Status of Introduced Fishes in Certain Spring Systems in Southern Nevada

Great Basin Naturalist

Volume 42 Number 3 Article 6

9-30-1982

Status of introduced fishes in certain spring systems in southern Nevada

Walter R. Courtenay Jr. Florida Atlantic University, Boca Raton, Florida

James E. Deacon University of Nevada, Las Vegas

Follow this and additional works at: https://scholarsarchive.byu.edu/gbn

Recommended Citation Courtenay, Walter R. Jr. and Deacon, James E. (1982) "Status of introduced fishes in certain spring systems in southern Nevada," Great Basin Naturalist: Vol. 42 : No. 3 , Article 6. Available at: https://scholarsarchive.byu.edu/gbn/vol42/iss3/6

This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Great Basin Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. STATUS OF INTRODUCED FISHES IN CERTAIN SPRING SYSTEMS IN SOUTHERN NEVADA

Walter R. Courtenay, Jr.," and James E. Deacon^

.Abstract.— We record eight species of exotic fishes as established, reproducing populations in certain springs in Clark, Lincoln, and Nye counties. Nevada. These include an unidentified species of Hi/postomus, Cyprinus carpio, Poecilia mexicana. Poecilia reticulata, a Xiphophorus hybrid, and Cichlasoma nigrofasciatiim. Tilapia mariae, established in a spring near the Overton Arm of Lake Mead, and Tilapia zilli, established in a golf course pond in Pah- rump Valley, are recorded for the first time from Nevada waters. Though populations of transplanted Gambusia affinis persist, other populations of Poecilia latipinna are apparently no longer extant. Cichlasoma severum, Notemigomis crysoleucas, Poecilia latipinna, and Carassius auratus were apparently eradicated from Rogers Spring in 1963.

Miller and Alcorn (1943), Miller (1961), La of Deacon et al. (1964) and Hubbs and Dea- Rivers (1962), Deacon et al. (1964), Hubbs con (1964). and Deacon (1964), Minckley and Deacon (1968), Minckley (1973), Hubbs et al. (1974), Clark County Deacon (1979), Hardy (1980), and others recorded the presence of non-native fishes in Indian Spring is 2 km south of U.S. High- Nevada. In those papers, it was stressed that way 95, approximately 62 km northwest of the introduction of nonnative fishes, be they Las Vegas in the village of Indian Springs. exotic (of foreign origin) or transplants native Minckley (1973) recorded a suckermouth cat- to otlier areas of the United States, can have fish {Hypostomiis) as successfully established serious, adverse impacts on the depauperate since at least 1966 "in a warm spring in and often highly endemic fish fauna in the southern Nevada"; this reference was to In- southwestern U.S. Deacon et al. (1964) em- dian Spring. Brief examination of Indian phasized that most of the endemic fishes are Spring by Deacon .since 1966 demonstrates small and, therefore, subject to more adverse that the population has remained common impacts through introductions of small bait and continues to reproduce successfully. The or ornamental fishes than with earlier in- deeply imdercut banks with numerous tree troductions of larger fishes, a subject re- roots and holes provide excellent refuge for viewed by Hubbs and Broderick (1963). this rather cryptic species. Our collection on In this paper, we document eight species 18 October 1980 yielded only one specimen, of exotic fishes in three counties of southern despite repeated seining. A local resident ad- Nevada. One of these fishes, the spotted ti- vised us that local youngsters had removed as lapia {Tilapia mariae), was previously known many as 500 individuals in recent months, to have become established only in Florida probably for sale to pet shops in Las Vegas; (Hogg 1974, 1976, Courtenay and Robins this, predation on eggs by an introduced snail 1975, Courtenay 1979b, 1980, Courtenay and {Melanoides tiiberciilata), competition from Hensley 1979, 1980). Another, the redbelly other introduced fishes, or a combination of

tilapia {Tilapia zilli), has been recorded as es- these factors could explain the apparent pop- tablished in Arizona, California, and Texas ulation decline of Hypostomus he felt had oc- (Courtenay and Hensley 1980). Our purpose curred. On 25 June 1981 a reexamination of

is to update the status of introduced fishes in the spring pond using a face mask and a light southern Nevada, primarily from the reports to observe the undercut banks demonstrated

'Department of Biological Sciences, Florida Atlantic University, Boca Raton. Florida 33431. 'Department of Biology, University of Nevada, Las Vegas, Nevada 891.54

361 362 Great Basin Naturalist Vol. 42, No. 3

that Hypostomus continues exist to in rela- from this spring. An attempt to remove the tively high density in Indian Spring. Individ- introduced fishes was made in December uals of all sizes were seen hiding in or around 1963. We seined Rogers Spring on 18 Octo- almost every available hole, tree root, or ber 1980. The dominant fish (in numbers and rock. biomass) was the spotted tilapia {Tilapia Suckermouth catfish have been recorded as mariae). Shortfin mollies were very abundant, established in Texas (Barron 1964, Hubbs et convict cichlids were rare, and two guppies al. 1978) and Florida (Courtenay and Robins were collected. Underwater observations 1973, Courtenay 1979b, 1980). The specimen made prior to the seine hauls correlated well collected at Indian Spring is morphologically with the population densities revealed by distinct from those collected in Texas and seining. No banded cichlids, sailfin mollies, Florida and represents a third species of Hy- golden shiners, or mosquitofish were seen or postomus established in the U.S. collected, and they are considered as no long- Deacon (pers. comm. to D. A. Hensley) er extant in Rogers Spring. also recorded the green swordtail (Xiph- Of particular interest were the underwater ophonis helleri) from Indian Spring in 1975. observations on spotted tilapia prior to sein- Although we found no green swordtails at In- ing activities. Most of the tilapias, even large individuals dian Spring on 18 October 1980, a yellow to (above 100 mm SL), displayed the banded juvenile pale orange hybrid swordtail (probably X. pattern as illustrated by Thys van den Audenaerde helleri x X. maculatus) was found to be the (1966). Only a relatively few large individuals dominant fish in number of individuals. Gup- showed the typical adult pattern of spots on their sides pies (Poecilia reticulata) were also abundant (Fig. 1). Moreover, it was later noted, and several large common carp (Cyprinus following seining, that most of the tilapias displaying the carpio) were seen but not collected. The only juvenile color pattern were missing parts or other species present was the mosquitofish most of their pelvic fins (Fig. 2) and that {Gambusia affinis). other fins (particularly the soft dorsal and up- Blue Point Spring is in the Lake Mead Na- per half of the caudal) often showed damage. tional Recreational Area above the Overton The only fish in Rogers Spring capable of in- Arm of Lake Mead, approximately 68 km flicting such damage were the adults with the northeast of Las Vegas. Deacon et al. (1964) typical adult color pattern; none of those had recorded guppies, shortfin mollies {Poecilia damaged fins. mexicana), and the southern platyfish {Xiph- At no time have population densities of Ti- ophorus maculatus) from Blue Point Spring. lapia mariae in Florida been observed to be In a collection made 18 October 1980, no approaching those seen in Rogers Spring. It is guppies or southern platyfish were found; probable that the trophic and spatial car- however, shortfin mollies, convict cichlids, rying capacities of Rogers Spring for spotted and a single spotted tilapia with damaged tilapia have been reached and that this be- pelvic fins were captured. Deacon et al. havioral hierarchy, led by a few highly ag- (1964) also reported a transplant, the sailfin gressive individuals, has developed to control molly {Poecilia latipinna), from Blue Point further overpopulation. Spring; we did not collect this species there and it is assumed that the population died out. Lincoln Gounty Rogers Spring is located 2 km southwest of Blue Point Spring in the Lake Mead National Deacon et al. (1964) did not find any exotic Recreational Area. Deacon et al. (1964) re- fishes at either Grystal Spring or Ash Springs ported convict cichlids, goldfish {Carassius in the Pahranagat Valley, some 145 km auratus) and transplanted sailfin mollies, north-northwest of Rogers Spring during col- golden shiners {Notemigonus crysoleucas), lecting trips on 2 February and 9 March and mosquitofish from Rogers Spring. Hubbs 1963. They did find an introduced population and Deacon (1964) reported convict cichlids, of mosquitofish at Ash Springs that was re- shortfin mollies, transplanted sailfin mollies, ported earlier by Miller and Hubbs (1960). and the banded cichlid {Cichlasoma severum) During a collecting trip on 3 June 1964, September 1982 COURTENAY, DeACON: INTRODUCED NevADA FiSHES 363

Francis McKittrick Watkins. FiiT. 1. An advilt spotted tilapia. 205 mm standard length. Drawing by

in the summer of 1975 (Soltz and convict cichlids, shortfin mollies, and trans- short time thus eliminating the goldfish. planted sailfin mollies were discovered in Ash Naiman 1978), the north of Manse Ranch Springs (Hubbs and Deacon 1964). The prob- About 10 km to of Pahrump Spring, origi- able source of these introduced fishes was Spring is the site the largest spring in Pahrump Valley. suggested as Rogers Spring because all three nally failed in the late 1950s be- species were known to exist there. The same Pahrump Spring excess pumping of groundwater for three non-native fishes subsequently spread cause of the late 1970s the sur- from Ash Springs to Crystal Spring, 8 km to irrigation. During area was subjected to a land devel- the north-northwest. rounding included construction of a On 17 October 1980, surface and under- opment plan that park area. The ponds and water observations, as well as seine collec- golf course and small stream associated with this devel- tions, made in the outflow of Ash Springs from the vicinity of showed convict cichlids to be dominant in opment use groundwater Examination of the biomass, followed by shortfin mollies that the former spring source. in Cottonwood Park by the Ne- were dominant in numbers of individuals. main pond Wildlife on 4 March Transplanted mosquitofish were common and vada Department of and by one of us (Deacon) on 16 July no sailfin mollies were seen or collected. In- 1980 the presence of large numbers troduced fishes were somewhat uncommon in 1981 revealed mosquitofish and relatively a pool occupied by 35-40 individuals of the of goldfish and Tilapia Pahranagat roundtail chub {Gila robusta small numbers of the redbelly tilapia, of redbelly tilapia col- prdani). zilli. The specimens lected were all small, but one pair of larger fish (to ca 250 mm) was seen in the water in Nye County July, apparently guarding nests or young. that large numbers of Goldfish, Carassius auratus, were reported The manager reported winter when the water tem- by Deacon et al. (1964) and by Deacon Tilapia died last reached 58 F (14 C). This species (1979) in Pahrump Valley at Manse Ranch perature at least two Spring. Manse Ranch Spring dried up for a has maintained itself through 364 Great Basin Naturalist Vol. 42, No. 3

Fig. 2. A spotted tilapia, 73.5 mm SL, from Blue Point Spring. Note damaged pelvic fins.

winters and has reproduced during the sum- the exotic species to disrupt habitats and mers of 1980 and 1981. A small population is niches {sensu lato) in new environments. able to exist through the winter apparently The introduction of any non-native fish because the inflowing water maintains a tem- will result in alterations in the host ecosys- perature of about 70 F (21 C). tem. Such alterations may range from minor, almost unnoticeable changes in native fish Discussion populations to the extinction of one or more native species (Courtenay 1979a, Courtenay Courtenay et al. (1974) termed the promis- and Hensley 1980). In Florida, for example, cuous introduction of exotic fishes to new en- comparatively small ornamental fishes, cich- vironments as biological pollution. Unlike lids in particular, are able to successfully in- chemical or thermal pollutants, biological ad- vade and become dominant in waters that ditives have the ability to reproduce and ex- contain larger native piscivores such as large- pand their ranges. Moreover, many exotic mouth bass {Micropterus salmoides) and Flor- fishes may appear to be trophic specialists in ida gar (Lepisosteus platyrhinciis). Invasion their native range but prove to be passive and domination by nonnative fishes in many generahsts (Birkeland and Neudecker 1981) parts of the desert southwest is facilitated by in new environments where most or all of the the absence of piscivores and the presence of biological constraints of the native range are small endemic fishes that have had no pre- absent (Courtenay and Hensley 1980). Such vious experience with trophic passive gener- trophic adaptation, coupled frequently with ahsts or piscivores. Therefore, a fish that

equally adaptable behavioral traits, permits feeds on phytoplankton or detritus in its September 1982 COURTENAY, DeACON: INTRODUCED NeVADA FiSHES 365 native range and either becomes a predator Deacon 1964, Courtenay and Hensley 1980), of smaller fishes or feeds on algae in the new but to date the exact mechanisms for these environment is a clear threat to many native declines have not been examined. The "cause fishes in the southwestern U.S. and effect" for such declines is suggested It is obvious that there have been several strongly but requires in situ observations and changes in the introduced fish fauna in south- evaluations. em Nevada since 1963. Species compositions Finding an established population of have changed. The green swordtail popu- spotted tilapia in southern Nevada is particu- lation in Indian Spring is gone and has been larly disturbing. Although this fish is omniv- a replaced with a hybrid of Xiphophorus; orous, it shows a preference for green algae catfish remains population of a suckermouth in Florida and in its native range has been extant there. Guppies, southern platyfish, and described as "une forme intermediaire entre to absent in Blue sailfin mollies appear be les Tilapia herbivores et les especes micro- Point Spring, and at least one spotted tilapia phages" (Thys van den Audenaerde 1966). before our was released, probably recently, The bottom of Rogers Spring was devoid of mollies, mosquito- collections there. Sailfin green algae, doubtlessly due to grazing by fish, and the banded cichlid are absent in spotted tilapia. A trophic preference of this Rogers Spring, the latter probably due to the type, coupled with omnivory, could prove eradication effort in 1963; convict cichlids disastrous to several endemic species and sub- are now rare, but guppies and spotted tilapia species of southwestern fishes if this western (the latter now dominant) have been added. African cichlid were moved elsewhere. We Sailfin mollies appear to be absent from the therefore recommend its immediate eradica- outflow of Ash Springs in the Pahranagat tion. Much the same result could be expected Valley, whereas convict cichlids and shortfin by future introductions of other tilapias {sen- mollies are dominant, 17 years after their sii lato) or such seemingly harmless fishes as introduction. Hypostomus spp. Also, the potential in- Frequent and closer monitoring of introduction of fish parasites via exotic fish troduced fish populations, particularly in vectors exists (Lachner et al. 1970, Courtenay areas that are potential or recognized release and Robins 1975, Courtenay 1979a) and has sites for unwanted pet fishes in southern Ne- been suggested to have occurred in southern vada and other areas in the desert southwest, Nevada (Deacon 1979) and elsewhere (Hoff- is needed. These "pockets" of introduced man 1970, Bauer and Hoffman 1976). fishes serve as potential and probable sources Fish introductions pose as great a tlireat to for futiu-e introductions elsewhere as appar- the continued existence of the depauperate ently occurred with the transfer of convict fish fauna in southern Nevada and adjoining cichlids and shortfin mollies from Rogers states as does water withdrawal for agricul- Spring to Ash Springs in 1963. A further in- tural, domestic, military, and industrial uses dication of the constant or continuing nature or other habitat modifications. of this problem is a verbal report from Mr. Charles Orr, a Las Vegas member of the American Cichlid Association, that he saw Acknowledgments and identified several specimens of the "mar- thank Paul Greger and Thom Hardy malade" form of Pseudotropheus zebra when We for assistance in the field and James A. he visited Rogers Spring in July 1981. Robert R. Miller, and Jeffrey N. Although the disappearance of some in- McCann, for their helpful comments on the troduced fishes in southern Nevada in recent Taylor manuscript. This study was supported by years may be of some interest, it is far more 14-16-0009-78-021, Cooperative important tliat studies be initiated to define Contract the impacts of introduced species on native Agreement 14-16-0009-80-952, and an Inter- fishes. Species interactions between non- governmental Personnel Act Assignment native and native fishes have been suggested from the Department of the Interior, U.S. as reasons for declines in populations of na- Fish and Wildlife Service, and by sabbatical tive fishes (Deacon et al. 1964, Hubbs and fmiding from Florida Atlantic University. 366 Great Basin Naturalist Vol. 42, No. 3

Literature Cited Snieszko, ed., A symposium on diseases of fishes and shellfishes. Amer. Fish. Soc. Spec. Publ. 5. Barron, C. 1964. Reproduction J. and apparent over- Hogg, R. G. 1974. Environmental hazards posed by winter survival of suckermouth armored catfish, exotic fish species newly established in Florida.

Plecostomus sp., in the headwaters of the San An- Environ. Conserv. 1(3): 176. tonio River. Texas Sci. 16:449-450. J. 1976. Established exotic cichlid fishes in Dade Bauer, O. N., and G. L. Hoffman. 1976. Helminth County, Florida. Florida Sci. 39(2):97-103. range extension by translocation of fish. Pages Hubbs, C, and H. J. Broderick. 1963. Current abun- 163-172 in L. A. Page, ed., Wildlife diseases. Ple- dance of Gambusia gaigei, an endangered fish num Publ. Corp., New York. species. Southwest Nat. 8:46-48. BiRKELAND, C, AND S. Neudecker. 1981. Foraging be- Hubbs, C, and J. E. Deacon. 1965. Additional in- havior in two Caribbean chaetodontids: Chaeto- troductions of tropical fishes into southern Ne- don capistratiis and C. aculeatus. Copeia 1981 vada. Southwest Nat. 9(4):249-251. (1):169-178. Hubbs, C, T. Lucier, G. P. Garrett, R. J. Edwards, CouRTENAY, W. R., Jr. 1979a. The introduction of exotic S. M. Dean, E. Marsh, and D. Belk. 1978. Survi- organisms. Pages 237-252 in H. P. Brokaw, ed.. val and abimdance of introduced fishes near San Wildlife and America. Government Printing Of- Antonio. Sci. Texas J. 30(4):369-376. fice, Washington. Hubbs, C. L., R. R. Miller, and L. C. Hubbs. 1974. Hy- 1979b. Biological impacts of introduced species drographic history and relict fishes of the north and management policy in Florida. Pages central Great Basin. California Acad. Sci. Mem. 237-257 in R. Mann, ed., Exotic species in mari- 7:1-259. culture. MIT Press, Cambridge, Massachusetts. Lachner, E. a., C. R. Robins, and W. R. Courtenay, 1980. Exotic fish: environmental roulette. Water Jr. 1970. Exotic fishes and other aquatic organ- %)ectrum 12(4): 10-17. isms introduced into North America. Smithson. CouRTENAY, W. R., Jr., AND D. A. Hensley. 1979. Range Stud. Zool. 59:1-29. expansion in southern Florida of the introduced La Rivers, I. 1962. Fishes and fisheries of Nevada. Ne- spotted tilapia. Environ. Conserv. 149-151. 6(2): vada St. Fish and Game Comm. 782 pp. 1980. Special problems associated with mon- Miller, R. R. 1961. Man and the changing fish fauna of itoring exotic species. Pages 281-307 in C. H. the American southwest. Pap. Mich. Acad. Sci.,

Hocutt and J. R. Stauffer, Jr., eds.. Biological Arts, and Lett. 46:365-404. monitoring of fish. Lexington Books, Lexington, Miller, R. R., and J. R. Alcorn. 1946. The introduced Massachusetts. fishes of Nevada, with a history of their in- CouRTENAY, W. R., C. R. Jr., and Robins. 1973. Exotic troduction. Trans. Amer. Fish. Soc. 73:U.3-193. aquatic organisms in Florida with emphasis on Miller, R. R., and C. L. Hubbs. 1960. The spiny-rayed fishes: a review and recommendations. Trans. cyprinid fishes (Plagopterini) of the Colorado Amer. Fish. Soc. 102(1):1-12. River system. Misc. Publ. Mus. Zool. Univ. Mich- 1975. Exotic organisms: an unsolved, complex igan 115:1-39. problem. BioScience 25(5):306-313. MiNCKLEY, W. L. 1973. Fishes of Arizona. Arizona CouRTENAY, W. R., H. F. Jr., Sahlman, W. W. Miley Game and Fish Dept., Phoenix. 293 pp. II, and D. Herrema. 1974. Exotic fishes in MiNCKLEY, W. L., J. AND J. E. Deacon. 1968. South- fresh and brackish waters of Florida. Biol. Con- western fishes and the enigma of "endangered serv. 6(4):292-,302. species." Science 159:1424-1432. Deacon, E. 1979. Endangered and threatened fishes SoLTZ, D. L., R. J. AND J. Naiman. 1978. The natural his- of the west. Great Basin Nat. Mem. No. 3:41-64. tory of native fishes in the Death Valley system. Deacon, E., C. Hubbs, B. J. and J. Zahuranec. 1964. Natural History Museum of Los Angeles County, Some effects of introduced fishes on the native Science Series 30:1-76. fish fauna of southern Nevada. Copeia 1964 Thys VAN den Audenaerde, D. F. E. 1966. Les tilapia (2):384-388. (Pisces, Cichlidae) du sud-Cameroun et du Ga- Hardy, T. 1980. The Inter-Basin area report. Proc. bon; etude systematique. Ann. Mus. Roy. Afr. Desert Fish. Coun. 11:5-21. Cent., ser. 8, Zool. 153:1-98. Hoffman, G. L. 1970. Intercontinental and trans- Wilson, B. L., J. E. Deacon, and W. G. Bradley. 1966. continental dissemination and transfaunation of Parasitism in the fishes of the Moapa River, Clark fish parasites with emphasis on whirling disease County, Nevada. Trans. California-Nevada Sec. {Myxosoma cerebralis). Pages 69-81 in S. F. Wildl. Soc. pp. 12-23.