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 A cataract is a cloudy area in the lens of the eye that leads to a decrease in vision. Cataracts often develop slowly and can affect one or both eyes. Symptoms may include faded colors, blurry or double vision, halos around light, trouble ...

(first taken from

Niagara Falls Niagara Falls () is a group of three waterfalls at the southern end of Niagara Gorge, spanning the Canada–United States border, border between the Provinces and territories of Canada, province of Ontario in Canada and the U.S. state, state ...

). 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.

Description

Longnose dace can be mistaken for suckers because of their subterminal "sucker-like" mouth. However, longnose dace (like all members of the family

cyprinidae Cyprinidae is a family of freshwater fish commonly called the carp or minnow family. It includes the carps, the true minnows, and relatives like the barbs and barbels. Cyprinidae is the largest and most diverse fish family and the largest ve ...

) 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 Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

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'',Bartnik, V.G. 1971. "Comparison of the breeding habits of two subspecies of longnose dace, ''Rhinichthys cataractae''". Canadian Journal of Zoology 50: 83-86. 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,Nelson, J.S. and M.J. Paetz. 1992. The Fishes of Alberta. The University of Alberta Press. Edmonton, Alberta. 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.

Geographic distribution

Longnose dace have the widest distribution of any cyprinid in North America, with a range reaching as far south as the

Rocky Mountains The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in straight-line distance from the northernmost part of western Canada, to New Mexico ...

in northern

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe, New Mexico, Santa Fe , LargestCity = Albuquerque, New Mexico, Albuquerque , LargestMetro = Albuquerque metropolitan area, Tiguex , Offi ...

and as far north as the Mackenzie River near the Arctic CircleMcPhail, J.D. and C.C. Lindsay. 1970. Freshwater Fishes of Northwestern Canada and Alaska. Freshwater Research Board of Canada. Ottawa, Ontario. 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 The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

glaciations: the Pacific, the Mississippi and the Atlantic. 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.Girand, A. and B. Angers. "The impact of postglacial marine invasions on the genetic diversity of an obligate freshwater fish, the longnose dace (''Rhinichthys cataractae''), on the Quebec peninsula". Canadian Journal of Fisheries and Aquatic Sciences 63: 1429-1438. Longnose dace in northwestern North America originated from a Pacific refuge.McPhail, J.D. and E.B. Taylor. "Phylogeography of the longnose dace (''Rhinichthys cataractae'') species group in northwestern North America – the origin and evolution of the Umpqua and Millicoma dace". Canadian Journal of Zoology 87: 491-497.

Ecology

Longnose dace occur in moderately cool water streams, rivers and lakes with temperatures up to 22 °C. Longnose dace are

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning " ...

and preferentially occupy rock and gravel substrate. During the day longnose dace hide under rocks. Longnose dace prefer shallow, fast-moving

riffle A riffle is a shallow landform in a flowing channel. Colloquially, it is a shallow place in a river where water flows quickly past rocks. However, in geology a riffle has specific characteristics. Topographic, sedimentary and hydraulic indica ...

s in streams and rivers and the turbulent, near-shore region of lakes.Edwards, E.A., H. Li and C.B. Schreck. 1983.
“Habitat suitability index models: Longnose dace.”
U.S. Department of the Interior, Fish and Wildlife Service. FWS/OBS-82/10.33 13 pp. 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.Brazo, D.C., C.R. Liston and R.C. Anderson. 1978. "Life history of the Longnose dace, ''Rhinichthys cataractae'', in the surge zone of the eastern Lake Michigan near Ludington, Michigan". Transactions of the American Fisheries Society 107(4): 550-556.Thompson, A.R., J.T. Petty and G.D. Grossman. 2001. "Multi-scale effect of resource patchiness on foraging behavior and habitat use by longnose dace, ''Rhinichthys cataractae''". Freshwater Biology 46: 145-160. They are

nocturnal Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite. Nocturnal creatures generally have highly developed sens ...

feeders, possibly to avoid predation and/or salmonid competitors.Culp, J.C. 1978. "Nocturnally constrained foraging of a lotic minnow (''Rhinichthys cataractae'')". Canadian Journal of Zoology 67: 2008-2012. Longnose dace have small home ranges and high site fidelity,Hill, J. and G.D. Grossman. 1987. "Home range estimates for three North American stream fishes". Copeia 1987(2): 376-380. however there is evidence that a small proportion are able to disperse distances greater than 500 km.Larson, G.L., R.L. Hoffman, and S.E. Moore. 2002. "Observations of the distribution of five fish species in a small Appalachian stream". Transactions of the American Fisheries Society 131(4): 791-796.

Life history

Longnose dace reach reproductive maturity at age two and have a mean lifespan of three years. Males and females have a maximum age of four and five, respectively. Longnose dace typically

spawn Spawn or spawning may refer to: * Spawn (biology), the eggs and sperm of aquatic animals Arts, entertainment, and media * Spawn (character), a fictional character in the comic series of the same name and in the associated franchise ** '' Spawn: A ...

from May to August in water 14 to 19 °C and some populations are multiple spawners.Roberts, J.H. and G.D. Grossman. 2001. "Reproductive characteristics of female longnose dace in the Coweeta Creek drainage, North Carolina, USA". Ecology of Freshwater Fish 10: 184-190 Time of spawning is dependent on water temperature. 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. Limited or no parental care is provided to young-of-the-year after hatching.

Anthropogenic disturbance

In southern Alberta longnose dace are exposed to organic, estrogen-like compounds.Jeffries, K.M., L.J. Jackson, M.G. Ikonomou, and H.R. Habibi. 2010. "Presence of natural and anthropogenic organic contaminants and potential fish health impacts along two river gradients in Alberta, Canada." Environmental Toxicology and Chemistry 29(10): 2379-2010. Downstream of wastewater effluent from the city of

Red Deer The red deer (''Cervus elaphus'') is one of the largest deer species. A male red deer is called a stag or hart, and a female is called a hind. The red deer inhabits most of Europe, the Caucasus Mountains region, Anatolia, Iran, and parts of ...

longnose dace are larger, increase in abundance, and have larger livers but males have reduced ability to produce

testosterone Testosterone is the primary sex hormone and anabolic steroid in males. In humans, testosterone plays a key role in the development of male reproductive tissues such as testes and prostate, as well as promoting secondary sexual characteristi ...

.Jeffries, K.M., L.J. Jackson, L.E. Peters and K.R. Munkittrick. 2008. "Changes in population, growth, and physiological indices of longnose dace (''Rhinichthys cataractae'') in the Red Deer River, Alberta, Canada." Archives of Environmental Contaminants and Toxicology 55: 639-65. Despite a morphologically healthy appearance, longnose dace in the Red Deer River are physiologically stressed. In the

Oldman River The Oldman River is a river in southern Alberta, Canada. It flows roughly west to east from the Rocky Mountains, through the communities of Fort Macleod, Lethbridge, and on to Grassy Lake, where it joins the Bow River to form the South Saskatchew ...

, some longnose dace populations are characterized by elevated vitellogenin expression, female biased sex ratios and intersex gonads.Jeffries, K.M., E.R. Nelson, L.J. Jackson and H.R. Habibi. "Basin-wide impacts of compounds with estrogen-like activity on longnose dace (''Rhinichthys cataractae'') in two prairie rivers of Alberta, Canada." Environmental Toxicology and Chemistry 27(10): 2042-2052.Evans, J.S., L.J. Jackson, H.R. Habibi, and M.G. Ikonomou. 2012.
"Feminization of longnose dace (''Rhinichthys cataractae'') in the Oldman River, Alberta, (Canada) provides evidence of widespread endocrine disruption in an agricultural basin."
Scientifica 11 pages. 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 The Bow River is a river in Alberta, Canada. It begins within the Canadian Rocky Mountains and winds through the Alberta foothills onto the prairies, where it meets the Oldman River, the two then forming the South Saskatchewan River. These w ...

References

{{Taxonbar, from=Q2178257 Rhinichthys Fish of the Western United States Fauna of the Rocky Mountains Fish described in 1842 Freshwater fish of North America