volume 14 • number 2 • spring 2006

Yellowstone Cutthroat Trout Conservation Source and Date of Lake Trout Introduction History of Lake Fish Hatchery NPS/MIKE YOCHIMNPS/MIKE

Southeast arm of . Manipulated Ecosystems

y fi rst job in Yellowstone was as a Youth Conserva- resulting in a few reported catches. Regardless, studies such as tion Corps crew leader in the summer of 1993. For Munro et al.’s indicate that the lake trout crisis is the Mthe last job of the season, our crew got to spend 10 result of recent, successful introductions. days camping at Trail Creek, near the southeast arm of Yellow- Yellowstone’s fi sheries have been tinkered with since at stone Lake. It was breathtaking to be on the lake in August. We least 1881, the date of the earliest fi sh stocking in the park. Tom felt thoroughly spoiled to be allowed to pass those long days in Olliff, the new Chief of the Yellowstone Center for Resources, what appeared to be such a remote, pristine environment. considers Yellowstone’s aquatic systems to be the park’s “most The next summer, news of the discovery that lake trout had disturbed” environments—not pristine at all. Also in this issue, been illegally introduced to the lake traveled quickly through- Lee Whittlesey records the history of former fi shery operations out the park’s administrative offi ces in Mammoth Hot Springs. and the hatchery at Yellowstone Lake, which were part of park People were sad and angry, wondering who did it and how, and managers’ early efforts to “improve” the fi shery for the benefi t what would happen to the lake’s native Yellowstone cutthroat of sportfi shers. Although park management later moved away trout. In this issue of Yellowstone Science, Andrew Munro et al.’s from manipulation toward protection of native species, today’s article reports on how they identifi ed the source and date of the ease and expansion of world travel and trade has brought with lake trout introduction in Yellowstone Lake. People continue it the movement and proliferation of non-native species, and to point out that Hiram M. Chittenden’s 1903 history, The new concerns. Yellowstone National Park: Historical and Descriptive, 4th ed., Invasive non-native species are now acknowledged world- lists “10,000 yearling lake trout” as having been planted by wide to be a major threat to biodiversity; once introduced, the U.S. Fish Commission “in the above the efforts to control or eliminate them can be time-consuming falls in 1890.” An exhaustive search by John Varley of offi cial and expensive. Prevention is the key. Yellowstone now spends records on translocations has found no indication that such roughly $400,000 annually just to suppress lake trout popula- a plant took place. But if it did, the introduction failed, as tion growth. In the meantime, the lake’s native Yellowstone did others—Atlantic salmon were also planted in the lake and cutthroat trout, which provide an important source of energy never seen again. According to writer and historian Paul Schul- to at least 42 species of birds and mammals and have recently lery, not a single lake trout appears in the offi cial records of gill- supported a $36 million annual sport fi shery, also suffer from netting and fi sh management work in the park between 1900 the effects of whirling disease and drought. In their article, and 1990. However, highly credible observers have reported Todd Koel et al. describe the efforts of the park’s aquatic sci- catching lake trout in Yellowstone Lake over the park’s history. ences program to conserve the park’s native Yellowstone cut- This may suggest early introductions of lake trout to the lake, throat trout in the face of these and other threats. NPS/JIM PEACONPS/JIM

a quarterly devoted to natural and cultural resources

volume 14 • number 2 • spring 2006

TAMI BLACKFORD Editor

ALICE WONDRAK BIEL Associate Editor

VIRGINIA WARNER Photo Editor and Graphic Designer

MARY ANN FRANKE Assistant Editor Aerial view of the Yellowstone River delta. ARTCRAFT PRINTERS, INC. Bozeman, Montana Printer FEATURES

4 Where Did They Come From? Natural Chemical Markers Identify Source and Date of Lake Trout Yellowstone Science is published quarterly. Introduction in Yellowstone Lake Support for Yellowstone Science is provided by the Yellowstone Association, a non-profi t educational organization dedicated to serving Andrew R. Munro, Thomas E. McMahon, and James R. Ruzycki the park and its visitors. For more information about the association, including membership, or to donate to the production of Yellowstone 13 Of Fairies’ Wings and Fish Science, visit www.yellowstoneassociation.org or write: Yellowstone Association, P.O. Box 117, Fishery Operations and the Lake Fish Hatchery in Yellowstone Yellowstone National Park, WY 82190. The opinions expressed in Yellowstone Science are the authors’ and may not refl ect either Lee H. Whittlesey policy or the views of the Yellowstone Center for Resources. Copyright © 2006, the Yellowstone Association 20 Conserving Yellowstone Cutthroat Trout for Natural Science, History & Education. Yellowstone’s Aquatic Sciences Program For back issues of Yellowstone Science, please see www.nps.gov/yell/publications. Todd M. Koel, Patricia E. Bigelow, Philip D. Doepke, Submissions are welcome from all investigators Brian D. Ertel, and Daniel L. Mahony conducting formal research in the Yellowstone area. To submit proposals for articles, to subscribe, or to send a letter to the editor, please write to the following address: Editor, Yellowstone Science, P.O. Box 168, Yellowstone National Park, WY 82190. You may also email: [email protected]. DEPARTMENTS

Yellowstone Science is printed on recycled paper 2 News & Notes with a soy-based ink. Winter Elk Count • Late Winter Bison Population Estimate • Frederick Turner’s Passing on the cover From the Archives Yellowstone cutthroat trout, 29 courtesy Mimi Matsuda. NEWS & NOTES

NPS/BECKY WYMAN

2006 Winter Elk Count recruitment year to move back into an interagency approach to answering a Standard Hunting Season package. questions and solving problems. The Northern Yellowstone Coop- However, this year’s data on recruit- erative Wildlife Working Group ment, harvest, migration size, and win- Yellowstone Late Winter conducted its annual, late winter clas- ter distribution may allow for a modest Bison Population Estimate sifi cation of northern Yellowstone elk increase in antlerless permits within on March 23, 2006. Biologists traveled the existing Restrictive Season frame- The recently completed 2006 late by helicopter to classify a total of 3,649 work for the January 2007 Gardiner winter bison population estimate is elk as bulls, cows, or calves in specifi ed late hunt.” Final elk permit quotas will 3,500 bison. sampling areas throughout the north- be set by the Fish, Wildlife and Parks Based on a late winter aerial survey, ern winter range during the one-day Commission in July 2006. the estimate takes into account the survey. Northern Yellowstone elk win- Due to a lack of snow cover and 2005 late summer population estimate ter between the northeast entrance of unusually windy conditions, the work- of 4,900 bison, known brucellosis risk Yellowstone National Park and Dome ing group was unable to complete the management mortalities, and scientifi c Mountain/Dailey Lake in the Paradise annual winter trend count of northern estimates of over-winter mortality rates. Valley. Yellowstone elk during the typical The population estimate is used to Estimated sex and age ratios for the period in late December or early Janu- guide adaptive management strategies population were 24 calves and 20 bulls ary. Biologists attempted to conduct under the Interagency Bison Manage- per 100 cows. Calf ratios averaged 20 a count on March 22, 2006, but elk ment Plan (IBMP). Specifi c manage- calves per 100 cows inside the park inside the park were widely distributed ment actions may be modifi ed based and 27 calves per 100 cows north of at higher elevations and in timbered on expected late winter population lev- the park boundary. The overall ratio of areas, which made detection diffi cult els as corroborated by the annual late 24 calves per 100 cows is higher than and unreliable compared to previous winter estimate. the late-winter ratios of 12–14 calves winters. Thus, the count was consid- During winter, 939 bison were per 100 cows during 2002–2005, and ered poor and inaccurate, and results removed from the wild bison popula- within the range of 22–34 calves per are not comparable to surveys during tion through capture operations at 100 cows observed during the previous good conditions in previous years. Stephens Creek, in accordance with six years. The working group, comprised the IBMP. This is the sixth winter the P.J. White, biologist for Yellow- of resource managers and biologists IBMP has been used to guide brucel- stone National Park, indicated, “The from the Montana Department of losis risk management actions. increase in recruitment this year prob- Fish, Wildlife and Parks; Yellowstone The IBMP is a cooperative plan ably refl ects less predation by wolves National Park; Gallatin National designed to protect Montana’s brucel- and, in part, a decrease in antlerless elk Forest; and U.S. Geological Survey– losis-free status while allowing for the harvest.” An apparent disease outbreak Northern Rocky Mountain Science conservation of a viable, wild bison reduced wolf numbers on the northern Center, will continue to monitor trends population. Protecting Montana’s range by 40% during summer 2005. of the elk population and evaluate the brucellosis-free status requires keeping Also, Montana Fish, Wildlife and Parks relative contribution of various compo- bison from mixing with cattle grazing signifi cantly reduced antlerless elk per- nents of mortality, including predation, on land outside the park. mits for the Gardiner area late season environmental factors, and hunting. The fi ve cooperating agencies oper- elk hunt over the last fi ve years, due The Working Group was formed in ating under the IBMP are the National primarily to four consecutive years of 1974 to cooperatively preserve and Park Service, the U.S. Forest Service, low recruitment. protect the long-term integrity of the the Animal and Plant Health Inspec- Tom Lemke, biologist for Mon- northern Yellowstone winter range for tion Service, the Montana Department tana Fish, Wildlife and Parks, added, wildlife species by increasing our scien- of Livestock, and the Montana Depart- “Improved elk recruitment this winter tifi c knowledge of the species and their ment of Fish, Wildlife and Parks. is defi nitely good news, but it will habitats, promoting prudent land man- probably take at least another good agement activities, and encouraging

2 Yellowstone Science 14(2) • Spring 2006 Passages — Frederick Brown Turner by Debra Patla and Charles R. Peterson Herpetology Laboratory, Idaho State University COURTESY OF PATLA DEBRA

Fred Brown Turner, 1927–2006 Mabel. During those years, Fred also had the company of his brother, Lewis, On February 6, 2006, Frederick who worked as a fi shing guide out of Brown Turner passed away in Encini- West Thumb. Lewis helped Fred map tas, California, at the age of 79. Dr. the study area, and together the broth- Turner was renowned for his ground- ers enjoyed backpacking trips in some breaking work on amphibians in Yel- of the wildest parts of the park. lowstone National Park in the 1950s. Fred received his PhD in Zoology The son of Lewis and Josephine from UC–Berkeley in 1957. His aca- Turner, Fred Turner was born on Feb- demic advisor was herpetologist Robert Fred Turner, left, with his brother at ruary 4, 1927, in Carlinville, Illinois. C. Stebbins, and their relationship the Lake Lodge study area, 1955. In 1943, when Lewis Turner was extended to lifelong mutual admiration named Dean of the School of Forestry and professional contact. After a short at Utah State University, the Turner stint as an instructor at Wayne State completed for this species. Its value as family moved to Logan, Utah. Fred University, Fred accepted a position the only detailed, historical study of an was quickly engaged in the western as a researcher at a UCLA laboratory, amphibian population in Yellowstone landscape when his father sent him to working at the Nevada Test Site on has only increased with time. Chuck work on white pine blister rust control experimental research for the Atomic and I feel very fortunate to have had in Idaho. Energy Commission. Collaborating Fred as a guide for several days in 1992 At the age of 16, Fred enrolled as a with colleagues he admired, and sup- and 1993. His observations, along freshman at Utah State University. He ported by unusually stable funding with his shock at the frog population enlisted in the Air Reserve and for fi eldwork, Fred was gratifi ed by decline, kindled our curiosity and was called to active duty in the summer a career that allowed him to conduct inspired our research efforts. Through of 1945. When he returned to civilian herpetological research in California, Fred’s work in the Lake Lodge area, life in 1946, Fred enrolled at University Nevada, and Utah. Fred retired from we can virtually observe a frog popula- of California–Berkeley and studied scientifi c work in 1986. He suffered tion of 50 years ago: how many frogs zoology. He received his master’s degree deterioration of memory in his last few were present, what habitat they used, in 1950, graduating with honors, and years, and was a resident of Silverado and how they moved from one area to was elected to Phi Beta Kappa. Fred Senior Living Center in Encinitas when another to meet their seasonal habitat then took a job as instructor of botany he died of complications due to pneu- requirements (see Yellowstone Science, at Illinois College. monia. winter 1999). Without Fred’s painstak- Longing for the West, he sought Fred Turner pioneered herpetology ing work, it would be impossible to summer employment as a ranger natu- in Yellowstone in the 1950s, provid- see the Lake Lodge frog population ralist in Yellowstone National Park, and ing the park with its fi rst for what it actually is today: a remnant was assigned to work at Fishing Bridge (1951) and guide (1955) of reptiles and persisting in habitat altered by human in 1952. Fascinated by the frogs he amphibians. He wrote articles about his activities and environmental change. encountered in the vicinity of “Soldier observations for Yellowstone’s Nature We have been inspired by Fred Creek” (now known as Lodge Creek), Notes, and published his fi ndings in sci- Turner’s scientifi c understanding of Fred conceived of investigating the entifi c journals. Fred’s PhD research on amphibians, his delight and patience structure and dynamics of the spotted the Lake Lodge spotted frog population in prying out the secrets of their lives, frog population for a doctoral degree. was published in Ecological Monographs his encouragement of our work, and For the following three years (1953– in 1960. This study of population his sorrow about amphibian declines. 1955), he engaged in intensive research structure, growth rates, and spatial rela- Walking in Fred’s footsteps in Yellow- while simultaneously working for the tionships (frog movements with respect stone, we are thankful for the legacy of park, compiling data collected in his to habitat features), remains one of the his admirable work. free time with the assistance of his wife, most comprehensive investigations ever

14(2) • Spring 2006 Yellowstone Science 3 Where Did They Come From? Natural Chemical Markers Identify Source and Date of Lake Trout Introduction in Yellowstone Lake

Andrew R. Munro, Thomas E. McMahon, and James R. Ruzycki NPS/PAT BIGELOW

Fisheries technician Brad Olszewski with a lake trout removed from a Yellowstone Lake spawning area.

XOTIC SPECIES pose one of the most pervasive threats ment actions for avoiding future occurrences and, in some to fresh waters worldwide (Hall and Mills 2000; Rahel instances, raises questions as to whether a presumed invader E2000; Kolar and Lodge 2002). Dramatic changes in is, in fact, native or has resided in the system longer than sus- species abundance and energy fl ow have been observed fol- pected but at low abundance (Kaeding et al. 1996; Wa ters et lowing the establishment of a single new species, even in large al. 2002). Recent investigations of freshwater zooplankton lakes (Zaret and Paine 1973; Vander Zanden et al. 1999). illustrate the utility of genetic markers as a forensic tool for Although many exotic species have been intentionally intro- studying invasion biology (Cristescu et al. 2001; Hebert and duced for commercial or recreational purposes, unauthorized Cristescu 2002). In this paper, we demonstrate the use of natu- transplants and invasions have also contributed substantially to ral chemical markers in fi sh otoliths to iden tify the probable exotic species expansion (McMahon and Bennett 1996; Fuller source and date of introduction of an exotic fi sh species. et al. 1999; Rahel 2000). Exotic lake trout (Salvelinus namaycush) were dis covered in When an exotic species is fi rst detected in a new location, Yellowstone Lake in 1994 (Kaeding et al. 1996). This 250,000- questions about where it originated and when it was trans- ha, high-elevation lake near the headwaters of the Yellowstone planted or invaded are frequently diffi cult to answer with con- River drainage is one of the largest relatively intact lake ecosys- fi dence (Radtke 1995; McMahon and Bennett 1996; Hebert tems in the United States, and is the primary remaining habitat and Cristescu 2002). This uncertainty hinders possible manage- for Yellowstone cutthroat trout (Oncorhynchus clarki bouvieri)

4 Yellowstone Science 14(2) • Spring 2006 (Gresswell and Varley 1988). The clear, deep, cold waters and The origin of the lake trout in Yellowstone Lake is abundant prey base of Yellowstone Lake provide prime habi- unknown. Although lake trout from the Great Lakes were tat for piscivorous lake trout, and by 1996 their population in troduced into Yellowstone National Park’s Shoshone and was estimated to be several thousand, including individuals as Lewis lakes in the late 1800s and later spread to , large as 91 cm in length (Ruzycki et al. 2003). Development these lakes are in the (Pacifi c) drainage, and of an abundant lake trout population was anticipated if left lack connection to the Yellowstone River (Atlantic) drainage unchecked, with the resultant high predation causing (Fig. 1) (Varley and Schullery 1983). Prior to 1994, no lake a signifi cant de cline in the Yellowstone cutthroat trout popu- trout had been reported in Yellowstone Lake despite exten sive lation (Varley and Schullery 1995; Ruzycki et al. 2003). Cut- population sampling and angler survey records dating back throat trout generally evolved in the absence of competing top more than 50 years (Gresswell and Varley 1988; Kaeding et al. predators (Behnke 1992), and declines have been documented 1996). Based on the age and size of lake trout when they were in several western North American lakes following lake trout discovered in 1994 (≤5 years and 43 cm), it was estimated that introduction (Cordone and Frantz 1966; Marnell 1988; Don- lake trout had reproduced in Yellowstone Lake since at least ald and Alger 1993). Consequently, an aggressive lake trout 1989, but when the original transplant occurred was unknown removal pro gram was initiated in Yellowstone Lake in 1995 (Kaeding et al. 1996). to protect a valuable recreational fi shery and the integrity of We used chemical analysis of otoliths (“ear stones” asso- the lake’s terrestrial and aquatic foodwebs, which are heavily ciated with hearing and balance, composed primarily of cal- depend ent on cutthroat trout (Varley and Schullery 1995; cium carbonate and an organic matrix) to estimate where the Koel et al. 2003). lake trout originated and when they were transplanted into

N

5 km 44.6° 5 mi

Continental WA MT Divide Yellowstone OR Lake ID WY

44.4° CA NV UT WY Latitude

Shoshone Lake AZ NM

Lewis Lake Heart Lake 44.2°

-110.7° -110.5° -110.3° Longitude

Figure 1. Map of the major lakes in the study area, Yellowstone National Park.

14(2) • Spring 2006 Yellowstone Science 5 Total length (mm) Age (years) Group Lake n Median Range Median Range Year-class range Known-origin Heart 10 490 327–691 15 8–22 1977–1991 Lewis 10 503 416–949 14 9–26 1973–1990 Yellowstone 10 720a 700–767 9 8–11 1988–1991 Suspected transplants Yellowstone 20 805 765–890 18 10–32 1965–1987

aLength data were not available for fi ve of the known-origin Yellowstone Lake fi sh.

Table 1. Summary of length, age, and year-class of the known-origin lake trout and suspected transplants collected from three lakes in Yellowstone National Park.

Yellowstone Lake. Because trace elements of ambient waters probable source lake of the transplant. We further surmised are incorporated into otoliths as a fi sh grows, analysis of natu- that among suspected transplants, the timing of the change in ral chemical markers in otoliths can be used to reconstruct Sr:Ca ratio in relation to the age of the fi sh could provide an environmental history, including timing of movements and estimated date of when transplantation had occurred. stock origins (Campana 1999; Limburg et al. 2001; Thorrold et al. 2001). However, to our knowledge, no one has used the Materials and methods elemental composition of otoliths to assess introductions of exotic species. Otolith collection and preparation The strontium-to-calcium ratio (Sr:Ca) has been the most Two groups of otoliths were analyzed for this study. The widely used marker in otolith composition studies because (i) fi rst group consisted of archived otoliths from lake trout that of the strong correla tion between otolith and ambient water had been collected from Yellowstone Lake during early stages ratios, (ii) strontium ions can substitute for calcium ions in of the lake trout removal program in 1996 and 1997. It was

the calcium carbonate (CaCO3) of the otoliths, and (iii) Sr is surmised that the largest fi sh in these samples were likely more apt to refl ect environmental than other some of the original fi sh transplanted to Yellowstone Lake, elements owing to a lack of physiological regulation (Cam- and smaller sizes were offspring of these suspected transplants. pana 1999). Organisms do not actively regulate Sr uptake like Twenty otoliths, 10 from each year, were ran domly selected other essential elements (e.g., Ca, K, Na, P). However, because from among the 164 largest lake trout that constituted the sus- the uptake is through several membrane barriers (water – gills pected transplant group. These fi sh were >70 cm total length – blood – endolymph [fl uid that bathes the otoliths] – otolith) and comprised the upper 10 to 20% of length range of lake the is not the same as in the water; there is some trout collected during 1996 and 1997 gillnet sampling (Table discrimination. Although similar, Ca and Sr ions are physically 1). The second group consisted of otoliths from lake trout of and chemically different; Sr is larger and heavier. Furthermore, known origin: suspected offspring of the original founding other physical and chemical factors can alter the incorpora- population in Yellowstone Lake and lake trout of various ages tion of Sr into the otolith during crystal formation. However, from Heart and Lewis lakes (Table 1). Otoliths from this group as seen in Fig. 3, there is a relation between the ratio of the were randomly selected from fi sh gillnetted in 1999 from all concentration of Sr and Ca in the source water and what is three lakes (n = 10 for each lake). eventually incorporated into the otolith. Otoliths were extracted, cleaned, and stored in polyethyl- We compared the Sr:Ca ratios in otoliths from suspected ene vials soon after collection. One otolith from each fi sh was transplants with those in (i) otoliths of lake trout from more sectioned, ground, and polished to expose the nucleus follow- recent year-classes, thought to have been spawned and reared ing the techniques of Secor et al. (1992). Prior to chemical in Yellowstone Lake, and (ii) otoliths of lake trout from Lewis analysis, otolith sections were ultrasonically cleaned in a series and Heart lakes, the two most likely source lakes in Yellow- of baths of Milli-Q water, analytical-grade hexane, and analyti- stone National Park. We hypothesized that lake trout reared in cal-grade methanol (<1 min each) to remove surface contami- a single lake would have similar otolith Sr:Ca ratios through- nants. out their lives, from the early-growth zone near the nucleus to the outer edge. In con trast, we predicted that lake trout Otolith chemistry transplanted into Yellow stone Lake would have a signifi cantly Otolith chemical composition was measured with a different chemical composition between the two zones, refl ec- Phi–Evans time-of-fl ight secondary ion mass spectrometer tive of a change in environmental history, and that the Sr:Ca (ToF-SIMS) (Schueler 1992). For each otolith, 88Sr and 44Ca ratio of the early growth zone could be used to identify the ion counts were measured at two sites, the early-growth zone

6 Yellowstone Science 14(2) • Spring 2006 into an opaque, acid-washed poly- ethylene bottle. Water samples were then preserved with 1 mL of analytical-grade concentrated nitric acid and refrigerated until analyzed. Yellowstone Lake water samples were collected at differ- ent depths in the water column in four areas of the lake (Southeast Arm, West Thumb, Mary Bay, and Stevenson Island) in 1997 (n = 30) and 1998 (n = 41) using a hydrobottle clean of trace metals (Balistrieri et al. In press). The water samples were fi ltered and preserved using the same methods de scribed above. Total dissolved Sr and Ca concentrations (mil- ligrams per liter) were measured Figure 2. Transverse section of a lake trout otolith from a suspected transplant into with a Perkin-Elmer Sciex Elan Yellowstone Lake. Analysis sites for 88Sr and 44Ca ion counts were located in the early- 6000 inductively coupled plasma growth zone (EG), near the nucleus (N), and the edge zone (E) in each otolith. Analyses mass spectrometer (Lamothe et along a transect were used to pinpoint the location of any temporal changes in Sr:Ca ratios. al. 1999) and converted to molar A, annuli. Scale bar = 0.5 mm. concentrations for calculation of the Sr:Ca ratio.

near the nucleus and a zone near the outer edge (Fig. 2), and Statistical analyses reported as Sr:Ca ratios. For a subset of otoliths from each A type III mixed model analysis of variance (ANOVA) and group (suspected transplants into Yellowstone Lake, n = 5; off- Tukey’s multiple comparison tests (SAS Institute Inc. 2000) spring of transplants, n = 1; Heart Lake, n = 2; , were used to compare Sr:Ca ratios among known-origin lake n = 1), additional ion counts were measured at three equidis- trout from Heart, Lewis, and Yellowstone lakes. Lake and tant points between the early-growth and edge sample sites. otolith zone (early growth and edge) were included as fi xed If large changes were detected between adjacent sample sites, factors, and individual fi sh, zone × fi sh interaction, and zone further sites were sampled to pinpoint the location of temporal replication as random factors in the ANOVA. For all tests, changes in Sr:Ca ratio along the otolith axis (Fig. 2). Abrupt signifi cance was measured at α = 0.05. changes in Sr:Ca ratio have been correlated with rapid changes Nearest-neighbor discriminant analysis was used to deter- in water chemistry (e.g., Limburg et al. 2001). The date of a mine the probable source of lake trout in Yellowstone Lake. In large change in Sr:Ca ratio, indicative of a movement to new this type of analysis, each new observation is assigned to the waters, was estimated by comparing the location of the change group to which the majority of its nearest neighbors belong on the otolith axis with the age of the fi sh at that time. Annuli (Johnson 1998). Mean otolith Sr:Ca ratios for known-origin were identifi ed using aging criteria developed for lake trout fi sh, weighted by number of sites sampled in each otolith zone, otoliths by Sharp and Bernard (1988). were used to construct the model. The Sr:Ca ratios from lake trout otoliths of suspected transplants were classi fi ed using the Water chemistry model developed for the known -origin data set. Sr:Ca ratios of water from each of the three study lakes Differences in lake water Sr:Ca ratio among the three were measured to assess whether geochemical differences study lakes were evaluated using a one-factor ANOVA, and existed among the lakes, and the degree to which these dif- Tukey’s multiple comparison test was used to test for pairwise ferences were imparted to lake trout otoliths. Surface water differences. Simple linear regression was used to assess the rela- samples were collected from Heart and Lewis lakes in 2000 (n tionship between otolith and lake water Sr:Ca ratio. Only Sr: = 4 per lake) following standard protocols (American Public Ca data from the otolith edge zones were used to best match Health Association 1998). Water was collected in 1-L poly- otolith composition with lake water composi tion at the times ethylene acid-washed bottles, and 100 mL of each sample was of sampling (within one year for Heart and Lewis lakes and two immediately fi ltered through a 0.45-µm-pore membrane fi lter years for Yellowstone Lake).

14(2) • Spring 2006 Yellowstone Science 7 Results between lake trout from Lewis and Heart lakes were not signif- icant at the α = 0.05 level. However, the Sr:Ca ratio for Lewis Lake water Sr:Ca ratios were signifi cantly different among Lake fi sh was strongly infl uenced by one fi sh with a Sr:Ca ratio Heart, Lewis, and Yellowstone lakes, with differences in mean much greater than that observed in the other nine fi sh sampled val ues among the lakes ranging from 160% to 270% (Fig. 3; (Fig. 4). When this outlier was removed, the pairwise differ- Table 2). Tukey’s multiple comparison tests indicated signifi - ence in otolith Sr:Ca ratios between Lewis Lake and Heart cant differences for all pairwise comparisons among the lakes. Lake lake trout was highly signifi cant. There was a signifi cant linear relation between the otolith Sr: Otolith Sr:Ca ratios between the early-growth and edge Ca ratios of known-origin lake trout and the lake water Sr:Ca zones among known-origin lake trout from each lake varied ratios (Fig. 3). Although water samples from Lewis and Heart little (Fig. 4), the average difference ranging from 0.1 to 5.3%, lakes were collected in a different year than were Yellowstone despite a wide range in the age of fi sh sampled (8–26 years) Lake samples, the small differences in lake water Sr:Ca between (Table 1). Variation of Sr:Ca ratios obtained from multiple the 1997 and 1998 samples in Yellowstone Lake suggest that sampling within a sample site on the otolith was also low, annual variation in water chemistry was minor com pared to averaging 3.92% (n = 25). Accordingly, there was no signifi - the among-lake differences (Table 2). cant interaction between lake and otolith zone as factors in the Otolith Sr:Ca ratios of known-origin lake trout were also ANOVA. Additional samples taken between the early-growth sig nifi cantly different among the three lakes (Fig. 4). Mean and edge zones also revealed consistent Sr:Ca ratios across the otolith Sr:Ca ratios of Yellowstone Lake lake trout were sig- otolith growth axis among lake trout sampled from different nifi cantly different from lake trout otolith Sr:Ca ratios from lakes (Fig. 5). Nearest-neighbor discriminant analysis cor- Heart Lake and Lewis Lake. Differences in otolith Sr:Ca ratios rectly classifi ed 90 to l00% of lake trout into their home lake (Table 3). In sharp contrast with lake trout of known origin, 18 of Lake Year n Mean (SD) 20 suspected transplants, ranging from 13 to 32 years of age Heart 1999 4 2.40 (0.23) at the time of their collection in 1996 and 1997, exhibited Lewis 1999 4 1.53 (0.71) substantial increases (mean = 256%) between the early-growth Yellowstone 1997 30 3.92 (0.10) 1998 41 4.01 (0.14) 6 ) Table 2. Lake water Sr:Ca ratios (mmol·mol-1) from -2 5 Heart, Lewis, and Yellowstone lakes, Yellowstone National Park. 4

3 ) -2 2 5 Ca ion counts (×10

44 1

4 Sr: 88 0 3

Heart Lake Lewis Lake Suspected Ca ion counts (×10 2 Yellowstone

44 transplants Lake Sr:

88 1 Figure 4. Comparison of Sr:Ca ratios of known-origin lake 0 trout otoliths and otoliths of suspected transplants. Two Otolith 0 1 2 3 4 5 zones were analyzed for each otolith: early-growth (open boxes) and edge zones (shaded boxes) for both known- Water [Sr:Ca] (mmol•mol-1) origin lake trout from Heart, Lewis, and Yellowstone lakes (n = 10 per lake) and suspected transplants gillnetted from Figure 3. Relation between mean lake water Sr:Ca ratios Yellowstone Lake (n = 20). Boxes show the mean Sr:Ca and mean otolith edge Sr:Ca ratios of lake trout from ratios (broken line), median (central solid line), fi rst and Heart (), Lewis (), and Yellowstone () lakes. The solid third quartiles (box edges), and individual outliers (circles) line denotes fi tted linear regression. outside the 10th and 90th percentiles (whiskers).

8 Yellowstone Science 14(2) • Spring 2006 % classifi cation into lake and otolith chemistry (Bath et al. 2000; Wells et al. 2003), Heart Lewis Yellowstone and (ii) that source waters, even in freshwater environments, Known-origin can be identifi ed with a moderate-to-high degree of precision Heart 100 0 0 based on otolith chemical composition (Thorrold et al. 1998; Lewis 0 90 10 Wells et al. 2003). Both attributes of otoliths are important in Yellowstone 0 0 100 determining stock origins, and our fi ndings indicate that this Suspected transplants is particularly relevant for exotic species where stock origin is Early growth 5 90 5 frequently unknown. Edge 20 0 80 Unlike known-origin lake trout, the large and rapid change in Sr:Ca ratio along the otolith axis of suspected trans- Note: Cross-validation results for the known-origin lake trout calibration data set (n = 10 fi sh per lake) were used to assess classifi cation accuracy. Early-growth and plants demonstrates that these fi sh experienced a rapid change edge zones of the otoliths from the group of suspected transplants captured in in water chemistry. The magnitude of the change in otolith Sr: Yellowstone Lake (n = 20) were classifi ed into one of the three lakes. The probable Ca ratio among suspected transplants (256% increase) mirrors origin of lake trout in Yellowstone Lake was based on the early-growth-zone Sr:Ca ratios of suspected transplants. that shown by anadromous fi sh migrating from freshwater to seawater. For example, Limburg (1995) found that otolith Sr: Table 3. Classifi cation of lake trout into probable source Ca ratios of age-0 American shad (Alosa sapidissima) increased lakes. by 250 to 620% during movement from freshwater to seawater. Such a large and rapid change in otolith chemistry among lake trout from older year-classes supports the hypoth- and edge zones (Fig. 4). Eighty percent of the edge zones of esis that lake trout were transplanted to Yellowstone Lake. All suspected transplants were classifi ed by the discriminant model as Yellowstone Lake, whereas 90% of the Sr:Ca ratios measured in the early-growth zone were classifi ed as Lewis Lake (Table 6 (a) 3). This percentage increased to 100% if the two fi sh that had similar early-growth and edge zone Sr:Ca ratios were excluded 4 from the classifi cation analysis. Sampling along the otolith axis 2 of a random subset (n = 3) of lake trout exhibiting the abrupt ) shift in Sr:Ca ratio revealed that Sr:Ca ratio increases occurred -2 6 (b) within a short period (Fig. 6). The increase in Sr:Ca ratios was 4 estimated to occur in 1989 for two fi sh (Figs. 6a and 6b) and 2 in 1996 for one fi sh (Fig. 6c) of the subset sampled. The other two fi sh, representing the lake trout with similar early-growth 6 (c) and edge zone Sr:Ca ratios, showed little variation in Sr:Ca ratios along the otolith axis (Figs. 6d and 6e). These fi sh were 4 Ca ion counts (×10 the youngest in the group of suspected transplants (ages 10 44 2 and 11). Sr: 88 6 (d) Discussion 4 Our work demonstrates that otolith chemical compo- 2 sition can be used to identify a probable source and date of exotic species introductions. Water chemistry differed signifi - 0.0 0.4 0.8 1.2 1.6 2.0 2.4 2.8 cantly among the three large lakes we studied, and these dif- ferences were directly imparted to lake trout oto liths. The low Distance from otolith nucleus (mm) variation in Sr:Ca ratios of known-origin lake trout along the otolith axis from the early-growth to the edge zone, despite a Figure 5. Patterns of Sr:Ca ratios along the otolith axes of wide range of ages, established that lake trout from each lake four known-origin lake trout from (a) Lewis Lake (26 years, lived in a similar water chemistry throughout their lives. This 949 mm), (b) Heart Lake (10 years, 481 mm), (c) Heart Lake temporal and spatial stability in otolith chemical signatures (15 years, 490 mm), and (d) Yellowstone Lake (10 years, 767 was refl ected by the high discriminatory power to classify lake mm). Analysis sites were classifi ed by discriminant analysis: trout by their home lake based on unique otolith Sr:Ca ratios. Lewis Lake (), Heart Lake (), and Yellowstone Lake (). These fi ndings corroborate previous work demonstrating (i) The dotted lines show the location of annuli and the broken a strong association between chemical composition of water line the otolith edge.

14(2) • Spring 2006 Yellowstone Science 9 Yellowstone Lake lake trout from younger age-classes, ≤11 likely occurred during the mid- to late l980s (Kaeding et al. years (1986 estimated year-class and later) at the time of col- 1996). Although our sample size was not large enough to pin- lection in 1996–1999, had similar early-growth and edge zone point the exact number and timing of transplants, Ruzycki et Sr:Ca ratios, indicating a constant environmental history. In al.’s (2003) estimate of 298 lake trout >10 years old in 1996 contrast, all lake trout from older year-classes had a marked (year-class 1986 and earlier) suggests that a rather large num- increase in Sr:Ca ratios between the early-growth and edge ber of individuals were transplanted. Moreover, the dating of zones, indicating that these fi sh had reared in waters of dis- the abrupt shifts in otolith chemistry as occurring in 1989 and tinctly different water chemistry during their life-span. These 1996 suggests that multiple transfers may have occurred. results therefore support the assertion that initial transplanting The classifi cation of 90% of the early-growth-zone Sr:Ca and natural re production of lake trout in Yellowstone Lake ratios of the suspected transplants into Lewis Lake by discrimi- nant analysis suggests that of the two lakes considered to be the most probable source lakes within Yellow stone National 6 (a) Park, Lewis Lake is the likely source of transplanted lake trout. Unlike Heart Lake, Lewis Lake is accessible by road, which 4 may have facilitated the unautho rized transfer of lake trout 2 1989 into Yellowstone Lake. Change in Sr:Ca ratios with age or maturation (ontoge- (b) 6 netic or physiologic effects) is a possible alternative explanation 4 ) to the transplant hypothesis. However, an age- or maturation- -2 2 1989 induced Sr:Ca ratio increase was unlikely given that lower Sr: Ca ra tios would be expected in the early-growth zone among 6 (c) all lake trout. Further, the pattern of increased Sr:Ca ratio was

4 only observed in suspected transplants and not in the early- 1996 growth zone or among younger age groups of other lake trout 2 sampled from Yellowstone Lake or from any of the lake trout

Ca ion counts (×10 sampled from Heart and Lewis lakes, which varied greatly in 44 6 (d) age. Sr:

88 4 Another possible explanation for the increase in Sr:Ca 2 ra tios in the otoliths of the suspected transplant group of lake trout is temporal or spatial variation in lake water Sr:Ca ratios 6 (e) of Yellowstone Lake. The large increase in otolith Sr:Ca ratios 4 in 1989 observed in some lake trout from the suspected trans- plant group coincided with the intense wildfi res in Yellowstone 2 National Park in 1988 that altered dissolved ion concentrations 0 of some streams in Yellowstone National Park (Minshall et al. 0.0 0.4 0.8 1.2 1.6 2.0 1997). Although Sr was not measured, other dissolved ions Distance from otolith nucleus (mm) in the lake showed only minor changes in concentration, and Lathrop (1994) and Theriot et al. (1997) found no evidence Figure 6. Patterns of Sr:Ca ratios measured along the for signifi cant changes in water chemistry resulting from the otolith axes of fi ve lake trout from the group of suspected 1988 wildfi res; therefore, temporal changes in water chemistry transplants collected from Yellowstone Lake: (a) 23 years, seem unlikely to account for the 256% increase in otolith Sr: 832 mm, (b) 18 years, 850 mm, (c) 16 years, 768 mm, (d) Ca ratios for Yellowstone Lake lake trout. Yellowstone Lake 11 years, 782 mm, and (e) 10 years, 765 mm. Three of the has many hydrothermal vents that may be a source of local fi sh show a rapid increase in Sr:Ca ratios corresponding to enrichment of Sr and Ca (Balistrieri et al. In press). However, transplant dates of 1989 (Figs. 6a and 6b) and 1996 (Fig. 6c), we found that lake water Sr:Ca ratios varied little (<3.5%) with whereas the two youngest fi sh (Figs. 6d and 6e) show little depth or among lake subbasins; therefore, it is also unlikely variation in Sr:Ca ratios, suggesting that they had lived in that the increase in otolith Sr:Ca ratios was a result of fi sh Yellowstone Lake throughout their lives. Analysis sites were inhabiting different areas within Yellowstone Lake with differ- classifi ed by discriminant analysis: Lewis Lake (), Heart ent Sr:Ca ratios. Lake (), and Yellowstone Lake (). The dotted lines show There are two important caveats when assessing the impli- the location of annuli and the broken line the otolith edge. cations of this study. First, the long life-span of lake trout Arrows mark the estimated year that the increase in Sr:Ca facilitated a long-term retrospective analysis of their environ- ratios occurred. mental history. Detection of unique chemical marks would

10 Yellowstone Science 14(2) • Spring 2006 have been more diffi cult in species with tescu et al. 2001; Thorrold et al. 2001; higher turnover rates or with extensive this study), a combination of both tools migrations between waters of differing could provide important insights into chemical signatures. Second, although the study of invasion biology. Lewis Lake was identifi ed as the source lake for transplanted lake trout with a high degree of probability, not all ambi- Acknowledgements ent waters have unique Sr:Ca signa- This article was reprinted in adapted tures (Gillanders et al. 2001; Wells et form with permission from the Canadian al. 2003; Munro 2004). Therefore, we Journal of Fisheries and Aquatic Sciences. The full version can be found in Can. J. Fish. Aquat. Tom McMahon is a professor of fi sher- cannot eliminate the possibility that lake ies at Montana State University–Bozeman trout were transplanted from some other Sci. 62:79–87 (2005). R. Avci, D. Mogk, and N. Equall of the where he teaches and conducts research on lake with Sr:Ca ratios similar to those of Montana State University Image and Chem- fi sh ecology and management. Tom holds Lewis Lake. In future studies, use of iso- ical Analysis Laboratory pro vided valuable a BA from University of California–Santa topes or other elements in addition to Sr technical assistance with the ToF-SIMS. Barbara and MS and PhD degrees from the We thank W. C. Shanks III for providing University of Arizona. Prior to coming to could enhance the accuracy of identify- MSU in 1990, Tom conducted research on ing source waters (Kennedy et al. 2002; Yellowstone Lake water chemistry data; B. Ertel for assistance with collection of fi sh Pacifi c salmon at Oregon State University Wells et al. 2003). and water samples; J. Borkowski for his sta- and in British Columbia with Canada’s There is growing appreciation for tistical advice; and L. Kaeding, P. Bigelow, D. Department of Fisheries and Oceans. just how extensive in troductions of Mogk, B. Kerans, A. Zale, and three anony- exotic species have been, and the formi- mous reviewers for helpful comments on dable problem they present for aquatic earlier drafts of the manuscript. This work was supported by Yellowstone National ecosystem management (Hall and Mills Park grant R99-09452. 2000; Rahel 2000; Kolar and Lodge 2002). For instance, in Montana alone, 375 cases of unauthorized introduc- tions of fi shes of 45 different species have been documented in 224 differ- ent waters (Vashro 1995). Detection of an exotic species often poses questions about when the invasion occurred and James R. Ruzycki is a fi sheries research the geographic origin of the exotic, but biologist at the Oregon Department of Fish few tools have been available to answer and Wildlife in LaGrande, Oregon, where he leads a team that investigates life his- them (McMahon and Bennett 1996; Andrew Munro (holding a Murray cod) is tory attributes and population status of Hebert and Cristescu 2002; Waters et currently an ARC Postdoctoral Research steelhead and Chinook salmon in north- al. 2002). Better knowledge of where Associate at the University of Adelaide, east Oregon. Jim holds a PhD in Fisheries exotic species originated and the relative Australia, where he is studying the impacts from Utah State University, where he esti- risks they pose is essential for the design of fi sh stocking on native fi sh populations mated the predatory impact of lake trout on cutthroat trout in Yellowstone Lake, of educational and regulatory programs in the Murray-Darling Basin and developing methods for the discrimination of hatchery an MS in Aquatic Ecology from Utah State to stem the of future unauthorized fi sh from wild fi sh. Andrew holds a PhD in University, and a BS in Zoology from the introductions (McMahon and Bennett Fish and Wildlife Biology from Montana University of Wisconsin. Jim worked as a 1996; Kolar and Lodge 2002). Genetic State University–Bozeman, an MS from East fi sheries biologist in Yellowstone National markers have recently been shown to Stroudsburg University, Pennsylvania, and Park from 1997 to 2000, directing the lake trout control program in Yellowstone Lake. be a useful forensic tool for studying a BS from Ursinus College, Pennsylvania. Andrew’s research focuses on the use of He discovered the fi rst spawning aggrega- invasion biology (Cristescu et al. 2001; chemical and growth patterns in the cal- tions for lake trout in the lake and demon- Hebert and Cristescu 2002; Waters et cifi ed structures of fi sh (otoliths, scales, strated that large numbers of adults could al. 2002). Our study demonstrates how spines) to answer questions relating to the be removed using nets. He also initiated the chemical analysis of otoliths can provide ecology, conservation, and management of netting program for the successful removal fi s .h of juvenile lake trout in deep-water habi- a novel forensic tool to estimate geo- tats while avoiding signifi cant bycatch of graphic origin and timing of exotic fi sh cutthroat trout. introductions. Be cause both chemical and genetic analysis techniques have dis- tinct advantages and limitations (Cris-

14(2) • Spring 2006 Yellowstone Science 11 Literature cited and K. H. Nislow. 2002. Reconstructing the examination and analysis. Canadian Special lives of fi sh using Sr isotopes in oto liths. Publication of Fisheries and Aquatic Sciences American Public Health Association. 1998. Canadian Journal of Fisheries and Aquatic 117:19 – 57. Standard methods for the examination of water Sciences 59:1–5. Sharp, D., and D. R. Bernard. 1988. Precision and wastewater, including bottom sedi ments and Koel, T. M., J. L. Arnold, P. E. Bigelow, B. D. of estimated ages of lake trout from fi ve sludges. 20th ed. New York: American Public Ertel, and D. L. Mahony. 2003. Yellowstone calcifi ed structures. North American Journal of Health Associa tion. fi sheries and aquatic sciences: annual report, Fisheries Management 8:367–372. Balistrieri, L. S., W. C. Shanks III, R. L. Cuhel, 2002. YCR-NR-2003-02. Yellowstone Theriot, E. C., S. C. Fritz, and R. E. Gresswell. C. Aguilar, and J. V. Klump. In press. The National Park, Wyo.: Yellowstone Center for 1997. Long-term limnological data from the infl uence of sublacustrine hydrothermal vents Re sources. larger lakes of Yellowstone National Park, on the geochemistry of Yellowstone Lake, Kolar, C. S., and D. M. Lodge. 2002. Ecological , U.S.A. Arctic and Alpine Research in L. A. Morgan, ed., Integrated geoscience predictions and for alien 29:304–314. studies in the Greater Yellowstone area: volca- fi shes in North America. Science 298:1233– Thorrold, S. R., C. M. Jones, S. E. Campana, nic, hydrothermal and tectonic processes in the 1236. J. W. McLaren, and J. W. H. Lam. 1998. Yellowstone ecosys tem. U.S. Geological Survey Lamothe, P. J., A. L. Meier, and S. Wilson. 1999. Trace element signatures in otoliths record Professional Paper. The determination of forty-four elements natal river of juvenile American shad (Alosa Bath, G. E., S. R. Thorrold, C. M. Jones, S. E. in aqueous samples by inductively coupled sapidissima). Limnology and Oceanography Campana, J. W. McLaren, and J. W. H. Lam. plasma–mass spectrometry. Denver, Colo.: 43:1826–1835. 2000. Strontium and barium uptake in ara- U.S. Geological Survey Open-File Report Thorrold, S. R., C. Latkoczy, P. K. Swart, and C. gonitic otoliths of marine fi sh. Geochimica et 99-151. M. Jones. 2001. Natal homing in a marine fi sh Cosmochimica Acta 64:1705–1714. Lathrop, R. G. 1994. Impacts of the 1988 wild- metapopulation. Science 291:297–299. Behnke, R. J. 1992. Native trout of western fi res on the water quality of Yellowstone and Vander Zanden, M. J., J. M. Casselman, and J. B. North America. American Fisheries Society Lewis lakes, Wyoming. International Journal of Rasmussen. 1999. Stable isotope evidence for Monograph 6. Wildland Fire 4:169–175. the food web consequences of spe cies inva- Campana, S. E. 1999. Chemistry and composi- Limburg, K. E. 1995. Otolith strontium traces sions in lakes. Nature 401:464–467. tion of fi sh otoliths: pathways, mechanisms environmental history of subyearling Varley, J. D., and P. Schullery. 1983. Freshwater and applications. Marine Ecology Progress American shad Alosa sapidissima. Marine wilderness: Yel lowstone fi shes and their Series 188:263–297. Ecology Progress Series 119 : 25 –35. world. Yellowstone National Park, Cordone, A. J., and T. C. Frantz. 1966. The Limburg, K. E., P. Landergren, L. Westin, M. Wyo.: Yellowstone Library and Museum Lake Tahoe sport fi shery. California Fish and Elfman, and P. Kristiansson. 2001. Flexible Association. Game 52:240–274. modes of anadromy in Baltic sea trout: mak- Varley, J. D., and P. Schullery, eds. 1995. The Cristescu, M. E. A., P. D. N. Hebert, J. D. S. ing the most of marginal spawning streams. Yellowstone Lake crisis: confronting a lake Witt, H. J. MacIsaac, and I. A. Grigorovich. Journal of Fish Biology 59:682–695. trout invasion. Yellowstone National Park, 2001. An invasion history for Cercopagis pen- Marnell, L. F. 1988. Status of westslope cut- Wyo.: Yellowstone Cen ter for Resources. goi based on mitochondrial gene sequences. throat trout in Glacier National Park. Vashro, J. 1995. The bucket brigade. Montana Limnology and Oceanography 46:224–229. Montana. American Fisheries Society Symposium Outdoors 26(5):34–35. Donald, D. B., and D. J. Alger. 1993. Geographic 4:61–70. Waters, J. M., M. Shirley, and G. P. Closs. 2002. distribution, species displacement, and McMahon, T. E., and D. H. Bennett. 1996. Hydroelectric de velopment and translocation niche overlap for lake trout and bull trout in Walleye and northern pike: boost or bane to of Galaxias brevipinnis: a cloud at the end of mountain lakes. Canadian Journal of Zoology northwest fi sheries? Fisheries 21(8):6–13. the tunnel? Canadian Journal of Fisheries and 71:238–247. Minshall, G. W., C. T. Robinson, and D. E. Aquatic Sciences 59:49–56. Fuller, P. L., L. G. Nico, and J. D. Williams. 1999. Lawrence. 1997. Postfi re responses of lotic Wells, B. K., B. E. Rieman, J. L. Clayton, D. L. Nonindigenous fi shes introduced into inland ecosystems in Yellowstone National Park, Horan, and C. M. Jones. 2003. Relationships waters of the United States. Bethesda, MD: U.S.A. Canadian Journal of Fisheries and Aquatic between water, otolith, and scale chemistries American Fisheries Society. Sciences 54:2509–2525. of westslope cutthroat trout from the Coeur Gillanders, B. M., P. Sanchez-Jerez, J. Bayle- Munro, A. R. 2004. Identifi cation of life history d’Alene River, Idaho: the potential applica- Sempere, and A. Ramos-Espla. 2001. Trace variation in salmonids using otolith microchem- tion of hard-part chemistry to describe elements in otoliths of the two-banded istry and scale patterns: im plications for illegal movements in freshwater. Transactions of the bream from a coastal region in the south- introductions and for whirling disease in Missouri American Fisheries Society 132:409–424. west Mediter ranean: are there differences River rainbow trout. PhD thesis, Montana State Zaret, T. M., and R. T. Paine. 1973. Species among locations? Journal of Fish Biology Uni versity, Bozeman, Montana. introduction in a tropi cal lake. Science 59:350–363. Radtke, R. L. 1995. Forensic biological pursuits 182:449–455. Gresswell. R. E., and J. D. Varley. 1988. Effects of exotic fi sh origins: piranha in Hawaii. of a century of human infl uence on the cut- Environmental Biology of Fishes 43:393–399. throat trout of Yellowstone Lake. American Rahel, F. J. 2000. Homogenization of fi sh faunas Fisheries Society Symposium 4:45–52. across the United States. Science 288:854– Hall, S. R., and E. L. Mills. 2000. Exotic species 856. in large lakes of the world. Aquatic Ecosystem Ruzycki, J. R., D. A. Beauchamp, and D. L. Yule. Health Management 3:105–135. 2003. Effects of introduced lake trout on Hebert, P. D. N., and M. E. A. Cristescu. 2002. native cutthroat trout in Yellowstone Lake. Genetic perspectives on invasions: the case Ecological Applications 13:23–37. of the Cladocera. Canadian Journal of Fisheries SAS Institute Inc. 2000. SAS/STAT software, and Aquatic Sciences 59:1229–1234. release 8.01. Cary, NC: SAS Institute Inc. Johnson, D. E. 1998. Applied multivariate methods Schueler, B. W. 1992. Microscope imaging by for data analy sis. Pacifi c Grove, Calif.: Brooks/ time-of-fl ight sec ondary ion mass spectrom- Cole Publishing Company. etry. Microscopy Microanalysis Microstructures Kaeding, L. R., G. D. Boltz, and D. G. Carty. 3:119–139. 1996. Lake trout discovered in Yellowstone Secor, D. H., J. M. Dean, and E. L. Laban. 1992. Lake threaten native cutthroat trout. Fisheries Otolith removal and preparation for micro- 21(3):16–20. structural examination, in D. K. Stevenson Kennedy, B. P., A. Klaue, J. D. Blum, C. L. Folt, and S. E. Campana, eds., Otolith micro structure

12 Yellowstone Science 14(2) • Spring 2006 PHOTO COURTESY NPS, YELLOWSTONE NATIONAL PARK, C.A. LORD, YELL 20798-1 Construction of the Lake fi sh hatchery building in 1928.

Of Fairies’ Wings and Fish Fishery Operations and the Lake Fish Hatchery in Yellowstone

Lee H. Whittlesey

“…for I have been unable to live in the beauty of Yellowstone without feeling the touch of fairies’ wings as they fl itted from fl ower to fl ower.” —Howard Back, The Waters of Yellowstone With Rod and Fly, 1938

ITH THOSE POETIC WORDS, angler/writer How- his article, “Their Numbers Are Perfectly Fabulous.”1 While ard Back gave us the background for his love of members of the Washburn party were not the fi rst to fi sh in Wfi sh and fi shing in Yellowstone National Park. The Yellowstone—archeological evidence indicates that Ameri- park was a place where his imagination could combine with can Indians fi shed there long ago, and that later fur trappers his love of angling to imbue him with the desire to share the or prospectors may also have done so—party members of magic of fi shing and the beauty of park lakes and streams with 1870 were the fi rst to write about it. readers. In his 1938 book, Mr. Back wrote of park beauty and Following the Washburn party, fi shing in Yellowstone fi shing tips while also discussing some history of the Yellow- was a continuous activity. In the 1870s, Hayden survey stone fi shery. members wrote quite a lot about fi sh and fi shing, and This fi shery history begins in 1870, with the explo- both the Earl of Dunraven in 1874 and General William rations and writings of the Washburn–Langford–Doane Strong in 1875 experienced angling in the park. A glance expedition. Historian Paul Schullery has chronicled it in at issues of Forest and Stream magazine from 1874 to 1890

14(2) • Spring 2006 Yellowstone Science 13 W.T. THOMPSON TO LLOYD BRETT, AUGUST 5, 1912, YNPA 5, AUGUST BRETT, TO LLOYD W.T. THOMPSON

Hand-drawn map showing locations of existing and proposed buildings, 1912.

reveals numerous pieces written about fi sh and fi shing in the nature often needed human ‘help’ to make fi sheries better.”8 new park.2 Or as another fi shery expert noted, the purpose of fi sh hatch- Early offi cials were inclined to try to “improve” the park’s eries in Yellowstone was “to assist nature with a job she had fi shery. The earliest fi sh stocking in Yellowstone National been doing adequately for thousands of years.”9 Managers Park occurred in 1881, when Superintendent P. W. Norris believed that fi sh should be heavily stocked in all available moved some native trout from Trout Lake to nearby ponds, waters in order to have the best possible sportfi shing (“the probably the small lakes known today as Buck Lake and best possible campfi re meal,” as Varley put it), and they Shrimp Lake. Norris also talked about introducing non- believed that fi sh eggs should be harvested and shared in native carp into park waters, dreaming of making modifi - great numbers with other locations around the nation and cations to the fi shery even before he had the personnel or the world. They also believed that the supply of trout might money to do so.3 Investigators from the U.S. Fish Com- someday dwindle due to fi shing pressure. “The hatcheries mission—David Starr Jordan, Barton W. Evermann, and are maintained,” explained Hugh Smith and William Ken- S. A. Forbes—began the stocking of park lakes and streams dall in 1921, “for the purpose of keeping up the supply of with exotic trout, and they all produced government reports [cutthroat] trout.”10 Finally, managers believed that many (1889–1893) about the park’s fi shery.4 fi sh eggs were lost naturally and that such “unfortunate” After 1900, park offi cials under the U.S. Army began events could and should be prevented.11 to develop the Yellowstone fi shery program, deciding to In accordance with these theories, the U.S. Bureau of offi cially tinker with the fi sh and their habitats. Although Fisheries (part of the Department of Commerce), made an manipulating fi sh populations of park lakes and streams initial egg taking on May 15, 1901, at West Thumb.12 Mr. began in earnest in 1889, when the U.S. Fish Commission D. C. Booth, superintendent of the national fi sh hatchery at decided to stock various fi shless waters, no shipping of Yel- Spearfi sh, South Dakota, conducted this operation, assisted lowstone fi sh eggs to locations outside the park began until by four U.S. Army soldiers.13 To support this activity, work- 1901.5 Fishery management operations at Yellowstone Lake men erected a hatchery building on Little Thumb Creek in began at West Thumb shortly after 1900, and from 1901 1903, and enlarged it in 1906 and 1912.14 to 1953, Yellowstone National Park was the largest single Park fi shery operations were limited to the West source of wild cutthroat trout eggs in the United States.6 An Thumb area until 1909, when a small cabin and hatching 1898 suggestion by Captain J. B. Erwin that a fi sh hatchery troughs were erected at Clear Creek and egg collecting was be established in the park had, according to a person who performed at Cub Creek.15 Fishery workers eventually set worked at the 1920s hatchery, “far reaching effects [that] up fi sh traps at numerous streams and lakes and established would forever alter the natural state of the Park.”7 other small hatcheries at Soda Butte, Trout Lake, and Grebe Support for fi sh hatcheries permeated the thinking of Lake.16 just about all nature managers in those days. “It was believed,” But what was to become the center of the park’s fi sh declared fi sh historians John Varley and Paul Schullery, “that culture operation for the next 40 years was planned for a

14 Yellowstone Science 14(2) • Spring 2006 location at Yellowstone Lake. In 1912, W. T. Thompson, in 1928 to build another hatchery. Workmen erected most superintendent of Yellowstone’s fi shery operations, asked of the new building that summer and added interior details the Commissioner of Fisheries for permission to erect four in 1929, so that the main building was ready for occupancy buildings on the shore of Yellowstone Lake one-half mile in 1930. Also erected that summer were a new bunkhouse west of the Lake Hotel. A log house was all that was “here and mess house. These buildings were of frame and log con- now,” opined Thompson, along with “a few open air [fi sh] struction of the type then being approved by the Landscape troughs subject to depredation by the bears.” He regretted Division of the NPS.23 that “the men cook and eat in the open.” Thompson asked The new hatchery building was 42' × 108' and con- for a 30' × 60' hatchery, a central storehouse, a mess build- tained an offi ce for the hatchery superintendent, a main ing with quarters in it, and a cabin/offi ce for himself.17 He room of 42' × 68' for hatching and packing eggs, and an needed these facilities, explained one of Thompson’s super- aquarium room “with seven large tanks” containing native visors, “in order to facilitate fi sh cultural operations in the park fi sh so that the public could view them at a lower level Yellowstone Park and extend its present fi eld operations.”18 through glass windows.24 A balcony, accessible via a stairway

The purpose of fi sh hatcheries in Yellowstone was “to assist nature with a job she had been doing adequately for thousands of years.”

A month later, Thompson was pleased to learn that the at the front of the building, allowed visitors to look down Department of the Interior had authorized construction of on workers at the hatching troughs without permitting his requested buildings. The buildings “will all be located entrance to the room. Workmen soon “wrecked” the old on the narrow strip of lake front,” he noted defi nitively, hatchery building, which was described as “very unsightly “betwixt the very small creek into which the Lake Hotel and in a very poor state of repair.” “All in all,” declared a sewers drain [Hotel Creek] and the next small creek S.W. report on the project, “the [new] hatchery building is one [Hatchery Creek] on the banks of which our boat house and of the most modern in the western part of the country, with temporary hatchery now stand.” Thompson concluded, a capacity of about 25 million or more eggs per year.”25 “the hatchery building will be located between the present Superintendent Roger Toll’s monthly report for July 1929 boat house and the creek.” He included a hand-drawn map was even more emphatic, stating that “37 men are working for the fi les that showed the locations of the current and [on the new building], and by the end of the season, the proposed buildings.19 Lake Fish Hatchery will then be the fi nest and most up-to- Workmen commenced construction on these build- date hatchery in the United States.”26 ings and completed them in 1913—a hatchery (34' × 60'), The burgeoning hatchery complex also included three a mess hall, a bunkhouse, and a shop. Laborers installed new rectangular rearing ponds about 75 yards west of the a small dam and pipeline to ensure an adequate

water supply to the complex, and erected new fi sh YELLOWSTONENPS, NATIONAL PARK, YELL 30040 troughs. The complex soon boasted 26 double and 2 single troughs, each with eight compartments of about 14' × 18' each. Each trough could hold 500,000 fi sh eggs.20 In 1914, workmen added a bungalow and a four-horse barn at the complex.21 “The workings of the plant have become a mat- ter of interest to so many tourists,” proclaimed the park superintendent that year, “as to require at times the services of one of the attendants con- stantly in showing them around.”22 Thompson’s buildings apparently were not built well, for park offi cials were describing the hatchery building at Lake as old and decrepit by the late 1920s. Yellowstone was now under the management of the recently established National Park Service (NPS), and park offi cials took steps Old Lake fi sh hatchery. 1928.

14(2) • Spring 2006 Yellowstone Science 15 M. S. Daum stated in 1929 that two buildings remained to be erected at the new hatchery, including a new boathouse to be built on the “end of the dock on the site of the old fi sh hatchery.”32 This boathouse appeared in the park’s 1941 master plan, but nothing else about it has NPS, YELLOWSTONE NATIONAL PARK, DAUM, YELL 30043 been found. A note in the history card fi le of the Yellowstone Research Library, compiled in the 1920s by Superinten- New Lake fi sh hatchery. 1928. dent Horace Albright, states that an old boathouse was torn down and replaced at new building on nearby Hatchery Creek. The ponds were Lake in 1926, but it is not known which boathouse this was.33 112', 108', and 98' long and each 5' wide. Workers stocked It may have been the second of the two boathouses that are the ponds with small fry (young fi sh), which were held there still there. A photo taken about 1928 that appears in Frank and fed before being planted in park waters. “This improve- H. Tainter’s and Bill Tanner’s “Fish Culture in Yellowstone ment,” explained Toll, “is a decided advantage in the propa- National Park The Early Years: 1901–1930,” shows a piece gation of fi sh at the Yellowstone Lake plant, as previously it of the boathouse next to the “old” Lake fi sh hatchery. The was necessary to plant fi sh direct from the hatchery which caption reads, “to the left is the boat house which was still in resulted in serious loss.”27 existence in 1986.”34 East of the new building, workmen built an exhibit The completion of the Lake hatchery and boathouse pond, 65' long × 5' wide, where mature fi sh could be kept complex gave the park fi shery operation the shot in the arm for viewing.28 A new bunkhouse and messhouse were located that it needed in order to function effi ciently for the next 25 nearby. The bunkhouse, completed in 1930, was 86' × 27', years. Activities continued to include the planting of both with a recreation room, a bathroom, and 15 individual native and non-native fi sh in park streams as well as the col- rooms for employees. The messhouse, constructed in 1929 lection and export of large numbers of trout eggs. Howard and 1930, was 56' × 24', with a large dining room, kitchen, Back described the process in 1938: pantry, and living quarters for the cook. A small woodshed The hatchery at Lake Junction on Yellowstone Lake con- built at the rear of the mess house was 15' × 20' in size. fi nes itself to the stripping of cutthroat trout, and large A donation of $15,000 by William E. Corey of Pitts- demands for these fi sh are satisfi ed from this origin. The burgh, Pennsylvania, in October 1926 made this hatchery Park, in return for supplying the eyed ova, has a fi rst call construction possible. The Bureau of Fisheries matched on the hatched fi sh to the extent of its own requirements. these funds, so that the fi nal result was to “enable the The Lake Junction hatchery, which is open to the public, Bureau to properly handle fi sh propagation and planting in and which you [the visitor] certainly ought to visit, is Yellowstone National Park.”29 After the buildings had been fed from traps on eleven different streams which run into extant for approximately 10 years, NPS offi cials ordered the the lake. In 1937 an all-time record—in fact a world Bureau of Fisheries regional director to paint all new build- record—for one hatchery was set. No less than forty mil- ings at Lake a gray-green color, and to include the existing lion eyed ova were handled and passed out in good condi- fi sh hatchery buildings in that order.30 During 1928–1930, tion to the feeding hatcheries, almost one hundred per cent the Bureau of Fisheries also reconditioned and extended its arriving in a perfect state at their destination, so skilled is nearby boat dock, from which three 33-foot launches and the work of dispatch.… I confess that my mind boggles at several smaller boats operated during summer months.31 the thought of forty million trout.35 Little is known about the history of the boathouses at Lake that supported the hatchery buildings. There was a boat- During the period 1930–1957, the National Park house of some sort at the Lake hatchery in 1912, but a more Service gradually changed some of the earlier policies substantial one was apparently built in 1930—probably one that manipulated natural conditions in the park. It thus of the two that are still there today. Assistant Superintendent made substantial strides in fi shery science and ecosystem

16 Yellowstone Science 14(2) • Spring 2006 management toward the “natural shifting toward general research and same park waters from which they regulation” philosophy that is in place protection of native species and away had originated. In any aquatic envi- today. For example, in 1936 the NPS from artifi cially “aiding” the fi shery. ronment, one potential result of such decreed that no exotic fi sh were to be Worries about angler pressure on actions can be the loss of genetic infor- planted in waters that contained only waters and the idea of returning live mation in fi sh subpopulations histori- native fi sh, wider distribution of exotic fi sh to the water (catch-and-release cally associated with a natal stream. For fi shes was to be prohibited, artifi cial fi shing) were also becoming primary example, the 60 or so active spawning improvements on lakes and streams considerations.38 streams that feed into Yellowstone were to be avoided, Lake are subject to exotic fi sh food local, environmen- was to be prohib- “[T]hey found [that] excessive removal of tal variations that ited, fi shless waters might have affected might be best left eggs was detrimental to reproduction.” The their natal cutthroat fi shless, and propa- hatchery program, it was learned, posed an subpopulations in gation of native fi sh the long term. Had was to be encour- actual threat to the lake’s cutthroat trout the hatchery opera- aged to the greatest population. tions not scram- possible extent.36 bled those natural In 1949, the distinctions, the NPS sought the advice of a team of Where does the Lake hatchery subpopulations might have been bet- fi shery research biologists from the stand in the history of the Yellowstone ter suited to deal with stressors such as U.S. Fish and Wildlife Service on how fi shery and in the history of fi sh hatch- invasive species and drought.40 egg-taking operations might be affect- eries across this nation, and how does None of that makes the old fi sh ing the ecology of the Yellowstone the history of the Yellowstone fi shery hatchery building at Lake any less his- Lake fi shery. As early as 1953, these play into the history of other fi sheries torically important, but it has much biologists recognized that egg-taking around the United States? The answers deteriorated. While the surrounding and restocking were not necessary to are straightforward, according to one buildings in the complex have con- maintain the fi shery. “In fact,” noted fi sh historian. In the history of the tinued to be used as park housing, for Phillip Sharpe, “they found [that] the Yellowstone fi shery, the Lake hatchery many years the main hatchery build- excessive removal of eggs was detri- stands tall. Its building was central to ing has been used only for storage. mental to reproduction.” The hatch- Yellowstone fi shery operations for 25 The building commemorates a time ery program, it was learned, posed an years (1930–1955), and today it is the in the national parks when natural actual threat to the lake’s cutthroat only physical remnant of Yellowstone’s processes were subordinated to the trout population.37 long history of active fi shery manipula- will of humans, and the story of what Thus in the 1950s, NPS offi cials tion. In regard to the country at large, it went on there in the history of Yellow- dramatically curtailed manipula- is important—if painful—to note that stone fi shery operations is fascinating tive park fi shery operations. The last the Lake fi sh hatchery, just like other indeed. For although buildings may substantial collection of eggs from hatcheries that produced fi sh destined not stimulate our imaginations in the Yellowstone fi sh occurred in 1953, to become harmful exotics when they way that fi sh do, they are part of the and the last fi sh stocking for the ben- arrived at their destinations, “was cultural resources that supported the efi t of anglers occurred in 1955. The the source of many, many harmful park’s natural resources—the “fresh- NPS closed all park fi sh hatcheries in infestations of Yellowstone cutthroat water wilderness” celebrated by John 1957, and made plans to return the trout beyond the park waters.”39 For Varley and Paul Schullery that is an entire park fi shery to its original, self- instance, Yellowstone cutthroats from integral part of the larger Yellowstone sustaining basis. In 1961, the Interior the Lake hatchery were often intro- wonderland. It was this freshwater Department’s Bureau of Sport Fisher- duced into waters populated by west- wilderness that so long ago caused ies and Wildlife replaced the advisory slope cutthroats vulnerable to such fi sherman Howard Back to imagine fi shery research biologists it had sta- non-native competition. The hatchery gossamer-garbed fairies “fl itting from tioned at Yellowstone with workers may also have been detrimental to the fl ower to fl ower” in accompaniment to who began long-term research on all park’s own Yellowstone cutthroat trout the dance of his fl y rod on Yellowstone park waters to learn about the fi shery population. Though they were native waters. and develop monitoring to aid man- to the park, hatchery-reared cutthroat agement. Fisheries management was were not necessarily returned to the

14(2) • Spring 2006 Yellowstone Science 17 of the Interior, 1898 (Washington, DC: Great,” American Fly Fisher 29 (Winter GPO, 1898), 12. 2003):2–12; John D. Varley, “A History 8 Varley and Schullery, Yellowstone Fishes, 94. of Fish Stocking Activities in Yellowstone 9 F. Phillip Sharpe, Yellowstone Fish and Fishing National Park Between 1881 and 1980,” (Yellowstone National Park: YMLA, 1970), U.S. Fish and Wildlife Service, Information 10. Paper No. 35, January 1, 1981, YRL; John 10 Hugh M. Smith and William C. Kendall, Byorth, “Trout Shangri-La: Remaking the Fishes of the Yellowstone National Park, Fishing in Yellowstone National Park,” Bureau of Fisheries Document No. 904 Montana the Magazine of Western History and Appendix III to the Report of the 52 (Summer 2002):38–47; and Mary U.S. Commissioner of Fisheries for 1921 Ann Franke, “A Grand Experiment: One (Washington, DC: GPO, 1921), 6. There Hundred Years of Fisheries Management is also a 1915 edition of this book that was in Yellowstone,” two parts, Yellowstone less complete. Science 4(4) (Fall 1996):2–7; 5(1) (Winter 11 Smith and Kendall (Fishes, 6) gave the rea- Lee H. Whittlesey is the historian for 1997):8–13. soning behind this theory in the following Yellowstone National Park. He is the 3 Norris’s mention of his trout stocking activ- paragraph: “The questions naturally arise, author, co-author, or editor of eight books ities as well as his interest in stocking carp why not let the trout run up the creeks and more than 25 journal articles related to in some park waters are in P. W. Norris, and spawn naturally? Why not permit the Yellowstone, including Guide to Yellowstone Fifth Annual Report of the Superintendent of eggs to hatch in the manner intended by Waterfalls and Their Discovery. His latest the Yellowstone National Park, December 1, nature and let the young remain for awhile two books are in press: Yellowstone Place 1881, 30–32. in the water where they were born and Names (revised edition) and Storytelling 4 The Evermann and Jordan studies are then run back to the lake at the proper in Yellowstone. Lee holds a JD from the cited in John D. Varley and Paul Schullery, time? These questions, which will, no Yellowstone Fishes: Ecology, History, and University of Oklahoma, an MA in History doubt, be asked by many thoughtful park Angling in the Park (Mechanicsburg, Pa.: from Montana State University, and was visitors, afford an opportunity to indicate Stackpole Books, 1998), while the Forbes awarded an Honorary Doctorate of Science one way in which it is possible to improve study is S. A. Forbes, “A Preliminary and Humane Letters from Idaho State on nature and to point out why in the Report on the Aquatic Invertebrate University in 2001. Yellowstone National Park, as elsewhere, Fauna of the Yellowstone National Park, it is desirable or necessary for the fi sh-cultur- Wyoming.” Pages 207–258 in U.S. Fish ist to go to nature’s assistance” (emphasis Commission, Bulletin 11, Vol. XI for 1891 Endnotes added). (Washington, D.C.: Government Printing 12 1 Arnold (“Ninety-Seven Year History,” Paul Schullery, “Their Numbers Are Offi ce, 1893). 10) refers to this site as “West Thumb Perfectly Fabulous: Sport, Science, and 5 The stocking of park lakes and stream with Creek,” possibly present-day Big Thumb Subsistence in Yellowstone Fishing, 1870,” exotic fi sh—brown, brook, lake, and rain- Creek, but it is more likely that the Annals of Wyoming 76 (Spring 2004):6–18. bow trout—had huge effects on the eco- stream was present Little Thumb Creek Whether he likes it or not, Schullery is system, as these fi sh suddenly inhabited where offi cials built the hatchery a few today considered by many to be the fore- many miles of formerly fi shless streams. years later. Howard Back explained the most expert on the history of fi shing in They also competed with the natives for egg-taking process in his 1938 book: “fi sh America. food and spawning space and in some cases 2 are trapped as they run up-stream and The 1871 Hayden survey is well treated interbred with natives to dilute or destroy stripped of a large part of their spawn, and cited in Marlene Deahl Merrill, native genotypes. which is then hatched out.… This hatching Yellowstone and the Great West (Lincoln: 6 B. B. Arnold, “A Ninety-Seven Year History is done in two stages. In the local hatchery University of Nebraska Press, 1999), of Fishery Activities in Yellowstone the eggs are ripened until they reached the who also cites Hayden’s 1872 and 1878 National Park, Wyoming,” 10, unpub- stage known as ‘eyed ova,’ which means reports. Dunraven’s fi shing is in Windham lished manuscript, U.S. Department of that through the transparent skin of the T. Wyndham-Quin, Fourth Earl of Interior, Bureau of Sport Fisheries and egg you can perceive the black spot of the Dunraven, The Great Divide: Travels in the Wildlife, Division of Fishery Services, embryo fi sh’s developed eye. At this stage Upper Yellowstone in the Summer of 1874 March 19, 1967, YRL. James R. Simon they are dispatched to ‘feeding hatcheries,’ (London: Chatto and Windus, 1876), while stated in 1939 that from Yellowstone where they are brought to full develop- Strong’s is in William A. Strong in Richard Lake and Yellowstone River “more clean ment. They are then and from there redis- A. Bartlett, ed., A Trip to the Yellowstone [cutthroat trout] eggs are now taken tributed as fry, under the direction of the National Park in July, August, and September, than from all other waters in the United Bureau of Fisheries, to the points where 1875 (Norman: University of Oklahoma States combined.” Simon, Yellowstone they are most needed.” Back, The Waters Press, 1968). Sarah Broadbent’s index to Fishes (Yellowstone National Park: YLMA, of Yellowstone With Rod and Fly (New York: Forest and Stream magazine is housed at 1939), 8. Currently missing from the park Lyons Press, 2000), 24. the Yellowstone National Park Research library and archives—and thus from this 13 Arnold, “Ninety-Seven Year History,” Library (hereafter YRL) and her master’s paper—are the Fishery Annual Reports, 10. The operation is mentioned in John thesis on the subject is at both Montana 1901–1953, which, if they could be found, Pitcher, Report of the Acting Superintendent State University and Yellowstone. See would explain much history to us. of the Yellowstone National Park to the also John D. Varley and Paul Schullery, 7 Frank H. Tainter and Bill Tanner, “Fish Secretary of the Interior, 1901 (Washington: Freshwater Wilderness: Yellowstone Fishes Culture in Yellowstone National Park, the GPO, 1901), 5. Booth removed an and Their World (Yellowstone National Early Years: 1901–1930,” 4, unpublished estimated one million fi sh eggs from Park: Yellowstone Library and Museum manuscript, 1987, YRL. Erwin’s original Yellowstone Lake this fi rst year. See also Association (hereafter YLMA), 1983); suggestion for a hatchery is in James B. R. J. Fromm, “An Open History of Fish Paul Schullery, “Edward in Wonderland: Erwin, Report of the Acting Superintendent of and Fish Planting in Yellowstone National Yellowstone Recollections of an Angling the Yellowstone National Park to the Secretary

18 Yellowstone Science 14(2) • Spring 2006 Park,” unpublished report, 1940, YRL ver- last year. This building is furnished with surement of the mess hall as 21' × 58', tical fi les. modern equipment. The loft was fi nished with dining room 20' × 21', kitchen 12' 14 Archive Document 6887, 1906, and used during the past season as quarters × 21', two bedrooms each 10' × 11', one Yellowstone National Park Archives for the employees and will be available for storeroom 10' × 11', and bathroom 5' × 6'. (hereafter YNPA), says the fi sh hatchery storage use after other contemplated build- Inconsistently, this same report gave the building erected at West Thumb in 1903 ings are constructed. This building furnishes measurement of the “dormitory” as 24' by the Department of Commerce was a room for apparatus with a capacity for eye- × 83', containing a recreation room 15' × frame structure with a main portion of ing 30,000,000 [fi sh] eggs. A small dam was 24', sixteen individual rooms of 8' × 10', 20' × 28' and rear (hatchery) portion of built across the [Hatchery] creek about 400 with a four-foot hall running through the 22' × 36', located one and one-half miles feet upstream from it, and water supply for center of the building. C. F. Culler, “Annual north of the West Thumb soldier station. the work is drawn from this pond through Report Fiscal Year 1929 and Season of A map drawn by hand onto the text of a 12-inch wooden stave pipe.” Lloyd Brett, 1929 Yellowstone Park Station,” 20, this document shows the new hatchery Report of the Acting Superintendent of the unpublished Bureau of Fisheries report in on “Fisheries Creek,” apparently present Yellowstone National Park to the Secretary box N-41, YNPA. Little Thumb Creek. Also built was a barn of the Interior, 1913 (Washington: GPO, 32 Daum, “Report on the Construction,” 22' × 28' and an offi ce/storage building 1913), 9. 3. For mention of the 1912 “U.S. Boat 20' × 30'. Permission to construct these 21 Tainter and Tanner, “Fish Culture,” 31. House,” see hand-drawn map, August 17, buildings is in documents 6888, 6889, 22 Lloyd Brett, Report of the Acting 1912, in fi le 50, item 45 (letter box 23), 6890, and 7323, all 1906. Thus it appears Superintendent of the Yellowstone National YNPA. that the hatchery was built in 1903 and Park to the Secretary of the Interior, 1914 33 History Card File, “Lake—Boathouse,” additional buildings were constructed in (Washington: GPO, 1914), 13. YRL. These white typed cards with 1906. Document 6886 is a 1906 map that 23 National Park Service, “Final Construction orange separators are marked “History shows the site, which appears to be a bit Report on Account 777, Donation in the Cards” and are located in the wooden farther north than the one and one-half Amount of $15,000 for Construction fi le cabinet next to the librarians’ work- miles fi gure given in document 6887. The in Connection with Furthering Fish room, Yellowstone Heritage and Research 1906 map shows the buildings on what Propagation at Lake Yellowstone in Center, Gardiner, Montana. appears to be present Little Thumb Creek. Yellowstone National Park. Appropriation 34 Tainter and Tanner, “Fish Culture,” 40. Document 5924 describes work done on 4 X 470 National Park Service, 35 Back, Waters of Yellowstone, 24–25. the West Thumb hatchery in 1906. Donations,” [1], unpublished manuscript 36 Fromm, “An Open History,” 28. 15 Arnold, “Ninety-Seven Year History,” 11. with photographs, 1928–1930, in fi le of 37 Sharpe, Yellowstone Fish and Fishing, 11–12; Fromm (“An Open History,” 14) says that same name as this document, box N-40, Mary Ann Franke, “A Grand Experiment D. C. Booth reported in 1909 that the YNPA. See also M. F. Daum, “Report (Part II),” 8. Adds Franke, “Although some West Thumb station was the “greatest on the Construction of the Lake and fry were returned to the lake, the eggs collecting center for [cutthroat trout] in Mammoth Fish Hatchery Season of 1929,” were scrambled, mixing together distinc- the United States.” fi le number 164, [1929], YRL vertical fi les. tive genotypes. In addition, the reduced 16 Smith and Kendall (Fishes, 5–6, 10) stated 24 Tainter and Tanner (“Fish Culture,” 34) escape of spawners had combined with that “in 1921, a permanent hatchery was give these sizes as 48' × 108' and 48' × 68', fi shing pressure to cause the virtual col- erected on Soda Butte Creek, which had respectively. lapse of spawning migrations in some been the site of a fi eld hatchery for a 25 “Final Construction Report on Account [tributary] streams.” See also O. B. Cope, number of years.” That same year, offi cials 777,” [1]–2. Inconsistently, the 1929 annual “The Yellowstone Fishery Investigations established a “small hatchery” at Fish Lake, report of the Bureau of Fisheries gave the from Their Inception to the Present,” now called Trout Lake. inside measurement of the building as 38' unpublished paper, U.S. Fish and Wildlife 17 W. T. Thompson to Commissioner of × 108' 6". C. F. Culler, “Annual Report Service, no date (1952), YNPA. Fisheries, June 25, 1912, in fi le 50, item 45 Fiscal Year 1929 and Season of 1929 38 Franke, “A Grand Experiment (Part (letter box 23), YNPA. Yellowstone Park Station,” 20, unpublished II),” 1, 8. The Annual Project Technical 18 Benjamin S. Cable to Secretary of Interior, Bureau of Fisheries report in box N-41, Reports, produced by the U.S. Fish and July 10, 1912, in fi le 50, item 45 (letter box YNPA. Wildlife Bureau of Sport Fisheries from 23), YNPA. See also C. A. Thompson to 26 Roger W. Toll, Monthly Report of the 1962 through at least 1992, have added Lloyd Brett, July 12, 1912, in same fi le. Superintendent, July 1929, 12, YRL. thousands of pages to our knowledge of 19 W. T. Thompson to Lloyd Brett, August 5, 27 Ibid. Similar rearing ponds were built at Yellowstone National Park streams, lakes, 1912, and hand-drawn map, both in fi l e 5 0 , Mammoth Hot Springs near the present and rivers. item 45 (letter box 23), YNPA. See also old powerhouse, but their existence was 39 E-mail, Paul Schullery to author, February Arnold, “Ninety-Seven Year History,” 11, short-lived. These ponds were abandoned 15, 2006. and Yellowstone National Park museum in 1934, when they proved unsatisfac- 40 Ibid. collection photos 6858 and 6859. tory in function. Chester Lindsley, The 20 Tainter and Tanner, “Fish Culture,” 21, Chronology of Yellowstone (unpublished 30–31; Arnold, “Completion dates and bound manuscript, YRL, no date), 306. improvement of buildings used for fi sh cul- 28 Ibid. ture and management during 1901–1951,” 29 Daum, “Report on the Construction,” 3; in “Ninety-Seven Year History,” 22. The “Final Construction Report on Account superintendent’s annual report for 1913 777,” 4. elaborated as follows: “A hatchery building 30 Paul Brown to Fred Foster, January 17, 34 by 60 feet was constructed of hewed 1940, in fi le “620-30 Fish Hatchery Part 2, logs, shingled over to present an attractive January 1, 1940 to December 31, 1943,” appearance, on the site near the outlet of box D-157, YNPA. Yellowstone Lake selected and approved by 31 Ibid. Inconsistently, the 1929 annual report the department [of Interior and Commerce] of the Bureau of Fisheries gave the mea-

14(2) • Spring 2006 Yellowstone Science 19 Conserving Yellowstone Cutthroat Trout for the Future of the GYE Yellowstone’s Aquatic Sciences Program

Todd M. Koel, Patricia E. Bigelow, Philip D. Doepke, Brian D. Ertel, and Daniel L. Mahony

N Yellowstone River (from lake outlet) W E

Fishing Bridge S Pelican Creek Hatchery Creek Lake

Storm Pt. Bridge Creek Stevenson Arnica Creek Island Cub Creek

Clear Creek Carrington el Island ann Dot e Ch Island Little Thumb Breez Columbine Creek Creek West Thumb Elk Pt. Geyser Basin Frank Island Beaverdam Creek Grant Southeast Arm South Arm Creek 1167

Sewer Creek Creek Peale Fall cutthroat trout netting sites Island Spawning migration traps Whirling disease exposure sites Lake water quality sites

Chipmunk Creek Montana Trail Creek

Yellowstone N.P.

Yellowstone Wyoming River (to lake inlet) Idaho

10 01020 Kilometers HE LARGEST States. Grizzly bears inland cutthroat Figure 1. Yellowstone Lake and several major tributary drainages (Ursus arctos), bald eagles Ttrout population within Yellowstone National Park. (Haleaeetus leucocephalus), in the world is the adfl u- and many other avian and vial Yellowstone cutthroat terrestrial species use YCT trout (YCT; Oncorhynchus clarki bouvieri) population of Yel- as an energy source (Swenson et al. 1986; Gunther 1995; lowstone Lake. These fi sh have great ecological, economic, and Schullery and Varley 1995). historical signifi cance, and they were noted by early explor- However, in streams throughout Yellowstone National ers of the lake area for their beauty and abundance (Schullery Park and elsewhere in the natural range of Yellowstone cut- and Varley 1995; Gresswell and Liss 1995; Doane 1871). This throat trout, populations have been compromised by intro- subspecies is important for maintaining the integrity of the gression with non-native rainbow trout (O. mykiss) or other Greater Yellowstone Ecosystem, arguably the most intact natu- cutthroat trout subspecies (Behnke 2002; Koel et al. 2004). rally functioning ecosystem remaining in the lower 48 United Recently, the population has also been exposed to three other

20 Yellowstone Science 14(2) • Spring 2006 potential stressors, including non-native lake trout (Salvelinus suggests that introduced lake trout will result in the decline of namaycush; Kaeding et al. 1996), the exotic parasite Myxobolus cutthroat trout (Cordone and Franz 1966; Dean and Varley cerebralis (the cause of whirling disease; Koel et al., in press), 1974; Behnke 1992). Bioenergetics modeling suggests that an and a drought that has persisted throughout the intermountain average-sized mature lake trout in Yellowstone Lake will con- West, 1998–2004 (Cook et al. 2004). sume 41 cutthroat trout per year (Ruzycki et al. 2003). In addition to the stream system, Yellowstone Lake and The cutthroat trout of Yellowstone Lake and its tributar- its drainages provide a great variety of environmental condi- ies have remained genetically pure due to isolation provided tions for the native cutthroat trout (Figure 1). At 34,000 ha, by the lower and upper falls of the Yellowstone River, located Yellowstone Lake is the largest lake above 2,000 m elevation 25 km downstream from the lake outlet near Canyon. The in North America. Of the 124 tributaries fl owing into the genetic purity of these fi sh makes them extremely valuable. lake, 68 have been used by spawning cutthroat trout (Jones With the recent invasions by lake trout and M. cerebralis, the et al. 1987; Gresswell et al. 1997). Geothermal features occur park is placing a high priority on preservation and recovery throughout much of Yellowstone Lake (Morgan et al. 2003). of YCT. Following the guidance of a lake trout expert advi- Unfortunately, the very presence of these many unique and sory panel (McIntyre 1995), the NPS has used gillnetting to variable environments may increase the vulnerability of this determine the spatial and temporal distribution of lake trout system to invasion by non-native and exotic species such as lake within Yellowstone Lake. The efforts have led to a long-term trout, M. cerebralis, and possibly others in the future. lake trout removal program for the protection of YCT in this Contemporary research points to non-native species as the system (Mahony and Ruzycki 1997; Bigelow et al. 2003). In greatest threat to cutthroat trout of the intermountain West addition, there are many other activities that the park con- (Gresswell 1995; Kruse et al. 2000; Dunham et al. 2004). Prior ducts for the conservation of native YCT, including long-term to Euro-American manipulation, Yellowstone Lake cutthroat monitoring, research on whirling disease, and environmental trout existed for approximately 10,000 years (since glacial planning that will lead to the restoration of stream popula- recession) in sympatry with only one other fi sh species, the tions in the northern range. This article will describe trends in longnose dace (Rhinichthys cataractae; Behnke 2002). Now, YCT abundance and size, examine the impacts of lake trout longnose suckers (Catostomus catostomus), lake chubs (Coue- on bears and anglers, and describe results of efforts to suppress sius plumbeus), redside shiners (Richardsonius balteatus), and lake trout population growth within Yellowstone Lake. lake trout are also present in the lake system due to introduc- tions. Non-native lake trout would not be a suitable ecological Methods substitute for cutthroat trout in the Yellowstone Lake system because they are inaccessible to most consumer species. Lake Yellowstone National Park’s Fisheries and Aquatic Sciences trout tend to occupy greater depths within the lake than do program employs a multi-faceted approach to YCT monitor- cutthroat trout. Lake trout remain within Yellowstone Lake at ing and conservation, consisting of fi sh trapping, netting, all life stages and they do not typically enter tributary streams, visual assessment, voluntary angler reporting, aggressive lake as do cutthroat trout. Evidence from other, similar systems, trout removal, and whirling disease research. A brief descrip- tion of each of those aspects follows.

BARB ROWDEN Cutthroat trout spawning migration traps. The NPS has monitored the Yellowstone cutthroat trout spawning popula- tion by counting upstream-migrating adults at Clear Creek and Bridge Creek since 1945 and 1999, respectively. From May to July each year, YCT are counted at permanent weirs as they move upstream from Yellowstone Lake to spawn. Until 1998, all fi sh were trapped and manually enumerated. Since then, electronic counters have been used. Cutthroat trout fall netting assessment. Within Yellow- stone Lake, cutthroat trout population abundance and length structure have been assessed by netting conducted during Sep- tember of each year since 1969. Multi-mesh-size (experimen- tal) gillnets (38.0 m length, 7.6 m graduated mesh panels of 19, 25, 32, 38, and 51 mm) are placed in sets of fi ve nets perpendicular to the shoreline overnight, in shallow water (0–5 Bioenergetics research suggests that each lake trout in m depth), at 11 sites throughout Yellowstone Lake (Jones et Yellowstone Lake has the potential to consume 41 cutthroat al. 1977). trout or more each year. Cutthroat trout spawning visual surveys. Visual surveys

14(2) • Spring 2006 Yellowstone Science 21 for cutthroat trout and bear activity have been conducted fi rm the presence of M. cerebralis DNA (Andree et al. 1998). annually since 1989 on 9–11 tributaries located along the The prevalence and severity of M. cerebralis within 15 western side of Yellowstone Lake between the Lake and Grant tributaries and the Yellowstone River (lake inlet and lake out- Village developed areas (Reinhart 1990; Reinhart et al. 1995). let) was determined by use of YCT sentinel fry exposures, Spawning reaches were initially delineated on each tributary, 1998–2003 (Koel et al. in press). In each cage (1 m height, and the standardized reaches are walked in an upstream direc- 0.5 m diameter, and constructed of 5 mm galvanized wire tion once each week from May through July. The observed mesh), 60–80 cutthroat trout fry (25–50 days post-hatch) were cutthroat trout are counted, and the weekly activity by black exposed for a 10-day period, July–September. Following the bears (U. americanus) and grizzly bears is estimated by not- exposures, fry were held in aquaria for an additional 90 days ing the presence of scat, parts of consumed trout, fresh tracks, at 10–13°C to allow for parasite development prior to being and/or bear sightings. sacrifi ced. The PCR technique (Andree et al. 1998) was used to Angler report card information. Since 1979, angler effort test for the presence of M. cerebralis. Histological examination and success have been assessed via a report card distributed was conducted on fry from M. cerebralis-positive exposures to to each angler who purchases a special use permit for fi sh- determine the severity of infection. Severity was ranked on a ing (Jones et al. 1980). Information on the waters fi shed, scale of 0 (no infection) to 5 (most severe infection) for each time spent, and species and sizes of fi sh caught by anglers is fry examined (Baldwin et al. 2000). obtained. Annually, approximately 4,000 anglers (5% of all anglers) have voluntarily completed and returned cards to the Trends in Cutthroat Trout Abundance park’s fi sheries program. Lake trout removal program. Gillnetting has been used to Shortly after the establishment of Yellowstone National suppress lake trout in Yellowstone Lake each year since 1994. Park as the world’s fi rst national park in 1872, the fi shery was Spatially, the gillnet locations have been concentrated in the widely publicized in national and local newspapers, as well as lake’s West Thumb, where lake trout densities have been found to be highest. Through the years of the program, however, both lake trout and gillnetting have expanded outward to include 80 25 the lake’s main basin and, to a lesser extent, its southern arms. Clear Creek Bridge Creek ) Migrating Cutthroat Trout (x 10 Small-mesh (19–44 mm mesh size) gillnets are placed on the 3 70 A 20 lake bottom in water typically 40–65 m deep. Gillnets are 300 60 Bridge Creek Upstream

m length, set in gangs of six contiguous nets (1,800 m total 50 15 length each), typically for more than seven days. During the 40

open water season (late May–late October), up to 16 km of 30 10

gillnet are in place fi shing for lake trout. Clear Creek Upstream 20 2 Migrating Cutthroat Trout (x 10 The mature lake trout of Yellowstone Lake begin congre- 5 ) gating near known spawning locations in late August each year. 10 The removal program targets these fi sh until early October, 0 0 when spawning is typically completed. The locations targeted 20 in the fall, including Breeze Channel, Carrington Island, Gey- Fall netting assessment ser Basin, and Solution Creek, are gillnetted using shallow-set 15 B (0–20 m depth), large-mesh gillnet (51–70 mm mesh size) sets

of short duration (typically one day) to reduce mortality of any 10 YCT bycatch. In 2004, boat-mounted electrofi shing was also

used to remove spawning lake trout and kill deposited eggs in 5 shallow waters (<5 m depth) at night. Mean Cutthroat Trout Per Net

Whirling disease prevalence and severity. The preva- 0 lence of M. cerebralis within Yellowstone Lake was determined 1945 1955 1965 1975 1985 1995 2005 by examination of juvenile and adult YCT mortalities from the fall netting assessment and lake trout removal program, Figure 2. Number of upstream-migrating cutthroat trout 1998–2003. Screening of these fi sh occurred initially by the counted at Clear Creek (1945–2004) and Bridge Creek pepsin trypsin digest (PTD) method, where the heads of fi sh (1999–2004) spawning migration traps (A), and mean suspected of carrying the disease were chemically broken down number of cutthroat trout collected per net during the fall and the resulting material was examined for the presence of netting assessment on Yellowstone Lake, 1969–2004 (B). myxospores (Andree et al. 2002). Samples were also tested by Note differences in scale between Clear Creek and Bridge the nested polymerase chain reaction (PCR) technique to con- Creek data.

22 Yellowstone Science 14(2) • Spring 2006 60 in periodicals such as Forest and Stream and American Angler. Anglers began 1997 50 n1 = 245 n2 = 363 visiting the lake, its tributary streams, and the Yellowstone River in great num- 40 bers, and the U.S. Fish Commission began looking for ways to propagate and 30 distribute the cutthroat trout of Yellowstone Lake to locations across North 20 America (Varley and Schullery 1998). The result was the development of a 10 0 federally operated fi sh culture facility on the north shore of Yellowstone Lake. 60 1998 From 1900 to 1956, more than 818 million YCT eggs were removed for use in 50 n1 = 176 n2 = 369 other waters, mostly outside Yellowstone National Park (Varley 1981; Varley 40 and Gresswell 1988). The cutthroat trout also were subject to a great amount 30 of angling pressure, and were commercially fi shed to provide food for visitors 20 10 until 1919, a few years after the creation of the National Park Service (NPS). 0 60 Evidence of a cutthroat trout population decline during the mid-1900s resulted 1999 50 in the closure of the egg-taking operations and implementation of increasingly n1 = 131 n2 = 315 restrictive angling regulations (Varley 1983; Gresswell and Varley 1988). 40 30 Impacts of historical egg-taking operations and liberal angler harvest 20 regulations for Yellowstone Lake cutthroat trout were observed in counts of 10 upstream-migrating fi sh at Clear Creek. Only 3,161 cutthroat trout ascended 0 60 Clear Creek in 1954, just two years prior to the cessation of fi sh culture opera- 2000 50 n1 = 79 n2 = 317 tions on Yellowstone Lake (Varley and Schullery 1998; Figure 2). With angling 40 restrictions, the number rebounded during the 1960s and 1970s to 70,105 30 YCT in 1978 (Jones et al. 1979). Although there was variation among years, 20 the increasing trend in cutthroat trout abundance within Yellowstone Lake 10 0 was also indicated by the fall netting assessment. An average of 10.0 fi sh per 60 2001 net were caught by this assessment in 1969, and 19.1 fi sh per net were caught 50 n1 = 133 n2 = 230 in 1984. 40 Since the late 1980s, however, there has been a signifi cant decline in the 30 20 Yellowstone Lake cutthroat trout population. The number of upstream-migrat- Number of Cutthroat Trout 10 ing cutthroat trout counted at Clear Creek was 1,438 during 2004. This count 0 was down from 3,432 in 2003, and 6,613 in 2002, and was the lowest count 60 2002 50 since 1954. The fi sh counting station operated on Bridge Creek, a small north- n1 = 178 n2 = 158 western tributary, indicated that only a single fi sh migrated upstream during 40 30 2004. The number of spawning cutthroat trout in recent years has declined by 20 more than 50% annually in Bridge Creek, and has decreased by more than 99% 10 since counts began in 1999, when 2,363 cutthroat trout ascended the stream to 0 60 spawn. The decline was also evident in the results of the fall netting assessment, 2003 50 n1 = 207 n2 = 200 where an average of 15.9 cutthroat trout per net were caught in 1994, and only 40 6.1 per net were caught in 2002. Prior to 2003, the reduction in catch by the 30 fall netting program averaged 11% per year since 1994, the year lake trout 20 were fi rst discovered in Yellowstone Lake. During 2003–2004, however, the 10 fall netting assessment provided some of the fi rst indications that the cutthroat 0 60 2004 trout population may be responding positively to efforts to remove non-native 50 n1 = 239 n2 = 167 lake trout. An average of 7.4 fi sh per net were caught in 2003, and 7.9 fi sh per 40 net were caught in 2004. 30 20 Trends in Cutthroat Trout Length 10 0

Length-frequency data from the fall netting program from 1997 to 2004 100 150 200 250 300 350 400 450 500 550 Total Length (mm) indicated an increase in length (>325 mm) and reduction in numbers of adult YCT in Yellowstone Lake (Figure 3). In 2004, fewer fi sh between the lengths Figure 3. Length-frequency distributions of 325 and 425 mm were collected than in earlier years. Historically, most of cutthroat trout collected during the fall cutthroat trout sampled in spawning tributaries such as Clear Creek were in netting assessment on Yellowstone Lake this size range (Jones et al. 1993). Despite this, an apparent increase in num- with total number of trout <325 mm (n1) bers of juvenile cutthroat trout (100–325 mm) has been noted in recent years and >325 mm (n2), 1997–2004.

14(2) • Spring 2006 Yellowstone Science 23 (2002–2004). Many of these juveniles have 80 0.9 Trout Bear been collected in the southern arms of Yel- 70 0.8

lowstone Lake, which may act as refuges for Mean Bear Activity Per Visit 0.7 YCT due to the low numbers of lake trout 60 and low incidence of M. cerebralis in these 0.6 50 areas (see below; Koel et al. 2004). 0.5 40 0.4 Infl uence on Cutthroat Trout 30 Consumers 0.3 20 Bears. Upstream-migrating cutthroat 0.2 Mean Cutthroat Trout Per Visit trout within Yellowstone Lake tributaries his- 10 0.1 torically have served as a signifi cant source of 0 0.0 energy for black bears and grizzly bears in the 1988 1992 1996 2000 2004 lake area (Reinhart and Mattson 1990). The average number of cutthroat trout observed each week during spawning visual surveys of Figure 4. Mean number of cutthroat trout and mean activity by black bears 9–11 tributaries (1989–2004) has declined and grizzly bears observed during weekly spawning visual surveys of 9–11 to the point where few trout have been tributaries located along the western side of Yellowstone Lake between Lake observed in recent years (Figure 4). In fact, and Grant, 1989–2004. only 35 cutthroat trout were seen on spawn- ing reaches of the nine streams surveyed over a period of eight weeks in 2004. A similar trend was observed cards have suggested that anglers on Yellowstone Lake experi- in use of these streams by black bears and grizzly bears. It was enced a decline in the number of cutthroat trout caught per apparent that few bears used these tributaries, as bear activ- hour from 2.0 in 1998 to 0.8 in 2004 (Figure 5), while lake ity was only evident a total of eight times during 2004. By trout caught per hour increased from 0.0 in 1998 to 0.1 in comparison, the visual surveys of spawning cutthroat trout 2004. In addition, the average length of cutthroat trout caught documented activities by bears 50 times in 1991. These results by anglers on Yellowstone Lake increased from 370 mm in suggest a trophic-level cascade (Spencer et al. 1991), possibly 1995 to 448 mm in 2004. The decline in numbers of YCT resulting from the introduction of non-native and exotic spe- caught by anglers has been even more signifi cant on Pelican cies into this pristine ecosystem (Reinhart et al. 2001). Bears Creek, the lake tributary where M. cerebralis infection has been may have been forced to use other energy sources in the region most severe (see below). There, the number of cutthroat trout during the spring spawning period when they previously relied caught per hour declined from 2.5 in 1979 to 0.3 in 2003. on cutthroat trout. Since 2001, regulations have required that YCT be immedi- Aside from localized displacement, it is not known what ately released unharmed. Angling on the Pelican Creek drain- the overall effect of cutthroat trout declines will be on bear age was completely closed in 2004 in an attempt to slow the populations, as bears of this region are also threatened by the dispersal of M. cerebralis to other park waters. decline of whitebark pine (Pinus albicaulis; Mattson and Mer- rill 2002). Despite this threat to important food sources, the Lake Trout Removal Program a Decade after status of the grizzly bear population in the Greater Yellowstone Discovery Ecosystem is currently considered to be stable to increasing. The grizzly bear population has increased from an estimated Since the discovery of lake trout in Yellowstone Lake in 136 bears in 1975, when it was listed as a threatened species, 1994 (Kaeding et al. 1996), efforts to counteract this non- to at least 431 bears in 2004 (Haroldson and Frey in press). In native species have intensifi ed. The NPS gillnetting program addition, grizzly bears have expanded their range by 48% over has removed >100,000 lake trout since 1994 (Figure 6). The the last two decades (Schwartz et al. 2002). On November 17, gillnetting effort has increased in recent years to an average of 2005, the U.S. Fish and Wildlife Service proposed to remove 10 times that of 1999. In 2004, a total of 26,634 lake trout the Greater Yellowstone Ecosystem population of grizzly bears were removed using 15,781 effort units (one effort unit = 100 from the threatened species list (USFWS 2005). m of net set over one night). Catch rate has declined since Anglers. Yellowstone National Park has long been a des- 1998, when an average of 5.5 lake trout per unit of effort tination for anglers from around the world. Historically, more were caught. In 2004, catch per unit effort (CPUE) for lake than one-third of visiting anglers fi shed Yellowstone Lake. In trout remained low (1.69) but was slightly higher than that of recent years, estimates derived from returns of angler report 2001–2003.

24 Yellowstone Science 14(2) • Spring 2006 2.5 450 Lake Trout Number CPUE Gillnet Effort Unit 30 6

2.0 Mean Length (mm) A 425 25 5

) 3 (#/100 m net/night) Lake Trout CPUE 1.5 20 4 400 1.0 15 3

375 10 2

Mean Trout Per Hour 0.5 Lake Trout Number or Gillnet Effort Unit (100 m/night) (x 10 5 1 0.0 350 0 0 1978 1982 1986 1990 1994 1998 2002 8 640 Cutthroat trout catch Lake trout catch Cutthroat trout length B 600

6 Spawning Lake Trout Mean Length (mm)

Figure 5. Angler-reported catch rate for cutthroat trout and ) 3 lake trout, and the average length of cutthroat trout caught 4 560 by anglers from Yellowstone Lake, 1979–2004. Number (x 10

Spawning Lake Trout 2 520 Avoiding bycatch of cutthroat trout has been a challenge for the lake trout removal program. Initially, the bycatch was 0 480 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 very high: 6.6 cutthroat trout for every lake trout netted in 1995. This high bycatch was in part due to the higher densi- Spawning Lake Trout Number Spawning Lake Trout Length ties of cutthroat trout and lower densities of lake trout that occurred within Yellowstone Lake during the mid-1990s. Figure 6. Number of lake trout removed, gillnet units of Since then, gillnetting protocols have been improved to reduce effort (1 unit = 100 m of net/night) used, and lake trout bycatch while maximizing removal of lake trout. Gillnets are catch per unit of effort obtained by the lake trout removal now consistently set very deep (40–65 m depth), except during program on Yellowstone Lake during the entire gillnetting lake trout spawning periods. Since 1998, the bycatch has been season, 1994–2004 (A). Number and mean length of 0.1 cutthroat trout or less for each lake trout netted. mature lake trout removed near spawning locations (Breeze As the lake trout population has grown and expanded in Channel, Carrington Island, Geyser Basin, and Solution recent years, spawning fi sh have become a focal point for the Creek) on Yellowstone Lake during late August–early removal program. In 2003, an additional lake trout spawning October, 1996–2004 (B). location was identifi ed near the West Thumb Geyser Basin. This area, along with areas near Carrington Island, Solution Creek, and Breeze Channel, has been gillnetted since 1996. In particular, using hydroacoustics, underwater cameras, and The total number of spawning lake trout caught by gillnet- high resolution (1 m) bathymetry, the NPS is currently delin- ting was 2,371 in 2003 and 7,283 in 2004. An additional eating and characterizing known lake trout spawning areas (all 1,063 spawning lake trout were removed by electrofi shing in presently in the West Thumb), to predict where new spawn- 2004. The average length of spawning lake trout removed near ing areas may be pioneered in the lake basin. These potential spawning areas has decreased each year. The recent decline in spawning areas will be closely monitored and targeted for lake the annual lakewide catch rate of lake trout and the annual trout removal if fi sh begin to use them in the future. reduction in the average length of sexually mature fi sh are posi- tive indications that the removal program is exerting measur- Whirling Disease and Drought as Additional able mortality on this population. Threats Lake trout densities in the West Thumb remain high, and a serious threat to YCT. Model simulations have suggested that Myxobolus cerebralis was discovered in Yellowstone Lake the YCT population might have declined by 60% or more in 1998 among juvenile and adult cutthroat trout (Koel et within 100 years if the lake trout population was permitted al. in press). Examination of gillnetting mortalities has since to grow uncontrolled (Stapp and Hayward 2002). Cutthroat confi rmed the presence of the parasite throughout Yellowstone trout abundance indices suggest that a decline of that magni- Lake, with highest prevalence existing in the northern region tude (or greater) has already occurred. The NPS will continue of the lake, near known infected streams (see below; Koel et to investigate new methods to target the lake trout population. al. 2004). Although the widespread presence of this harmful

14(2) • Spring 2006 Yellowstone Science 25 NPS/TODD KOEL parasite in the lake is disturbing, the discovery of M. cerebralis spores in adult fi sh each year suggests that at least some cut- throat trout are surviving initial M. cerebralis infection. By 2001, cutthroat trout sentinel fry exposures confi rmed the presence of M. cerebralis in three important spawning streams: Pelican Creek, Clear Creek, and the Yellowstone River downstream from the lake outlet near Fishing Bridge (Koel et al. in press). Since then, sentinel exposures in the Yellow- stone River upstream of the lake inlet and 13 other spawning tributaries have failed to detect the presence of the parasite. The impacts of M. cerebralis have been most severe in Pelican Creek, where few wild-reared fry have been observed in recent years (2001–2004). Cutthroat trout sentinel fry exposures in this tributary have indicated that >90% of the fry were infected Columbine Creek, at its mouth along the eastern shore, with M. cerebralis, with an average severity (by histological disconnected from Yellowstone Lake in August 2004. examination) of >4 on a scale of 0 (no infection) to 5 (most severe infection; Koel et al. 2004). Consistent, annual counts of upstream-migrating adult throat trout consumers, the black bear and grizzly bear (icons cutthroat trout have not been made in Pelican Creek in recent for Yellowstone National Park and highly sought by millions of years, but records exist from an historic weir that was previ- visitors each year), are using cutthroat trout spawning streams ously used to enumerate spawning fi sh from 1964 through much less frequently. Yellowstone National Park anglers, a 1981 (Jones et al. 1982). Netting near the location of the weir third of whom fi sh Yellowstone Lake, also have experienced a (near the tributary mouth) for upstream-migrating adults in signifi cant reduction in catch. 2002–2004 indicated that the spawning cutthroat trout popu- Of great interest to park managers is the timing and origi- lation of Pelican Creek, which in 1981 was nearly 30,000 fi sh, nal source of lake trout that were illegally introduced to Yel- has been essentially lost. With a drainage area of 17,565 ha, lowstone Lake. Research on the microchemistry (Sr:Ca ratios) Pelican Creek is the second largest tributary to Yellowstone of otoliths has suggested that a lake trout introduction likely Lake in terms of discharge. occurred in the late 1980s (Munro et al. 2005; and this issue Drought in the intermountain West since 1998 may have of YS). These results suggest that lake trout existed in Yellow- impacted cutthroat trout populations due to increased water stone Lake for at least fi ve years prior to being reported to the and a reduction in peak stream fl ows (USGS NPS by an angler. The otolith microchemistry, as well as com- 2004). In many cases, fl ows in tributary streams have become parative DNA analyses, has provided evidence that the lake sub-terminal near the lake, fl owing through large sand and trout origin was Lewis Lake (Stott 2004; Munro et al. 2005), gravel bars. This disconnect of tributary streams from the lake a lake within the park that was intentionally stocked with lake has been occurring during mid-summer and fall, when cut- trout from Lake Michigan in 1890 (Varley 1981). To date, it throat trout fry would typically be outmigrating to Yellow- remains unknown exactly how the lake trout were introduced stone Lake. Biologists have consistently noted cutthroat trout to Yellowstone Lake. fry that are stranded in isolated side channels and pools in At present, a mandatory kill regulation is in place for all seasonally disconnected tributaries. Although cutthroat trout lake trout caught on Yellowstone Lake, and the NPS asks have existed in the Yellowstone Lake ecosystem since glacial anglers each year to assist with the lake trout removal effort in recession (Behnke 2002), and evolved in the face of great varia- this way. The Yellowstone Lake situation represents a unique tion in thermal and other environmental regimes, the current case in which anglers are solicited to fi sh for lake trout without drought is occurring during a period when the cutthroat trout the desire to preserve the fi shery. In NPS requests for angler are also impacted by lake trout predation and M. cerebralis. support, it is made clear that the goal is removal of as many lake trout as possible and suppression of the population for the Conclusions purpose of cutthroat trout conservation. Because lake trout in Yellowstone Lake are known to prey Our results identify long-term impacts of lake trout and on the native YCT (Ruzycki et al. 2003), the removal of M. cerebralis on cutthroat trout in Yellowstone Lake and the >100,000 lake trout has reduced predation on this important Greater Yellowstone Ecosystem. Even with the Yellowstone population. The lake trout removal program on Yellowstone National Park fi sheries program dedicated to the preservation Lake represents a test case for the development of similar pro- and recovery of the Yellowstone Lake cutthroat trout popula- grams to preserve native salmonids in the intermountain West. tion, it appears to be in peril. In addition, two important cut- For example, lake trout removal is currently being experimen-

26 Yellowstone Science 14(2) • Spring 2006 tally conducted on Lake Pend Oreille in funding. Lynn Kaeding, Jeffrey Lutch, John Literature cited northern Idaho, and is being considered McIntyre, S. Thomas Olliff, James Ruzycki, Andree, K. B., E. MacConnell, and R. P. and James Selgeby were instrumental in the for Lake McDonald of Glacier National Hedrick. 1998. A nested polymerase chain early development of the lake trout removal reaction for the detection of genomic DNA Park and Swan Lake of northwestern program. Cutthroat trout monitoring and of Myxobolus cerebralis in rainbow trout Montana. lake trout removal would not occur without Oncorhynchus mykiss. Diseases of Aquatic The cumulative effects of lake trout the dedicated assistance of many seasonal Organisms 34:145–154. technicians and volunteers, and we are Andree, K. B., R. P. Hedrick, and E. MacConnell. and M. cerebralis have put stress on 2002. A review of the approaches to detect grateful for their support. Special thanks the Yellowstone Lake cutthroat trout Myxobolus cerebralis, the cause of salmo- to Barbara Rowdon for her leadership on nid whirling disease. Pages 197–211 in J. L. population during a period of intense Yellowstone Lake, 2001–2004. Funding for Bartholomew and J. C. Wilson, eds., Whirling drought in the intermountain West. The whirling disease research has been provided disease: reviews and current topics. American cutthroat trout population size of this by the National Partnership for the Manage- Fisheries Society Symposium 29, Bethesda, Md. Baldwin, T. J., E. R. Vincent, R. M. Silfl ow, and system was once considered to be in the ment of Wild and Native Coldwater Fisher- ies, Montana Water Center, U.S. Fish and D. Stanek. 2000. Myxobolus cerebralis infec- millions; however, current abundance Wildlife Service, Whirling Disease Founda- tion in rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo trutta) exposed indices suggest that only a fraction of tion, and NPS Rocky Mountains Coopera- under natural stream conditions. Journal of that population exists today. The poten- tive Ecosystem Studies Unit. Through col- Veterinary Diagnostic Investigation 12:312–321. tial for lake trout control and rehabilitat- laboration with the Department of Ecology, Behnke, R. J. 1992. Native trout of western North ing historical cutthroat trout abundance Montana State University; U.S. Fish and America. American Fisheries Society Monograph Wildlife Service Bozeman Fish Health Labo- 6, Bethesda, Md. are yet to be achieved. Relatively low ratory; the U.S. Geological Survey West- ———. 2002. Trout and salmon of North CPUE and an annual decrease in the ern Fisheries Research Center in Seattle; America. New York: The Free Press. size of sexually mature fi sh are indica- the Montana Department of Fish, Wildlife Bigelow, P. E., T. M. Koel, D. Mahony, B. Ertel, B. Rowdon, and S. T. Olliff. 2003. Protection of and Parks; and the Wyoming Game and Fish tors that the removal program is exerting native Yellowstone cutthroat trout in Yellowstone pressure on this lake trout population. A Department, we have learned a great deal Lake, Yellowstone National Park, Wyoming. about whirling disease in the Yellowstone continued focus on lake trout removal Technical report NPS/NRWRD/NRTR- Lake ecosystem. Information on annual 2003/314. Fort Collins, Colo.: National Park will be required into the future if cut- cutthroat trout spawning migration surveys Service, Water Resources Division. throat trout are to persist in Yellowstone and bear use of Yellowstone Lake tribu- Cook E. R., C. Woodhouse, C. M. Eakin, D. M. Lake at a level allowing the overall integ- taries was provided by Kerry Gunther of Meko, and D. W. Stahle. 2004. Long-term YNP’s Bear Management Offi ce and Daniel aridity changes in the western United States. rity of the Greater Yellowstone Ecosys- Science 306:1015–1018. Reinhart, Patrick Perrotti, and Eric Reinert- tem to be maintained. Cordone, A. J., and T. C. Franz. 1966. The Lake son of the park’s Resource Management and Tahoe sport fi shery. California Fish and Game Author’s note: Monitoring of YCT Visitor Protection Division. 52:240–274. at Clear Creek has continued since this Dean, J., and J. D. Varley. 1974. Fishery manage- paper was prepared and originally pub- ment investigations, Yellowstone National Park. Bureau of Sport Fisheries and Wildlife, lished. During 2005, 917 YCT were technical report for 1973. Yellowstone counted moving upstream into Clear National Park, Wyo. Creek to spawn. This count is the lowest Doane, G. C. 1871. Senate letter from the Secretary of War communicating the ever recorded at this trap, with records Yellowstone Expedition of 1870. 41ST dating back to 1945. Although the inva- Congress, 3RD session, executive document sion of Yellowstone Lake by lake trout 51. Washington, D.C.: U.S. Government Printing Offi ce. and the whirling disease parasite has Dunham, J. B., D. S. Pilliod, and M. K. Young. certainly taken its toll, we remain hope- 2004. Assessing the consequences of nonna- tive trout in headwater ecosystems in west- ful that recent snowpack and resulting ern North America. Fisheries 29(6):18–26. higher stream fl ows will benefi t YCT Gresswell, R. E. 1995. Yellowstone cutthroat and assist in a rebound of this ecologi- trout. Pages 36–54 in M. K. Young, techni- cally important population. cal ed., Conservation assessment for inland Todd Koel (above) is supervisory fi sh- cutthroat trout. U.S. Forest Service General eries biologist, Center for Resources, Technical Report RM-GTR-256. Yellowstone National Park and affi li- Gresswell, R. E., and W. J. Liss. 1995. Values Acknowledgements associated with management of Yellowstone ate professor, Department of Ecology, This article was reprinted in adapted cutthroat trout in Yellowstone National Montana State University. Pat Bigelow is form with permission from Fisheries, the Park. Conservation Biology 9:159–165. fi sheries biologist, Center for Resources, journal of the American Fisheries Society. Gresswell, R. E., W. J. Liss, G. L. Larson, and Yellowstone National Park and doctoral The full version can be found in Fisheries P. J. Bartlein. 1997. Infl uence of basin-scale student, Department of Zoology and physical variables on life history charac- 30(11):10–19 (November 2005). Physiology, University of Wyoming. Phil teristics of cutthroat trout in Yellowstone Lake trout removal was enhanced Doepke and Brian Ertel are fi sheries Lake. North American Journal of Fisheries through a three-year NPS Natural Resource technicians, and Dan Mahony is fi sheries Management 17:1046–1064. Challenge, Natural Resource Preservation Gresswell, R. E., and J. D. Varley. 1988. Effects biologist with the Center for Resources, Program grant, and subsequent NPS base of a century of human infl uence on the cut- Yellowstone National Park.

14(2) • Spring 2006 Yellowstone Science 27 throat trout of Yellowstone Lake. American investigations towards the development of a Schwartz, C. C., M. A. Haroldson, K. A. Fisheries Society Symposium 4:45–52. lake trout removal program in Yellowstone Gunther, and D. Moody. 2002. Distribution Gunther, K. 1995. Grizzly bears and cutthroat Lake. Pages 153–162 in R. Hamre, ed., Wild of grizzly bears in the Greater Yellowstone trout: potential impacts of the introduction Trout VI. Fort Collins, Colo.: Trout Unlimited Ecosystem, 1990–2000. Ursus 13:203–212. of non-native lake trout to Yellowstone Lake. and Federation of Fly Fishers. Spencer, C. N., B. R. McClelland, and J. A. Information paper BMO-8. Yellowstone Mattson, D. J., and T. Merrill. 2002. Extirpations Stanford. 1991. Shrimp stocking, salmon National Park, Wyo.: Bear Management of grizzly bears in the contiguous United collapse, and eagle displacement: cascad- Offi ce, Yellowstone Center for Resources. States, 1850–2000. Conservation Biology ing interactions in the food web of a large Haroldson, M. A., and K. Frey. In press. Grizzly 16:1123–1136. aquatic system. Bioscience 41:14–21. bear mortalities. In C. C. Schwartz and McIntyre, J. D. 1995. Review and assessment Stapp, P., and G. D. Hayward. 2002. Effects M. A. Haroldson, eds., Yellowstone grizzly of possibilities for protecting the cutthroat of an introduced piscivore on native trout: bear investigations: annual report of the trout of Yellowstone Lake from introduced insights from a demographic model. Biological Interagency Grizzly Bear Study Team, 2004. lake trout. Pages 28–33 in J. D. Varley and Invasions 4:299–316. Bozeman, Mont.: U.S. Geological Survey. P. Schullery, eds., The Yellowstone Lake Stott, W. L. 2004. Molecular genetic char- Jones, R. D., J. D. Varley, D. E. Jennings, S. crisis: confronting a lake trout invasion. A acterization and comparison of lake trout M. Rubrecht, and R. E. Gresswell. 1977. report to the Director of the National Park from Yellowstone and Lewis Lake, Wyoming. Fishery and aquatic management program Service. Yellowstone Center for Resources, U.S. Geological Survey research comple- in Yellowstone National Park. U.S. Fish and Yellowstone National Park, Wyoming. tion report for project 1443-IA-15709-9013 Wildlife Service, technical report 1976, Morgan, L. A., W. C. Shanks III, D. A. Lovalvo, to the National Park Service, Yellowstone Yellowstone National Park, Wyoming. S. Y. Johnson, W. J. Stephenson, K. L. National Park, Wyoming. Jones, R. D., R. E. Gresswell, D. E. Jennings, D. Pierce, S. S. Harlan, C. A. Finn, G. Lee, M. Swenson, J., K. L. Alt, and R. L. Eng. 1986. C. Lentz, S. M. Rubrecht, J. S. Vandeventer, Webring, B. Schulze, J. Duhn, R. Sweeney, Ecology of bald eagles in the greater and J. D. Varley. 1979. Fishery and aquatic and L. Balistrieri. 2003. Exploration and Yellowstone ecosystem. 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28 Yellowstone Science 14(2) • Spring 2006 FROM THE ARCHIVES NPS, YELLOWSTONENPS, NATIONAL PARK, YELL 1949

A group of Lake Hotel employees gathered for a photo after a successful day’s fi shing on Yellowstone Lake in 1901. Today every cutthroat trout seems precious, but back then anglers had the luxury of large kills, and often the fi sh were thrown away after the picture was taken.

The printing of Yellowstone Science is made possible through a generous annual grant from the nonprofi t Yellowstone Association, which supports education and research in the park. Learn more about science in Yellowstone through courses offered by the Yellowstone Association Institute and books available by visiting www.YellowstoneAssociation.org.

The production of Yellowstone Science is made possible, in part, by a generous grant to the Yellowstone Park Foundation from Canon U.S.A., Inc., through Eyes on Yellowstone is made possible by Canon. This program represents the largest corporate donation for wildlife conservation in the park.

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