Campostoma ornatum
Encyclopedia
The Mexican stoneroller (Campostoma ornatum) is a small fish of the American Southwest
Southwestern United States
The Southwestern United States is a region defined in different ways by different sources. Broad definitions include nearly a quarter of the United States, including Arizona, California, Colorado, Nevada, New Mexico, Oklahoma, Texas and Utah...

 and northern Mexico
Mexican Plateau
The Central Mexican Plateau, also known as the Mexican Altiplano or Altiplanicie Mexicana, is a large arid-to-semiarid plateau that occupies much of northern and central Mexico...

. It belongs to family Cyprinidae. There are three other species in this genus, Campostoma anomalum (the central stoneroller), Campostoma oligolepis (the largescale stoneroller), and Campostoma pauciradii (the bluefin stoneroller), which are morphologically similar.

Description

The Mexican stoneroller has a very stout body with a very large head and snout. The mouth is unique in that its teeth have cartilaginous sheaths, while the size of its mouth is usually very small. The fish’s mature length can range anywhere from 3 to nearly 6 inches, however 6 inches is rare, and the average is about 3.5 inches. They have small scales that run along the lateral line, much like the Gila longfin dace
Agosia chrysogaster chrysogaster
- Description :The Gila Longfin Dace , is the only Agosia species found in Arizona. The only other form of fish closely related to Agosia is the Rio Yaqui, which also occurs in Arizona. The body of the fish is “Fusiform”, meaning it has very small scales that travel laterally along the body...

 and the Yaqui longfin dace
Agosia chrysogaster sp 1
The Yaqui longfin dace, official name Agosia chrysogaster sp. 1, is a small fish of the American Southwest and northern Mexico.- Description :...

. The scales of the Mexican stoneroller can sometimes form arches on its back. Sexual selection has dictated exaggerated male characteristics, which include larger heads and pre-dorsal areas in more successful males. These fish have color patterns with lighter bottoms and darker backs, with a distinct black stripe along the lateral line. They also have a somewhat blotched appearance.

Distribution

The Mexican stoneroller has been found as far as south as the Rio Yaqui
Yaqui River
The Yaqui River is a river in the state of Sonora in northwestern Mexico. Being the largest river system in the state of Sonora, the Yaqui river is used for irrigation....

 drainage in Mexico and in tributaries of the Rio Grande
Rio Grande
The Rio Grande is a river that flows from southwestern Colorado in the United States to the Gulf of Mexico. Along the way it forms part of the Mexico – United States border. Its length varies as its course changes...

 near the Big Bend region of Texas. The habitat of the Mexican stoneroller ranges in elevation between 2600 and 6500 feet.

Arizona

Campostoma ornatum is the only fish in this genus endemic to Arizona. It has a narrow distribution being found only in Rucker Canyon and San Bernardino Creek in the Chiricahua Mountains
Chiricahua Mountains
The Chiricahua Mountains are a mountain range in southeastern Arizona which are part of the Basin and Range province of the southwest, and part of the Coronado National Forest...

. The San Bernardino Wildlife Refuge is trying to preserve the endangered stoneroller by reintroducing it to Whitewater Creek near Black Draw.

Habitat

The Mexican stoneroller prefers shallow waters near gravel and stone substrates, and larger adults can be found in sandy-bottomed streams. They will use under-covered banks to protect themselves from predators and humans. The biotic community of the fish is primarily the Montane Conifer Forest in the Chiricahua Mountains. They are restricted to higher elevations because of their restricted diet of detritus and algae that thrive in colder waters. Aquatic insects are also part of the fish’s diet, if these primary sources are not available due to droughts.

Reproduction

Very few studies of the reproduction of this species have been conducted, leaving a limited amount of information about their patterns. This species is capable of changing the colors on their fins during breeding. The color changes are more dramatic in males, due to sexual selection and female mate choice. The winter and late spring months seem to be the primary times in which the bulk of spawning occurs. Mexican stonerollers use their tubercles as weapons during male-to-male competition, and also to stimulate and attract females. The name stoneroller was given to the genus because males excavate breeding areas by rolling stones with their heads to invite the female. This also helps males defend against their rivals.

Biology and Conservation

The cartilaginous sheaths on their jaws are used for scraping algae and detritus along the gravel and stones within the habitat. An unusual amount of sexual selection has occurred in this species for unknown reasons, and large amounts of energy are expended in male competition and mating success because of this selection. This extra energy is perhaps wasted, and it could be contributing to the decline in fitness and ultimately the disappearance of the species. Populations are declining rapidly in Rucker Canyon
Rucker Canyon
Rucker Canyon is a major canyon draining the western central-south of the Chiricahua Mountains, the central landform of the eastern third of Cochise County, Arizona's extreme southeast, bordering southwest New Mexico. It is famous for historic Camp Rucker....

 along with 'San Bernardino
San Bernardino National Wildlife Refuge
The San Bernardino National Wildlife Refuge is located on the U.S.-Mexican border in Cochise County, Arizona. Situated at 3,720 to elevation in the bottom of a wide valley, the refuge encompasses a portion of the headquarters of the Yaqui River, which drains primarily western Chihuahua and eastern...

 Creek', however numbers in Texas and Mexico remain stable. The Arizona Game and Fish Department gave the species endangered status in 1988, and the Mexican stoneroller still remains on the list. Aquifer pumping, reduction in stream flows, and predation from non-native green sunfish, are all major contributing factors to the decline of the species. The San Bernardino Ranch has current plans to reintroduce individuals in an attempt to recharge the population, and other projects involve federal habitat preservation.

External links

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