Management of the Owens Pupfish, Cyprinodon radiosus, in Mono County, California

ROBERT RUSH MILLER Museum o/ Zoology, The University o/ Michigan Ann Arbor, Michigan 48104 EDWIN P. PISTER Cali/ornla Department o/ Fish and Game Bishop, Cali/ornia 93514

ABSTRACT The Owenspupfish, Cyprinodon radiosus Miller, is restrictedto OwensValley along the eastern base of the Sierra Nevada Range of California. When it was describedin 1948 it was thought to be extinct. Its depletion,rediscovery, and reestablishmentin the OwensValley Native Fish Sanctuary,a cooperativeundertaking between the City of Los Angelesand the California Depart- ment of Fish and Game, are described.Two other refugesin OwensValley are completedor underconstruction, and the threeadditional native fishes of this valleywill be establishedin one of these. Such conservationactivity reflects the growing concern of the scientific community and the public over the threat to native fishes.

INTRODUCTION feed Fish Slough,Mono County,about 10 to The Owenspupfish (Figure 1), Cyprinodon 12 milesnorth of Bishop(Figure 2). In the radiosusMiller (1948), a memberof the killi- early part of the century,the Owenspupfish rishfamily Cyprinodontidae,is confinedto the wasabundant in the springs,shallow sloughs, OwensRiver drainagein OwensValley, Cali- swamps,irrigation ditchesand bog pastures fornia. It is one of the severalspecies of this alongand near Owens River. Mosquitoeswere genusthat inhabit springsand creeksof the then relativelyuncommon, but as the species desertregion in easternCalifornia and south- became scarce these insectsbecame pests western Nevada. A number of these fishes are (Miller, 1948: 93). now threatened with extinction and the Owens DEPLETION pupfishwas recentlyclassified as a rare and endangeredspecies (U.S. Dept. Int., 1968: With the establishment of exotic fishes in F-26; Miller, 1969a). OwensValley and the disappearance or marked OwensValley is without outlet and lies at reductionof marshyareas due to removalof the base of the eastern escarpmentof the much of the water supply through the Los Sierra Nevada. In the first generaltreatment Angelesaqueduct (Heinly, 1910), Cyprinodon of the fishesof this valley, Snyder (1917) radiosusrapidly declined. In 1934, Carl L. referred this speciesto the desert pupfish, Hubbsfound only a few shallow,fishless pools Cyprinodonmacularius Baird and Girard,but alongthe big bend of OwensRiver northeast subsequentlyit was shown that C. macularius of Bishopwhere Kennedy,19 years earlier, livesin Californiaonly in the SaltonSea basin had observedbig schoolsof this pupfishnear (Miller, 1943). the margin of a large rule swampthat lay Just prior to Snyder's paper, Kennedy betweenLaws and Bishop.Neither in the river (1916) describedthe habitat,abundance, and near Laws nor at other localities between feedinghabits of the Owenspupfish, noting Bishopand Independencedid the Hubbsparty that "... it canprobably be usedto advantage find anypupfish. At that timethe speciesdid in combatingthe mosquitoin thoseparts of survivein at least two places,for the Mono- the state where theseinsects are a pest about Inyo surveyof the U.S. Bureau of Fisheries permanentfresh-water marshes." Evidently its found it to be abundantin Fish Sloughin natural rangewas from near Lone Pine, Inyo "wide,flat, reedybasins, mostly in water only County,northward to the sourcesprings that about3 to 6 inchesdeep and very warm," and 5O2 MILLER AND PISTER--MANAGEMENT OF OWENS PUPFISH 503

F•cuRœ1.--Cyp•inodon radiosus(UMMZ 189879),male above (33.5 mm S.L.), female below (36.0 mm S.L.). From BLM Spring, on E. side of Fish Slough, Mono Co., California, collected June 29, 1970. The speciesat- tains a maximum size here of about 60 mm, total length •.50 mm S.L.). common in a spring or series of springs the speciesin numbersadequate for their re- (Morton'sSlough?) near OwensRiver eastof search.No pupfishwere observedby them at Independence!.Miller, 1948: 94•. any distancebelow the spring sources,how- In July, 1937, a rather hurried checkof the ever. lower and middle parts of Fish Slough re- On August31 and September1. 1942, not a vealedprincipally carp (Cyprinuscarpioi and singlepupfish was found by Miller and party largemouthbass ( Micropterussalmoides • . the in any of the three springsin Fish Slough latter having been planted in OwensValley where they had previously lived. Their around 1913 (Kennedy, 1916: 1801; a few complete disappearancefrom these waters suckers and minnows were also seen, but no within three years may be attributed chiefly pupfish(Miller, 1948: 941. In the upperpart to direct predation by largemouthbass, a of Fish Slough,in 1937,Cyprinodon radiosus speciesnot notedin any of the springsduring was still rather common at the head of the 1937-1940. Also, in contrastto earlier years. westernmostspring and a few individualswere there were fewer minnows and suckers in these observedin the outflowof the mostnortherly sprin• in 1942 and within about the next spring I Figure2. sta. 1 I. In 1937. only exotic decadethey too virtually disappeared.Con- fisheswere seinedin the many valley sloughs siderablelocal inquiry at Bishopin 1942 and betweenIndependence and Big Pine. some investigationof waters between Fish In July, 1938, the westernmostspring of Sloughand Big Pine failed to rexrealany pup- Fish Sloughstill supportedan adequatepop- fish. Consequently,when the specieswas ulation and in April. 1939, Sumner and Sar- describedsix yearslater it was thoughtto be gent(1940: 46-47) hadno difficultycollecting extinct. 504 TRANS. AMER. FISH. SOC., 1971, 1YO.3

FIGURE2.•Aerial view of Fish Slough from north end looking •utheast, April 29, 19•. 1, nor•e•ost spring; 2, the two westerlysprings, comprising the Owens Valley Native Fish Sanctua•; 3, "Rediscove• Pools," where pupfish were taken in 1956 and 19•; 4, BLM Spring.

REDISCOVERY Departmentof Fish and Game,spent two days In June or July 1956, W. M. Richardson in the Fish Slougharea searchingfor Cyprino- and Ralph V. Beck of the California Depart- don radiosus. In the northernmostspring and ment of Fish and Game, using a small seine, its outflowthey found only mosquitofishand collecteda few Owenspupfish from shallow largemouthbass and saw, in the springhole, ponds200 to 300 feet westof the unimproved a "cyprinid2 to 6 incheslong" (perhapssome roadthat traverses the eastside of Fish Slough, were Catostomus,seen in 1964). Fish were approximately1.5 milessouth of the northern- generally scarce. In the two northwestern mostspring. The pondslay east of the main springsfeeding Fish Slough,they found only channelof the Sloughat this point and were mosquitofish.They did not relocatethe pop- no morethan a foot deep. They alsocontained ulationsampled by Richardsonand Beck. a chub,carp, sucker, small bullheads, mosquito- On July 10, 1964, Hubbs,Miller, Pisterand fish,and juvenile largemouth bass. About one party "rediscovered"the populationof Owens pupfish was obtainedper three seine hauls. pupfishthat had been sampledin 1956. It The fish were kept alive in an aquarium for inhabited an elongatepool maintainedby awhile, and Mr. Richardsonwas impressed overflowof coolwater from the adjacentmain, with their pugnacity,but sincehe did not know spring-fedditch, 2.2 milesby jeep road south that the specieswas thought to be extinct,they of the northernmostspring of Fish Slough weresubsequently discarded. (Figure 2, sta. 3; TSS, R32E, near 1NEcorner In early April, 1963, Robert K. Liu, E. P. of sec.25•see U.S. GeologicalSurvey Bishop Pister and other personnelof the California Quadrangle, 15-minute series, 1949). The MILLER AND PISTER--MANAGEMENT OF OWENS PUPFISH 505

" , I, •" •, ,

/ . F[cu• &--Typical pupfishhabitat--wide, flat, open,shallow, marshy pools•at "Re•scove• Pools,"July 10, 19•. From a Kodachrometransparency. pool of very clearwater wasabout 100 )ards sexes and sometimes it formed a bilateral long, varied from 15 to 40 feet in width, and melanism (on caudal peduncleand base of therewas dense Chara covering the firm, mud caudal fin). The caudal fins of the showiest bottom;scattered stands of Scirpusgrew in breedingmales have a narrow,dusky to black the shallowwater (2 to 6 inchesdeep) and terminal border, which was quickly lost on the shorewas an open marshyswamp and preservationor as the malesceased reproduc- meadow(Figure 3). Onlya slightcurrent was tive or aggressivebehavior. Hence, it is not perceptibleat the end nearestthe ditch. The surprisingthat this specieswas describedas air was 91 F and the water 92 F at 3 PM. lacking the terminal black border on the Cyprinodonradiosus had an estimatedpopula- caudal fin that characterizes the male of the tion of perhaps200 individuals,comprising genus Cyprinodon. (The occurrenceof this juvenilesto largeadults and includingfish in feature in C. radiosus was first noted and breedingcolors. photographedby RobertK. Liu in 1964.) At In life. the brightest(breeding) males have the height of nuptial or aggressivebehavior thedorsal fin pinkishtan to orangeand either the broad vertical bars on the side become black-borderedor not. The analfin is pinkish intensified and take on a brilliant metallic blue tan to chalky blue or turquoise,sometimes color: the first bar (shorter than the second) with a black border. In bright sunshineone lies just behindthe head and is followedby can see a blue to turquoisepredorsal stripe. about five bars of which the longest and and the whole body may be brilliant blue broadestare the secondand third. They are under such favorablelight conditions.No• not narrowedventrally, as in other speciesof infrequentlya unilateralblackened area (head. the genus. The developmentof this banding side, and caudal peduncle)was noted in both may be unique for speciesof Cyprinodon. 506 TRANS. AMER. FISH. SOC., 1971, iXO. 3

FIGURE4.•Most westerly spring and outflow in Fish Slough, type locality of Cyprinodonradiosus, looking southeastward. Februa• 2, 1968.

When the fish are not engagedin mating or at times that of figure eights, at other times fighting thesebars pale to a grayish blue, or a circular (counterclockwise) motion, leaping they may disappearaltogether and such fish over-swimmingunder-and leaping over. This appear pale grayish or chalky blue or even t)pe of behaviorwas also noted for the mos- brownish. The narrower interspacesbetween quitofish( Gambusiaa. a//iais), whichswarmed the vertical bars are milky white in life. The in the pool. Also associatedwith the pupfish pectoralfin. chalky blue to turquoise.is black- were speckled dace (Rhinichth.ysosculus), margined. The pelvicsare whitish to chalky scarce,and juvenile largemouthbass. At 10 blueor turquoiseand light-bordered,definitely AM the next day, the water temperaturewas lighter overallthan the pectorals;they may be only 79 F and very few pupfish,chiefly young black-tipped,however. and juveniles,were seen. Femaleshave smaller dorsal, anal, pectoral, and pelvicfins, lack the terminalcaudal band, RE ESTABLISH M EI•IT may or may not showa black blotchor spot The obviouslyprecarious position of C. along the midbaseof the dorsal or on its radiosus demanded that action be initiated at posteriorrays (occasionallyalso on the pos- the earliest possibledate to create refugia terior rays of the anal fin), are generally •here the speciescould be reestablishedwith- olivaceousbrown to deep olive on the back out danger of exterminationby predatory, and uppersides and silvery or whitishbelow, exotic fishes or further threatenedby com- and have an increasednumber of irregularly petition with mosquitofish. With this basic shapedbrownish vertical bars that are much thought in mind, C. L. Hubbs, R. R. Miller, narrower than those of the male. and E. P. Pister toured the Fish Slough area At the time of observation (late afternoon) on June 26, 1967, and conceived the idea of a behavior aptly termed leapfroggingwas establishinga refugiumutilizing the two north- repeatedlyobserved and was engagedin by westernsprings, of which the mostwesterly is both sexes. This consistedof individualsleap- the typelocality of the Owenspupfish (Figure ing sidewaysnearly vertically over a fallen •. In addition, it was decided that the other stem of Scirpus; some of the fish bit at the native fishes of the Owens Basin (a dace, stem as they passedover it. whereasothers Rhinichth.ys;a chub, Gila; and a sucker, only butted it and did not jump. The same Catostomus)should also be establishedthere. fish oftenflipped back and forth severaltimes Thisconcept was discussed and agreedupon over the stem. The pattern of movementwas with the landowner(the Los AngelesDepart- MILLER AND PISTER--MANAGEMENT OF OWENS PUPFISH 507

FIcuaz 5.--Vie* sontheas•ard acrosswesterly spring in Fish Sloughafter completionoi OwensValley NativeFish Sanctua•. Comparewith wate•level in Figure4. Oatflowf•o* northwesterlyspring in left back- ground. Febru• 2, 1970. ment of Water and Power), and all engineer- chemicaltreatment and desiccateany eggsof ing assistanceand designwork wasprovided exoticspecies (e.g., carp and bass) that might by that agency. The exotic fish barrier was have beendeposited earlier. On May 20 the basedon a designworked out by the engineer- sanctuarywas treatedwith calciumh}pochlo- ing staff of the NevadaDepartment of Fish rite lcommercial HTH) in the shoals and and Gameand usedsuccessfully for the White liquid rotenonein the deeperparts. To assure Riverspringfish, Crenichthys baileyi (Gilbert), a completekill, this procedurewas repeated at Sunnyside,Nevada, in 1963. on June 3. The sanctuarywas then filled to Approvalfor the OwensValley Native Fish optimum tmaximum) volume in anticipation Sanctuarywas granted by the CaliforniaFish of the forthcomingintroduction of the native and Game Commissionat its April, 1968, species. meeting,funds were budgeted,and construc- The precariousposition of C. radiosusis tion was completedin October, 1969, b) well illustratedby the followingevent which inmate labor crewsfrom the lnyo-Mono Con- occurredduring August, 1969, and which servationCamp underthe directionof John nearlyresulted in theloss of the few remaining N. Clark of the California Divisionof Forestry. individualsin Fish Sloughand, consequently, The refugecovers a surfacearea of 5.6 acres in completeextinction of the species.At that and is surroundedby a five-strandbarbed time an insidious decrease in the flow of the wire fence(Figure 5•. The totalarea enclosed springssupplying Fish Sloughoccurred. The is 21 acres. Depth may be loweredas much exact cause of the failure has not been deter- as three feet by the removalof flashboards mined,but is presumedto be the result of a in the outlet structure. At maximum depth natural summer decrease combined • ith trans- (about six feet) an ideal range of depths piration from an unusualamount of riparian exists,from abundantshoals for the pupfish vegetationcaused by abnormallyheavy pre- to deeperwater best suitedfor dace,chubs, cipitationduring the winterof 1968-69. Irre- and suckers. In April, 1970, the refuge was spectiveof the cause,the level of Fish Slough reduced to minimum volume to facilitate dropped to a point where the marsh area 508 TRANS. AMER. FISH. SOC., 1971, NO. 3 supportingthe only knownremaining pupfish Laura C. Hubbs, FrancesH., LaurenceB., and populationcompletely lost its water supply. BenjaminR. Miller, David Soltz (a graduate Fortunately,this condition was noted by studentfrom U.C.L.A. undersummer employ- Robert E. Brown, a graduatestudent at the mentby the Departmentof Fish and Game), Universityof California(Los Angeles), work- Robert E. Brown, Fred Partridge (a student ing as a summeremployee for the Department from HumboldtState College), Raimond Clary of Fish and Game. Approximately800 indi- (a graduatestudent from the University of vidualswere rescuedfrom the small,rapidly California at Berkeley), and was filmed for dryingponds below the northwesternsprings televisionby Bill BurrudProductions of Holly- of Fish Slough and placed in hastily con- wood. All fish trappedand nettedwere held structedlive cagesin the mainslough channel. in a live cage in the outlet of the Sanctuary. Again, inmate labor crews from the Inyo- It wasdecided that only Cyprinodonradiosus MonoConservation Camp provided invaluable would be introduced at this time in order to assistanceby deepeningthe watersupply chan- assureestablishment of the speciesprior to nels to the habitat areas. stockingthe threeother native fishes of Owens As thesechannels were deepened,gravel Valley (seebelow). percolatordams were placedin them to mini- Prior to introductioninto the Sanctuary, mize the possibility of invasion by exotic the pupfishwere sortedby age and sex, with species,and groups of C. radiosuswere re- the followingresults: males,142; females, introduced into four locations within the 249; immatures, 37. The total introduced slougharea. One introductionwas madeinto during the afternoonof June 30, 1970, was "BLM Spring,"an isolatedspring source on 428; water temperaturein the Sanctuarywas the eastside of the slough(Figure 2, sta.4). 74 F. Subsequentobservations reveal that the This site was hurriedly preparedfor a trans- Owenspupfish is becomingadjusted to the plant by chemicaltreatment (calcium hypo- newlycreated habitat. Long-termobservations chlorite) to removethe residentfish popula- on the successof the transplantwill be made. tion (carp, mosquitofish,and largemouth Plans also call for the settingaside of this bass), and 400 pupfishwere introducedinto areaas an ecologicalreserve by the California this springon August18, 1969. Three gravel Fish and Game Commission under a recent act barriers were placed in the stream channel (1969) of the Californialegislature. leading out of BLM Spring to assurethat A sanctuaryfor C. radiosusat BLM Spring, predatoryspecies could not ascendinto the on the eastside of FishSlough, will be jointly springarea. Althoughchemical treatment was designedby the Bureauof LandManagement successfulin removing the larger species, and CaliforniaDepartment of Fish and Game enoughmosquitofish survived to start another andwill be constructedby inmatelabor. Costs populationin competitionwith the pupfish. will be borne in part by the John Muir In- However,this transplantis the only oneknown stitute. to be completelysuccessful, although one A third refugium was constructedin the femalepupfish was seen in the main(northern- springof 1970 at Warm Springs,located at most) springby E. P. Pisteron May 15, 1970. the base of the White Mountainsin Inyo Sincethe August18, 1969,transplant, the pup- County, about five miles north of the town fish in BLM Spring increasedsignificantly of Big Pine. This was also built by inmate from the 400 initially transplanted;in late crewsfrom the Inyo-MonoConservation Camp June, 1970, it was conservativelyestimated with a designsimilar to that used at Fish that the springcontained 1,000 individuals. Slough. Constructionwas under the super- BetweenJune 26 and 30, 1970, collections vision of the California Departmentof Fish of Owenspupfish were made in the lowerpart and Gameon City of Los Angelesproperty. of BLM Spring by trapping and seining in The Warm SpringsSanctuary was inspected order to secure a stock for introduction into by us, accompaniedby Dr. and Mrs. Hubbs, its rehabilitatedhabitat, the Owens Valley on June 29, 1970. It was decided that this Native Fish Sanctuary. This operationwas siteshould be usedinitially as an area to test assistedby the authorsand by Carl L. and the interspecificrelationships and reactions of MILLER AND PISTER -MANAGEMENT OF OWENS PUPFISH 509 all four of the OwensValley native fishes. from the John Muir Institute to aid in the Plans are now under way to locate suitable constructionof a sanctuaryat BLM Springin stocksof the dace, chub, and sucker for trans- Fish Slough. Carl and Laura Hubbs enthu- plantationto this sanctuary,at which time C. siastically assistedin the developmentand radiosus will also be introduced. realizationof the OwensValley Native Fish The above-mentioned activities reflect an Sanctuary. Robert E. Brown may well have increasedawareness among both the scientific preventedthe loss of the last stock of the communityand the public concerningendan- Owenspupfish, and Robert K. Liu obtained geredspecies in generaland the Death Valley informationleading to the rediscoveryof the systemfishes in particular (Miller, 1969b; speciesas well as providingimportant infor- Bunnell, 1970; Deacon and Bunnell, 1970). mationon its breedingbiology. The National A PupfishTask Force (U.S. Departmentof ScienceFoundation (GB-4854), the National the Interior, 1970) chairedby JamesT. Mc- Park Service,the ZoologicalSociety of San Broom,Assistant Director of the U.S. Bureau Diego, and the National Wildlife Federation of Sport Fisheries and Wildlife, was estab- madepossible several field trips (by Miller) lished by the Departmentof the Interior in to OwensValley that were essentialto the May, 1970. completionof this paper. A symposiumconcerning the rare and en- dangeredfishes of the Death Valley system LITERATURE CITED was held at FurnaceCreek in November,1969 BUNNELL,STERLING. 1970. The desert pupfish. Cry (Pister,1970), and a secondmeeting is sche- California 5(2): 2-13. DEACON,JAMES, AND STERLINGBUNNELL. 1970. Man duledfor November,1970. A generalplan for and pupfish. Cry California 5(2): 14-21. speciespreservation was prepared and is con- HEINLY, Buu? A. 1910. Carrying water through a stantly being updated as old problemsare desert. Nat. Geog.21(7): 568-596. KENNEDY,CLARENCE HAMILTONß 1916. A possible solvedand new onesare created. Hopefully, enemy of the mosquito. California Fish and these activities will provide adequate safe- Game 2(4): 179-182. guardsfor the protectionof all desertfishes MILLEa, ROSEaTR. 1943. The statusof Cyprinodon maculariusand Cyprinodonnevadensis, two desert and other aquatic organismsin the face of fishes of western North America. Occ. Pap. Mus. ever-increasingencroachments into their native Zool. Univ. Mich. 473: 1-25. habitats. ß 1948. The cyprinodont fishes of the Death Valley system of eastern California and south- ACKNOWLEDGMENTS western Nevada. Misc. Publ. Mus. Zool. Univ. We are indebted to a number of individuals Mich. 68: 1-155. ß 1969a. Rare and endangered freshwater and organizationsfor their contributionsto fishes. In Fisher, James and others, The Red the completionof this project. Robert V. Book: Wildlife in danger. Collins, St. James's Phillips,Paul H. Lane, and DuaneM. George- Place, London, pp. 339-344. ß 1969b. Conservation of fishes of the Death son of the Los AngelesDepartment of Water Valley systemin California and Nevada. Trans. and Power made available the vast resources California-Nevada Section, Wildlife Soc. 1969: of their agencyin both land procurementand 107-122. PISTEa,E.P. 1970. The rare and endangeredfishes engineeringdesign. RussellRawson designed of the Death Valley system--a summaryof the the entireFish Slough facility. JohnN. Clark, proceedingsof a symposium relating to their J. Phil Thomas, and the foremen and work protection and preservation. California Depart- ment of Fish and Game (mimeographedreport), crewsof the CaliforniaDivision of Forestry's Sacramento.18 pp. q- Appendix. (Unpublished.) Inyo-Mono ConservationCamp constructed SNYDER,JOHN OTTERBEIN.1917. An account of some fishes from Owens River, California. Proc. U.S. theFish Slough and Warm Springs.sanctuaries Nat. Mus. 54: 201-205. and continueto provide assistancein their SUMNEE, F. B., AND M. C. SAEGENT. 1940. Some maintenance.Interest and supportwere pro- observationson the physiologyof warm spring vided by William M. Richardsonand Alex fishes. Ecology 21: 45-54. U.S. DEPARTMENT OF THE INTERIOR. 1968. Rare Calhounof the Departmentof Fish and Game. and endangeredfish and wildlife of the United Many other employeesof that agencyhave States. Wildlife Res. Publ. 34, U.S. Dept. Int., renderedinvaluable assistance throughout the Washington,D.C., 183 pp. ß 1970. A task force report on Let's Save the project. SterlingBunnell of the Nature Con- Desert Pupfish. U.S. Dept. Int., Fish and Wild. servancywas instrumentalin acquiringfunds life Service,Washington, D.C. 1970: 1-8.