insects and are important forage minnows for larger predatory fish.
Longnose dace can be mistaken for suckers because of their subterminal "sucker-like" mouth. However, longnose dace (like all members of the family cyprinidae) lack small fleshy projections, called papillae, on their mouths.
Juveniles have a black lateral line that extends from the beginning of the eye to the caudal fin that fades as the fish matures. The lateral line in juveniles is not present in all populations. In adults, the dorsal side is dark green to black, the lateral side is darkish to silvery with mottling often present, and the ventral side is pearly. Both adult males and females may have bright orange-reddish colouration at the base of pectoral, pelvic, and anal fins and on the upper lip. This colouration is typically associated with breeding males in the subspecies Rhinichthys cataractae cataractae,[2] but the validity of this subspecies has yet to be confirmed. Museum specimens of females also show intense orange-reddish colouration at the base of the fins and upper lip,[3] therefore colouration is not an accurate predictor of sex.
The maximum length of longnose dace is 170 mm, but they are usually less than 100 mm.
Longnose dace have the widest distribution of any cyprinid in North America, with a range reaching as far south as the Rocky Mountains in northern New Mexico and as far north as the Mackenzie River near the Arctic Circle[4] and across the continent from the Pacific to Atlantic coast. Multiple refugia during the most recent glacial maximum may explain the broad geographic distribution of longnose dace. There were up to three possible glacial refuges during Pleistocene glaciations: the Pacific, the Mississippi and the Atlantic.[4] Longnose dace on the Quebec peninsula likely originated only from the Atlantic refuge, in contrast to other fish species on the peninsula that originated from multiple refugia.[5] Longnose dace in northwestern North America originated from a Pacific refuge.[6]
Longnose dace occur in moderately cool water streams, rivers and lakes[3] with temperatures up to 22 °C. Longnose dace are benthic and preferentially occupy rock and gravel substrate. During the day longnose dace hide under rocks. Longnose dace prefer shallow, fast-moving riffles in streams and rivers and the turbulent, near-shore region of lakes.[7]
Longnose dace are opportunistic foragers. Small longnose dace (≤ 50 mm) primarily consume algae and benthic invertebrates dace (> 50 mm) feed on fish scales, fish eggs, terrestrial insects, and aquatic benthic macroinvertebrates, although diet varies seasonally.[8][9] They are nocturnal feeders, possibly to avoid predation and/or salmonid competitors.[10]
Longnose dace have small home ranges and high site fidelity,[11] however there is evidence that a small proportion are able to disperse distances greater than 500 km.[12]
Longnose dace reach reproductive maturity at age two[8] and have a mean lifespan of three years. Males and females have a maximum age of four and five, respectively.[3]
Longnose dace typically spawn from May to August in water 14 to 19 °C[8] and some populations are multiple spawners.[13] Time of spawning is dependent on water temperature.[4] Longnose dace are polygynandrous and males create and defend territories to attract females to enter and spawn. Males form a depression in the rocky substrate and vibrate to attract a female. When a female is receptive, she enters the territory and pushes her snout into substrate in a similar manner as the male. Both male and female tremble over the depression and release eggs and milt.[2] Limited or no parental care is provided to young-of-the-year after hatching.
In southern Alberta longnose dace are exposed to organic, estrogen-like compounds.[14] Downstream of wastewater effluent from the city of Red Deer longnose dace are larger, increase in abundance, and have larger livers but males have reduced ability to produce testosterone.[15] Despite a morphologically healthy appearance, longnose dace in the Red Deer River are physiologically stressed. In the Oldman River, some longnose dace populations are characterized by elevated vitellogenin expression, female biased sex ratios and intersex gonads.[16][17] Feminization is likely caused by estrogen-like compounds present in municipal wastewater effluent, agriculture, and cattle operations near the Oldman River, however this mechanism is not well understood. It is not known if increased vitellogenin expression and intersex gonads significantly decrease reproductive success and will impact the long term viability of longnose dace in these systems. There is not evidence of skewed sex ratios in the Bow River.[16]
Fish caught in the Thunder Bay District, Ontario. The longnose dace (Rhinichthys cataractae) is a freshwater minnow native to North America. Rhinicthys means snout fish (reference to the long snout) and cataractae means of the cataract (first taken from Niagara Falls). Longnose dace are small, typically less than 100 mm and characterized by their fleshy snout that protrudes past the mouth. They are well adapted for living on the bottom of fast-flowing streams among stones. Longnose dace eat algae and aquatic insects and are important forage minnows for larger predatory fish.
