TECHNICAL REVIEW DRAFT

PAHRANAGAT ROUNDTAIL CHUB RECOVERY PLAN U.S. Fish and Wildlife Service 500 NE Multnomah Street Portland, Oregon 97232

September, 1982 DISCLAIMER FOR TECHNICAL REVIEW DRAFT

This is a technical review draft of the Pahranagat Roundtail chub recovery plan. It is not an official government document. It has not been approved by the U.S. Fish and Wildlife Service or any other agency. It does not necessarily represent official positions of the U.S. Fish and Wildlife Service or any other agencies (and it does not necessarily represent the views of all indi- viduals involved in the plan formulation). It has been prepared by the U.S. Fish and Wildlife Service to delineate reasonable actions believed required to place the Pahranagat roundtail chub species in the best possible position. This proposal is subject to modification following review and receipt of comments by cooperating agencies and other informed and interested parties. Goals a-nd objectives will be attained and funds expended contingent upon appro- priations priorities and other budgetary constraints. TABLE OF CONTENTS

Page

I. introduction A. Historic Range B. Present Range C. Reasons for Decline D. Life History E. Habitat Requirements F. Conservation Efforts

II. Recovery A. Objective B. Step-down Outline C. Narrative D. References

III. Implementation Schedule

IV. Appendix Part 1 Introduction

The Pahranagat roundtail chub, Gila robusta jordani, was listed as endangered by the U.S. Fish and Wildlife Service on October 13, 1970 (CFR 35:16047). The Board of Wildlife Commissioners also lists this species as endangered (NRS 503:065). This member of the minnow family is endemic to waters of the , Lincoln County, Nevada; its closest relatives are associated with the drainage (Miller 1946, Hubbs and Miller 1948, La Rivers 1962). The entrance of its progenitor into the Pahranagat Valley is believed to have occurred during the Pleistocene Epoch when the pluvial White River was tributary to the Colorado River (Hubbs and Miller 1948, Smith 1978).

The exact distribution and population size of this roundtail chub prior to its decline is uncertain; however, it has been collected in Crystal, Hiko, and the Pahranagat River downstream from Ash Springs. It was first collected in 1948 (La Rivers 1962) then described in 1950 from three individuals collected in Hiko Spring and three individuals collected in Crystal Springs (Tanner 1950). The few roundtail chubs caught during intensive sampling for this description suggests the fish was rare during 1950. This paucity prompted Tanner (1950) to voice concern for the continued existence of the species. The species has become even less common today; it has been eliminated in Crystal and Hiko Springs and is now restricted to the Pahranagat River on the Burns Ranch where less than 40 adults are believed to constitute the single remaining population (Hardy 1981).

The decline of the Pahranagat roundtail chub is attributed to alteration of its habitat for agricultural irrigation and cattle grazing and to the introduction of a variety of competing and predatory aquatic organisms such as the convict cichlid (Cichlasoma nigrofasciatum), carp Cyprinis carpio), mosquitofish (Gambusia affinis), shortfin molly a mexicana), the bullfrog (Rana catesbeiana), and the oriental snail anoides sp.).

The Pahranagat roundtail chub is taxonomically aligned with the round- tail chub (Gila robusta) complex associated with the Colorado River drain- age (Miller 1946, Minckley 1973). Tanner (1950) granted the chub specific recognition; later authors have, however, recognzied its similarity with other roundtail chubs and concluded it is a subspecifically distinct form (La Rivers 1962; Hubbs et al. 1974). G. r. jordani is most similar to G. r. robusta of the larger tributaries and mainstem Colorado River; differing from it by typically having more scales in, above, and below the lateral line, being less elongate, and having a greenish color with black blotches (Tanner 1950, La Rivers 1962).

The Pahranagat roundtail chub is one of six fishes native to the 'Pahranagat Valley. The other native fishes are: the White River spring- fish (Crenichthys baileyi baileyi), Hiko White River springfish (Crenichthys baileyi grandis), Pahranagat spinedace (Lepidomeda altivellis), White River speckled dace (Rhinichthys osculus velifer), and the White River desert sucker (Catostomus intermedius). Of these species, the two springfish, the spine- dace, and the roundtail chub are recognized as being endemic to the Pahranagat Valley; the speckled dace and the desert sucker, while being local forms, are found in other portions of the pluvial White River system. All of these species have undergone dramatic declines during recent times. The most catastrophic declines affected the extinction of Pahranagat spinedace in the 1950's (La Rivers 1962, Minckley and Deacgn 1968) and the desert sucker in the 1960's (J. E. Deacon field notes 1967). The springfishes were the most abundant of fishes inhabiting the source pools of Hiko, Crystal, and Ash Springs when initial fishery surveys were conducted in the Pahranagat Valley during 1891 (Gilbert 1893). These two fishes have been displaced in portions of their historic habitat and now exist in extremely low numbers amidst large populations of competing and predatory species. Whereas the Hiko White River springfish once occupied Hiko, and Crystal Springs, it is now restricted to a small popualtion in Crystal Spring. A depressed population of the White River springfish persists in its single locality, Ash Springs. Both of these fish are presently being considered for listing as endangered by the USFWS. The local form of speckled dace is currently the only native fish that is found with any regularity in the Pahranagat Valley.

Springs in the Pahranagat Valley also provide habitat for a rare mollusk, the White River tryonia snail (Tryonia clathrata). This species is found only in portions of the pluvial White River system and was proposed for list- ing as threatened (CFR 41, 6-28-76) but dropped because of 1978 amendments to the Endangered Species Act.

The close ecological relationship of the aquatic species native to the Pahranagat Valley mandates that all management practices undertaken for a particular organism shall proceed only with consideration for the conserva- tion of all members of the aquatic system. Although this recovery plan outlines those actions necessary to recover the Pahranagat roundtail chub, it is mandatory that such actions consider all native members of the springs in the Pahranagat Valley.

Because the Pahranagat roundtail chub is in extreme danger of extinction, it must be given high priority in recovery programs to insure its continued existence and restore it to non-endangered status.

Historic Range

The Pahranagat roundtail chub is endemic to the thermal waters in the Pahranagat Valley. Precise distribution within these waters is uncertain because the species was not collected before aquatic habitats in the area had been dramatically altered, beginning in the later portion of the 1800's, and exotic fishes introduced. However, collections made in the late 1940's, and its present distribution show that the species existed in portions of Crystal, Hiko, Ash Springs, and the Pahranagat River. The springs provide the primary source of surface water in the Pahranagat Valley. Early (Gilbert 1893) and recent (Hardy 1981: Kamin 1981 field notes), investiga- tions and consideration of those habitats preferred by its closest relatives, indicate it preferentially inhabitated the spring outflow channels rather than the spring source areas. The amount of historically occupied habitat is estimated to have included three springs, a total of approximately 30 miles of stream, and a small lake at the south end of the valley.

Present Range

The Pahranagat roundtail chub is now limited to the Pahranagat River on the Burns Ranch. It hasn't been seen in either Crystal or Hiko Springs since the early 1950's (Deacon, field notes; La Rivers, 1962). Distribution within the Pahranagat River is restricted from that found historically, because much of the outflow channel has been lined with concrete. Approximately 2,300 meters of unlined channel of the Pahranagat River are presently occupied by a total of 37 to 45 adult chubs (Hardy 1981). This habitat is on the Burns Ranch.

Distribution within the Pahranagat River is local and changes seasonally. From late April through January the adult population does not move from a single pool that is approximately 10 meters in length.

Reasons for Decline

Reasons for the decline of the Pahranagat roundtail chub are poorly understood; however, there is strong indication that influences that have been quantified as causing the decline of other native fishes in the southwest are similar to those associated with affecting G. r. jordani. The two factors believed to have had the greatest detrimental influence on this roundtail chub are the dramatic physical alteration of habitat resulting from modification to facilitate irrigation, and the introduction of competing and predatory species.

These two factors have eliminated or seriously degraded the status of numerous native fishes in the southwest (Deacon et al. 1979; Hubbs, et al. 1974; Deacon and Minckley 1968). Habitat alteration typically involves construction activities that dry habitats and/or change them so they are no longer inhabit- able by native species. This has recently happened with the White River spine- dace (Lepidomeda albivallis) in Preston Big Spring. Deacon (1980 field notes) notes that the disappearance of spinednce from Preston Big Spring closely fol- lowed the installation of a delivery pipe to facilitate irrigation. The Tecopa pupfish (Cyprinodon nevadensis calidae) and Shoshone pupfish (Cyprinodon nevadensis shoshone) became extinct following dramatic alteration of their habitats for municipal and recreational purposes, respectively (Soltz and Naiman 1978). Aquatic habitats in the Pahranagat Valley have been dramatically altered by diversion and concrete lining of spring outflow channels. The 2,300 meters of habitat on the Burns Ranch that is occupied by G. r. jordani is one of the few areas where habitat has not been concrete.

Introduction of non-native fishes has caused the demise of numerous populations of native fishes in the southwestern United States (Miller 1961, Deacon et al. 1964; Minckley and Deacon 1968, Hubbs, et al. 1974, Moyle 1978, Deacon et al. 1979, Schoenherr 1981). Reasons for these declines vary with the species and habitats being considered; however, they typically involve competition, predation, and/or hybridization (Schoenherr 1981). Hardy (1981) identifies the presence of convict cichlids, carp, mosquito fish, and shortfin mollies in the Pahranagat Valley waters. Largemouth bass (Micropterus salmoides) are also known to inhabit these springs (Allan pers. comm.). These species, and/or their close relatives are known to have detri- mentally influenced populations of other native fishes (Deacon et al. 1964). The mosquitofish has eliminated or dramatically reduced populations of Pahrump killifish (Empetrichtys latos) (USFS 1980), Gila topminnow (Poeciliopsis occidentalis) (Minckey 197-3), ind the Owens pupfish (Cyprinodon radiosus) (Pister 1974), among others (Schoenherr 1981).

A dramatic decline in the desert pupfish (Cyprinodon macularius) in the Salton Sea, California is associated with introduction of the sailfin molly (Poecilia latipinna) in 1965 (Black 1980). Hubbs et al. (1974) note the influence of carp on several populations of native fish in the north-central . Predation by the largemouth bass has dramatically reduced or eliminated populations of the relict dace (Relictus solitarius), Clover Valley speckled dace (Rhinichthys osculus oligoporus), Independence Valley tui chub ila bicolor lethoporus) (Hubbs et al. 1974), and White River springfish renichthys bailer') (Williams and Wilde 1981). Allan (pers. comm.) reports rCIntroduction of largemouth bass into Nesbitt Lake on the Key-Pitman Wildlife Management Area and Crystal Springs. The Pahranagat roundtail chub remained in Crystal Springs until the bass were introduced. Bullfrogs are also introduced, and known to predate on native fishes (Sada field notes 1981).

Life History

Little is known about the life history of G. r. jordani because it is restricted to a single, small population inhabiting a limited area. These factors make it difficult to sacrifice individuals, to collect information that can be acquired in no other manner, without seriously affecting the livelihood of the species. Recent observations have, however, provided basic information about characteristics of their occupied habitat, seasonal migrations, population fluctuations, and feeding.

During the late spring, summer, and early winter, what is believed to constitute the entire adult population of chubs is consistently found in a single pool in the Pahranagat River on the Burns Ranch. During 1980 and 1981 the adult population in this single locality totaled between 37 and 45 individuals. Spawning has not been observed but is assumed to occur during the spring when adult chubs migrate from this pool. The timing of spawning is substantiated by initial observations of young-of-the year chubs during May (Hardy 1981). The particulars of spawning migrations are unknown; however, small concentrations of adults have been observed several thousand meters upstream from the Burns Ranch pool (Kanim field notes, 1981). It is doubtful that movement is downstream during spawning migrations because spawning habitat is not believed to exist in the lengthy concrete channel capturing the river immediately downstream from the Burns River. Nothing is known of the species' spawning habitat requirements, fecunidty, or egg incubation period.

The estimate of 200 juvenile chubs observed in the Pahranagat River during the summer of 1980 indicates that spawning is successful. A dramatic decline of juveniles during the autumn, and the stability in the small size of the adult chub population, indicates, however, that recruitment is extremely limited. Hardy (1981) speculates that recruitment is low because of difficulty encountered during the change in feeding strategy that occurs as juveniles approach maturity. This speculation is based on an observed decrease in the availability of aquatic vegetation when the diet of juvenile chubs presumably changes from one consisting of insects to one consisting of vegetation.

Visual observation of feeding, conducted when fish were localized in the holding pool on the Burns Ranch, indicate that adult G. r. jordani are primarily herbiverous. Observations of juveniles in a variety of habitats in the outflow of Ash Springs indicate they are primarily insectiverous (Hardy 1981). This difference in food items between juveniles and adults is known in other members of the Gila robusta complex (Vanicek and Kramer 1969).

Nothing is known about G. r. jordani growth rates, age and size at maturity, or longevity. Adult chubs reach .a length of approximately 25 cm.

Habitat Requirements

Habitat requirements of the Pahranagat roundtail chub are poorly understood because the existing population of fish is so small and restricted in its habitat that statistical analysis is difficult, the aquatic habitat in the Pahranagat Valley is extremely altered from pristine conditions, and historic accounts discussing the species are not thorough.

Recently compiled information concerning the population remaining in the Pahranagat River indicate that adult chub activity is localized in protectsd 0 pools in spring outflows where water temperatures range between 27 and 30 C. Current velocities within the pool most frequently occupied reached a maximum of 0.18 meters/second and average 0.03 meters/second. Dissolved oxygen con- centrations range between 5.9 milligrams/1 and 6.4 milligrams/1, and the concentration of hydrogen ions (pH) continually measured 8.1. Water hardness fluctuated between 184 milligrams/1 and 234 milligrams/liter, and alkalinity ranged from 160 milligrams/1 to 170 milligrams/1.

Vegetation in the occupied habitat is not unlike that found in other southern Nevada springs. Hardy (1981) notes that Spirogyra sp. is the dominant algae during the spring and summer. Chara zeylanica, Compsopogon coeruleus, Najas marina, and a variety of diatoms constitute the remainder of vegetation.

Habitats occupied by juvenile chubs are seemingly not as specific as those of adults. Juveniles are most commonly found in runs where the average current is 0.23 meters/second and depth is 0.54 meters. They do occupy areas where current velocities reach 0.35 meters/second and depths range from 0.73 meters to 2.3 meters. Substrate types depend on the current velocity of a particular locality and include mud to firm sand.

Conservation Efforts

Tanner (1950) first recognized the status of Gila robusta jordani 32 years ago and noted the species would soon become extinct. In 1970 (CFR 35:16047) the species was formally recognized as endangered and added to the Federal List of Endangered Species. The species is also listed as endangered by the State of Nevada Board of Wildlife Commissioners. Conservation efforts for the Pahranagat roundtail chub have been minimal. Twenty adult chubs were transplanted on September 26, 1971 into the Bureau of Land Management endangered fish facility at Shoshone Ponds near Ely, Nevada (Hubbs et al. 1974). These fish survived for several years but did not reproduce. The population no longer exists. The Fish and Wildlife Service has discussed recovery of Gila robusta jordani with the Lincoln County Com- missioners during meetings in 1980, 1981, and 1982.

These discussions are a portion of efforts being conducted to actively accomplish recovery through private actions. A Protection Strategy Study for the Pahranagat roundtail chub has been prepared as a means to inform the Lincoln County Commissioners of those actions required for recovery of the species. The Pahranagat roundtail chub recovery plan is prepared to formally outline actions that are necessary to recover this species and remove it from the list of endangered species. References

Allan, R. Regional Fisheries Supervisor, Nevada Department of Wildlife, Las Vegas, Nevada.

Black, G. 1980. Status of the desert pupfish, Cyprinodon macularius (Baird and Girard), in California. California Department of Fish and Game Special Publication Number 80-1. 42p.

Deacon, J. Department of Biology, University of Nevada, Las Vegas.

Deacon, J., C. Hubbs, and B. Zahuranec. 1964. Some effects of introduced fishes on the native fish fauna of southern Nevada. Copeia, 1964, Number 2:384-388.

Deacon, J., G. Kobetich, J. Williams, and S. Contreras. 1979. Fishes of North America endangered, threatened, or of special concern: 1979. Fisheries, Volume 4, Number 2:29-44.

Gilbert, C. 1893. Report on fishes of the Death Valley Expedition collected in southern California and Nevada in 1891, with descriptions of new species. North American Fauna, Number 7:229-234.

Hardy, T. 1981. Ecological status of the aquatic community within the outflow of Ash Springs, Nye County, Nevada with special reference to the Pahranagat roundtail chub (Gila robusta jordani). Unpublished Report. 72p.

Hubbs, C. and R. Miller. 1948. The zoological evidence/correlation between fish distribution and hydrographic history in the desert basins of western United States. In The Great Basin, with emphasis on Glacial and Postglacial times. Bulletin of the University of Utah, Volume 38, Number 20:17-166.

Hubbs, C., R. Miller, and L. Hubbs. 1974. Rydrographic history and relict fishes of the north-central Great Basin. Memoirs of the California Academy of Sciences, Volume VII. 259p.

Kanim, N. Department of Biology, University of Nevada, Las Vegas.

La Rivers, I. 1962. Fishes and fisheries of Nevada. Nevada State Fish and Game Commission, Carson City, Nevada. 782p.

Miller, R. 1946. Gila cypha, a remarkable new species of cyprinid fish from the Colorado River in Grand Canyon, Arizona. Washington Academy Science Journal, Volume 36, Number 6:206-212.

Miller, R. 1961. Man and the changing fish fauna of the American Southwest. Papers of the Michigan Academy of Science, Arts, and Letters, Volume 46, 1961: 365-404.

Minckley, W. 1973. Fishes of Arizona. Arizona Game and Fish Department, Phoenix, Arizona. 293p.

Minckley, W. and J. Deacon. 1968. Southwestern fishes and the enigma of "endangered species." Science, Volume 159, Number 3822:1424-1432. Moyle, P. 1978. Inland Fishes of California. University of California Press. 405p.

Pister, E. 1974. Desert fishes and their habitats. Transactions of the American Fisheries Society, Volume 103, Number 3:531-540.

Sada, D. Fisheries Biologist, U.S. Fish and Wildlife Service, Reno, Nevada.

Schoenherr, A. 1981. The role of competition in the replacement of native fishes by introduced species. In R. J. Naiman and D. L. Soltz (Eds.), Fishes in North American deserts. John Wiley and Sons, New York, New York.

Smith, G. 1978. Biogeography of intermountain fishes. Great Basin Naturalist Memoirs, Number 2:17-42.

Soltz, D. and R. Naiman. 1978. The natural history of native fishes in the Death Valley system. Natural History Museum of Los Angeles County, Science Series 30. 76p.

Tanner, V. 1950. A new species of Gila from Nevada (Cyprinidae). The Great Basin Naturalist, Volume 10, Number 1-4:31-36.

U.S. Fish and Wildlife Service. 1980. Pahrump killifish recovery plan. 30p.

Vanicek, C. and R. Kramer. 1969. Life history of the Colorado squawfish, Ptychocheilus lucius, and the Colorado chub, Gila robusta, in the Green River in Dinosaur National Monument, 1964-1966. Transactions of the American Fisheries Society, Volume 98, Number 2:193-208. 2612. Determine interaction of the Pahranagat roundtail chub with exotic aquatic species. 26121. Determine ecology of exotic species. 261211. Physical requirements. 261212. Biological characteristcis. 26122. Compare ecology of the Pahranagat roundtail chub with ecology of exotic species. 261221. Physical requirements. 261222. Biological characteristics. 26123. Determine affect of exotic species on the Pahranagat roundtail chub. 261231. Physical. 261232. Biological 261233. Physiological.

262. Determine effect of habitat alteration. 2621. Physical alteration. 26211. Biological. 26212. Physical. 26213. Physiological. 2622. Presence of exotics. 26221. Biological. 26222. Physical. 26223. Physiological.

3. Reestablish ecosystems that will support viable populations of the Pahranagat roundtail chub and cohabitating native fishes. 311. Identify Pahranagat roundtail chub habitat. 3111. On Pahranagat NWR. 3112. Off of Pahranagat NWR. 312. Prepare Ascertainment Report. 3121. Pahranagat River on Burns Ranch. 3122. Ash Springs. 3123. Crystal Springs. 3124. Hiko Spring. 32. Apply life history and ecological information to restoration and enhancement of secured habitats. 321. Restore and enhance Pahranagat River on Burns Ranch. 3211. Prepare aquatic habitat management plan. 3212. Remove competing and predatory exotics. 3213. Prevent reintroduction of exotics. 3214. Reestablish native fish habitat. 322. Restore and enhance Ash Springs. 3221. Prepare aquatic habitat management plan. 3222. Remove competing and predatory exotics. 3223. Prevent reintroduction of exotics. 3224. Reestablish native fish habitat. 323. Restore and enhance Crystal Springs. 3231. Prepare aquatic habitat management plan. 3232. Remove competing and predatory exotics. 3233. Prevent reintroduction of exotics. 3234. Reestablish native fish habitat Part II Recovery Step-down Outline

Goal: To prevent the Pahranagat roundtail chub, Gila robusta jordani, from becoming extinct and restore it to non-endangered status by: 1) devel- oping artificial propagation techniques; 2) conducting life history and ecological studies to provide guidance in reconstructing altered habitats; and 3) securing and reconstructing habitats within its historic range.

1. Develop artificial propagation techniques. 11. Artificial streams. 12. Traditional hatchery.

2. Determine ecology of Pahranagat roundtail chub. 21. Conduct reproductive studies. 211. Determine fecundity. 212. Determine spawning season. 213. Determine spawning habitat. 214. Determine spawning migration characteristics. 215. Determine egg incubation time. 216. Determine nursery areas. 22. Conduct food and feeding habitat studies. 221. Determine food items of fry and adults. 222. Determine feeding areas and their characteristics. 23. Conduct age and growth studies. 231. Determine size and growth rate of all stages in life cycle. 232. Determine longevity. 24. Determine preferred habitat. 241. Juveniles. 2411. Physical preferences. 2412. Biological preferences. 242. Adults. 2421. Physical preferences. 2422. Biological preferences. 25. Determine population dynamics. 251. Annual and seasonal population fluctuations. 252. Annual recruitment. 253. Mortality rates and causes. 26. Determine factors affecting population dynamics. 261. Conduct inter-and intraspecific interaction studies. 2611. Determine interaction of the Pahranagat roundtail chub with other Pahranagat Valley native fishes. 26111. Determine ecology of native fishes. 261111. Physical requirements. 261112. Biological characteristics. 26112. Compare ecology of the Pahranagat roundtail chub with ecology of native fishes. 261121. Physical requirements. 261122. Biological characteristics. 26113. Determine effects of native fishes on the Pahranagat roundtail chub. 261131. Physical. 261132. Biological. 261133. Physiological. 324. Restore and enhance Hiko Spring. 3241. Prepare aquatic habitat management plan. 3242. Remove competing and predatory exotics. 3243. Prevent reintroduction of exotics. 3244. Reestablish native fish habitat. 325. Restore and enhance habitat on Pahranagat NWR. 3251. Prepare aquatic habitat management plan. 3252. Remove competing and predatory exotics. 3253. Prevent reintroduction of exotics. 3254. Reestablish native fish habitat.

4. Reintroduce the Pahranagat roundtail chub into restored habitat. 41. Ash Springs. 42. Crystal Springs. 43. Hiko Spring. 44. Pahranagat NWR.

5. Monitor existing and reestablished populations. 51. Pahranagat River on Burns Ranch. 52. Ash Springs. 53. Crystal Springs. 54. Hiko Spring. 55. Pahranagat NWR.

6. Protect populations of the Pahranagat roundtail chub. 61. Enforce the 1973 Endangered Species Act. 62. Protect aquifer discharging in the Pahranagat Valley.

7. Establish public information program. 71. Publish information brochure. 72. Erect information signs. 73. Coordinate activities with Lincoln County Board of Commissioners. NARRATIVE

The goal of this recovery effort is to prevent extinction of the Pahranagat roundtail chub by developing techniques for its artificial propagation, and to recover the species to non-endangered status by reestablishing it in viable populations within its historic range. The development of artificial propagation techniques are required to immediately establish the species in a second locale to prevent its extinction should the single, extremely small, natural population be extirpated because of unforeseen, catastrophic events. The 1973 Endangered Species Act, as amended, requires that recovery can only be accomplished by insuring that viable populations are secure within the species' historic habitat. It is the opinion of the U.S. Fish and Wildlife Service that the Pahranagat roundtail chub will no longer be threatened with extinction, and can be removed from the Federal List of Threatened and Endangered Animals and Plants when all of the actions in this recovery plan have been implemented.

The Pahranagat roundtail chub is endemic to the thermal waters of the Pahranagat River and Crystal, Niko, and Ash Springs in the Pahranagat Valley, Nevada. It presently exists in extremely low numbers only in the Pahranagat River on the Burns Ranch. Altenation of aquatic habitats to facilitate water delivery to agricultural lands, and the introduction of several aquatic species that compete with and prey on the chub are believed to have caused the decline of this species.

Development of artificial propagation techniques (1) are necessary to insure the continued existence of the Pahranagat roundtail chub in the immediate future. Experimentation will be required to determine whether artificial stream (11) or traditional hatchery situations (12) will provide the best continued yield of fish. Fish from this program will also be used to reestablish populations of this chub within the historic range.

Recovery of the Pahranagat roundtail chub will proceed first by conducting investigations to provide information that will guide specific management activities necessary to reestablish secure populations. Little is known about the ecology of this roundtail chub, and cohabitants of the Pahranagat Valley aquatic ecosystems; therefore these investigations will be primarily directed toward determining the ecology of the chubs (2), other Pahranagat Valley native aquatic species (26111) and competing and predatory exotic species (26121). Knowledge of the ecology of a particular species of fish is frequently gathered by reviewing that existing for closely related species. This is not possible for the Pahranagat roundtail chub, however, since recently collected information suggests that the life history characteristics and habitat requirements of this species differ from those known for close relatives. Therefore, original research is required to determine Pahranagat roundtail chub ecology.

Studies of the life history of this chub will provide a basis for determining its ecology. Studies of chub reproduction (21) will determine its fecundity (211) and spawning season (212). These studies will also provide information about the time required for egg incubation (215), and the characteristics of spawning migrations (214), spawning habitat (213), and nursery areas (216). Food and feeding habitat studies (22) will reveal the preferred food items of adults and fry (221), and the characteristics of their feeding areas (222). Studies of age and growth (23) will determine the size and growth rate of the species at each stage of its life cycle (213) and its longevity (232). Determining the preferred habitat (24) of juveniles (241) and adults (242) is important in indicating how altered habitats that once supported the chub must be managed to again support secur viable populations. These studies will describe the physical (substrate, cover, water depth, and velocity, water temperature, turbidity, etc.) (2411, 2421) and biological characteristics (food availability, vegetation type, cohabitating fishes, invertebrate community of preferred habitats, etc.) of this habitat (2412, 2422). A knowledge of population dynamics (25) is necessary to determine the mechanism of annual and seasonal population fluctuations (251), annual recruitment rates (252, and the causes and rates of mortality (253). This information is necessary to evaluate the livelihood of populations.

Determining the ecology of the Pahranagat roundtail chub will permit an analysis of how it responds to factors altering the aquatic environments in the Pahranagat Valley (26). This analysis will show how the Pahranagat roundtail chub interacts with cohabitating aquatic species (261) and how its livelihood is affected by habitat alteration (262). Like other aquatic systems in the Great Basin, that occurring in the Pahranagat Valley is habitat for a number of other native species. The 1973 Endangered Species Act, as amended, requires that listed species be conserved by conserving the ecosystems of which they are a part. Therefore, recovery of the Pahranagat roundtail chub can only be accomplished by managing the aquatic ecosystem of the Pahranagat Valley as a whole. This requires a biological knowledge of the entire system; including the ecology of other native (26111) and exotic (26121) organisms. This management will also permit reestablish- ment of chub populations without excluding other native members of the aquatic com- munity. It will also provide for the livelihood of the White River and Hiko White River springfishes that are currently being considered for listing as endangered, and the White River turban snail formerly proposed for listing as threatened. Sueh a program may secure these candidate species so their listing may no longer be necessary.

Investigations of the physical requirements (261111, 261211) and biological characteristics (261112, 261212) of cohabitating species will provide information on the ecology of all animal members of the Pahranagat Valley aquatic ecosystem (26111, 26121). Comparison of the ecology of coinhabitators with the ecology of the Pahranagat roundtail chub (26112, 261121, 261122, 26122, 161222) will enable determination of interspecific interactions (2611, 2612) and allow quanti- fication of the influence that coinhabitors have on the distribution, biological requirements, and physiology of the chub (26113, 261131, 261132, 261133, 26123, 261232, 261233).

Although habitat alteration is known to adversely affect the Pahranagat roundtail chub, the mechanisms of these effects are poorly understood (262). There are two factors that have mostly degraded aquatic habitats in the Pahranagat Valley: 1) physical disturbance (2621) such as vegetation control, channelization, and habitat changes caused by exotics; and 2) competition and predation associated with the presence of exotics (2622). The effects of these two factors are interrelated since they each cause the elimination of the chub. Direct displacement of the chub results when habitats are so thoroughly altered that they can no longer be occupied by the chub; secondary displacement occurs when habitats are altered so conditions are less than optimum for the chub and more suitable for occupancy by exotics. The chub, in this instance, is eliminated by the influence of the exotic, not by the immediate result of habitat alteration. PART 111 Implementation Schedule

Resnonsihle Aooncv Task Priorit Fiscal Year Costs (EST.) General Plan Task Task FW5 . Category f 1 Duration Other FY83 FYR4 FY85 Comments - Notes Region Program -...... 3 yrs. M1 Propagation 1 I 1 SE NDOW 3,000 3,000 3.000 9 R3 Reproduction 21 1 2 yrs. Research 7,000 1 9 R3 Food and Feeding 22 2 yrs. Research 7.000

RI4 Growth 23 1 2 yrs. 9 Research 4,000

R3 Preferred habitat 24 1 2 yrs. 9 Research 10,000

RI Population dynamits 25 1 2 yrs. 9 Research 7,000

9 RIO Competition 261 1 2 yrs. Research 12,000

R2 Effect of habitat alteration 262 1 2 yrs. 9 Research 15,000

RI3 Determine reintro- duction locations 311 1 2 yrs. 9 Research

A7 Acquisition Report 312 1 1 yr. 1 Acqui- sition

M3 Pahranagat River Management Plan 3211 1 1 yr. 1 SE NDOW 1,000

M3 Ash Springs Management Plan 3221 1 1 yr. 1 SE NDOW 1,000

_ — Investigations of the biological (26212, 26221), physical (26212, 26222), and physiological (26213, 26223) response to habitat alteration will determine the mechanisms of the chub's reaction to this type of stress. This information will enable management activities to quantify the influence of habitat alteration on the chub and make recommendations of how to proceed in the future without having a serious detrimental influence on the chub.

Information provided by all research will guide the reconstruction of ecosystems that will support viable populations of the Pahranagat roundtail chub (3) in the Pahranagat Valley. These populations will be established or enhanced in habitats secured from activities that may threaten the fish's livelihood (31). The known distribution of the species before its decline will provide the basis for determining the habitats needing to be secured (311). All local aquatic habitats will be investigated; including that located within and outside the boundaries of the Pahranagat National Wildlife Refuge (NWR) (3111, 3112).

The U.S. Fish and Wildlife Service will prepare an Ascertainment Report to investigate the methods for securing habitats for Pahranagat roundtail chub recovery (312). This report will be concerned with chub habitat in the Pahranagat River on the Burns Ranch (3121), Ash Springs (3122), Crystal Springs (3123), and Hiko Spring (3124). Upon securing these habitats for the chub, information gathered from studies about the Pahranagat Valley aquatic eco- system will be applied to management practices designed to reestablish the species in feasible localities (32). Specific aquatic habitat management plans (3211, 3221, 3231, 3241, 3251) will be prepared to guide the restoration and enhancement of habitats in the Pahranagat River on the Burns Ranch(9321), Ash Springs (322), Crystal Springs (323), Hiko Spring (324), and on the Pahranagat NWR (325). These plans will detail how native fish habitat will be reestablished (3214, 3224, 3234, 3244, 3254), and how exotic species will be removed (3212, 3222, 3232, 3242, 3252) and their reestablishment prevented (3213, 3223, 3233, 3243, 3253). These plans will be prepared with the involve- ment of the land owners and the State of Nevada.

Once these habitats are secure and the actions presented in the respec- tive management plans have been implemented, the Pahranagat roundtail chub will be reintroduced (4) into Ash (41), Hiko (43), and Crystal Springs (42), and waters on the Pahranagat NWR (44). Since the chub currently exists in the Pahranagat River on the Burns Ranch, reintroduction is not necessary in this habitat. The success of these populations will be evaluated during a monitor- ing program (5) to periodically assess the size, structure, and viability of each population (51, 52, 53, 54, 55).

The populations of Pahranagat roundtail chub will be further protected (6) in their secured habitats by statutes of the 1973 Endangered Species Act, as amended (61). Efforts will also be made to protect the groundwater aquifer discharging in the Pahranagat Valley to insure the integrity of spring dis- charge supporting chub populations (62).

A public information program will be conducted (7) to involve the public in recovery activities. This program will include, but not be limited to, publishing informational brochures (71) and placing signs at appropriate localities (72). Activities will be coordinated with the Lincoln County Commissioners (73).