{{Short description|Species of fish}} {{cs1 config|name-list-style=and}} {{Speciesbox | image = River chub - Nocomis micropogon.jpg | image_alt = side view of a common North American minnow | image_caption = ''Nocomis micropogon'' | status = LC | status_system = IUCN3.1 | status_ref = <ref name="iucn status 20 November 2021">{{cite iucn |author=NatureServe |author-link=NatureServe |year=2013 |title=''Nocomis micropogon'' |article-number=e.T202276A18230616 |doi=10.2305/IUCN.UK.2013-1.RLTS.T202276A18230616.en |access-date=20 November 2021}}</ref> | status2 = G5 | status2_system = TNC | status2_ref = <ref name=NatureServe>{{cite web |title=''Nocomis micropogon'' |url=https://explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.2.101786/Nocomis_micropogon |website=NatureServe Explorer An online encyclopedia of life |version=7.1 |publisher=NatureServe|access-date=20 November 2021}}</ref> | taxon = Nocomis micropogon | authority = (Cope, 1865) | synonyms = {{Specieslist | Ceratichthys micropogon | Cope, 1865 }} | synonyms_ref = <ref name = "Cof genus">{{Cof genus|genus=Nocomis|access-date=15 March 2025}}</ref> }}
The '''river chub''' ('''''Nocomis micropogon''''') is a species of freshwater ray-finned fish belonging to the family Leuciscidae, the shiners, daces and minnows.<ref name = "Cof genus"/> It is one of the most common fishes in North American streams.
==Appearance and anatomy== The river chub is a robust minnow, dark olivaceous above to dusky yellow below, with orange-red fins, large scales, a large slightly subterminal mouth, and a small barbel (whisker-like organ) at the corners of the jaw. During the breeding season, sexually mature males develop pinkish-purple coloration, and swollen heads with tubercles between the eyes and snout tip (they are sometimes called hornyheads).<ref name=etnier>{{cite book|author=Etnier, David A |author2=Wayne C Starnes|title=The Fishes of Tennessee|location=Knoxville |publisher=University of Tennessee Press|year=1993|pages=196–199}}</ref> The river chub grows to a maximum of about {{convert|33|cm|in}}, with males larger than females. Common length is about {{cvt|13.5|cm|in}}.<ref name=FishBase/>
==Distribution== The river chub is among the most common fishes in North American streams.<ref name=mcm/><ref name=johnston>{{cite journal|author=Johnston, CE|year=1999|title=The relationship of spawning mode to conservation of North American minnows (Cyprinidae)|journal=Environmental Biology of Fishes|volume=55|issue=1–2 |pages=21–30|doi=10.1023/A:1007576502479 |bibcode=1999EnvBF..55...21J }}</ref> Its range extends primarily through most of the Great Lakes and Appalachian regions.<ref name=FishBase>{{FishBase|genus=Nocomis |species=micropogon|id=2810}}</ref> The river chub is found in clear, medium to large creeks and rivers with moderate to swift current over rock and gravel substrate, from southeast Ontario and southern New York to Michigan and Indiana, south to northwest South Carolina to northwest Alabama. This includes the Susquehanna River system, James River system, Great Lakes basin (except Lake Superior), Ohio River basin, Santee River, Savannah River, and Coosa River.<ref name=NatureServe/> It has been introduced into the Ottawa River system in Ontario, and may owe its presence in the Santee, Savannah and Coosa Rivers to introduction by fishermen emptying bait buckets.<ref>{{cite web|author=Nico, Leo|author2=P Fuller|title=''Nocomis micropogon''|website=USGS Nonindigenous Aquatic Species Database |location=Gainesville, FL|url=https://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=577|date=4 January 2010}}</ref> The river chub is generally considered widespread and abundant with no apparent major threats. Exceptions are Illinois, where it is considered Critically Imperiled in its very limited range on the Wabash River; Alabama, where it is considered Imperiled; and in Georgia it is ranked as Vulnerable. Populations in Ohio have been extirpated by turbidity and siltation in western regions and are threatened by acid mine drainage in the coal region.<ref>{{cite web |publisher=Ohio Department of Natural Resources|year=2012|title=Riverine Fish of Ohio's Scenic Rivers |url=http://ohiodnr.com/watercraft/tabid/2592/Default.aspx|access-date=November 18, 2012}}</ref> Also, dams have inundated areas that were once habitat for the river chub eliminating bits of its range.{{citation needed|date=March 2014}}
==Ecology==
The river chub is prey for larger fish and is used as bait by fishermen seeking large game fish such as bass and catfish. Its diet consists primarily of aquatic invertebrates. One study of river chub stomach contents in western New York found that insects were 70% of the volume of food consumed, plants or protists 20% (mainly filamentous algae), crustaceans 5% (primarily ''Cambarus''), and mollusks 4% (primarily gastropods), plus a few fish and arachnids. Caddisfly larvae and fly larvae (primarily ''Simulium'' and ''Chironomus'') made up just over half the total food consumed. Mayflies (mainly baetids) were about 6% of the total. Other insects consumed were Coleoptera (beetles), Hemiptera (true bugs), Hymenoptera (bees, wasps, and ants), Plecoptera (stoneflies), Neuroptera (net-winged insects like laceflies), and Lepidoptera (butterflies and moths).<ref>{{cite journal|author=Lachner, EA|year=1950 |title=The Comparative Food Habits of the Cyprinid Fishes ''Nocomis biguttatus'' and ''Nocomis micropogon'' in Western New York|journal=Journal of the Washington Academy of Sciences |volume=40|pages=229–236}}</ref>
The river chub presence in a stream is a good indicator of water quality. They are intolerant of pollution, turbidity and siltation, and require a minimum pH 6.0.<ref name=cravotta>{{cite journal|author=Cravotta CA |author2= RA Brightbill |author3= MJ Langland|year=2010|title=Abandoned Mine Drainage in the Swatara Creek Basin, Southern Anthracite Coalfield, Pennsylvania, USA {{!}} Stream Water Quality Trends Coinciding with the Return of Fish|journal=Mine Water and the Environment|volume=29|issue=3|pages=176–199|doi= 10.1007/s10230-010-0112-6 |bibcode= 2010MWE....29..176C }}</ref> They provide ecological services to mussels (as glochidia hosts), and nest associates, some of which may not spawn in its absence.<ref name=weaver>{{cite journal|author=Weaver LR|author2= GB Pardue|author3= RJ Neves|year=1991|title=Reproductive Biology and Fish Hosts of the Tennessee Clubshell ''Pleurobema oviforme'' (Mollusca: Unionidae) in Virginia|journal=American Midland Naturalist|volume=26|issue=1|pages=82–89|doi= 10.2307/2426152|jstor= 2426152|bibcode= 1991AMNat.126...82W}}</ref><ref name=bru>{{cite journal|author=Bruenderman, SA |author2=RJ Neves|year=1993|title=Life-History of the Endangered Fine-Rayed Pigtoe ''Fusconaia cuneolus'' (Bivalvia, Unionidae) in the Clinch River, Virginia|journal=American Malacological Bulletin|volume=10|issue=1|pages=83–91}}</ref><ref name=rakes>{{cite journal|author=Rakes PL|author2= JR Shute|author3= PW Shute|year=1999 |title=Reproductive behavior captive breeding, and restoration ecology of endangered fishes |journal=Environmental Biology of Fishes|volume=55|issue=1.2|pages=31–42|doi= 10.1023/A:1007531927209|bibcode= 1999EnvBF..55...31R}}</ref> Fresh-water mussels release small masses of microscopic larvae known as glochidia in a loose gelatinous matrix. The glochidia encyst on the gills of river chubs where they metamorphose into juveniles and then drop off. It is suspected that the river chub feeds on the gelatinous masses as it does drifting insects.<ref name=weaver/><ref name=bru/> The river chub is host to mussels including the endangered fine-rayed pigtoe, Tennessee clubshell and probably many other amblemine glochidia.<ref name=weaver/><ref name=bru/>
Nest associates of the river chub include species of the ''Clinostomus'', ''Luxilus'', ''Lythrurus'', ''Notropis'', ''Chrosomus'', ''Rhinichthys'', and ''Semotilus'' genera.<ref name=etnier/><ref name=cooper/> Preference for river chub nests by nest associates may be due to a lack of spawning habitat for some species, but some require the association with pebble nest builders to reproduce. For example, in an effort to establish a more viable population, pebble nest associate ''Chrosomus cumberlandensis'' was bred in aquaria with a man made pebble nest, and milt from a breeding male river chub was added to induce spawning.<ref name=rakes/> Nest associates and host may equally benefit from their affiliation. Also, hybridization among nest associates is not uncommon. One example is the ''Nocomis micropogon X Rhinichthys cataractae'' which is sometimes identified as ''Pararhinichthys bowersi''.<ref name=cooper/>
==Life history==
The river chub lives up to 5 years, reaching sexual maturity in its second year. In late spring the breeding male builds a pebble nest close to the bank of the stream in low to moderate current.<ref name=mcm>{{cite journal|author=McManamay RA|author2= DJ Orth|author3= CA Dolloff|author4= MA Cantrell|year=2010 |title=Gravel addition as a habitat restoration technique for tailwaters|journal=North American Journal of Fisheries Management|volume=30|issue=5|pages=1238–1257|doi= 10.1577/M10-007.1|bibcode= 2010NAJFM..30.1238M}}</ref> Females produce about 500–1000 eggs that are probably spread among several different males' nests.<ref name=etnier/> The pebble nest also provides spawning habitat for several other minnow species.<ref name=cooper>{{cite journal|author=Cooper JE|year=1980|title=Egg, Larval and Juvenile Development of Longnose Dace, ''Rhinichthys cataractae'', and River Chub, ''Nocomis micropogon'', with Notes on Their Hybridization|journal=Copeia|issue=3|pages=469–478|doi=10.2307/1444524 |jstor=1444524 }}</ref>
In early spring the adult male river chub undergoes pronounced changes in his appearance in preparation for breeding. His head swells and grows well-developed tubercles from eyes to snout tip. Small tubercles grow on the outer part of his first several pectoral fin rays and his body develops a pinkish-purple coloration.<ref name=lachner52>{{cite journal|author=Lachner, EA|year=1952|title=Studies of the Biology of the Cyprinid Fishes of the Chub Genus ''Nocomis'' of Northeastern United States|journal=American Midland Naturalist|volume=48|issue=2 |pages=433–466|doi=10.2307/2422260 |jstor=2422260 }}</ref> When the water temperature reaches {{cvt|16|-|19|°C}} he finds an area in low to moderate current, typically {{cvt|0.5|-|1|m}} deep and begins to build a pebble nest.<ref name=mcm/> Nest construction begins with the river chub male creating a shallow depression {{cvt|0.5|-|1|m}} in diameter by removing the stones with his mouth and depositing them on the lateral margins. Next, collecting a relatively uniform set of up 10,000 pebbles about {{cvt|1|cm}} in size from as far away as {{cvt|25|m}}, he builds a short platform and then a {{cvt|20|–|30|cm}} high circular mound with a central trough on the upstream slope. When a gravid female enters the trough he presses her against the side by placing his caudal peduncle over hers and lodging her head between his opercle and pectoral fin. The male fans the nest and defends it from rivals with head butting and circle swim behaviors.<ref>{{cite journal|author=Maurakis, EG|author2= WS Woolcott |author3= MH Sabaj|year= 1991|title= Reproductive Behavioral Phylogenetics of ''Nocomis'' Species Groups|journal=American Midland Naturalist |volume=126|issue=1|pages=103–110|doi= 10.2307/2426154 |jstor= 2426154 }}</ref>
The eggs hatch in 5–6 days and the larvae grows to become a {{cvt|19|mm}} long juvenile in about 57 days.<ref name=cooper/> At two years the river chub is {{cvt|95|-|110|mm}} and sexually mature. Its maximum life span is 5 years and it can grow up to {{cvt|33|cm}}.<ref name=FishBase/> In addition to the breeding male's changes, other sexual dimorphic characters include slightly larger paired, anal, and dorsal fins in the female, and faster growth rate and larger size in the male. For example, a typical four-year-old male is about {{cvt|18|cm}} and female about {{cvt|13|cm}}.<ref name=lachner52/>
==Current management==
River chub is one of the most common fishes in its range. About 20% of North American minnows are considered imperiled. None of the imperiled is a mound builder like the river chub.<ref name=johnston/> The main threats it faces are pollution, siltation, and habitat destruction primarily by dam building. Like many minnow species it requires flowing water over coarse substrate to reproduce so dams impact its range negatively. Dams can also trap the stone and gravel sediments and keep them from replenishing the waters below. This sediment-starved condition has impacted some species, such as the redd nesting northern hog sucker and black redhorse, that require natural deposits of coarse material to spawn, but typically the river chub continues to be able to find gravel to build its own spawning habitat.<ref name=mcm/>
The river chub does suffer where pollution, turbidity and siltation, acid mine drainage and acid precipitation/deposition impact its habitat. It has been extirpated in areas with excess turbidity and siltation in western Ohio. Riparian buffers in agricultural areas can help keep turbidity and contaminants from waterways. The Swatara Creek in Pennsylvania had no fish due to acid mine drainage. Limestone treatments and wetlands were built to mitigate the acid mine drainage and the river chub was one of the first species to return.<ref name=cravotta/>
==References== {{Reflist}}
{{Taxonbar|from=Q6417895}}
Category:Nocomis Category:Fish of North America Category:Taxa named by Edward Drinker Cope Category:Fish described in 1865 Category:Freshwater fish of North America