10842 Federal Fhgister / Vol. 51, No. 61 / Monday, March 31, 1988 / Rules and Regulations DEPARTMENT OF THE JNTERJOR Fish and Wildlife Ssrviw 50 CFR Part 17 Endangered and Threatensd Wildllfe and plant% Detsm&mtion of Endangered Status end Crltkal Habitat for the Desefi Pupfish AGENCY: Fish and Wildlife Service, Interior. ACTNN Final ruie. SUMMARY The Service,determines the desert pupfish [Cyprinodon macuiarius] to be an endangered species. Critical habitat is also designated for this species in Imperial County, California, and Pima County, Arizona. Viable, self- Federal Register / Vol. 51, No. 61 / Monday, March 31, 1986 / Rules and Regulations 10843 /- sustaining populations of desert pupfish wetland San Sebastian Marsh, Imperial New Mexico. These fish were obtained are now believed to exist in only two of County, and Salt, Creek. Riverside from Santa Clara Slgugh. They are being the historic habitats in the United County) and a few shoreline pools and maintained in that facility for use in States. The remaining populations in irrigation drains along the Salton Sea in research and for future reintroduction Mexico are also reported to be declining Imperial and Riverside Counties. In efforts in Arizona. or vulnerable. The surviving natural Arizona, it still inhabits Quitobaquito Desert pupfish-were recently populations are impacted by Spring within the Organ Pipe Cactus introduced into one natural and two competition from exotic fishes for food National Monument in Pima County. manmade spring habitats on Bureau of and space, predation by exotic fishes, The species is also believed to inhabit Land Management (BLM) land in water pollution, ground-water pumping, the Colorado River system in the Rio Arizona. These populations, which were agricultural pesticide drift, stream Sonoyta drainage and Santa Clara established from the stock at Dexter channelization, and possibly the habitat Slough in Sonora. Mexico. Recent National Fish Hatchery, are located at modifications associated with flooding surveys of Salt Creek and the irrigation Peoples Canyon in the Bill Williams in the Colorado River delta in 1963 and drains around the Salton Sea (Moore, River drainage [Yavapai County), 1984. Designation of the desert pupfish 1983) and the Rio Sonoyta (McMahon Howard Well in the Gila River drainage as an endangered species affords this and Miller, 19851 indicate that the (Graham County), and Mesquite Spring species the full protection provided by populations there may now be reduced in the Gila River drainage (Pinal the Endangered Species Act of 1973, as to such low levels that they are no County). However, it will be some time amended. longer viable. The current status of the beforeit is known whether these DATE: The effective date of this rule is population in Santa Clara Slough is introductions have resulted in the April 30* 1986. unknown. However, the floods that establishment of self-sustaining ADDRESS: The complete file for this rule inundated vast reaches of the Colorado populations that can survive the local is available for inspection, by River delta in 1983 and 1984 may have climatic regime. appointment, during normal business given tilapia (TJopja zj11il], largemouth Land ownership of the remnant hours at the U.S. Fish and Wildlife bass (Micropterus sulmoides), and other natural habitats in the United States is Service, Lloyd 500 Building, Suite 1692, exotic fishes that compete with, or prey divided between private and Federal 500 NE., Multnomah Street, Portland, upon* the desert pupfish, access to this interests. Quitobaquito Spring is entirely Oregon 97232. slough. These recent high flows also on National Park Service Lands within may have enhanced habitat conditions FOR FURTHER INFORMATION CONTACT: the boundaries of Organ Pipe Cactus Mr. Wayne S. White, Chief, Division of for exotic fishes by improving water National Mounment. Title to the lands Endangered Species, at the above quality in the delta. along San Felipe Creek is arranged in a Refugia populations of desert pupfish checkerboard pattern, about evenly address, [503/231&131 or FTS 429-6131). have been established in Arizona at Bog SUPPLEMENTARY INFORMAltON: divided between Federal and private Hole [Santa Cruz County), Research holdings. Background Ranch (Santa Cruz County), Arizona- Desert pupfish are adapted to harsh Sonora Desert Museum (Pima County), desert environments and are capable of The desert pupfish [Cyprjno&n Boyce Thompson Arboretum (Pinal mucuhhs) is a small, laterally- surviving extreme environmental County), and Arizona State University conditions. They have been reported to compressed fish with a smoothly (Maricopa County). The Bog Hole and rounded body shape. Adult fish rarely survive water temperatures in excess of Research Ranch populations are 43.3 Centigrade [llO Fahrenheit) (Moyle, grow larger than 75 millimeters (3 . believed to be derived from inches) in total length. Males are larger 1976). oxygen levels as low as 0.1 to 0.4 Quitobaquito Spring. The fish at parts per million [Lowe et al., X%7), and than females and during the Arizona-Sonora Desert Museum and reproductive season become brightlv salinities nearly twice that of seawater Boyce Thompson Arboretum were (Barlow, 1958). They are also capable of colored with blue on the dorsal portjon obtained from Dexter National Fish of the head and sides and yellow on the surviving extreme fluctuations in Hatchery, which obtained its fish from temperature (Lowe and Heath, 1969) and caudal fin and the posterior part of the the Santa Clara Slough population. Two caudal peduncle. Females and juveniles populations have been established in daily salinity changes of as much as 10 tvpically have tan to olive backs and to 15 parts per thousand (Kinne, 1960). refugia at Arizona State University, one Although desert pupfish are extremely &very sides. Most adults have narrow. derived from Quitobaquito Spring and vertical, dark bars on their sides, which the other from Santa Clara Slough. hardy in many respects, they cannot are often interrupted to give the In California. refugia populations exist tolerate competition or predation and impression of a disjunct, lateral band. at Salton Sea State Park (Riverside are thus readily displaced by exotic The desert pupfish was described in County), the Living Desert Reserve fishes. 1853 by Baird and Girard fr9.m (Riverside County), and three separate Desert pupfish mature rapidly and specimens collected in the San Pedro . locations in Anna-Borrego State Park may produce up to three generations per River of Arizona. (San Diego County). The populafions in year. Spawning males typically defend a The desert pupfish was once common Salton Sea State Park and the Living small spawning and feeding territory in in the desert springs, marshes, and Desert Reserve are derived from Salton shallow water. The eggs are usually laid tributary,streams of the lower Gila and Sea Stock. Two of the refugia and fertilized on a flocculent substrate Colorado River drainages in Arizona, populations at Anza-Borrego State Park and hatch within a few days. After a California, and Mexico. It also formerly {Palm Spring and the Visitor Center) are few hours, the young begin to feed on occurred in the slow-moving reaches of derived from the Salton Sea: the third small plants and animals. Spawning some large rivers, including the [Palm Canyon) is derived from San occurs throughout the spring and Colorado, Gila, San Pedro, and Santa Felipe Creek. Most of these refugia summer months. Individuals typically Crux. The species is currently known populations are maintained in highly survive for about a year. These characteristics, along with the from only two historic locations in the artificial. environments,. and--. contain . United States. In California, it still exists relatively small numbers of tish. adaptability of the desert pupfish to in two Salton Sea tributaries [San Fehpe Desert pupfish are also being held at laboratory aquaria, make it a valuable Creek system and its associated Dexter National Fish Hatchery, Dexter, research animal for ichthyologists and 10644 Federal Re&ster / Vol. 53, No. 61 / Monday, March 31, 1966 / Rules and Regulations other biologists. A great deal has been recommendations for protecting critical introduced andxefugia populations learned from this species about fish habitat without expressing support or desert pupfish is discussed in the ecology. genetics, behavior, and opposition. background section. Continued physiology. In addition, the rapidity with Comments were received from the monitoring of the desert pupfieh and which the desert pupfish and other Arizona Game and Fish Department habitat, including Santa Clara Slough, members of the genus Cypr~z~o&~ (AGFD), Bureau of Land Management will be part of the recovery effort. differentiated into distinct species may (BLM) and Arizona-New Mexico BLM noted that the proposal failed give scientists valuable insights into the Chapter of the American Fisheries recognize that BLM has designated process of speciation. Society (AFS) expressing support for area around San Sebastian Marsh The precarious status of the desert listing the desert puPfish as endangered Imperial County, California, as an pupfish is recognized by the State of but recommending that introduced of Critical Environmental Concern California, which has classified the populations in all or parts of Arizona be (ACEC), and that BLM and other desert pupfish as an “endangerea’ excluded. The Service replies that the agencies are involved in cooperative species,