Status and Life History Notes on the Native Fishes of the Alvord Basin, Oregon and Nevada

Great Basin Naturalist

Volume 43 Number 3 Article 5

7-31-1983

Status and life history notes on the native fishes of the Alvord Basin, Oregon and Nevada

Jack E. Williams U.S. Fish and Wildlife Service, Sacramento, California

Carl E. Bond Oregon State University, Corvallis, Oregon

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Recommended Citation Williams, Jack E. and Bond, Carl E. (1983) "Status and life history notes on the native fishes of the Alvord Basin, Oregon and Nevada," Great Basin Naturalist: Vol. 43 : No. 3 , Article 5. Available at: https://scholarsarchive.byu.edu/gbn/vol43/iss3/5

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 AND LIFE HISTORY NOTES ON THE NATIVE FISHES OF THE ALVORD BASIN, OREGON AND NEVADA

Jack E. Williams' and Carl E. Bond-

.\bstract.— Three fishes, two species of Gila, and an undescribed subspecies of cutthroat trout, are endemic to the Alvord Basin. Historically, the Alvord cutthroat trout, Salmo clarki ssp., inhabited the larger creeks of the basin but has been extirpated in pure form because of introgression with introduced rainbow trout, Salmo gairdneri. Gila boraxobitis is restricted to the thermal waters of Borax Lake and its outflows in the northern part of the basin. This

species is endangered because of alteration of its fragile habitat. The Alvord chub, G. alvordensis, is recorded from

16 localities throughout the basin, including springs, creeks, and reservoirs. Although G. alvordensis as a species is not in jeopardy, many populations are small and could be easily eliminated by habitat destruction or by the introduction of exotic fishes. Competition with exotic guppies, Poecilia reticulata, has extirpated the Thousand Creek Spring population of Alvord chubs. Both species of Gila are opportunistic omnivores, consuming primarily chironomids, microcrustaceans, and diatoms. Tlie Borax Lake chub also consumed large numbers of terrestrial insects, but specialized feeding on molluscs was noted in the West Spring population of Alvord chubs. Borax Lake chubs spawn throughout the year; however, most spawning occurs in early spring. Borax Lake chubs mature at a small size, occasionally less than 30 mm standard length, and seldom live more than one year. Alvord chubs are typically much larger than the Borax Lake species and live at least into their fifth year.

The Alvord Basin of southeastern Oregon and Whitehorse creeks just east of the Trout and northwestern Nevada is an endorheic Creek Mountains in a separate basin. Al- part of the Great Basin province. Aquatic though exhibiting affinities for the Alvord habitats are sparse and consist primarily of cutthroat trout, the subspecies foimd in Wil- Trout Creek in Oregon, the Virgin-Thousand low and Whitehorse creeks will not be Creek system in Nevada, as well as several treated further in this report. small streams and springs (Fig. 1). During the Our knowledge of the native fishes of the late Pleistocene, a lake of over 1,200 km^ Alvord Basin is limited. The monograph of covered much of the valley floor (Snyder et Great Basin fishes by Hubbs and Miller al. 1964). As pluvial waters dried, fishes were (1948) provided the first detailed account of restricted to remaining permanent springs the Great Basin ichthyofauna and included a and creeks. Three native fishes are endemic brief discussion of the native Alvord Basin to the Alvord Basin. Chubs, genus Gila, oc- fishes and their isolation. However, all the cupy many of the isolated waters in the Al- Alvord Basin fishes remained undescribed un- vord Basin and have diverged into two spe- til 1972, when Hubbs and Miller (1972) diag- cies. The Alvord chub, Gila alvordensis, is nosed the Trout Creek population of Gila as the most common fish in the basin and occurs G. alvordensis. Our studies have resulted in in a variety of springs and creeks. The Borax the description of Gila boraxobitis (Williams

Lake chub, G. boraxobitis, is restricted to Bo- and Bond 1980) and a further description of rax Lake and its outflows in Oregon. The Al- G. alvordensis with a taxonomic analysis of vord cutthroat trout, Salmo clarki ssp., is the seven disjunct populations of the species third fish native to the basin. Historic habitat (Williams 1980, Williams and Bond 1980). for the Alvord cutthroat trout consisted of Characters of the Alvord cutthroat trout have the larger streams in the basin, such as Trout been provided by Behnke (1979), but the sub- and Virgin creeks. Another undescribed subspecies remains undescribed. The only pub- species of cutthroat trout occurs in Willow lished life history information on Alvord

'Endangered Species Office, U.S. Fish and Wildlife Service, 1230 "N" Street, 14th Floor, Sacramento, California 95814. 'Department of Fisheries and Wildlife, Oregon State University, Corvallis, Oregon 97331.

409 410 Great Basin Naturalist Vol. 43, No. 3

o 119 mJk

/^ Borax Lake. ,^

4 /

^Dufurrena Area ^og Hot Thou Cr . I T.- . Res :^J

I 1 I 1 km

Fig. 1. Map of major aquatic habitats in the Alvord Basin, Oregon and Nevada.

Basin Gila consists of a study of feeding ecol- of the native fishes of the Alvord Basin and ogy by Williams and Williams (1980). This presents additional information on their life paper documents the distribution and status history. July 1983 Williams, Bond: Native Fishes 411

Materials and Methods enumerated in larger females by multiple subsamples of the ovary. Age was determined The distribution and status of fishes was by examining annuli of scales taken from the determined by field surveys, museum records, left side of the body above the lateral line. and testimony of local residents. Many of the Monthly collections were grouped into sea- habitats in the Oregon part of the basin were sons as follows: spring (March-N4ay), summer known prior to this work. On the other hand, (June-August), fall (September-November), the Nevada part of the basin had received and winter (December-February). little attention by ichthyologists, and there- fore most of our survey efforts were focused in the southern one-half of the basin. Surveys Population Accounts were conducted from 12 June 1978 to 26 Au- to gust 1979 and from 13 15 April 1982. Alvord Cutthroat Trout, Salmo clarki ssp. Habitats were sampled with 3 m seines (9.5 mm mesh), dip nets, fish traps, backpack The Alvord cutthroat trout, Salmo clarki ssp., is extinct in electroshocker, and 15 m gill nets (51 mm now pure form. This native mesh). Fishes utilized in this study are depos- trout was known from Virgin Creek in Ne- vada ited at Oregon State University (OS), The and Trout Creek in Oregon, but probably existed in several of the larger University of Michigan Museum of Zoology Alvord Basin creeks during recent times (UMMZ), Tulane University (TU), and the (Hubbs and Miller 1948). University of Nevada, Las Vegas (UNLV). Trout Creek (Harney County, Oregon).— Information concerning reproduction, lon- The Alvord cutthroat trout occurred in the gevity, and adult sex ratio was determined headwater canyon area of Trout Creek, for Borax Lake chubs collected monthly from where it flows through the Trout Creek March 1978 to January 1979. Fish were col- Mountains. Introgression of introduced rain- lected from the southwest one-quarter of Bo- bow trout, Salmo gairdneri, with the native rax Lake. Specimens were preserved in 10 cutthroat was already noticeable in 1934 col- percent formalin and transferred to 45 per- lections of fish made in Trout Creek by Carl cent isopropanol after one week. Standard L. Hubbs, although trout from more head- length (SL) of specimens was measured to the water localities were quite similar in appear- nearest 0.1 mm with dial calipers. After ance to pure Alvord cutthroat trout (Behnke blotting fish dry on paper towels, wet weight 1979). Cutthroat trout pigmentation was evi- was measured to the nearest 0.01 gona- g. A dent in many specimens collected by one of dosomatic index was calculated weighing by us (CEB) in 1953 and 1957, but none had the left testis ovary or to the nearest 0.001 g, basibranchial teeth. Trout collected from* multiplying by two, thereby accounting for Trout Creek in 1972 (Behnke 1979) and 1978 the right gonad, and dividing by fish weight. to 1980 (our collections) exhibited only rain- Three classes of ova were identified: class 1— bow trout characteristics and we conclude mature ova, yellow color, 0.7 to 1.2 mm di- that the native trout has been extirpated ameter; class II— immature ova, opaque from this creek. Collections made from Cot- white color, 0.4 to 0.6 mm diameter; and tonwood Creek and other streams draining class III—immature ova, transparent, 0.1 to the Trout Creek Mountains yielded only rain- 0.3 mm diameter. The number of ova was bow trout. enumerated in females that possessed only Virgin Creek (Humboldt County, Ne- class I and/ or class II ova. By this method, vada).— Thirty small (<15 cm) Alvord cut- accurate counts could be obtained and these throat trout were collected from Virgin numbers are probably more indicative of the Creek in or near Virgin Creek Gorge by Carl actual number of eggs deposited during L. Hubbs in 1934 (UMMZ 130532). Behnke spawning. In females shorter than 35 mm SL, (1979) considers these specimens to be pure all ova were counted in both ovaries. In fe- native cutthroat trout and provides their de- males 35 to 50 mm SL, all ova were counted scription as follows: body with fewer than 50 in the left ovary, then multiplied by two to relatively large round spots, spots concen- derive the total number of ova. Ova were trated posteriorly and above lateral line; few 412 Great Basin Naturalist Vol. 43, No. 3

spots on caudal fin. Gill rakers 20 to 26. Lat- and soft, easily roiled silt in the remainder of eral series scales 122 to 152. Scales above lat- the lake. The lake shoreline consists of salt eral line 33 to 37. Pelvic fin rays 8 or 9. crusts, which have been deposited by the lake Branchiostegal rays 8 or 9. Vertebrae 59 to waters. These salt deposits have built up over 63. Trout collected in 1971 (OS 3832, OS hundreds or, more probably, thousands of

3834) from approximately the same region of years until the lake is now 10 m higher in Virgin Creek exhibited typical rainbow trout elevation than the surrounding land. Histori- features (Behnke 1979). During 1978 surveys, cally, the lake waters overflowed along the we found only rainbow trout or introgressed south and southwest shoreline, creating a trout in Virgin Creek at and upstream of the marsh. These outflows also provided water north end of Virgin Creek Gorge. No fish for Lower Borax Lake, a reservoir southwest were found in Virgin Creek Gorge at the of Borax Lake. Adjacent to Borax Lake are Virgin creeks. up- nexus of Hell and The two small pools, one about 25 m southwest of stream sections of Virgin Creek, in Virgin Borax Lake and an artificial pool about 75 m Creek Gorge near Alkali Ranch, also are fish- west of the lake. less. Although received reports of large we Borax Lake chubs occur throughout Borax trout from beaver ponds in Virgin Creek Lake except in the hot spring inflows. Obser- Gorge downstream of Wilson Ranch, none vations at Borax Lake indicated that Borax could be secured for examination. The large Lake chubs avoided water with a temper- number of introduced rainbow trout in Vir- ature above 34 C. These observations are gin Creek Gorge would seem to preclude the supported by unsuccessful attempts to chase survival of pure Alvord cutthroat trout in the chubs into hot spring inflow areas. In Virgin Creek. An extensive survey of Hell aquaria. Borax Lake chubs lost equilibrium Creek, the only permanently flowing tribu- when water temperature was raised to 34.5 tary of upper Virgin Creek, revealed only a C, indicating a critical thermal maximum single fish, which was typically rainbow in near this temperature. Borax Lake chubs also character. This individual was apparently occurred in small numbers in the two small able to ascend the falls separating Hell and pools near Borax Lake. The pools are appar- Virgin creeks during a flood. The negative ently formed from Borax Lake overflow survey of Hell Creek in 1978 and 1979 causes waters. us to consider the Alvord cutthroat trout to The Borax Lake chub is a dwarf species be extinct. that typically reaches maturity at 30 to 35 mm SL. Males as small as 28.6 mm SL are highly tuberculate and females as small as Borax Lake Chub, Gila boraxobius 31.8 mm SL have been found with mature The Borax Lake chub, Gila boraxobius eggs. Typical adult size is 33 to 45 mm SL. Williams and Bond, is restricted to the ther- The largest male collected from Borax Lake mal waters of Borax Lake and its outflows. was 50.6 mm SL, whereas two exceptionally Gila boraxobius was described in 1980 and is large females, 90.4 and 93.0 mm SL, have considered a dwarf relative of G. alvordensis been collected from Borax Lake. (Williams and Bond 1980). Most spawning probably occurs in early Borax Lake (T37S, R33E, Sec 14; Harney spring, although some spawning can occur County, Oregon).— Borax Lake is a relatively year around. The gonadosomatic index was shallow 4.1 ha natural lake that receives wa- highest in females during March and April, ter from several thermal springs. These with mature, class I ova present during springs issue into the bottom of the southwest March, April, and January (Table 1). Ovaries portion of the lake at approximately 35 to 40 were usually poorly developed during May C. Lake temperature is typically 29 to 32 C through August. In males, the gonadosomatic but can vary from 17 to 35 C depending on index was highest in April and September, season, weather, and distance from the spring when testes averaged 0.97 and 1.11 percent sources. The water is clear. Substrates range body weight, respectively. A search of mu- from rocky outcroppings in the southeast seum specimens disclosed large females with portion of the lake to gravels in the north mature ova collected on 17 June (OS 4137) July 1983 Williams, Bond: Native Fishes 413 and 11 September (OS 4106). Thus, spawning Most older fish are females. Adults (>33 mm may occur at any time of the year. However, SL) typically comprised less than 25 percent a major spawning in early spring is supported of specimens collected during March, April, by observation of numerous larval chubs dur- and May. The percentage of adults in month- ing April, May, and early June. Young fish, ly collections then increased until reaching a eight to 15 mm SL, typically inhabit the shal- peak of 82 percent during November. low cove areas along the west and south mar- Based on monthly collections made gins of Borax Lake. Water is cool, only a few throughout the year, the sex ratio of 190 indi- cm deep, and vegetation is common in the viduals greater than or equal to 30 mm SL coves. was 1.0(5 :1.3 ? . Seasonally, the sex ratio was increases = Ova number dramatically with as follows: spring (n 23) 1.0(5 :1.3 ? , sum- fish length. The number of ova was deter- mer (n = 67) 1.0(5:1.9$, fall (n = 50) mined in eight females 32.7 to 93.0 mm SL, 1.0 5:11?, and winter (n = 50) 1 <5 :1 ? . that contained only class I and/ or class II The larger number of females may be in- ova. The smallest females examined, 32.7 and dicative of higher survivorship following 34.5 mm SL, contained 75 and 82 ova, re- spawning. spectively. Larger females, 39.0, 39.3, 44.6, The feeding ecology of Borax Lake chubs and 49.4 mm SL contained 252, 246, 380, has been reported by Williams and Williams and 362 ova, respectively. The exceptionally (1980). The relative importance of foods var- large females, 90.4 and 93.0 mm SL con- ied seasonally, but diatoms, microcrustaceans, tained 2,143 and 6,924 ova, respectively. Al- and chironomid larvae were often the pri- though females larger than 60 mm SL are mary foods consumed. Terrestrial insects very rare in Borax Lake, their contribution to were important foods during summer and fall recruitment may be substantial. (Williams and Williams 1980). Lake (T37S, Sec Most Borax Lake chubs live one year, with Lower Borax R33E, 15; Harney County, Oregon).— Lower Borax few age I and II fish present. Annuli devel- Lake is a reservoir that receives water from opment, although difficult to discern, in- the southwest outflow creek of Borax Lake. dicated that the 90.4 and 93.0 mm SL fe- Water levels of Lower Borax Lake fluctuated males were probably age III. This appears to seasonally, often holding little water during be the maximum age achieved by chubs in summer. Unfortunately, alteration to Borax Borax Lake. A length frequency analysis of Lake during 1979 diverted water away from 113 individuals collected 5 August 1977 ap- the reservoir. Prior to the diversions, the res- pears in Figure 2. Because most spawning oc- ervoir occasionally harbored Borax Lake curs in spring, with young of approximately chubs that entered from the southwest out-

10 mm SL prominent in May and June, most flow creek. It is doubtful that Borax Lake fish in the August collection are probably chubs ever spawned in Lower Borax Lake* young-of-the-year. Some age I fish, 33 mm to and the population was probably dependent 51 mm SL are present, whereas the two on an influx of fish from Borax Lake via the larger individuals are probably age II (Fig. 2). outflow creek.

Table 1. Monthly reproductive characteristics of female Borax Lake chubs longer than 30 mm SL. 414 Great Basin Naturalist Vol. 43, No. 3

>« u c 0) 3 10 O" 0>

n I n 15 21 27 33 39 45 51 57 63 696<

Standard Length in mm

Fig. 2. Length frequency of 113 Borax Lake chubs, Gila boraxobius, collected 5 August 1977 from Borax Lake, Oregon.

Alvord Chub, Gila alvordensis during the summer. Adult males are typically about 50 mm SL and adult females average The Alvord chub, Gila alvordensis Hubbs approximately 65 mm SL, but females great- and Miller, was found in 16 habitats located er than 80 mm SL are occasionally collected. throughout much of the basin in Oregon and Alvord chubs from Serrano Pond are high- Nevada. The species was collected from a va- ly opportunistic feeders. Bottom in- riety of habitats, including springs, creeks, vertebrates are grazed extensively, as are and reservoirs. The species has been collected midwater crustaceans and diatoms. Very few from Jimiper Lake, Oregon (Bond 1974), al- foods are consumed from the water's surface. though its presence appears attributable to Chironomid larvae, diatoms and cladocerans an introduction because the lake dries during were the principal foods during summer, and drought years. ostracods, harpacticoid copepods, and chi-

Serrano Pond (T36S, R33E, Sec 1; Har- ronomid pupae were of secondary impor- ney County, Oregon).— Serrano Pond is a 0.1 tance (Williams and Williams 1980). Eighty- ha reservoir that receives water from a cool- nine percent of the intestines examined by water spring approximately 60 m distant. Williams and Williams (1980) contained one Water flows from the spring at approx- food that accounted for more than 50 per- imately 17 C and water temperature in the cent of intestinal volume. Thirty-nine per- pond is typically 16 to 21 C during the sum- cent of the intestines contained one food, chi- mer. The substrate of the relatively shallow ronomid larvae, diatoms, or cladocerans, pond is primarily silt. The water is somewhat almost exclusively. turbid and aquatic vegetation is abundant. Trout Creek and Alvord Lake (Harney Recent alteration to this area has resulted in County, Oregon).— Trout Creek is the largest a diversion canal draining part of the flow stream in the Alvord Basin and discharges an away from the pond. Alvord chubs are absent average of 15 cfs, as measured in the canyon from the spring, but are abundant in remain- area 8 km east of Trout Creek Ranch (Libbey ing waters of the pond and in the diversion 1960). The creek heads in Trout Creek creek. More than 100 fish can be easily col- Mountains just north of the Nevada border. lected from the pond in a single seine haul In the headwaters. Trout Creek flows July 1983 Williams, Bond: Native Fishes 415 through canyon areas where its waters are by Van Horn and Colony creeks, which drain clear and fast-flowing. Water temperature in the Pueblo Mountains, as well as at least 25 the canyon is cool during summer, near 15 C, springs in the slough itself. These springs are and colder during winter months. As Trout mostly cool and shallow. Red Point School leaves the enters the val- Creek canyon and (T40S, R35E, Sec 14) is located in approx- ley floor, flows decrease and water temper- imately the center of the slough. In August, atures increase. Naturally lower summer Alvord chubs were collected from a shallow, flows and irrigation diversions often reduce clear pool at Red Point School where water the lower portions of Trout Creek to in- an and air temperatures were 15 and 17 C, re- termittent stream during late summer. Turbi- spectively. Alvord chubs were abundant in dity is often high (visibility 1 cm) in lower the pool. Despite searches for chubs in reaches during summer. Substrate type streams draining the Pueblo Mountains, none changes from mostly gravel in upstream areas could be found— although small rainbow to silt in downstream sections. Trout Creek trout were collected in lower Van Horn eventually empties into Alvord Lake, a rem- Creek. nant of the large lake that covered the valley Bog Hot Reservoir (T46N, R28E, Sec 17; during pluvial times. Alvord Lake varies Humboldt County, Nevada).— Bog Hot Res- greatly in size and occasionally dries com- ervoir is a relatively small impoundment fed pletely during drought years. by thermal waters flowing from Bog Hot Alvord chubs are common, although not Springs. Water issues from Bog Hot Springs abundant, in upstream canyon areas, and at approximately 44 C and flows for 1.2 km abundant in downstream sections. Introduced before entering Bog Hot Reservoir. Water rainbow trout, Salrno gairdneri, also occur in from Bog Hot Springs enters the reservoir at upstream regions of Trout Creek. This is the about 30 C. Typical water temperatures in only habitat where Gila occur sympatrically the reservoir are 20 to 21 C during early with another fish in the Alvord Basin. Alvord summer. The waters of Bog Hot Reservoir chubs in the canyon area are large, the long- are slightly turbid (visibility 31 cm), and the est measuring 122 mm SL. Three specimens substrate is mostly silt with some gravel. Al- 113 to 122 mm SL are all age class IV. vord chubs are abundant in Bog Hot Reser- Downstream areas also produce large Alvord voir but are absent in Bog Hot Springs and in chubs, although maximum length appears practically all the inflow creek between the somewhat less. Color differences between Al- springs and the reservoir. No Alvord chubs vord chubs in the canyon and downstream were found upstream of the 31.1 C boundary, areas are striking. Alvord chubs from the can- where water from the inflow creek enters yon are very dark, nearly black, dorsally, Bog Hot Reservoir. with golden sides possessing some black Alvord chubs collected from Bog Hot Res- speckles, and a silver belly. In sections of ervoir on 13 June 1978 were in spawning Trout Creek in the valley floor, Alvord chubs condition. On that date, water and air tem- are lighter in color, exhibiting a light green peratures were 20.4 and 20.7 C, respectively. color on the dorsal part of the head and The fish were collected from open, slightly body, silver sides without speckles, and a turbid water, 30 to 40 deep. Young-of- white belly. All fins of Gila from Trout cm the-year fish to 15 were abundant Creek are translucent red or orange in color 10 mm SL in reservoir indicating except at the tips, which are white. the during June 1978, Pueblo Slough (T40S, R35E and T41S, a spawning season from at least April imtil R35E; Harney County, Oregon).— Pueblo July. Most young were observed in the shallow northwest end of the reservoir near the ( = Denio) Slough is a wetland area approximately 13 km long, extending from Tum warm inflow creek. Turn Lake in the north to just north of the Bog Hot Creek (T46N, R28E; Humboldt Nevada border in the south. Various marsh, County, Nevada).— Bog Hot Creek flows for spring, and creek areas south of Tum Tum approximately 5.2 km below Bog Hot Reser- Lake provide most of the habitat in the voir before entering Thousand Creek. Parts slough. Water in Pueblo Slough is provided of Bog Hot Creek below the reservoir have 416 Great Basin Naturalist Vol. 43, No. 3

been diverted or otherwise modified by agri- with some silt. Water and air temperatures cultural practices. Alvord chubs were not during June were 27.1 and 18.2 C, respec-

collected in Bog Hot Creek except in the tively. Currently, the spring is inhabited by lower reaches near Thousand Creek. One swarms of exotic guppies, Poecilia reticulata. poeciliid, probably a guppy, was observed in Guppies have become established here and in the highly modified section of the creek the spring pool at nearby Dufurrena Camp- about halfway between the reservoir and ground. Competition from introduced gup- Thousand Creek. In the downstream part of pies probably extirpated Alvord chubs from Bog Hot Creek, Alvord chubs were rare to Thousand Creek Spring. Alvord chubs have common during an April 1982 svirvey and oc- not been recorded from Thousand Creek curred primarily in pools 20 to 46 cm in Spring, but their historic presence is in- depth. Water and air temperatures on 15 dicated by the occurrence of Alvord chubs in April 1982 were 2.3 C and 1.5 C, respective- downstream areas of Thousand Creek and in ly. The water was clear, but appeared brown a nearby spring. Except for the presence of and quite acidic. guppies. Thousand Creek Spring appears to Unnamed spring (T46N, R26E, Sec 31; provide a suitable habitat for Alvord chubs. Humboldt Covmty, Nevada).— This spring, Thousand Creek and Continental Lake measuring 2.4 wide and 5 long at its m m (Humboldt County, Nevada).— Thousand maximiun extent, is by far the smallest habi- Creek heads at Thousand Creek Spring, flows tat supporting fish in the Alvord Basin. Max- through the Dufurrena area, where it re- imum depth is 77 cm. The water is clear and ceives Virgin Creek, and then enters Thou- the substrate is an easily roiled silt. Water sand Creek Gorge. Below the gorge. Thou- temperature was 11.4 C (air 7.5 C) during sand Creek becomes braided and receives April and 18.2 C (air 20.4 C) during June. water from Bog Hot Creek before eventually The unnamed spring is well isolated from emptying into Continental Lake. In the Du- nearby Thousand Creek by approximately furrena area, Thousand Creek is dammed at 100 m of greasewood flat. The closest waters several locations to create reservoirs. Thou- of Thousand Creek do not support Alvord sand Creek is usually turbid (visibility 7 cm), chubs. The nearest population occurs approx- shallow, and about 1 to 2 m wide. The sub- imately 1 km away in Dufurrena Pond 19. strate is mostly silt. In Thousand Creek A very small population of Alvord chubs, Gorge, the creek is surprisingly deep (>300 estimated at slightly less than 100 individuals, cm) and cool, near 15 C during late summer. inhabits the spring. Many seine hauls, each Below the gorge. Thousand Creek is often in- encompassing the entire spring, yielded 52 termittent during summer, when water tem- fish during an April 1982 survey. The Alvord peratures can reach 27 C. Typical summer chubs ranged in size from 32 mm SL to, con- and fall water temperature is 16 to 18 C. Al- sidering the small size of the habitat, an ama- vord chubs are abundant in Thousand Creek zingly large 87 mm SL individual. No juve- except in some upstream areas where guppies niles were seen during April, but young-of- have been introduced or habitat has been al- the-year were observed on 14 June, when wa- tered reservoir are ter temperature had risen to 18.2 C. Juveniles by construction. Guppies in Spring oc- occurred among rushes, Juncus sp., in water abundant Thousand Creek and only a few cm deep. Adults were occasionally cur sporadically in Thousand Creek between observed darting across the open center of Thousand Creek Spring and Dufurrena Pond the spring, but spent most of the daylight 19. None were found downstream of Dufur- hours under a narrow band of floating algal rena Pond 19. Thousand Creek contains mats along the periphery of the spring. many large Alvord chubs; the largest mea- Thousand Creek Spring (T46N, R26E, sured 104.9 mm SL. During summer, Alvord Sec 31; Humboldt County, Nevada).— Thou- chubs concentrate in deep pools in down- sand Creek Spring forms the headwaters of stream areas of Thousand Creek. Continental Thousand Creek. The clear spring waters Lake usually dries completely during sum- achieve a maximum depth of approximately mer, but harbors Alvord chubs during winter 31 cm. Substrates are mostly fine gravels months. July 1983 Williams, Bond: Native Fishes 417

The sex ratio of 23 adults greater than 35 Creek from the north end of Virgin Creek mm SL was 1.1 5 :1.0 ? . Food habits of Al- Gorge to the nexus of Virgin and Thousand vord chubs collected during Jime from Thou- creeks. Alvord chubs are absent in Virgin sand Creek were reported by Williams and Creek Gorge, where introduced rainbow Williams (1980). They found 10 foods in the trout are common. Virgin Creek below the intestines, of which chironomid larvae, cla- gorge is cool, relatively shallow, and moder- docerans, copepods, and ostracods were of ately turbid (visibility 10 cm). Below the greatest importance. Chironomid larvae oc- gorge, water temperature is typically 15 to curred in all intestines examined and ac- 18 C during summer months and maximum counted for approximately 26 percent mean depth is usually less than 75 cm. The sub- volume (Williams and Williams 1980). Mi- strate is mostly silt. crocrustaceans comprised almost 45 percent Warm Spring (T45N, R25E; Humboldt mean volimie of intestines, whereas diatoms County, Nevada).— Warm Spring and its out- accoimted for only 5 percent mean volume. flow are tributary to Virgin Creek approx- No terrestrial insects were observed in the in- imately 2.5 km downstream from Virgin testines. Alvord chubs in Thousand Creek ap- Creek Gorge. The outflow creek is a small, pear to feed primarily on bottom in- clear-water stream with an easily roiled silt vertebrates and midwater crustaceans, bottom. Summer water and air temperatures avoiding surface foods. of the creek just below the spring were 26.0 DuFURRENA PoND 19 (T46N, R26E, Sec and 26.4 C, respectively. Alvord chubs are

32; Humboldt County, Nevada).— Dufurrena abundant in the outflow creek. The spring it- Pond 19, approximately 1 km downstream of self was not sampled, but Carl Hubbs col- Thousand Creek Spring, is the first reservoir lected Alvord chubs from the spring in 1934 on Thousand Creek. The reservoir is shallow ("Italian Camp Spring," UMMZ 130533). (typically < 50 cm) and moderately turbid The steep gradient and low flow of the

(visibility 14 cm). Alvord chubs occur in the Warm Spring crenon as it approaches Virgin reservoir but are not abundant. Young-of-the- Creek inhibits mixing between the Virgin year (<20 mm SL) were abundant during Creek and Warm Spring populations of Al- June in the inflow diversion creek feeding the vord chubs. Although Warm Spring flows reservoir. At this time, the inflow creek was through Virgin Valley Ranch, the spring and shallow (< 8 cm) and clear, with water and outflow creek have been only slightly altered air temperatures of 14.5 and 13.0 C, and no exotic fish were present during a 1978 respectively. survey of the spring system. Dufurrena Pond 22 (T45N, R26E, Sec 2; Dufurrena Pond 13 (T45N, R26E, Sec Humboldt County, Nevada).— Dufurrena 17; Humboldt County, Nevada).— Dufurrena

Pond 22 is a reservoir fed by waters of Thou- Pond 13 is the only reservoir on Virgin Creek sand and Virgin creeks. The water is very between Virgin Creek Gorge and Thousand turbid (visibility 2 cm) and shallow (typically Creek. Water characteristics are typically 15 to 20 cm deep). Water level fluctuates those of Virgin Creek except that maximum greatly with season. During late summer, the depth is greater (almost 2 m) and aquatic reservoir is reduced to a small pool. Water vegetation is abundant. Alvord chubs are and air temperatures during June were 17.6 common to abundant just upstream and and 13.2 C, respectively. Alvord chubs are downstream of the reservoir but are rare in abundant and achieve a large size in the the pond itself. reservoir. Gridley Springs (T44N, R27E, Sec 22; Virgin Creek (Humboldt County, Ne- Humboldt County, Nevada).— Gridley vada).— Virgin Creek heads near the southern Springs is a series of approximately 17 cool- extent of the Alvord Basin, flows north water springs located on an alkali flat just through the more than 300-m-deep Virgin south of the Gridley Lake playa. Many of the Creek Gorge, and then flows east until reach- springs are little more than seeps, but a few ing Thousand Creek. Springs scattered along have spring pools nearly 2 m deep with out- most of the length of Virgin Creek provide flow creeks 30 or 40 m in length. During its flow. Alvord chubs are abundant in Virgin April 1982, most of the spring waters were 418 Great Basin Naturalist Vol. 43, No. 3

10-

5- R U4 ^ 27 33 39 45 51 57 63 69 75 81 87 93

Standard Length in mm

Fig. 3. Length frequency of 44 Alvord chubs, Gila alvordensis, collected 14 April 1982 from Gridley Springs, Nevada. clear, with a temperature of 12 C (air 10 C). spring and its outflow creek. The largest of Rushes, Juncus sp., were the dominant plants 33 individuals collected on 18 August 1978 around the springs, with some larger springs was 62.8 mm SL. The sex ratio of 30 adults also harboring pondweed, Potamogeton sp., greater than 40 mm SL was 1^:1$. Alvord and cattails, Tijpha sp. Only one of the 17 chubs collected during August from West springs examined contained Alvord chubs. Spring fed exclusively or almost exclusively

This spring is located near the northwestern on small hydrobiid snails. This snail, which margin of the Gridley Springs series. Alvord occurs in great abundance, apparently repre- chubs were found in the outflow creek, sents an undescribed species endemic to West which extended approximately 40 m and was Spring (Jerry Landye, pers. comm.). 3 m wide at its greatest extent. Only a trace West Creek (T44N, R27E, Sec 20, 28, 29; of current could be detected in the creek. Humboldt County, Nevada).— West Creek The water was imusually turbid, visibility 4 flows for nearly 3 km before emptying into cm, with a maximimi depth of 30 cm. Water the alkali flat approximately 2 km south of temperature was 11.5 C (air 6.8 C) on 14 Gridley Springs. Because West Creek is

April 1982. The bottom was silt. Unlike most formed by West Spring, water characteristics of the larger springs in the area, this spring are similar for both. The creek is quite small,

contained only rushes along its margin. The often 1 to 2 m in width and less than 15 cm

Gridley Springs area is overgrazed by cattle deep. Current is moderate in the upper

and horses, but it is not known to what extent reaches but slows considerably upon reaching

this is detrimental to the Alvord chub the flat. Alvord chubs occur throughout the population. creek, but are somewhat smaller than those Alvord chubs were not abundant in the in West Spring. outflow creek, but were common enough to collect 50 fish in three short seine hauls. Discussion Forty-four individuals collected in April 1982 ranged in size from 27 to 91 mm SL, but The Alvord cutthroat trout, Alvord chub, were mostly 30 to 38 mm SL (Fig. 3). The sex and Borax Lake chub are all restricted in dis- ratio of 32 individuals greater than 35 mm tribution to waters of the Alvord Basin. The Alvord cutthroat trout is now extinct but for- SL was 1 5 :3 ? . West Spring (T44N, R27E, Sec 20; Hum- merly occurred in larger creeks of the basin. boldt County, Nevada).— West Spring issues Hybridization with introduced trout caused from the base of Big Mountain and forms the demise of the native form. The Borax West Creek, which flows into the alkali flat Lake chub has the most restricted natural dis- south of Gridley Springs. The waters of West tribution of the three fishes, occurring only in Spring are clear and shallow. Maximum Borax Lake and adjacent lake outflows. The depth is 12 cm over a gravel and sand sub- Alvord chub is relatively widespread in the strate. Water and air temperatures recorded basin and was recorded from 16 localities, in- during summer were 21.8 and 20.4 C, respec- cluding Bog Hot Reservoir, Bot Hot Creek, tively. Alvord chubs are common in the Thousand Creek Spring, an unnamed spring. July 1983 Williams, Bond: Native Fishes 419

Dufurrena Pond 19, Dufiirrena Pond 22, Du- very small springs, such as the unnamed furrena Pond 13, West Spring, and West spring and Gridley Springs, Alvord chubs Creek as new locality records. achieve 90 mm SL. The presence of large Because of the fragility of the small aquat- chubs in the cool springs and creeks indicates ic habitats and the overall paucity of water in a longer life span for the Alvord chub than the basin, the two extant native fishes are typically occurs for the Borax Lake species. easily threatened by the activities of man. Borax Lake chubs spawn year around in their The naturally restricted range of the Borax thermal lake habitat, but a spring spawning

Lake chub and threats from geothermal peak is indicated. Alvord chubs appear to energy development prompted the American spawn only once a year in their thermally

Fisheries Society to list the species as threat- fluctuating habitats. Both species of Gila are ened in 1979 (Deacon et al. 1979). Also dur- opportunistic omnivores, consuming primari- ing 1979, several portions of the north and ly chironomids, microcrustaceans, and dia- east shoreline of Borax Lake were altered so toms. The Borax Lake species also consumed that overflow waters exited the lake to the large quantities of terrestrial insects during north and east rather than to the south and summer and fall. The Alvord chubs in West Spring are unusual in that west, as was the historical condition. This al- they are greatly dependent on the endemic hydrobiid snail for teration caused Lower Borax Lake as well as food. the marsh and pools to the south and west to dry, thus eliminating Borax Lake chubs from these waters. Leasing of surrounding lands Acknowledgments for geothermal exploration and alteration of Funds to study the Alvord Basin fishes the shoreline caused the U.S. Fish and Wild- were provided by U.S. Fish and Wildlife Ser- life Service temporarily to list the Borax vice contract 14-16-0001-78025 to inventory Lake chub as an endangered species on 28 the fishes of the Sheldon National Wildlife May 1980. As a result of the listing, geother- Refuge and by the Department of Fisheries mal exploration was prohibited from a one- and Wildlife at Oregon State University. The mile buffer zone around Borax Lake. The study greatly benefited from the field and listing emergency has since been supple- editorial assistance of Cynthia D. Williams. a final rulemaking that mented by designated S. Taylor, Ray J. J. Long, K. M. Howe, G. the species as endangered pursuant to the DeMott, B. Boccard, A. Tiehm, J. E. Deacon, Endangered Species Act. The Alvord chub M. S. Deacon, D. E. Deacon, and E. M. Lo- has fared better than the Borax Lake species rentzen assisted with field collections. Robert of its distribution. because wider Never- R. Miller lent museum specimens and collec- theless, competition with exotic guppies has tion notes of our late mentor, Carl Leavitt extirpated the Thousand Creek Spring popu- Hubbs. Reviews of this paper were provided lation of Alvord chubs, and other populations Williams, E. E. P. Pister, by C. D. J. Deacon, are threatened by habitat alteration. The Al- and S. V. Gregory. This contribution is Tech- vord chub appears easily eliminated by the nical Paper 6510 of the Oregon Agricultural presence of exotic fishes. Thousand Creek Experiment Station. reservoirs stocked with game fish, such as Dufurrena Ponds 20 and 21, lack Alvord Literature Cited chubs. White crappie, Pomoxis annularis, R. 1979. of the native troiits of pumpkinseed, Lepomis gibbosiis, and large- Behnke, J. Monograph America. Re- mouth bass, Micropterus sahnoides, were col- the genus Salmo of western North port to U.S. Fish and Wildlife Service. 215 pp. lected from Dufurrena Ponds 20 and 21. Bond, C. E. 1974. Endangered plants and animals of Borax Lake are dwarf typically chubs and Oregon I. Fishes. Agricultural Exp. Station, Ore- mature at 30 mm SL. Adults are usually 33 gon State Univ. Spec. Rept. 205. 9 pp. Deacon, E., G. Kobetich, D. Williams, S. mm to 45 mm SL and typically live for one J. J. Co.NTRERAS, et al. 1979. Fishes of North America year. A few Borax Lake chubs, mostly fe- endangered, threatened, or of special concern: males, live year. more than one Adult Alvord 1979. Fisheries 4:29-44. chubs are larger, achieving more than 100 Hubbs, C. L., and R. R. Miller. 1948. The zoological mm SL in Trout and Virgin creeks. Even in evidence: correlation between fish distribution 420 Great Basin Naturalist Vol. 43, No. 3

Systematics and hydrographic history in the desert basins of Williams, J. E. 1980. and ecology of chubs western United States. Pages 17-166 in The {Gila: Cyprinidae) of the .\lvord Basin, Oregon Great Basin, with emphasis on glacial and post- and Nevada. Unpublished dissertation. Oregon glacial times. Bull. Univ. Utah, Vol. .38. State Univ. 175 pp. E., E. 1980. Gila boraxohius, HuBBS, C. L., AND R. R. Miller. 1972. Diagnoses of new Williams, J. and C. Bond. cyprinid fishes of isolated waters in the Great Ba- a new species of cyprinid fish from southeastern sin of western North America. Trans. San Diego Oregon with a comparison to G. alvordensis See. Nat. Hist. 17:101-106. Hubbs and Miller. Proc. Biol. Soc. Washington LiBBEY, F. W. 1960. Boron in Alvord Valley, Harney 93:293-298. 1980. County, Oregon. Ore-Bin. 22:97-105. Williams, J. E., and C. D. Williams. Feeding Snyder, C. T., G. Hardman, and F. F. Zdenek. 1964. ecology of Gila boraxohius (Osteichthyes: Cypr- Pleistocene lakes in the Great Basin. U.S. Geol. inidae) endemic to a thermal lake in southeastern Surv., Misc. Geol. Investigations, Map 1-416. Oregon. Great Basin Nat. 40:101-114.