Desert Pupfish

Cyprinodon macularius

Description

The desert pupfish, Cyprinodon macularius, is a small, laterally compressed fish with a smoothly rounded body. The larger male rarely grows longer than 3 in (7.5 cm). During the reproductive season males turn bright blue on the head and sides and yellow on the caudal fin and tail. Females and juveniles usually have tan to olive backs and silvery sides. Adults have narrow, vertical, dark bars on the side, which are often interrupted to give the impression of a disjunct, lateral band.

Behavior

The desert pupfish matures rapidly and may produce up to three generations per year. Spawning occurs throughout the spring and summer months. Females lay eggs on submerged plants in shallow water. Males defend the eggs, which hatch within about three days. After a few hours, the young begin to feed on small plants and insects. Individuals survive for about a year.

Habitat

This species is adapted to a harsh desert environment and is capable of surviving extreme conditions, sometimes living in water with temperatures in excess of 110°F (43.3°C). It is capable of withstanding oxygen levels as low as 0.1 parts per million, and salinities nearly twice that of seawater.

Distribution

The desert pupfish was described in 1853 from specimens collected in the San Pedro River of Arizona. It was once common in the desert springs, marshes, and tributary streams of the lower Gila and Colorado River drainages in Arizona, California, and Mexico. It was also found in the slow-moving reaches of some large rivers, including the Colorado, Gila, San Pedro, and Santa Cruz.

The desert pupfish is composed of two sub-species in the United States: a Colorado River form and a Quitobaquito form. Natural populations of the Colorado River form have been extirpated from Arizona, and are restricted to three natural locations in California and the non-natural irrigation drains around the Salton Sea in California—San Felipe Creek and San Sebastian Marsh (Imperial County), and Salt Creek (Riverside County). It is also found in shoreline pools and irrigation drains in the region. Surveys of Salt Creek and related irrigation ditches indicate that the populations there may no longer be viable.

In Arizona, the Quitobaquito form persists in a single, modified spring at the Organ Pipe Cactus National Monument (in Pima County). The pupfish is also thought to survive in low numbers in the Rio Sonoyta of Sonora, Mexico, but little is known of this Mexican population.

Threats

The construction of dams on the Gila, Colorado, and Salt Rivers for irrigation and flood control de-watered the lower Gila and Salt Rivers and eliminated many of the marshy pools in which the Colorado River desert pupfish bred. The desert pupfish was then forced into mainstream channels where it was preyed upon by larger fishes. Although it is extremely hardy in many respects, the desert pupfish cannot tolerate competition and is readily displaced by introduced fishes, such as tilapia, shortfin mollies, mosquitofish, and largemouth bass.

Many historic pupfish localities have been dried by groundwater pumping (affecting both spring and stream discharges), channel erosion, and arroyo formation (resulting in marshland drainage, the creation of sheer banks and lateral habitat loss). An additional threat comes from poor grazing practices by domesticated livestock, which may reduce terrestrial vegetative cover, enhancing watershed erosion, exacerbating problems of arroyo cutting, and increasing sediment loads and turbidity in receiving waters. Habitats may be further impacted by trampling where cattle feed or drink, in or adjacent to water.

Conservation and Recovery

Breeding populations of desert pupfish have been established in Arizona at Bog Hole and Research Ranch, Arizona-Sonora Desert Museum, Boyce Thompson Arboretum, and Arizona State University. In California, captive populations were established at Salton Sea State Park, the Living Desert Reserve, and Anza-Borrego State Park. Most of these small populations are maintained in artificial refugia.

Desert pupfish are also held at Dexter National Fish Hatchery in Dexter, New Mexico. These fish, obtained from Santa Clara Slough, were used to stock reintroduction efforts in Arizona. Populations were also introduced into three springs on Bureau of Land Management land in Arizona at Peoples Canyon in the Bill Williams River (Yavapai County), Howard Well in the Gila River (Graham County), and Mesquite Spring (Pinal County).

The 1993 U. S. Fish and Wildlife Service (FWS) recovery plan for the desert pupfish calls for the eventual downlisting of the Colorado River form (its delisting, however, is not considered feasible in the foreseeable future), and the protection of the two other subspecies (downlisting of the Quitobaquito form appears to be unattainable). To achieve the goals of downlisting and protection by 2009, the plan calls for a variety of actions, including the protection of natural populations and their habitats, the re-establishment of populations, and the establishment of a refugium population of the Quitobaquito form. The plan also calls for the development of a protocol for exchange of genetic material, the monitoring of natural and replicated populations, and the determination of factors affecting population persistence. As with all recovery efforts, the FWS also calls for a public information and education program to spread the word about the importance of protecting the species.

Contacts

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Complex
911 N. E. 11th Ave.
Portland, Oregon 97232-4181
Telephone: (503) 231-6121
http://pacific.fws.gov/

Regional Office of Endangered Species
U. S. Fish and Wildlife Service
P. O. Box 1306
Albuquerque, New Mexico 87103
http://southwest.fws.gov/

References

Black, G. F. 1980. "Status of the Desert Pupfish,Cyprinodon macularius, in California." Special Publication 80-1. State of California, Department of Fish and Game, Sacramento.

Kynard, B. E. 1981. "Study of Quitobaquito Pupfish:Systematics and Preservation." Final Report. National Park Service.

McMahon, T. E., and R. R. Miller. 1985. "Status of the Fishes of the Rio Sonoyta Basin, Arizona and Sonora, Mexico." Proceedings of the Desert Fishes Council, Vol. 14. Bishop, California.

U. S. Fish and Wildlife Service. 1993. "Desert Pup-fish Recovery Plan." U. S. Fish and Wildlife Service, Albuquerque.