Arroyo chub
Encyclopedia
The arroyo chub Gila orcuttii is a cyprinid
fish
found only in the coastal streams of southern California
, United States
.
The shape of the arroyo chub is somewhat chunky, with a deep body and thick caudal peduncle. The eyes are larger than average for cyprinids. Coloration ranges from silver to gray to olive green above, shading to white below, usually with a dull gray band along each side. The dorsal fin has 8 rays, while the rounded anal fin has 7. Males have larger fins than females, and, during the breeding season, patches of breeding tubercles on the upper surfaces of the pectoral fins. This is a small fish, with most adults in the 7-10 cm length range, and a maximum of 12 cm.
Omnivorous
, their diet includes algae
, insects, and crustaceans. Studies of fish from warmwater streams shows a preponderance of algae in the stomach (60-80%), and they are also known to feed on the roots of Azolla (floating water ferns). In cooler streams, molluscs and caddisfly larvae predominate in the diet.
Arroyo chub habitat is primarily the warm streams of the Los Angeles Plain, which are typically muddy torrents during the winter, and clear quiet brooks in the summer, possibly drying up in places. They are found both in slow-moving and fast-moving sections, but generally deeper than 40 cm.
They are native to Los Angeles
, Santa Margarita
, San Gabriel
, San Luis Rey
, and Santa Ana River
s, as well as to Rainbow, Temecula, Malibu
and San Juan Creek
s. Many of the original populations have been extirpated, but it has recently been reestablished in the Arroyo Seco (Los Angeles County)
, a tributary of the Los Angeles River. The species also has been successfully introduced in a number of other rivers in the area, and can be found as far north as Chorro Creek in San Luis Obispo County, and as far east as the Mojave River
. The Mojave and Cuyama River
populations extend into the ranges of related fishes, and hybridize with Mojave chub and California roach
, respectively.
The species epithet was chosen in honor of C. R. Orcutt, who in 1889 made the first collection of this fish, improvising by using a blanket as a seine
. It is often misspelled as orcutti, although this is still considered a valid synonym, and is for instance used by Moyle in his book.
Cyprinid
The family Cyprinidae, from the Ancient Greek kyprînos , consists of the carps, the true minnows, and their relatives . Commonly called the carp family or the minnow family, its members are also known as cyprinids...
fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
found only in the coastal streams of southern California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
.
The shape of the arroyo chub is somewhat chunky, with a deep body and thick caudal peduncle. The eyes are larger than average for cyprinids. Coloration ranges from silver to gray to olive green above, shading to white below, usually with a dull gray band along each side. The dorsal fin has 8 rays, while the rounded anal fin has 7. Males have larger fins than females, and, during the breeding season, patches of breeding tubercles on the upper surfaces of the pectoral fins. This is a small fish, with most adults in the 7-10 cm length range, and a maximum of 12 cm.
Omnivorous
Omnivore
Omnivores are species that eat both plants and animals as their primary food source...
, their diet includes algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...
, insects, and crustaceans. Studies of fish from warmwater streams shows a preponderance of algae in the stomach (60-80%), and they are also known to feed on the roots of Azolla (floating water ferns). In cooler streams, molluscs and caddisfly larvae predominate in the diet.
Arroyo chub habitat is primarily the warm streams of the Los Angeles Plain, which are typically muddy torrents during the winter, and clear quiet brooks in the summer, possibly drying up in places. They are found both in slow-moving and fast-moving sections, but generally deeper than 40 cm.
They are native to Los Angeles
Los Angeles River
The Los Angeles River is a river that starts in the San Fernando Valley, in the Simi Hills and Santa Susana Mountains, and flows through Los Angeles County, California, from Canoga Park in the western end of the San Fernando Valley, nearly southeast to its mouth in Long Beach...
, Santa Margarita
Santa Margarita River
The Santa Margarita River is a short intermittent river on the Pacific coast of southern California in the United States, approximately long. One of the last free-flowing rivers in southern California, it drains an arid region of the Coast Ranges between Los Angeles and San Diego at the southern...
, San Gabriel
San Gabriel River (California)
The San Gabriel River flows through southern Los Angeles County, California in the United States. Its main stem is about long, while its farthest tributaries extend almost altogether...
, San Luis Rey
San Luis Rey River
The San Luis Rey River is a river in northern San Diego County, California. The river's headwaters are in the Cleveland National Forest near Palomar Mountain. The river drains into the Pacific Ocean on the northern end of the city of Oceanside. The river is over long and drains...
, and Santa Ana River
Santa Ana River
The Santa Ana River is the largest river of Southern California in the United States. Its drainage basin spans four counties. It rises in the San Bernardino Mountains and flows past the cities of San Bernardino and Riverside, before cutting through the northern tip of the Santa Ana Mountains and...
s, as well as to Rainbow, Temecula, Malibu
Malibu Creek
Malibu Creek is a year-round stream in western Los Angeles County, California. It drains the southern Simi Hills and the westernmost San Fernando Valley, flows south through the Santa Monica Mountains, and enters Santa Monica Bay east of Malibu. The Malibu Creek watershed drains and its tributary...
and San Juan Creek
San Juan Creek
San Juan Creek, also called the San Juan River, is a stream in Orange County, California that consists of a catchment basin encompassing . Its mainstem rises in the Santa Ana Mountains, in the Trabuco Ranger District of the Cleveland National Forest...
s. Many of the original populations have been extirpated, but it has recently been reestablished in the Arroyo Seco (Los Angeles County)
Arroyo Seco (Los Angeles County)
The Arroyo Seco, meaning "dry stream" in Spanish, is a seasonal river, canyon, watershed, and cultural area in Los Angeles County, California, United States. The Arroyo Seco has been called the most celebrated canyon in Southern California.-River course:...
, a tributary of the Los Angeles River. The species also has been successfully introduced in a number of other rivers in the area, and can be found as far north as Chorro Creek in San Luis Obispo County, and as far east as the Mojave River
Mojave River
The Mojave River is an intermittent river in the eastern San Bernardino Mountains and Mojave Desert in San Bernardino County, California. The river is notable as most of its flow is underground, while its surface channels remain dry most of the time, with the exception of the headwaters and several...
. The Mojave and Cuyama River
Cuyama River
The Cuyama River is a river in southern San Luis Obispo County, northern Santa Barbara County, and northern Ventura County, in the U.S. state of California. It joins the Sisquoc River forming the Santa Maria River...
populations extend into the ranges of related fishes, and hybridize with Mojave chub and California roach
California roach
The California roach, Hesperoleucus symmetricus, is a cyprinid fish native to western North America and abundant in the intermittent streams throughout central California. It is the sole member of its genus....
, respectively.
The species epithet was chosen in honor of C. R. Orcutt, who in 1889 made the first collection of this fish, improvising by using a blanket as a seine
Seine
The Seine is a -long river and an important commercial waterway within the Paris Basin in the north of France. It rises at Saint-Seine near Dijon in northeastern France in the Langres plateau, flowing through Paris and into the English Channel at Le Havre . It is navigable by ocean-going vessels...
. It is often misspelled as orcutti, although this is still considered a valid synonym, and is for instance used by Moyle in his book.