''Mylocheilus caurinus'', the peamouth, peamouth chub, redmouth sucker or northwestern dace, is a species of freshwater

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or h ...

from 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 ...

, the carps and minnows, that is found in western

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and th ...

. It is the only species in its genus. Mycau j0

Description

The peamouth is a slender fish, with a somewhat compressed body and a subterminal mouth, large eyes, a rounded snout and a forked tail. It has a dark back, contrasting with silvery underparts separated by two dusky, longitudinal stripes. The mouth is reddish at the corners where there are small barbels. When breeding the mature males develop a red stripe along the sides on the belly, mouth, gill cover and

pectoral 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 ...

base. The

dorsal fin A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through c ...

and the

anal 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 see ...

each have 8 soft rays and the

lateral line The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelial ...

has 66-84 scales. They can grow to in total length.

Distribution

The peamouth occurs in western North America from the Mackenzie River in the

North West Territories The Northwest Territories (abbreviated ''NT'' or ''NWT''; french: Territoires du Nord-Ouest, formerly ''North-Western Territory'' and ''North-West Territories'' and namely shortened as ''Northwest Territory'') is a federal territory of Canada. ...

, the

Nass River The Nass River is a river in northern British Columbia, Canada. It flows from the Coast Mountains southwest to Nass Bay, a sidewater of Portland Inlet, which connects to the North Pacific Ocean via the Dixon Entrance. Nass Bay joins Portland In ...

and the

Peace River The Peace River (french: links=no, rivière de la Paix) is a river in Canada that originates in the Rocky Mountains of northern British Columbia and flows to the northeast through northern Alberta. The Peace River joins the Athabasca River in ...

British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, for ...

and the

Columbia River The Columbia River ( Upper Chinook: ' or '; Sahaptin: ''Nch’i-Wàna'' or ''Nchi wana''; Sinixt dialect'' '') is the largest river in the Pacific Northwest region of North America. The river rises in the Rocky Mountains of British Columbia ...

drainage in

Washington state Washington (), officially the State of Washington, is a U.S. state, state in the Northwestern United States, Pacific Northwest region of the Western United States. Named for George Washington—the first President of the United States, U.S. p ...

Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...

Montana Montana () is a state in the Mountain West division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Canadian provinces of Alberta, British Columb ...

and

Idaho Idaho ( ) is a U.S. state, state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Monta ...

. It is relatively tolerant of salt water and this has allowed it to colonise rivers on

Vancouver Island Vancouver Island is an island in the northeastern Pacific Ocean and part of the Canadian province of British Columbia. The island is in length, in width at its widest point, and in total area, while are of land. The island is the largest by ...

and other islands off the coast of British Columbia. It has been introduced to the

Redwood National Park The Redwood National and State Parks (RNSP) are a complex of one national park and three state parks, cooperatively managed, located in the United States along the coast of northern California. Comprising Redwood National Park (established 1968 ...

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

Habitat

The peamouth can be found in the shallow, weedy zones of lakes and rivers, where it is most common among vegetation. It is usually found near the bed in depths of less than , although in winter they will move to the deeper parts of lakes.

Biology

Young peamouths feed predominantly on micro-crustaceans which are also preyed on by the adult fish but their diet is expanded to include snails, adult aquatic and terrestrial insects and even the occasional small fish. The peamouth reaches sexual maturity at 3–4 years old, the males normally reaching it faster than the females. Spawning takes place in May and June when the water reaches temperatures of , and happens in streams or along the shores of lakes where there are gravel or stony substrates in shallow water which is within of the bank. The eggs adhere to rocks or other substrates. The fish may spawn several times in a season, and the timing of spawning is not fully understood. The spawning runs of the peamouth make an impressive natural spectacle as the brightly colored fish move into areas of warm, shallow, flowing water in large numbers. These schools attract many fish-eating predators. The newly hatched fry form schools near the shore, moving into deeper water later in the summer. Each female is normally attended by at least two males and can lay between 5,000 and 30,000 eggs, the amount being dependent on the age and size of the individual fish. The fish may spend the day in deeper water and move to the shallows to feed at night. They are preyed on by a variety of piscivorous mammals and birds, as well as by larger fish species. They may attain a life span of 8 years

Human use

They have been used as a food fish by people the past and are still fished for by anglers. In Bellevue City near Seattle has an online alert system which informs people when the peamouth appear to spawn in the local streams so that interested people can observe the spectacle, being informed by email whenever the fish are observed.

Hybridisation

Hybrids between the peamouth and the

Northern pikeminnow The Northern pikeminnow, Columbia River dace or formerly Squawfish (''Ptychocheilus oregonensis'') is a large member of the minnow family, Leuciscidae. This predatory freshwater fish is native to northwestern North America, ranging from the Na ...

(''Ptychocheilus oregonensis'') and the redside shiner (''

Richardsonius balteatus The redside shiner (''Richardsonius balteatus'') is a species of cyprinid fish found in the western United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country pr ...

'') have been recorded in Montana.

References

{{Taxonbar, from=Q2706124 Leuciscinae Monotypic fish genera Fish of North America Fish of the United States Fish described in 1836