ellowstone Lake in Yellowstone National Park is hometo the premier surviving inland cutthroat trout fisheryin North America. Two significant threats to the

native Yellowstone cutthroat trout, discovered over a five-yearperiod during the 1990s, irreversibly altered the future of thisthriving and diverse ecosystem. Without swift and continu-ing action, negative affects on this trout population—akeystone energy source for at least 42 species of mammalsand birds and a recreational focus for visitors—have thepotential to produce ecosystem-wide consequences.

Predatory, nonnative lake trout, illegally introduced tothe lake at least 20 years ago and not discovered until 1994,can consume over 40 Yellowstone cutthroat trout annually.They have the potential to decimate the Yellowstone Lakefishery in our lifetime without heightened and maintainedmanagement efforts. Lake trout also occupy an ecologicalniche unavailable to cutthroat-eating predators, imperilingthe many species, such as grizzly bears, bald eagles, and riverotters, that depend on the cutthroat for survival.

Whirling disease, a parasite that attacks the developingcartilage of young fish resulting in skeletal deformity, whirl-ing behavior, abnormal feeding, and increased vulnerability

Y to predation, was first detected in Yellowstone Lake in 1998and in the Firehole River in 2000. This devastating diseasefurther threatens already declining Yellowstone cutthroattrout populations. Although whirling disease is currentlybelieved to be concentrated in the northern regions of theYellowstone Lake watershed, several other tributaries havealready been identified as high risk.

In addition to native trout preservation, aquatics pro-gram goals include restoration of isolated but genetically purewestslope cutthroat trout, monitoring to track aquaticecosystem health and to expedite early warnings for otherinvasive exotic species, and encouragement of public involve-ment in various fisheries programs.

The stakes are high, raising the bar for innovativemanagement. The increased magnitude of the problemsfaced by the park’s fisheries and the accelerated rate at whichthey are occurring are straining Yellowstone’s resources. Thisannual report describes historic and continuing park aquaticsprograms as well as specific initiatives for 2002. It is ascientific call for action—action urgently needed to assurecutthroat trout survival and overall fishery health in Yellow-stone National Park.

Yellowstone cutthroat trout

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Yellowstone FisheriesAquatic Sciences

Annual Report2002

Yellowstone cutthroat trout

Todd M. Koel, Jeffrey L. Arnold, Patricia E. Bigelow,Brian D. Ertel, and Daniel L. Mahony

National Park ServiceYellowstone Center for Resources

Yellowstone National Park, WyomingYCR-NR-2003-02

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Suggested citation:Koel, T.M., J.L. Arnold, P.E. Bigelow, B.D. Ertel, and D.L. Mahony. 2003. Yellowstone Fisheries & Aquatic Sciences: Annual Report,2002. National Park Service, Yellowstone Center for Resources, Yellowstone National Park, Wyoming, YCR-NR-2003-02.

Cover illustrations courtesy Joseph R. Tomelleri.

Inside front and back covers and title page art courtesy Mimi Matsuda.

All photos in this report not otherwise marked are by Todd Koel.

Contents

BACKGROUND .................................................................................... 2MAP OF MAJOR SURFACE WATERS OF YELLOWSTONE NATIONAL PARK .... 4SUMMARY .......................................................................................... 4YELLOWSTONE CUTTHROAT TROUT PRESERVATION ............................... 6

Maintaining long-term monitoring programs ............................... 6Removal of nonnative lake trout from Yellowstone Lake ............... 9Understanding the effects of whirling disease .............................. 12Movement patterns within Yellowstone Lake .............................. 13Hydroacoustic surveys to document population change.............. 14

WESTSLOPE CUTTHROAT TROUT RESTORATION ................................. 15Population surveys ...................................................................... 15Genetics surveys .......................................................................... 15Life history strategies at Fan Creek.............................................. 15Restoration potential .................................................................. 16

STREAM FISHERY SURVEYS AND FISH HEALTH ..................................... 17Population surveys ...................................................................... 17Surveys for fish health ................................................................. 18Genetics surveys .......................................................................... 18

AQUATIC ECOSYSTEM HEALTH ........................................................... 19Invasive aquatic exotic species threaten the park ......................... 19Establishment of long-term water quality monitoring ................. 19Limnology of Yellowstone Lake .................................................. 20Macroinvertebrate monitoring .................................................... 20

ANGLING IN THE PARK ..................................................................... 21Trends from the volunteer angler report cards ............................. 21

PUBLIC INVOLVEMENT ...................................................................... 22Yellowstone volunteer fly-fishing program .................................. 22Long-term volunteer assistance ................................................... 22Educational programs ................................................................. 22

COLLABORATIVE RESEARCH ............................................................... 23Projects by graduate students ...................................................... 23Other research and collaboration ................................................ 23

ACKNOWLEDGMENTS ........................................................................ 24LITERATURE CITED .......................................................................... 25APPENDICES ..................................................................................... 26

i. Fish species list ......................................................................... 26ii. Long-term volunteers .............................................................. 26iii. Seasonal staff ......................................................................... 26

reated in 1872, Yellowstone NationalPark was for several years the onlywildland under active federal

management. Early visitors fished and huntedfor subsistence, as there were almost no visitorservices. At the time, fishes of the park wereviewed as resources to be used—by sport anglersand to provide park visitors with fresh meals.Fish-eating wildlife, such as bears, ospreys,otters, and pelicans, were regarded as a nuisance,and many were destroyed as a result.1

To supplement fishing and to counteract this“destructive” consumption by wildlife, a fish“planting” program was established inYellowstone. Early park superintendents notedthe vast fishless waters of the park, andimmediately asked the U.S. Fish Commission to“see that all waters are stocked so that thepleasure seeker can enjoy fine fishing within afew rods of any hotel or camp.”2 The first fishesfrom outside the park were planted in 1889–1890, and included brook trout in the upperFirehole River; rainbow trout in the upperGibbon River; and brown trout and lake trout inLewis and Shoshone Lakes.3 During the earlyhistory of the park, stocked fisheries wereextremely important. The harvest-oriented fishmanagement program accounted for theplanting of over 310 million fish in Yellowstonebetween 1881 and 1955. In addition, from 1889to 1956, some 818 million eggs were strippedfrom Yellowstone trout and shipped throughoutthe U.S.4

C

Largely due to these activities in YellowstoneNational Park and the popularity of its fisheries,recreational angling became a long-term,accepted use of national parks throughout thecountry. In Yellowstone, fisheries management,as we understand that term today, began withthe U.S. Army and was assumed by the NationalPark Service in 1916. Fish stocking, datagathering, and other monitoring activities beganwith the U.S. Fish Commission in 1889, werecontinued by the U.S. Fish and Wildlife Serviceuntil 1996, and have been the responsibility ofthe National Park Service since 1996.

Since 40 percent of Yellowstone’s waterswere once fishless,5 the stocking of nonnativefishes has had profound ecological consequences.The more serious of these include displacementof intolerant natives such as westslope cutthroattrout and grayling, hybridization of Yellowstoneand westslope cutthroat trout with each otherand with nonnative rainbow trout, and, mostrecently, predation of Yellowstone cutthroat troutby nonnative lake trout. Over the years,management policies of the National ParkService have drastically changed to reflect newecological insights, as highlighted in the LeopoldReport of 1963.6 Subsistence use and harvestorientation once guided fisheries management.Now, maintenance of natural biotic associationsor, where possible, restoration to pre-Europeanconditions have emerged as primary goals.

A perceived conflict exists in the NationalPark Service mandate that states the people will“use and enjoy”, and also “protect and preserve”our pristine, natural systems.7 To date, we knowof 18 fish species or subspecies in Yellowstone

Background

NPS fisheries worker removing cutthroat trout from thePelican Creek trap for egg-taking operations in 1936.

2

Tremendous numbers of cutthroat trout were once harvested by sportanglers and commercial fishermen.

NPS PH

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Maintenance ofnatural bioticassociations or,where possible,restoration topre-Europeanconditions haveemerged asprimary goals.

National Park;8 13 of these are considered native(they were known to exist in park waters prior toEuro-American settlement) and five areintroduced (nonnative or exotic; see Appendix i).Fisheries management efforts in Yellowstone arecurrently focused on preservation of nativespecies, while allowing for use of these fisheriesby visiting anglers through a complete catch-and-release regulation. As our primary mission is thepreservation of natural ecosystems and ecosystem

processes, we will not emphasize maintenance ofestablished nonnative fish stocks. Along withnative fish preservation, our Fisheries andAquatic Sciences Section (Aquatics Section)activities include native fish restoration, streamand lake inventory and monitoring, and a newemphasis on aquatic ecosystem health includingwater quality and macroinvertebrate monitoringof lakes and streams to serve as an early warningfor advancing invasive exotic species.

3

Fisheries authority David Starr Jordan produced this map of Yellowstone waters in 1889,showing the large portion of the western side of the park as an AREA WITHOUTTROUT, in anticipation of the extensive stocking program that followed. (From Baron W.Evermann, Report on the Establishment of Fish Cultural Stations in the Rocky MountainRegion and Gulf States, U.S. Government Printing Office, 1892).

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the end of the 2002 field season in earlyNovember, annual population assess-ments for native Yellowstone cutthroat

trout indicated yet another year of decline inYellowstone Lake members of this precioussubspecies. A total of 6,613 upstream-migratingcutthroat trout were counted at Clear Creek,down from 9,581 in 2001 and the lowest countsince 1994. Catches by our annual fall nettingprogram averaged 5.1 cutthroat trout per net,the lowest catch recorded since the initiation ofthe program in 1969. Reductions in cutthroattrout catch have averaged 11 percent per yearsince 1994, the year lake trout were firstdiscovered in Yellowstone Lake.

While catch and release angling certainlycontributes to total annual mortality ofYellowstone cutthroat trout, the relatively recentillegal introduction of nonnative lake trout andthe presence of the invasive exotic parasiteMxyobolus cerebralis (which causes salmonid

2002 Summarywhirling disease) appear to be increasing theseverity of these declines. An all-out effort hasbeen launched to remove as many lake trout aspossible and control the expansion of thisdestructive population. The Aquatics Sectionacquired a new gillnetting boat, the NPSFreedom, in 2001. Designed after commercialvessels in the Great Lakes, this boat provides asafe work environment for processing the nearly10 miles of gill net that are in place each dayduring the open water season (May–October).Since 1994, more than 56,200 lake trout havebeen removed from Yellowstone Lake viagillnetting, with 12,549 fish removed in 2002alone.

Intensive research on whirling disease hasbeen conducted since 1998 when it was firstdiscovered in Yellowstone Lake. To date,examination of 12 spawning tributaries locatedthroughout the lake basin and the YellowstoneRiver below Fishing Bridge indicates a

4

Figure 1. Major surface waters of Yellowstone National Park with 12 stream sites established for long-termmonitoring of water quality. Labels for Fan Creek and Soda Butte Creek indicate locations but streamsare not shown.

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MissouriRiver

Snake River

YellowstoneRiver

BechlerRiver

LeHardysRapids

SnakeRiver

YellowstoneRiver

MiddleCreek

SloughCreek

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LamarRiver

PelicanCreek

FireholeRiver

MadisonRiver

GardnerRiver

GallatinRiver

YellowstoneRiver

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Grant

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Stream Water Quality Sites

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ShoshoneRiver

concentration of this disease near Fishing Bridgeand in lower Pelican Creek.

The status of westslope cutthroat trout inYellowstone National Park has been a seriousconcern for several years. Intensive research andmonitoring to date indicates that the onlyremaining genetically pure population of thisprecious subspecies exists in the remote NorthFork of Fan Creek. Efforts are underway toensure the stability of this population and toassist with brood stock development efforts forwestslope cutthroat trout in Montana’s UpperMissouri River system.

Stream fish surveys have been conductedthroughout the park to monitor populationabundance, genetic integrity, and overall fishhealth. Many of these surveys are conducted inassociation with ongoing road reconstructionprojects. Of special note is a major survey of theGibbon River fisheries (1999–2002) and the firsttwo years of sampling to assess the fishery statusof Slough Creek.

In 2002 we initiated a new program aimedat tracking the ecological health of aquaticsystems in Yellowstone National Park. Thequality of the park’s surface waters is nowmonitored biweekly at 12 fixed sites located nearthe confluences of major streams and rivers(Figure 1). The physical and chemical

The Yellowstone Center for Resources lake trout gillnetting boat Freedom,christened in 2002.

characteristics of Yellowstone Lake are monitoredseasonally to assist the targeting of nonnativelake trout. Macroinvertebrates are now sampledusing regionally standardized methods to allowfor easy comparison of data among agencies.

Public involvement with the AquaticsSection has greatly increased primarily throughthe incorporation of many volunteers. In 2002alone, 81 volunteers dedicated 6,382 hours oftheir time to our projects. A highlight of the yearwas the development of the YellowstoneVolunteer Fly-fishing Program, where volunteeranglers from across the United States participatedin five specific fisheries projects throughout thepark.

5

The interior of the NPS Freedom provides a safe work space for processing lake trout gill nets.Worker in the foreground is long-term international volunteer, Silvia Matesanz. The lake troutprogram benefits from thousands of hours of donated time by volunteers each year.

ellowstone Lake and its tributaries rep-resent the majority of undisturbed nat-ural habitat and the home to the last

stronghold of remaining genetically pureYellowstone cutthroat trout (Onchorhynchusclarki bouvieri).9 Now faced with pressure bynonnative and exotic invaders, the YellowstoneCenter for Resources and Aquatics Sectionconsider the preservation of this subspecies a topmanagement and research priority. Ecosystem-level degradation is a possibility if the cutthroattrout population of Yellowstone Lake is allowedto decline.10

Maintaining Long-termMonitoring Programs

Annual assessment of the Yellowstonecutthroat trout population of Yellowstone Lakehas been conducted by counts of upstream-migrating spawners at Clear Creek, BridgeCreek, and Arnica Creek; by dip-netting adultspawners at LeHardys Rapids; and by a nettingprogram on the lake conducted duringSeptember each year.

Using multi-mesh-size gill nets set in shallowwater at 11 sites throughout Yellowstone Lake,the Aquatics Section has been able to collectvaluable cutthroat trout population informationover time (Figure 2). Data collected in 2002continued to show some very disturbing trends.The number of fish collected per net has reachedthe lowest point recorded since the lake nettingprogram began in 1969 (Figure 3).11 Thereduction in catch has been 0–21 percent eachyear (averaging 11% per year) since 1994, theyear lake trout (Salvelinus namaycush) were firstdiscovered in Yellowstone Lake.12 Examination oflength-frequency data from the fall netting

survey shows a severe decline in adult cutthroattrout numbers in Yellowstone Lake (Figure 4).

Entire age classes are virtually missing fromthe lake population. In 2002, few fish betweenthe lengths of 300 and 430 mm were caught.Historically most cutthroat trout noted inspawning tributaries such as Clear Creek13 and atLeHardys Rapids of the Yellowstone River14 havefallen in this size range. Despite this, we see anapparent increase in juvenile cutthroat trout in2001 and 2002 as an encouraging sign and anindication that the lake trout removal program’seffects may be significant, making a majorcontribution to the preservation of Yellowstonecutthroat trout.

The South Arms of Yellowstone Lake mayact as refuges for cutthroat trout due to the lownumbers of lake trout found there. Our long-term netting site near Peale Island in the SouthArm produced 132 cutthroat trout (and no laketrout) over one night. This represented a largercatch than all other sites—39 percent of allcutthroat trout sampled by the September 2002netting program.

The Yellowstone cutthroat trout populationdecline is also evident in total numbers ofupstream-migrating cutthroat trout at ClearCreek, a major spawning tributary on the lake’seastern side (Figure 3). A total of 6,613upstream-migrating cutthroat trout werecounted at Clear Creek, down from 9,581 in2001 and the lowest count since 1994. Fishcounting stations were also operated on Arnicaand Bridge Creeks. In Arnica Creek, 455cutthroat trout were counted migrating upstreamduring the 2002 field season. Problems with ourcounting system coupled with a bank washingout around our counting station prevented usfrom obtaining an accurate count. Our total isconsidered a minimum estimate. We have not

Yellowstone Cutthroat Trout Preservation

6

The South Armsof YellowstoneLake may act asrefuges forcutthroat troutdue to the lownumbers of laketrout found there.

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Yellowstone N. P.

Wyoming

Montana

Idaho

Grant

Yellowstone River(from lake outlet)

Pelican Creek

Clear Creek

YellowstoneRiver(to lake inlet)

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Lake

Solution Creek

Bridge Creek

Arnica Creek

Fishing Bridge

PealeIsland

StormPt.

Elk Pt.

StevensonIsland

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Fall cutthroat trout netting sites

Spawning migration traps

Whirling disease exposure sites

Lake water quality sites

Chipmunk Creek

Trail Creek

Beaverdam Creek

Little ThumbCreek

Creek 1167

Sewer Creek

CarringtonIsland

Cub Creek

Columbine Creek

Hatchery Creek

DotIsland

Breeze Channel

10 0 10 20 Kilometers

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Figure 2. Yellowstone Lake and several major tributary drainages within Yellowstone National Park.

had a season without mishap at Arnica Creek, soit is unfair to make comparisons to past counts.Repairs have been made and the counting stationwas moved to a new location in 2002 to aid inobtaining a more accurate count in the future. In

Bridge Creek, 373 cutthroat trout were countedmigrating upstream from late-April to mid-June,2002. This represents a 67 percent decrease fromthe 2001 total of 1,140, and an 84 percentdecrease since monitoring began in 1999.

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Lake trout control initiated

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Egg taking ceased

5 fishany size

3 fish any size

2–3 fish 356 mm

Total catch & release

Mean trout per net

2 fish 330 mm

8

Figure 4. Length frequency data collected from Yellowstone cutthroat trout, Yellowstone Lake, during fall nettingassessments, 1998 through 2002. Note the severe decline in adults greater than 300 mm over time. Also note anincrease in juveniles during 2001 and especially 2002.

Figure 3. Total annual number of upstream migrating Yellowstone cutthroat trout at Clear Creek and mean numberof cutthroat trout collected per net by fall gillnetting on Yellowstone Lake. Arrows indicate dates of changes in sportfishing restrictions and other significant events including the likely year for lake trout introduction as indicated byotolith microchemistry.

9

Removal of Nonnative Lake Troutfrom Yellowstone Lake

Following the discovery of lake trout inYellowstone Lake in 1994, efforts haveintensified to counteract this nonnative threat.15

In June 2001, the addition of a new boat, theNPS Freedom, designed specifically for gill netoperations on Yellowstone Lake, greatlyimproved operation efficiency and workingconditions for employees. This helped increasethe gillnetting effort approximately nine-foldover the 1999 level (Figure 5).

Over 12,000 lake trout were removed fromYellowstone Lake in 2002 using approximately14,570 net units (one net unit is 100 m of netset over one night). On a typical day during theopen water season on Yellowstone Lake, nearly10 miles of gill net are in place for lake trout.Catch rate (catch per unit of effort) has declinedfor the third year in a row and was the lowestseen since 1995. Mean total length of lake troutcaught near Solution Creek and in BreezeChannel during spawning showeda decrease from previous years; itrose slightly at Carrington Island,the main lake trout spawning site(Figure 6). Overall number ofspawners caught was down from2001.

Since 1994, more than 56,200lake trout have been removed fromYellowstone Lake via gillnetting.The majority of these fish havecome from West Thumb andBreeze Channel where most of thegillnetting effort is concentrated.Bioenergetics modeling (estimatesof how many cutthroat trout a laketrout potentially consumes)suggests that an average maturelake trout will consume 41cutthroat trout per year.16 Thus,the control project has saved alarge number of cutthroat troutfrom lake trout predation.

Although recent numbersfrom the lake trout removalprogram are encouraging, we haveby no means declared victory over

the lake trout crisis in Yellowstone Lake. Laketrout densities in the West Thumb remain highand a serious threat to the Yellowstone cutthroattrout. Given the available habitat in YellowstoneLake, the effect of an expanding lake troutpopulation will be very real if control efforts arereduced or eliminated. Model simulationsindicate that a 60 percent or greater decline inthe cutthroat population could be expectedwithin 100 years if the lake trout populationwere permitted to grow uncontrolled.17 Also, wehave been unsuccessful at developing a techniqueto remove lake trout in the mid-size range(400–600 mm total length). This component ofthe population coexists with our cutthroat troutpopulation, making it impossible to effectivelygillnet them without also incurring anunacceptable mortality rate in cutthroat trout.We are still investigating new methods to targetthis segment of the population before the fishreach full maturity and perhaps pioneer newspawning sites.

Figure 5. Total numberof lake trout removed bygillnetting in YellowstoneLake with total gillnettingeffort and catch per unit ofeffort, 1994–2002. Eachunit of effort represents100 meters of gillnet setover one night.

Figure 6. Total numberand mean total length oflake trout removed fromor near spawning areas,Yellowstone Lake,1994–2002.

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Total Number Carrington Island Solution Creek Breeze Channel

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Where did those lake trout come from?When were they introduced to YellowstoneLake? Although we may never know “who

did it,” scientists recently narrowed the “where” and“when” possibilities using some fascinatingdetective work.

Lake trout were first discovered inYellowstone Lake in 1994. Although Lewisand Heart Lakes were stocked with laketrout in the 1890s, Yellowstone Lake wasnever officially stocked. Lewis Lake,located 10 highway kilometers (6.2 miles)from the West Thumb of Yellowstone Lake,is considered the most likely source forlake trout, as road access exists to bothlakes. Heart Lake is accessible only bytrail 13 km (8 miles) fromYellowstone Lake. Since bothLewis and Heart Lakes arelocated across the ContinentalDivide from Yellowstone Lake andnot connected to its drainage, it isunlikely that lake trout movedthere by natural means.

Lake trout otolith “fingerprints”helped unravel questions of bothstocking origin and timing. Otoliths

are calcium carbonate structures located in the innerears of fish that grow by continually adding newlayers, and they are used to age fish. Trace elementsfrom the water, such as strontium, are incorporated

into the new layers of otolith, imparting aunique elemental signature, or fingerprint,that can then be used to help identifywhere a fish lived at different times of itslife.

During lake trout removals in 1996–97,some comparatively large fish werecaptured in Yellowstone Lake. Aquaticsbiologists suspected that these larger fishcould be original transplants.

We analyzed otolith microchemistry of20 of these fish and compared them to lake

trout thought to have spent theirentire lives in Yellowstone Lake.We also compared them to laketrout from Lewis and Heart Lakes.

Strontium/calcium (Sr:Ca)ratios in the otolith edgerepresenting recent years takenfrom the suspected transplantsmatched the Sr:Ca of lake troutthat had spent all of their lives inYellowstone Lake.

Where Did Those Lake TroutCome From?

Identification of the Source Population of Lake Trout inYellowstone Lake Using Otolith Microchemistry

Adapted from an article byAndrew R. Munro, and Thomas E. McMahon, Montana State University;

James R. Ruzycki, Yellowstone National Park

Since 1994,

more than

56,200 lake

trout have been

removed from

Yellowstone Lake

via gillnetting.

10

Cross section of an otolith.

11

We estimated the date of introduction bymeasuring otolith Sr:Ca from three fish suspected tobe transplants. The location where ratios changedwere compared with annual banding patterns inhopes of estimating the year that unauthorizedintroduction(s) took place. Low Sr:Ca ratios from theearly growth period of these three fish increasedabruptly about three-fold to the edge of the otolith.The inner zone matched that of Lewis Lake fish whilethe outer zone matched suspected offspring sampledfrom Yellowstone Lake. The abrupt increase occurredabout 1989 in two of the fish (Figure 7) but not until1996 in the third. We also analyzed two 10–11 yearold fish with Sr:Ca ratios in both zones matchingother Yellowstone Lake fish, suggesting they werenaturally reproduced in the lake.

These studies suggest that lake trout have beennaturally reproducing in Yellowstone Lake since 1986or 1987. Many lake trout were transplanted intoYellowstone Lake from Lewis Lake, or from a lakewith a similar Sr:Ca fingerprint, and the introductionsbegan as early as the mid-1980s and possiblycontinued as late as 1996. Our initial detective workwill guide management strategies to prevent futureillegal introductions.

In contrast, the Sr:Ca near the center of theotoliths, reflective of the environment the fishexperienced during their first year of life, was muchlower in 18 out of 20 of the suspected transplantsand did not match that of lake trout in YellowstoneLake. This lower ratio, however, did match that ofLewis Lake fish, making it the likely source of theintroduced lake trout.

Figure 7. The shift in the

strontium/calcium ratio

noted in 1989 provides

evidence that these lake

trout inhabited both Lewis

and Yellowstone Lakes.

Distance from otolith nucleus (mm)

1989

Sr:C

a(x1

0-3)

Otolith #96-12723 yrs, 832 mm

1.0

0.6

0.2

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

12

Understanding the Effectsof Whirling Disease

The causative agent of salmonid whirlingdisease—Myxobolus cerebralis—was first detected

in Yellowstone Lake in1998.18 This discoveryimmediately causedgreat concern becausethe disease hasdevastated wild trout

populations in other waters ofthe Intermountain West.19 Annually, adultYellowstone cutthroat trout that are incidentallykilled by lake trout removal efforts are tested forthe disease. We have determined that the

incidence of whirling diseaseappears to be higher in thenorthern region of the lake (19%)

compared to the south arms (9%) orWest Thumb (12%).

Also, NPS fisheries biologists have exposedage-zero Yellowstone cutthroat trout to lake

tributary waters each year since 1999 in anattempt to determine the distribution of M.cerebralis in the basin, and the characteristics ofthe environment that are conducive to thedisease. In 2001, positive tests for the presence ofM. cerebralis were obtained from trout exposedin the Yellowstone River and Pelican Creek(Table 1). Fishes exposed in all other streams didnot become infected, including those exposed atClear Creek, where a single fish tested positiveduring September 2000. Lower Pelican Creek inthe vicinity of the road viaduct is highly infected.All Yellowstone cutthroat trout exposuresconducted there to date have resulted in positivetests for the presence of whirling disease. Theseexposure tests were repeated in 2002 andlaboratory examination of fishes is now beingconducted to determine the extent of infection.

In 2001 and 2002, we completed the firstsurvey of Tubifex tubifex worms and substrateconditions in the same streams used forexposures of trout.20 T. tubifex is the alternatehost and is required for whirling disease to

Table 1. Results of Yellowstone cutthroat trout sentinel fry exposure testing 1999–2001. Positive (Pos)indicates the causative agent of whirling disease (Myxobolus cerebralis) was detected in the cutthroattrout fry. The average histological score (Avg Histo) is from lab examination and is based on rankingfrom 0–5, with 5 being the most severe infection.

Stream Year Period Dates Pos/Neg Avg Histo

Yellowstone River 1999 1 08/12–08/23 Pos 0.202000 1 09/12–09/23 Neg 0.002000 2 09/25–10/05 Neg 0.002000 3 10/09–10/19 Neg 0.002001 1 07/14–07/23 Pos 0.402001 2 08/07–08/17 Pos 0.072001 3 08/29–09/07 Neg 0.00

Pelican Creek 2000 1 09/12–09/23 Pos 2.762001 1 07/12–07/23 Pos 4.002001 2 08/07–08/17 Pos 1.002001 3 08/29–09/07 Pos 2.72

Clear Creek 1999 1 08/12–08/23 Neg 0.002000 1 09/12–09/23 Pos 0.022000 2 09/25–10/05 Neg 0.002000 3 10/09–10/19 Neg 0.002001 1 07/12–07/23 Neg 0.002001 2 08/07–08/17 Neg 0.002001 3 08/29–09/07 Neg 0.00

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The microscopic wormTubifex tubifex is thealternate host for thewhirling disease lifecycle and a focus of studyfor understanding thisdisease in Yellowstone.

representing six of the 24tagged fish. Of these, three fishwere tagged at the YellowstoneRiver near Fishing Bridge, twowere tagged at Pelican Creeknear the road viaduct, and onewas tagged at the Clear Creekfish trap. Eight of the ten taglocations and relocationsoccurred in the northern region of the lake nearStorm Point, Pelican Creek, the YellowstoneLake outlet, and Stevenson Island. The greatestmovement we observed was by a Clear Creekfish relocated in the West Thumb near ArnicaCreek, and by a Yellowstone River fish relocatedsouth of Elk Point along the lake’s eastern shore.This research provides additional evidence thatYellowstone cutthroat trout can disperse widelythroughout Yellowstone Lake followingspawning in specific tributary streams.

persist in streams. We located T. tubifex hostingactinospores in Yellowstone River, Bridge Creek,Arnica Creek, Little Thumb Creek, Creek 1167,Sewer Creek, and Beaverdam Creek. Recentresults of genetic examination of these wormshas determined that the infection in YellowstoneRiver and Pelican Creek (from worms sampledin 2002) is indeed M. cerebralis, the parasite thatcauses whirling disease.

There is a high risk of infection in additionaltributaries to Yellowstone Lake that are suitablefor the persistence of the disease. Results fromour analyses of landscape-level basincharacteristics indicate that Beaverdam Creek,Trail Creek, and Chipmunk Creek, tributaries tothe South and Southeast Arms of YellowstoneLake, are likely candidates for infectingmigrating Yellowstone cutthroat trout with M.cerebralis. These tributaries flow through broaddeltas with abundant fine sediments (similar toPelican Creek) prior to entering the lake.Additionally, the Yellowstone River and/or itstributaries in the vast region above YellowstoneLake may harbor whirling disease. To date, wehave not had the ability to conduct exposurestudies or take fish samples in this extremelyremote section of the park. Our overall goal is todetermine the portion of our annual Yellowstonecutthroat trout year class that we are losing towhirling disease each year. Results will haveimplications for management in YellowstoneNational Park and also for many other regionalmanagers concerned about whirling disease andnative cutthroat trout conservation.

Movement PatternsWithin Yellowstone Lake

Whirling disease research has suggestedyoung Yellowstone cutthroat trout are becominginfected primarily in the Yellowstone River andPelican Creek. We were interested indetermining the movement patterns of spawningadults from these streams and Clear Creek, thesite of our long-term spawning migration trap,in Yellowstone Lake. Twenty-four Yellowstonecutthroat trout adults were fitted with ultrasonictags and tracked from July through September2002. Ten fish locations were identified

NPS Fisheries Technician Mike Ruhl listens for thesignal from an ultrasonic tagged cutthroat trout inYellowstone Lake, July 2002.

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Volunteers on a T. tubifex search.

14

Hydroacoustic Surveys toDocument Population Change

Surveys using state of the art hydroacousticequipment, for estimating fish densities, wereconducted three times throughout YellowstoneLake during the 2002 field season. Thoroughanalysis of hydroacoustic data collected this pastfield season will allow us to determine areas ofhigh density, size ranges of fish in given areas,

NPS Fisheries Biologist Patricia Bigelow measures the angle of sonar equipment attached to the side of the fisheriesboat Hammerhead. Bigelow uses the sonar equipment to determine and track densities of cutthroat trout andnonnative lake trout in Yellowstone Lake.

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and depths at which fish are residing.Combining this data with detailed bathymetrydata produced by the U.S. Geological Surveywill allow us to identify lake areas where we needto either increase or decrease our lake troutgillnetting effort to improve efficiency. We willalso be able to use this technology to evaluate theeffectiveness of our removal efforts by estimatinglake trout and cutthroat trout populationdensities annually.

Population Surveys

or the past few decades, park fisherypersonnel have been gathering populationabundance data and size structure

information about the westslope cutthroat trout(Onchorhynchus clarki lewisi) residing in FanCreek. This native trout was historicallyabundant in the Gallatin and Madison Rivers,but currently only remnant populations reside inheadwater sections of the Gallatin River water-shed. Since 1998, fish population estimates havebeen conducted periodically at the mainstemmonitoring site (WC3) and at several 100-metersections in each of the two forks of Fan Creek(Figure 8). Multiple samplings indicate that theabundance of westslope cutthroat trout isrelatively low throughout the watershed. Theconsistently higher densities of trout in theNorth Fork were observed in areas withabundant woody debris in the stream channel.Westslope cutthroat trout from the drainagewere typically small (less than 200 mm totallength), although several individuals from theEast Fork measured more than 10 inches (Figure8). Preliminary age analyses in 2001 suggestedthat at least three distinct year classes ofcutthroat trout reside in Fan Creek. Anothernative species, the mottled sculpin (Cottusbairdi), was frequently collected at all sites exceptthe upstream areas of the North Fork of FanCreek.

Genetics Surveys

Surveys initiated by park fishery biologists inthe early 1990s suggested that the most likelyconcentrations of genetically pure westslopecutthroat trout were located in the Gallatin andMadison watersheds. With the advent of non-lethal analyses in the past several years (i.e., use

of fin tissue rather than major organs), theAquatics Section has expanded this geneticinventory. More than 300 individual fish havebeen sampled, but only about half of them havebeen analyzed thus far. Data from multiplesamplings indicate that the only genetically purepopulation of westslope cutthroat trout in thepark resides in Fan Creek (Figure 9). Althoughfive genetically pure westslope cutthroat troutwere collected near the confluence of Fan Creekand the Gallatin River in 1997, subsequentsamplings upstream suggest that the populationhas hybridized with Yellowstone cutthroat trout,rainbow trout (Onchorhynchus mykiss), or both,in most of the Fan Creek mainstem. Dependingon the particular site, population levelhybridization varied from low to moderate. Forexample, 25 of 31 trout analyzed in the EastFork of Fan Creek were genetically purecutthroat, but the population level purity is only81 percent due to nonnative genetic materialbeing present in the other six fish.

Life History Strategies atFan Creek

To achieve adequate protection of westslopecutthroat trout in the Fan Creek watershed, parkbiologists needed a more completeunderstanding of seasonal distribution andmovements. We began a cooperative graduatestudy in fall 2000 to examine some of thesepatterns (see Acknowledgments). During thefollowing 18 months, 30 adult and subadultwestslope cutthroat trout were radiotagged andtracked. As this study nears completion, threepreliminary findings are worth noting. First, alarge majority of the tagged fish could beregarded as resident fish that migrated only a fewkilometers over the course of the year. Second,many of the tagged fish migrated downstream in

Westslope Cutthroat Trout Restoration

15

Data obtainedfrom multiplesamplingsindicates that theonly geneticallypure populationof westslopecutthroat trout inthe park residesin Fan Creek.

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late fall. The reason for this movement isunknown; however, similar results were observedduring 1998 genetic surveys, when low-gradientmeadow stream sections that containedabundant numbers of cutthroat trout during thesummer were barren in the fall as fish apparentlymoved to more complex, forested habitats

downstream. Finally, thelargest concentration ofspawning cutthroat observedin 2002 was located in theNorth Fork of Fan Creek.This is also the portion of thewatershed containing thegenetically pure population.

Restoration Potential

Along with protection ofaquatic resources as pristineecosystems, preservation andrestoration of native species isone of the most importantaquatic managementobjectives in YellowstoneNational Park. The electro-fishing, genetic, and radio-tagging fishery surveys of the

past several years have demonstrated that theonce abundant westslope cutthroat trout is nowconfined to a single, small tributary in thenorthwest corner of the park. Unlike many otherareas in historical westslope cutthroat troutrange, habitat degradation and continuous highangler harvest rates are not implicated in thedecline of westslope cutthroat trout inYellowstone National Park. Extensive stockingand subsequent establishment of populations ofnonnative competing species (rainbow trout andbrown trout (Salmo trutta)) and interbreedingwith rainbow trout and Yellowstone cutthroattrout have led to serious reductions in residentwestslope cutthroat trout populations.

The current status assessment of westslopecutthroat trout indicates that the North ForkFan Creek population is the only viablepopulation in the park and should be consideredan “at risk” population. Although these fish areprotected from habitat degradation or strongimpacts by anglers, the evidence from oursurveys reveals that these fish could be affectedby nonnative fish species. The capture of anonnative brown trout at the WC3 site in 2002indicates an apparent lack of barriers and thevulnerability of the headwater cutthroat troutpopulations to invasion from downstreamsources.

Complete protection requires that the NorthFork Fan Creek population be permanentlyisolated from invading species. To address thisobjective, a three-phase approach will beutilized. First, plans are being developed to selecta site and design a barrier that will preventupstream migration of competing species intothe North Fork. After the barrier is constructedand shown to be effective, removal of hybridizedindividuals (primarily in the East Fork of FanCreek) will be initiated to lessen opportunities ofhybridization. Concurrently, a brood stockderived from the North Fork westslope cutthroattrout population will be developed incooperation with Montana and Wyoming statefishery agencies. As ongoing abundanceestimates and genetic testing dictate, juvenilefish produced from the North Fork of Fan Creekpopulation will be available for restorationprojects at suitable sites in nearby streams.

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Figure 9. Genetic purity of westslopecutthroat trout in the Gallatin Range, 1998–99. The North Fork Fan Creek population isthe only known genetically pure populationremaining in Yellowstone National Park.

Figure 8. Relative length frequencies of westslope cutthroat trout at samplesites in the Fan Creek drainage, 2002.

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raditionally, these projects have involvedlong-term monitoring to describe theresponses of a fish population to a

particular type of angler impact (e.g., minimumsize, reduced creel, or catch and releaseregulations). As the number of threats to fishpopulations increases, these studies have becomeshorter term (i.e., 3–5 years) so parkmanagement can attempt to respond to impactsin a more timely manner.

For the third consecutive year, we sampledfour separate sections of the Gibbon River. Theprincipal objective of this study was to monitorimpacts to portions of the stream near areas ofmajor road reconstruction. The Madison-to-Norris road reconstruction is probably one of themost ambitious projects that the park hasundertaken in recent years. In addition to typicalmodernization of much of the existing road,several kilometers of road are to be removed anda new route and bridge over the Gibbon Riverwill be built. Thus the potential for increasedsediment input into the stream and resultinghabitat degradation is very high. Moreimportantly, this project represents one of thefirst attempts to restore a stream segment thathas been seriously affected by historical roadbuilding. Much of the work will occur in an areathat was originally barren of fish, but thesections downstream from Gibbon Falls (TuffCliffs and Canyon Creek sample areas)historically contained westslope cutthroat troutand the riverine form of arctic grayling.Cutthroat trout have been eliminated from theGibbon River, but occasionally grayling arecaptured. Our secondary objective in this studyis to examine effects of the construction projecton the few grayling that may reside in the lowersections of the stream.

No grayling were captured during 2002 inthe Gibbon River and only two were caught theprevious year. Brown trout was the mostcommon fish collected at each of the four sampleareas and was the only species captured in theTanker Curve section. Rainbow trout were onlycaptured downstream from Gibbon Falls.Estimated abundance of brown trout has varied

Stream Fishery Surveys and Fish Health

Figure 10. Population abundance of brown trout estimatedby electrofishing at road reconstruction sites, 1999–2002.

17

among years, but typically averages from 400 to800 fish per kilometer (Figure 10). Thiswidespread high density of a competitivenonnative species could be one of the factorscontributing to the rarity of native graylingthroughout the Gibbon River watershed.

Another multiple year road constructionsurvey was conducted at Antelope Creek, whichenters the Yellowstone River just upstream fromTower Falls. The stream contains a population ofsmall Yellowstone cutthroat trout. Abundanceand average size of these fish were similar to thatnoted for the headwater population of westslopecutthroat trout in Fan Creek. Because access totributary streams is extremely limitedthroughout most of the Grand Canyon of theYellowstone, the cutthroat trout residing inAntelope Creek may represent an unusual localadaptation to restricted habitat.

In response to concerns related to perceivedexcessive angler use and potential ripariandamage, the fisheries staff initiated a multi-yearpopulation assessment of Yellowstone cutthroattrout in Slough Creek. In the mid-1990s, annualangler use occasionally exceeded 25,000 hoursbut has since returned to levels observed tenyears earlier. Concurrently, hourly catch ratesdeclined to below one fish per hour. With thisinformation as background, some of the moreheavily used portions of Slough Creek weresampled in 2001 and 2002. Preliminary results

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indicate that the Yellowstone cutthroat troutpopulation has changed little since the streamwas last sampled in 1989.21 Despite high levels ofangler use in this catch and release fishery, weestimate that there are several hundred adultcutthroat trout (longer than 330 mm) perkilometer in Slough Creek.

Surveys for Fish Health

In addition to population abundance, overallphysical health of specific fish populations isimportant to fishery management objectives inthe park. Most of the work has focused onwhirling disease; more than 60 rainbow troutand brown trout from the Firehole River weresampled in 2002. However, other surveys arealso conducted to monitor the status ofpopulations in the park. As part of the U.S. Fishand Wildlife Service National Fish HealthSurvey, park biologists periodically collect fishthat are lethally sampled and examined for avariety of parasitic infections and bacterial andviral diseases. In 2002, rainbow trout and brooktrout from Tower Creek were collected andsubmitted for analyses. Water from thisparticular stream is being proposed for dustabatement during Dunraven Roadreconstruction. Because Antelope Creek parallelsportions of the project, a source of pathogen-freewater is needed. As part of the national baselinesurvey, we also submitted several dozen

mountain whitefish (Prosopium williamsoni)from the Snake River for analyses. Finally, 25rainbow trout and brown trout from a tributaryof Fan Creek were collected and submitted fordisease analyses. These fish will function as“surrogates” for fish health testing in the FanCreek watershed. This allows us to assure thatpure cutthroat trout are not sacrificed, yet stillobtain critical information about the disease-freestatus of the watershed. Results from these healthstatus surveys are pending.

Genetics Surveys

Preservation of native trout genes is animportant management priority in Yellowstone.As nonlethal analysis techniques are nowavailable, extensive sampling of small or other atrisk populations is possible. In addition to thelarge amount of sampling of suspected westslopecutthroats in the Gallatin River watershed, fintissue samples for genetic determination havebeen collected from Antelope Creek, SloughCreek, Soda Butte Creek, and Gneiss Creek, atributary of the Madison River. At all of thesesites, the possibility of hybridization withnonnative rainbow trout may have occurred.Several hundred fish have not yet been analyzed.Large backlogs of samples at the analyticallaboratories and funding constraints continue todelay determination of the genetic status of theseimportant fish populations.

NPS fisheries technicians Anna Maki and Mike Ruhl use electrofishing gear to sample fishes in the upper Gallatin River, August 2002.

Invasive Aquatic Exotic SpeciesThreaten the Park

n addition to the parasite that causeswhirling disease, Yellowstone National Parkaquatic systems have been invaded by the

New Zealand mudsnail (Potamopyrgusantipodarum). Mudsnails are extremely small(about 4–5 mm long) and highly prolific.22 Firstfound in the park in 1994, mudsnails nowoccupy the Firehole, Gibbon, Madison, andGardner Rivers, Polecat Creek, and likely others.Recent research indicates that these animals havebeen out-competing and displacing nativeinvertebrates. Dr. Billie Kerans at Montana StateUniversity reported that mudsnails comprised25–50 percent of macroinvertebrates in theGibbon and Madison Rivers, and that fewernative mayflies, stoneflies, and caddisflies occurin areas occupied by mudsnails.23 The effect ofthese invaders on fish is unknown, but recentresearch indicates that mudsnails can passcompletely through the gut of a fish unharmedwhile offering no nutritional value.

It would be nice to think that the waters ofYellowstone National Park could remain in arelatively pristine condition for futuregenerations to enjoy, but this will not be the casewithout changes to the way we manage themovement of equipment, boats, and other gearamong waters in our region. Presently, invasiveexotic aquatic species occur in streams, rivers,and lakes (both near the coasts and inland) allacross the United States.24 While we may neverknow exactly how the parasite that causeswhirling disease and the New Zealand mudsnailwere introduced to the park, anglers can helpprevent the additional spread of these animals, orof the many other invasive exotic speciesapproaching our boundaries (e.g., zebra mussels,Eurasian watermilfoil, round goby).

Anglers should thoroughly clean all mud,plants, and debris from fishing equipment andinspect footwear before leaving the angling site.We also recommend treating waders and bootswith a 10 percent bleach solution. Boatersentering the park must completely remove plantmaterial or any other debris from trailers andboat hulls; bilge areas and livewells must bethoroughly drained and likewise cleared of

Aquatic Ecosystem Health

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NPS Aquatic Ecologist Jeffery Arnold lowers a monitoringprobe into the Yellowstone River as a part of the long-termwater quality monitoring program, August 2002.

debris. The entire boat should be cleaned withhot (higher than 140o F) water and allowed todry for several days. Boat transport is a primarymethod by which these harmful animals aremoving among waters in our country. Onlythrough actions like these will we be able to stopthe additional spread of invasive exotics.

Establishment of Long-termWater Quality Monitoring

During 2002, we initiated a water qualitymonitoring program in Yellowstone NationalPark. The goal of this program is to evaluate theecological integrity of park ecosystems bymonitoring a variety of aquatic environments.Twelve water quality sites were established onmajor river basins (Figure 1). Biweekly samplingwas initiated in May and is now being continuedthroughout the year. For each sample location,field instruments are used to collect temperature,dissolved oxygen, pH, conductivity, andturbidity. These parameters are easy to collect,influence abundance and distribution of aquaticorganisms, and are universally used in mostwater quality programs.

Temperature and dissolved oxygen readingsvaried considerably throughout the 2002 seasonand at various locations. These differences areprimarily due to seasonal temperature changes,altitude differences, and thermal influences thataffect many of the water quality sites. Highestaverage temperatures occurred on the FireholeRiver, which is heavily influenced by thermalactivity, with temperatures ranging from 17.9o Cto 25.7o C (64.2oF to 78.3oF) see Figure 11.Lowest averagetemperatures occurred onupper Soda Butte Creekwith ranges between 3.8o Cand 14.6o C (38.8oF to58.3oF) from 28 May–27 September. PelicanCreek, a slow movingtributary of YellowstoneLake, exhibited the lowestrecorded dissolved oxygenconcentration of 6.1mg/L on 02 July.

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system for the presence of additional exoticinvasive species entering the park. Aquaticmacroinvertebrates are ideal biotic indicators—easy to collect, relatively immobile, long in lifespan, and sensitive to environmental changes.Because macroinvertebrates are sensitive toenvironmental stressors, changes in communitystructure will indicate pollution problems(physical or chemical) that may not be detectablewith routine, chemical water quality analysis.During 2002, the Aquatics Section worked inconjunction with the Greater Yellowstone VitalSigns Monitoring Network to conductinvertebrate studies within three National ParkService units (Bighorn Canyon NationalRecreation Area, Grand Teton National Park,and Yellowstone National Park). Yellowstonestaff sampled a total of 40 sites during Augustand again in October to assess aquaticmacroinvertebrate communities, inventoryspecies distributions, and evaluate overall healthof various lotic environments.

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The new programfor monitoringmacroinvertebrateswill also serve asan early warningsystem for thepresence ofadditional exoticinvasive speciesentering the park.

Limnology of Yellowstone Lake

Five water quality sites were reestablished onYellowstone Lake during the 2002 season (Figure2). Biweekly sampling was initiated in June andcontinued through September. This work isextremely important because the physical andchemical conditions within Yellowstone Lakedictate fish distribution patterns. For example,thermocline (region of great water temperaturechange) establishment during July will typicallycause lake trout to retreat to lower depths withinthe lake (Figure 12).

Macroinvertebrate Monitoring

Aquatic macroinvertebrate monitoring wasinitiated to supplement water quality data andestablish current inventories and distributionalpatterns. The new macroinvertebrate monitoringprogram will also serve as an early warning

Figure 12. Understanding the physical and chemical characteristics of Yellowstone Lake willbe extremely useful for efforts to target and remove nonnative lake trout.

Figure 11. Water quality monitoring is documenting long-term trends in critical parameterssuch as temperature and dissolved oxygen of significant waters in the park. During the summer of2002, the Firehole, Madison, and lower Gibbon Rivers were closed to fishing for several weeksdue to high water temperatures.

Trends from the VolunteerAngler Report Cards

isitation at Yellowstone National Parkhas been at an all-time high of 2.9–3.1million each year since 1991. In 2002,

55,092 fishing permits were issued. A voluntaryangler report card is provided with each permitand anglers have the opportunity to providecritical information to the Aquatics Section byreturning these cards to the park.

Recent data from these report cards suggestthat the average angler in Yellowstone typicallyfishes 2–3 days for about three hours each day.Greater than 80 percent of single-day anglers willland one or more fish, with cutthroat trout beingthe most frequently captured, followed byrainbow trout, brook trout (Salvelinus fontinalis),

Angling in the Parkand brown trout. Most anglers (more than 80%)have reported being satisfied with their overallfishing experience while in Yellowstone, andmore than 70 percent of anglers have reportedbeing satisfied with numbers and sizes of fishlanded. The most popular fishery in the park isYellowstone Lake, which consistently attractsmore than half of all anglers. The average angleron Yellowstone Lake lands about one cutthroattrout for every hour of fishing (Figure 13). Inrecent years, the average size of cutthroat troutcaught in Yellowstone Lake has increased tomore than 400 mm (Figure 14). This trend issimilar to that noted by our Aquatics SectionSeptember netting program, in that largecutthroat trout have comprised a significantproportion of the catch (Figure 4).

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Figure 14. Average length of cutthroat trout landed by anglers in Yellowstone Lake. A significant increase in size ofcuttroat trout in recent years is consistent with results of collections of NPS long-term monitoring programs.

Figure 13. Yellowstone Lake remains the primary destination for over 50 percent of anglers visiting the park.Despite apparent declines in cutthroat trout densities there, the catch rate by anglers has remained very good atabout one cutthroat caught per hour of fishing.

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Public InvolvementYellowstone VolunteerFly-fishing Program

uch of the effort by Yellowstone’sfisheries staff in recent years has beenredirected at emerging crises such as

lake trout removal and whirling disease, yet thereare a multitude of other fisheries issues andquestions to be addressed. There are an estimated2,650 miles of streams and 150 lakes withsurface waters covering 5 percent of Yellowstone’s2.2 million total acres. Realizing that NPS staffcould not address many issues, a new programwas established to incorporate fly-fishingvolunteers and use catch-and-release angling as acapture technique to gather biologicalinformation on fish populations locatedthroughout the park. In 2002 the Volunteer Fly-fishing Program was coordinated by Dr. TimothyBywater, an avid fly-fisherman and long-timesupporter and promoter of Yellowstone’sfisheries. Projects addressed included:

• determination of the range of hybridizedYellowstone cutthroat trout in the LamarRiver and its major tributaries;

• documentation of the Pebble Creekfishery;

Dr. Timothy Bywater (left) coordinated the fly-fishingvolunteer program, leading anglers to sites throughoutthe park.

Yellowstone’sfisheries programsbenefited from 81volunteers whodedicated a totalof 6,382 hoursin 2002.

• status and genetic uniqueness of brooktrout in special regulation lakes;

• status and genetic uniqueness of westslopecutthroat trout in Grayling Creek; and

• documentation of the status andmovement patterns of grayling originatingin Grebe and Wolf Lakes of the GibbonRiver system.

Under this incredibly successful program, 40volunteer anglers from across the United Statestraveled to the park and participated as an activecomponent of the Aquatics Section. Solid bondshave been developed between the anglingcommunity and the Yellowstone fisheriesbiologists. Volunteers experienced first-handmany fisheries issues, and biological datacollected will assist in our understanding of thepark’s fisheries status. However, the programsuffers from a complete lack of funding; we areactively searching for support to continue thisvaluable work.

Long-term Volunteer Assistance

The Aquatics Section recruits long-term(more than 12 week) volunteers from theStudent Conservation Association and othersources (see Appendix ii). Volunteers stay in parkhousing at Lake and work a full-time schedulesimilar to paid NPS seasonal staff. All aspects ofthe Aquatics Section are affected and greatlybenefit from both long- and short-termvolunteer support. In 2002, 81 volunteersdedicated a total of 6,382 hours.

Educational Programs

Aquatics Section staff continued to provide avariety of short-term educational programs forvisiting schools and other interested groups. Ofspecial note in 2002 was the incorporation offour high school scholars from St. Steven & St.Agnes School, Washington D.C. and theirleader, Mansir Petree. This group spent over aweek in the park interior working closely withNPS fisheries biologists, primarily on tributaryspawning migration trap operations.

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Collaborative Research

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he Yellowstone Center for Resourcesthrough the Aquatics Section hasprovided direct and indirect support for

collaborative research with scientists at otherinstitutions, primarily universities. The studiesaddress some of the most pressing issues faced byNPS biologists and other regional managers ofaquatic systems.

Projects by Graduate Students

Graduate Student: Carrie Brooke (Master ofScience candidate). Committee Chair: Dr. AlZale, U.S. Geological Survey CooperativeFisheries Research Unit and Department ofEcology, Montana State University. Title: Lifehistory strategies of native westslope cutthroattrout in Fan Creek, Yellowstone National Park.

Graduate Student: Silvia Murcia (Master ofScience candidate). Committee Chair: Dr. BillieKerans, Department of Ecology, Montana StateUniversity. Title: Relating Myxobolus cerebralisinfection in native Yellowstonecutthroat trout Oncorhyncusclarki bouvieri withenvironmental gradients atthree spawning tributaries toYellowstone Lake in YellowstoneNational Park.

Other Research andCollaboration

The Aquatics Sectioncontinued to support a varietyof other research projects inYellowstone National Park. Ofspecial mention is the researchby the Great Lakes WATERInstitute, University ofWisconsin at Milwaukee;Marquette University,Milwaukee; the U.S. GeologicalSurvey, Denver; and EasternOceanics, Connecticut.Scientists from theseinstitutions set up a laboratoryat Lake and outfit the NPS

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Aquatics Section boat the Cutthroat with asubmersible remotely-operated vehicle, or ROV,and study the physical, chemical, and biologicalcharacteristics of Yellowstone Lake, especiallyassociated with hydrothermal vent systems.

A limited number of Yellowstone cutthroattrout gametes are collected by MontanaDepartment of Fish, Wildlife and Parks fromMcBride Lake (Slough Creek drainage) and byWyoming Game and Fish Department from theYellowstone River at LeHardys Rapids. TheAquatics Section also intends to provide gametesfrom a small number of genetically purewestslope cutthroat trout from the North Forkof Fan Creek to the new broodstockdevelopment program at the Sun Ranch in theMadison Valley. In all cases, gametes are used forenhancement of native cutthroat broodstock andrestoration activities in Montana and Wyoming.Each year, age-zero Yellowstone cutthroat troutfrom the broodstock (LeHardys Rapids origin)in Wyoming are returned to the park forwhirling disease exposure studies.

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NPS Supervisory Fisheries Biologist, Dr. Todd Koel, assists students searching for exotic New Zealandmudsnails on the Gardner River, September 2002.

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uch appreciated administrativesupport for the Aquatics Section wasgiven by Becky Anthony, Rene Farias,

Melissa McAdam, Joy Perius, Beth Taylor, andColleen Watson.

Jeff Lutch, who served as a BiologicalTechnician for the Aquatics Section in 1995–2001, made significant contributions to ourunderstanding of Yellowstone’s fisheries,especially regarding the current status ofwestslope cutthroat trout in the Gallatin Range.

Many additional dedicated individuals fromwithin Yellowstone National Park havecontributed to the success of Aquatics Sectionactivities; unfortunately we cannot mentionthem all here. However, we would like toespecially thank Dave Hill, Earl McKinney,Susan Ross, Bruce Sefton, Melinda Sefton, ArtTruman, Mark Vallie, Lynn Webb, and DaveWhaley from Lake Maintenance; Rick Fey andKim West from Lake District rangers; and WallyWines from Ranger Corral Operations.

The Aquatics Section is supported throughYellowstone Center for Resources base fundingand by anglers visiting Yellowstone National Parkthrough a portion of the fees collected from theFishing Special Use Permits each year. We havereceived additional funding (2001–2002) fromthe following sources:

• Federal Highway Administration,Park Roads and Parkways Program

• Greater Yellowstone CoordinatingCommittee

• National Park Service, NaturalResource Challenge, Natural ResourcePreservation Program

• National Park Service, RecreationalFee Demonstration Program

• National Park Service, Rocky Moun-tain Region, Cooperative EcosystemStudies Unit

• National Park Service, Inventory andMonitoring Program, Vital SignsMonitoring Program

• National Partnership for the Manage-ment of Wild and Native ColdwaterFisheries, Whirling Disease Initiative

• Whirling Disease Foundation

• Yellowstone Association

• Yellowstone Park Foundation

We thank the many volunteers who havededicated their time and also a great deal of otherexpense to our Aquatics Section; without them,much of what we do would not be possible.

Fly-fishing anglers from Trout Unlimited, FlyFishing Federation, Henry’s Fork Foundation,and many other organizations in the region andthroughout the United States contributedhundreds of hours of time and costs associatedwith travel to our Volunteer Fly-fishing Program;for that we are extremely grateful.

Through collaboration with the U.S. Fishand Wildlife Service’s Bozeman Fish HealthLaboratory, the U.S. Geological Survey’s WesternFisheries Research Center in Seattle, theDepartment of Ecology at Montana StateUniversity, the Montana Department of Fish,Wildlife and Parks, and the Wyoming Game andFish Department, we have been able to learn agreat deal about whirling disease in theYellowstone Lake basin. We thank all theindividuals from these agencies for their kindsupport.

Acknowledgments

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25

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wonder in the last wilderness. Houghton Mifflin Compa-ny, New York. 338 pp.

2Boutelle, F.A. 1889. Supplemental report of the Super-inten-dent of the Yellowstone National Park. Washington D.C.:U.S. Government Printing Office.

3Varley, J.D. 1981. A history of fish stocking activities in Yel-lowstone National Park between 1881 and 1980. Informa-tion paper No. 35. Yellowstone National Park. 94 pp.

4Varley, J.D. 1979. Record of egg shipments from Yellow-stone fishes, 1914–1955. Information paper no. 36. Yel-lowstone National Park. 45 pp.

5Jordan, D.S. 1891. A reconnaissance of streams and lakesin Yellowstone National Park, Wyoming in the interest ofthe U.S. Fish Commission. Bulletin of the U.S. Fish Com-mission 9 (1889): 41–63.

6Leopold, A. S., S.A. Cain, C.M. Cottam, I.N. Gabrielson,and T.L. Kimball. 1963. Wildlife management in the na-tional parks. Transactions of the North American Wildlifeand Natural Resources Conference. Volume 28.

7National Park Service. 2000. Management policies 2001.National Park Service, U.S. Department of the Interior.137 pp.

8Varley, J.D. and P. Schullery. 1998. Yellowstone fishes: ecolo-gy, history, and angling in the park. Stackpole Books, Me-chanicsburg, PA. 154 pp.

9Gresswell, R.E. and J.D. Varley. 1988. Effects of a century ofhuman influence on the cutthroat trout of Yellowstone Lake.American Fisheries Society Symposium 4:45–52.

10Schullery, P. and J.D. Varley. 1995. Cutthroat trout and theYellowstone Lake ecosystem. Pages 12–21 In J.D. Varley andP. Schullery, Eds. The Yellowstone Lake crisis: confronting alake trout invasion. A report to the director of the NationalPark Service. Yellowstone Center for Resources, NationalPark Service, Yellowstone National Park, WY.

11Dean, J.L. and L.E. Mills. 1970. Annual project report for1969. Fishery management program, Yellowstone NationalPark. U.S. Department of the Interior, Bureau of SportFisheries and Wildlife, Division of Fishery Services, Yel-lowstone National Park, WY. 104 pp.

12Keading, L.R., G.D. Boltz, and D.G. Carty. 1996. Laketrout discovered in Yellowstone Lake threaten native cut-throat trout. Fisheries 21(3):16–20.

13Jones, R.D., G. Boltz, D.G. Carty, L.R. Keading, D.L.Mahony, and S.T. Olliff. 1993. Fishery and aquatic man-agement program for Yellowstone National Park. Techni-cal report for calendar year 1992. U.S. Department of theInterior, Fish and Wildlife Service. 171 pp.

14Keading, L.R., D.G. Carty, and D.L. Mahony. 1994. Fish-ery and aquatic management program in YellowstoneNational Park, 1993 annual report. U.S. Department ofthe Interior, Fish and Wildlife Service. 71 pp.

15Mahony, D.L. and J.R. Ruzycki. 1997. Initial investigationstowards the development of a lake trout removal program inYellowstone Lake. Pages 153–162 in R. Hamre, Ed. WildTrout VI. Trout Unlimited and Federation of Fly Fishers, Ft.Collins, CO.

16Ruzycki, J.R., D.A. Beauchamp, and D.L. Yule. 2002. Ef-fects of introduced lake trout on native cutthroat trout inYellowstone Lake. Unpublished manuscript.

17Stapp, P. and G.D. Hayward. 2002. Effects of an intro-duced piscivore on native trout: insights from a demograph-ic model. Biological Invasions 4:299–316.

18Koel, T.M., D.L. Mahony, S. Murcia, B.L. Kerans, and C.Hudson. 2002. Prevalence and severity of Myxobolus ce-rebralis infection related to water temperature and flowregimes of native cutthroat trout spawning tributaries ofYellowstone Lake. Proceedings of the 8th Annual Whirl-ing Disease Symposium, Denver, CO.

19Nickum, D. 1999. Whirling disease in the United States: asummary of progress in research and management. Cold-water Conservation Fund, Trout Unlimited, Arlington,VA. 36 pp.

20Kinnin, K.L., T.M. Koel, B.L. Kerans, A.E.L. Colwell, J.R.Winton, and C. Rasmussen. 2002. Distribution of Myx-ozoan-infected tubificids and genetic analysis of Tubifextubifex from the Yellowstone Lake basin. Proceedings of the8th Annual Whirling Disease Symposium, Denver, CO.

21Jones, R.D. and ten coauthors. 1989. Fishery and aquaticmanagement program in Yellowstone National Park. Tech-nical report for calendar year 1989. U.S. Department of theInterior, Fish and Wildlife Service, Fisheries and Federal Aid.284 pp.

22Richards, D.C. 2002. The New Zealand mudsnail invadesthe Western United States. Aquatic Nuisance Species Di-gest 4:42–44.

23Kerans, B.L., M. Dybdahl, and R. Hall. 2002. The inva-siveness of an exotic snail in the Greater Yellowstone Eco-system: performance, competition, and energy flow un-der ambient conditions. Final report to the Research Per-mit Office, Yellowstone Center for Resources, YellowstoneNational Park. 55 pp.

24Glassner-Shwayder, K. 1998. Biological invasions. Great LakesPanel on Aquatic Nuisance Species. Great Lakes Commis-sion, Ann Arbor, MI. For recent invasions see also the Non-indigenous Aquatic Species information resource for the U.S.Geological Survey at http://nas.er.usgs.gov/

Appendix i. Fish Species List

Native (N) and introduced (nonnative or exotic, I) fish species and subspecies known to exist in Yellowstone National Parkwaters including the upper Missouri (Missouri, Madison, and Gallatin Rivers), Snake River (Snake), and Yellowstone River(Yell R.) drainages.

Family Common Name Scientific Name Status Missouri Snake Yell R.Salmonidae Yellowstone cutthroat trout Oncorhynchus clarki bouvieri Native I I N

westslope cutthroat trout Oncorhynchus clarki lewisi Native Nfinespotted Snake River Oncorhynchus clarki behnkei Native N cutthroat troutrainbow trout Oncorhynchus mykiss Nonnative I I Imountain whitefish Prosopium williamsoni Native N N Nbrown trout Salmo trutta Exotic I I Ieastern brook trout Salvelinus fontinalis Nonnative I I Ilake trout Salvelinus namaycush Nonnative I IMontana grayling Thymallus arcticus montanus Native N I

Catostomidae Utah sucker Catostomus ardens Native Nlongnose sucker Catostomus catostomus Native Nmountain sucker Catostomus platyrhynchus Native N N N

Cyprinidae lake chub Couesius plumbeus Nonnative IUtah chub Gila atraria Native I Nlongnose dace Rhinichthys cataractae Native N N Nspeckled dace Rhinichthys osculus Native Nredside shiner Richardsonius balteatus Native N I

Cottidae mottled sculpin Cottus bairdi Native N N N

Appendices

Name Period of Involvement

Bear, Beth 01/01/2002–09/27/2002

Bywater, Timothy 06/03/2002–08/18/2002

Delheimer, Matt 05/19/2002–11/02/2002

Farias, Rene 01/01/2002–09/22/2002

Gale, Steve 01/01/2002–09/19/2002

Harnish, Ryan 05/19/2002–10/22/2002

Kasitz, Jon 05/19/2002–08/14/2002

Kinnin, Kendra 06/30/2002–09/22/2002

Maki, Anna 07/14/2002–11/02/2002

Morgan, Theresa 06/02/2002–11/02/2002

Rowdon, Barb 01/01/2002–12/31/2002

Ruhl, Mike 05/19/2002–10/26/2002

Seibel, Amanda 05/19/2002–08/30/2002

Wethington, Don 05/05/2002–11/02/2002

White, Davina 04/21/2002–10/18/2002

Name Period of Involvement Hours

Anderson, Krisi 08/11/2002–11/02/2002 480

Clark, Kali 05/19/2002–08/10/2002 480

Favrot, Scott 04/15/2002–09/29/2002 960

Ivan, Lori 02/24/2002–03/20/2002 240

Ivans, Kelly 08/04/2002–10/26/2002 480

Jamin, Valerie 06/16/2002–08/10/2002 480

Lillesand, Michael 05/26/2002–08/17/2002 480

Matesanz, Silvia 08/11/2002–10/19/2002 480

Owens, Nathan 08/11/2002–11/02/2002 480

Steed, Amber 06/02/2002–09/29/2002 680

Appendix ii. Long-term Volunteers, 2002 Appendix iii. Seasonal Staff, 2002

26

westslope cutthroat trout

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