George A. Liknes and William R. Gould, lvontanaCooperat ve F shery ResearchUn t, BiologyDepartment, N,4ontana State University,Bozeman Monlana59717

The Distribution,Habitat and PopulationCharacteristics of FluviafArctic Grayling( arcticus) in

Abstract

The only subsfantialpopulalion of native strean dwelling Arctic erayling (Thynollus arcticus)in the iower 48 sralesis locared in the upper drainage of Montana. This population, a laxon o{ specialconce.n, is geneticailydifferenr from any other Montana or Wyonins population in allele kequenciesar rariable loci. Ir representsa unique genepool which should be preserved.In 1978and 1979, {€re found in three sectionsofihe Bis Hole Rirer and in l1 rriburary streans. Where Arctic grayling were nost abundant, the n€an waler deprh lstandard deviarion){as 28.4 (22.6)cn, mean }idth {as 12.21(4.92) m, nean velocity vas 0.21 (0.I5) m/s, and nean vater temperarure{or the p€riod 2l April ro I Seprmber, l9?9 was 13.7(a.l' C. In this area, the sradient llas 0.29 percent, rubble and gravej conprised 85 percent of the subsrrareand total shoreiin€ cover wa! approxinatelt 262 mz/kn of strean. Gro{th rates (nean incremenr of back-calculat€dlength) of Arctic grayling within th€ s!ud} area {ere greatesr(l l8 mn) during their first year of life and decreasedto 23 mm berweenrhe 4th and sth ]ear. A.ctic grayling reacheds€xual naturity at age three at which tin€ they had a back-calculatedlength of 2?5 mn. The core of the population was confined to &e Big Hole River irself or the lo{er portions of triburaries above ibe nou$ of rhe Norrh Fork Big Hole River. This baselineinformation will allow future comparisonsto asssessthe popularion's status and insure that nanagenenl actions beneficial io the population can be inptemented vhen necessary.B€cause the.ange of this g€neticallydisrinclive population has dwindled over s€reral decad€s,it may be endangeredand suirablebabitat siresshould be identified ro which Arciic grayling can b€ lransplanied.

Introduction physical factors may be impacting the popula- trout (Salmo'rzt'a) At the turn ofthe centuryin the lower48 Unired and 'ainbow lionl (5'*o*i goirdnerr) States, populations of fluvial Arctic grayling trout may be pioneering the area (Thymailus arcticus) ocatrred in n'o.irt",i and,oil exPlorationhas occurred in the drainage' ln this studywe examinedthe distribution, Michiganand westernMontana east of the con. , tinentil divide and in a srnallportion of the up- habiraluse.and populationcharacteristics of the per MissouriRiver drainage within Yellowstoie relictpopulation ofsfeam-dwelling Arctic gray- ilational Park, Wyomingl The Michigan form ling in the upperBig Hole Riverto: (l) provide becameextinct aro;nd l9i6 (Scottand 6.ossman a databasefor monitoring the well'beingof this genepool and (2)identify Arctic grayling 1973)and in Montana,Arctic graylingrhat rere }nique wideiy but intermittently di"strib,rrledio the habitatcharacteristics so suitableareas outside MissouriRiver and its ributaries abovethe Grear the Presentrange could be identifiedas areasfor Falls (Vincent 1962,Henshall 1906) are now possibletransplants. foundonly in theupppr Big HoleR;""" "".1it. tributaies. Description of Study Area The study.area The greatlyreduced range led to rhedesigna- encompassedthe upperBig Hole Hiver.drainageof tion oftie fluvialArctic grJylingof Monran?as southwesternMontana and a taxonof specialconcein by iL" Eodung"."d containstributaries from the Bitterroot and speciescommittee of the Ahs (Deacon'etal. AnacondaRanges and the PioneerMountains- 1979).Concern for the continuedexistence of this lt extend^edapproximately 90 km from the head- warers uniquepopulation in the upper Big Hole River of the Big.HoleRiver to SportsmanPark -has (Figure drainage recently increased.Only small t). The Big HoleRiver flows in braided, numbeis of Arctic grayling were found 1n mlanderingchannels above Pintlar Creek(Figure previous sampling alnd'ne"v biological and l) but is confinedto a singlechannel by a nar- rowcanyon below that poinl. Grasses, sedges. and tl..lrono," co"o*,rt" FisherJResearch unir isjointly spon, willows.verepresent on the extensivelyirigared soredby rhe U.s. Fish & wildlifeSenice, Monrana bepaitment land adjacentto the river and conifersalso were of Fish,Wildlife and Paiks, and Montana Stale Universitv. presentin the riparian zonebelow Pintlar Creek.

122 NorthwestScience, Vol. 61, No. 2, I9B7 in length) and one on its p ncipal tributary, the North Fork (2050m in length),were electrofished to obtain fish populationestimates (Figure l). In areasof the river containingmultiple channels, work wasconfined to the major channel. Populationestimates $ere calculatedusing Chaprnan'smodification of the Petersenformula (Ricker1975). Weights and total lengthsof cap- tured Arctic graylingwere recorded and scales weretaken from an areaposterior of the dorsal fin abovethe lateralline for age-growthanalysis. Back-calculatedlengths of fish at eachage were determinedusing Hile's (1941)modification of the Monastyrskymethod. Predicted and mean weightsat eachage $ere computedusing the logarithmic form of the standardlength-weight relationshipequation (Bagenal and Tesch 1978). Physicalhabirat features of Sectionsl, 2, and 3 were measuredto corelate with Arctic gray- ling abundance.The length of eachsection, pool, and riffle were measuredin the center of the channel.A pool-riffle periodicity (Leopold and Langbein1966) and ratio werecalculated for each section.Pools were defined as areaswith reduced Figure l. Map of siudy area showing locntions of study watervelocities, smooth surfaces, and maximum depths> 0.5 m. The remainingportions of the study sectionswere designated riffles. Gradients A sagebrush-grasslandvegetation type was pres- for eachsection were estirnated using U.S. Geo- ent on the foothillssurrounding the tributary Iogical Survey topographicalmaps. stteams. In 1979,37 transectswere established perpen- The maximumand minimum recordeddis- dicular to the channelon eachsection where chargesat a site 15 km upstreamof Jackson physicalhabitat data wasgathered; distances be- (Figurel) from 1940-1954was 26.56 m"/s and tweenthe transectson Sectionsl-3 were45, 100, 0.142m'/s, respectively (Aagaard 1969). During and 150m, respectively.Transects vere located the first year of the study, the mean discharge only on the upper half of SectionI sincethe at a site approximately8 km downstreamfrom lower half was completelydewatered in l9?9. Jacksonwas 4.4 m3/sbetween 26 July and 15 However,the habitat in the upper portion of Sec- September,l97B (Wells and Rehwinkel 1980). tion I appearedto be representativeof the en- NationalOceanic and AtmosphericAdministra- tire section.On eachtransect, water depth was tion(1977, 1978, and 1979)precipitation records recordedto the nearestI cm at intervalsof 0.5 at Wisdom(Figure l) and summerflow measure- m. Velocitieswere measured to the nearest0,003 mentsin 1979indicate that dischargesmay have m/secat I m intenals in SectionsI and 2 and beenup to 40% lower in 1979than in 1978. at 3 m in Section3 with a GurleyAA current meter,Discharge in eachsection was calculated Methods from measurementsof selectedtransects. The distributionof fluvialArctic grayling in the Shorelineor instreamcover 1.5 rn to each upperBig Hole Riverdrainage was determined side of a line transect was measured to the frorn collectionsmade at numeroussites by an- nearest0.01 m. Shorelinecover was defined as gling and electrofishingfor adultsand juveniles; overhangingbrush within 1.0m of the watersur- seiningand drift netswere used to samplefor face or debris and undercut banksrvithin 0.6 rn larvae.Four sectionson the river (3500-4900m of the water surface.Instream cover included

Distribution.Habitat and PopulationCharacteristics of FluvialArctic Graylins t23 both aquaticplants and debris.The generalcon- dition of banksat eachtransect was qualitatively evaluatedas stableor unstable;unstable banks weredefined as those showing recent soil erosion. Substratecomposition was determinedby visuallyestimating the amountof eachtype of materialalong each transect. Bottom materials wereclassified after Wentworth(1922) as bedrock (unbroken,solid rock),boulders (>26.0 cm in diamerer),rubble (6.4-26.0 cm in diameter),gravel (2.0mm - 6.3 cm in diameter),and fines( ( 2.0 mm in diameter). Waterquality analysis at Sectionsl, 2, 3, and 5 occurredbimonthly from l6 June-lSeptember, 1979. Dissolvedoxygen concentrationswere determinedto the nearest0.1 mg/l by the azide modificationof the Winkler method(American PublicHealth Association 1976). Alkalinity and hardnesswere determined by titration with preci- sionto 5 mg/l CaCO3and the specificelectrical conductancewas measuredwith a Beckman RB3-Solu Bridge to the nearest0.5 g.mhos/cm. The pH wasdeterrnined in the field with an Orion model407Specific Ion Meter(resolution = 0.01 pH units). Water temperature was continually monitoredto the nearest0.5 C with Ryanmodel figure 2. Collectionsites of Arctic graylingin the upper Big D-15thermographs. Hole River drainage, l9?8-?9. Statisticaltests were performed according to methodsin Snedecorand Cochran(1967) using Arctic grayling251-297 mm in totallength were MSUSTAT(Lund 1979)and SPSS(Nie er aL 35(r I l)/kmand 6.7 (+2.5) kg/krn or 28(r9)hec 1975).Values having probabilities of p < 0.05 and 5.5 (t2) kg/hec,resepctively. Population were termed significantly different. estimateswere not obtainedin any other section.

Results Age, Growth, and Spawning Dstribution and Abundance Back-calculatedlengths and weightsof Arctic graylingfrom locationsthroughout the upper Big Arcticgrayling were collected at sevenlocations Hole River drainagewere similar, so all the data mainriver on the and from I I tributarystreams werecombined (Table I). Their growthrate was (Figure2). Fry or young of the year(yoy) vere most rapid the first year and displayeda pro- collectedat 14points, I + andolder fish at four nounceddecline between the secondand third locationsand fry and I + and older fish together years.Arctic graylingin at l2 sites.None were observed in Deep,Warm the upper Big Hole River attained sexualmaturity at age three when Springs,Johnson or Fishtrapcreeks. Johnson their Creekis a tributaryof the North Fork Big Hole back-calculatedlength was 275 mm. River. The largest nurnber of Arctic grayling cap- The relativeabundance of Arctic graylingwas tured wereobtained in July and August,l97B; greatestin Section l The averagenumber of these312 fish allowedus to exaninethe popula- Arctic grayling81-335 mm in total lengthcaptured tion's sizestructure. The dominantage groups per kilometer on eachelectrofishing run in Sec- weretwo and three,comprising 47.1 and 30.4per- tions 1,2, and 5 were16.9,5,3, and 4.9,respec- cent of the sample,respectively. Young of the tively.No Arctic graylingwere obtained in Sec- yearrepresented only ?.7 percentof thesefish; tions 3 and 4. In Sectionl, the numberand stand- however,this is due to bias of samplinggear ing crop (80 percent confidence intervals) of which is more efficient capturing age one and

124 Liknes and Gould TABLE 1. Mean rolal length and weight (srandarddeyiation in parenlheses)al tine of caprureand calculat€dmean total lengrh and weight at each annulus for A.ctic gralling Age I + and older caprured in the upper Big Hole River drainage in 1978 and 19?9.

Calculatedlengrh (mrn) ar ase ^ge Mean total Mean lotal Group N length (nm) weight (gn)

198 76 6 (20) (23) 190 261 168 119 22t (16) (34) 292 231 1l? (1e) (4s) 316 282 t19 230 (22) (s6) 381 431 150 272 320 356 319

Mean back-calculated length (nn) lt8 222 275 309 379

Mean incrernent of back-calculated length (nn) 8 104 52 28 23

Calculated weight (gm) 27 188 247 395

older fish. Age one fish also made up a relative- trout (5. ,rrrrd) vas collectedduring this study. Iy low portion of the sample,12,2 percent- Age Brook,rainbow and areintroduced classfour vas representedby onlyB individuals speciesin Montana. Also, mour.tair. (C.platyhln- (2.6percent). c&.us)and white suckers(C. commersoni)ha-te been reportedto inhabit the area (Wellsand Most spawningactivity in the Big Hole River Rehwinkel 1980),but none were observeddur- during 1979occurred in late April and earlyMay. ing this investigation. A total of 146age 0 Arctic graylingwere collected throughoutthe upper Big Hole River drainage from27 May-27July, i979. The meantotal length HabilatCharacteristics ofyoy increasedfrom 12.2mm during 2?-31May StreamMorphology and Cover to 55.2mm for the period I l-15 July. Somefry apparentlyleft the spawningstreams and moved Morphologicalmeasurements made on Sections into the main river shortly after hatching,while l-3 showedthat mean,pool, and riffle vidth in- othersremained much longer, even in intermit- creasedin a downstreamdirection (Table 2). tent streamssuch as SandhollowCreek (Figure Analysisof variance sholvedsignificant dif- 2).Mo.t 1oyArctic grayling captured moving out ferencesin sornehabitat parametersbetween the of SandhollowCreek were obtained from over- sections.Comparison of samplemeans (Q test; night drift net sets. P (0.05) showedthat Sectionl, with the greatest densityof Arctic grayling, wassignificantly nar- Sympatrc species rowerthan Section3, significantlyshallower than Elevenspecies of fish coexistedwith Arcticgray- Sections2 and 3, and had a significantlyslower Iing in the study area. Mountain whitefish (Pro- meanthalveg velocity than Section2. Also,the sopium uilliamsonl and (Saltelinas percentageof stablebanks and the pool-riffle periodicity lower than in the two down- fontinalis) werc the most abundant game fish pres- were ert throughoutthe study area.Longnose suckers slreamseclions. The pool-riffle ratio was grPalesl (Catostomus catostomus\,bvbot (Lota lota), in SectionI and decreasedin a donnstream mottled sculpin(Cottus bairdi\, longnose dace directionthrough the studysections, as did the (Rhinichthys cataractae), (So/mo gradient.The compositionof bottommaterials gairdner0,cl.l:.throat trout (S. clarAr)and rainbov- in all threeseclions nere similar.consi'ting cutthroat trout hybrids(5, gairdneriX S. clarki) primarily of rubble and gravel,The area of vere alsofound in the studyarea. Only one brown shorelineand instreamcover per kilometerin

Distribution.Habitat and PopulationCharacteristicsof Fluvial Arctic Grayling 125 TABLE 2. Mean values and srandard deviations(in paren- than any other month. During this month, theses)of physicalhabiral paraneters measured temperatureswere above l7o C about60, 60, and in study sectionson the upper Big Hole River be- 83 percentof the time on Sectionsl, 2, and 3, tween16 and 20 Augus!,19?9. July respectively. There wereno significantdifferences among otherparameters from anysection on the main river(Table 3). The warerin the upperBig Hole widrh (m) 12.21(4.92) r5.95(5.02)4€.0qr4.?5) Rivervas soft,its pH wasnearly neutral, it had Rifile vidth (m) 10.83(4.77) 12.62(4.46)sr.5qls.8r) a fairly low capacityto neutializeacids and had Pool {idth (m) 8.9515.23) 13.40(5.30)40.0q7.60) a low electricalconductance. Mean valuesof Thalwegdepth dissolvedoxygen were similar throughoutthe (cn) 54.7(24.0) ??.3(33.s) 6r.q22.0) studyarea. Each individual value was above 85 Depth (cm) 28.q22.6) 39.?(30.6) 3?.3(23.r) percentand mean values were all ) 100percent Thalwegveloc' saturation.Data from Section5 on the North ity (mh) 0.2?(0.18) 0.12(0.28) 0.32(0.rs) Fork showedthat the principaltributary had (nt) Velocity 0.2(0.1s) 0.33(0.23) 0.21(0.1s) Iowermean alkalinity, hardness and conductiv- Stablebanks(%) ?0.3(5.0) 78.4(4.8) 93.2(2.9) ity valuesthan the main river. Pool-rif{le periodiciry 6.3(4.2) 7.2{4.5) l t.6(?.6) Discussion Pool,riffleratio l.5l t.29 0.27 Cradient(%) 0.29 0.23 0.rl Virtually all of the fluvial Arctic grayling col- Frow{m,rs) 0.68 2.07 3.50 lected during this study were from locations in Botton marerials(%) the Big Hole River itself or from sites in Boulders 0.9(5.s) 0.0 0.(0.8) tributaries near the river. The only Arctic gray- Rubble 41.5(19.8) 38.8(14.2) 51.(15.6) ling found far upslreamin tributarie. werein Gravel 42.qt6.2) 39.302.9) 33.q11.3) Miner and Mussigbrodcreeks. They werecap- Fines 14.8(17.7) 2t.q20.3) 15.s(15.5) tured upstreamand downstream,respectively, Shorelinecover from lacustrinepopulations and probablydo not (m1km) 26r.4 representportions of the fluvial population.Fur- thermore,the core of the Arctic grayling popula- (n,rkn) s1.0 tion waslocated in the drainageabove the mouth of the North Fork Big Hole River.Twelve col- lections (excluding those from Miner and SectionI was57 and55 percentof thr.rserespec- Mussigbrodcreeks) were made in this area,while tivefeatures in Section2. Bothshoreline and in- only four collectionswere made below this point. streamcover were virtually absent in Section3. However,in previousyears, Arctic graylinghave alsobeen found at sitesbelow the North Fork Water Temperatureand Quality (Peterson1974, Wells and Rehwinkell9B0) and individuals have appeared as far as 85 km Analysisof varianceon watertemperatures of downstreamfrom the study area.(J. Wells,Mon- Sectionsl-3 showedsignificant differences. The tana Departmentof Fish,Wildlife and Parks, meanwater temperature (Table 3) in SectionI Bozeman,MT, personalcommunication). wassimilar to that in Section2, but significant- ly lowerthan in Section3 (Q test;P<0.05). Mean The relative abundanceof Arctic grayling watertemperatures in SectionsI and2 werealso alsoryas greater upstream from the mouth of the significantly lower than in Section 5 for com- North Fork. In this study,densities above the parableperiods of time (Q test;P<0.05). The North Forkwere about 5-17 fishikm per electro- recordednumber of hourswater temperatures ex- fishing run, while thosebelow were 0 fish/km in ceededl7o C wassimilar in both SectionsI (895) the study areaand 0.6-2.8Arctic graylingper and 2 (727\,and was significantly lower than in electrofishingrun/km in other surveys(Peterson Section3 (1342)for cornparableperiods of time l9?4, Wells and Rehwinkel1980). (Chi square;P<0.05). More hours of water Summerwater temperatures may be an im- temperaturesabove l?o C wererecorded in July portant limiting factor for Arctic grayling in the

126 Liknes and Gould TABLE 3. Mean and .anges(in parenrhese!)of waler quality parametersand temperaturesfron sludy sectionson the upper Big Hole River,21 April'l Sept€nber,1979

Temperature('C) I3.7 I3.6 15.2 r8.0. (0-24) (r.25) (2.25) (r2.s-23) Total alkalinity (mg/l CaCO3) 5t 5l 56 37 (3s-60) (40-60) (3s-70) (30-40) Total hardness(mg/l CaCO3) 43 4l 36 26 (40-50) (40-s0) (30,4s) (15-30)

Calcium hardness(mg/l CaC03) 32 34 30 22 (25-40) (30-40) (20-40) (15-30)

Magnesiun hardness(mg/t CaCO3) l1 7 3 (0.20) (0-10) (0-10) (0-r0) pH 7.44 ?.38 7.24 (7.22.7.64) (6.78-7.80) (7.26.7.72) (7.04-7.38) ConducdYity(rnhos/cm) 94.1 100.3 105.8 7t.7 (50-r20) (52.5,120) (s2.5,140) (ss-90)

Dissolvedoxygen (mg/l) 8.8 8.8 (7.7.r0.2) (?.6-r0.3) (6.5-lr.6) (?.9-r0.0)

'Based on dara collected from 23 June-25August, 1979.

ver downstreamof the North Fork. Although Arctic grayling usuallyreach sexual maturity be- the thermal tolerance of Arctic grayling is not tween age four and six (Bishopl9?1, Wojcik preciselyknown, Vincent (I962) reportedthat the 1955).The minirnumlength at malurity!ras range of temperaturetolerance for Arctic gray- similar to the 270 mm length suggestedby Wo- ling wasusually between l0 and 18.3"C. Further- jcik (1955)for AlaskanArctic grayling. more,water temperatures of l7 o C and above phenomenonis presentin the exceedthe physiologicaloptimum for growthand ReverseLee's fish havea larger food conversionefficiency of salmonids(Brett et back-calculatedlengths. 0lder for a given age than younger ol 1969,Wurtsbaugh and Davis 1977).The high calculatedlength the sameage. Possible causes of this in- summerwater temperaturesmeasured in the fish at or scalereading lover portion of the study area may have been clude incorrectback-calculation of the stock, Iargelyresponsible for the absenceof adultArctic procedures,non-random sampling mortality that affects grayling there during this study. and selective natural smallerfish in a particular agegroup more.Such Hole drain- Arctic grayling in rhe upper Big natural mortality may result from either in' first two ageunderwent rapid growth during the terspecificor intra"pecificcompelition. yearsof life with a large reduction betweenthe secondand third, which wassimilar to that of ManagementApplications Arctic grayling from the Red Rock drainage (Nelson1954). However, their growth rateswere The data obtained on the distribution, relative lessthan thosein two other Montanastreams out- abundance,and biological parametersof Arctic side the Big Hole drainage(Peters 1964). The graylingin the upper Big Hole River provide rninimum age and back-calculatedlength at sex- baselineinformation for future comparisons.Any ual maturity for individuals found during this significantand persislenldecrease in range. study wasthree yearsand 275 mm, respectively. relativenumbers, growth rates oi increasein age In other Montana populations,a few individuals at sexualmaturity should be a stimulusfor ad- havebeen reported to matureal agetwo (Lund ditional and immediate managementaction on 1974,Peterman 1972, Nelson 1954, Brown 1938) this population,which has beendetermined to while in the northern portion of their range, be geneticallydifferent than any other Montana

Distribution. Habitat and Population Characteristicsof Fluvial Arctic Grayling 127 or Wyomingpopulation sampled to date in allele The presenceof other fish at the potential frequenciesat variableIoci (Everettand Allen- transplantsites is anotherfactor which must be dorf l9B5). considered.Sites with only cutthroattrout and mountainwhitefish should receive highest prior- One of the most pressingmanagement ac- ity sinceArctic graylingevolved in sympatrywith tions neededto be addressedis the identifica- thesespecies. Competition with introducedfish tion of suitablehabitat sitesoutside the Big Hole hasoften been suggested as a majorreason for River for transplantsfrom this uniquepopula- the reductionin the Arctic grayling'srange in tion. In that portion of the river whereArctic Montanaand Michigan.While this may be ac- graylingwere most abundant,the meandepth curate,the competitiveinteractions responsible (standard deviation) was 28.4 (22.6) cm, mean for the Arctic grayling'sdecline have not been widthwas 12.21 (4.92) m, meanvelocity was 0.21 identified.The possibilitythat non,nativefish (0.15)m/s, mean water temperature for the period simplyreplaced Arctic graylingpopulations de- 2l April to I September,1979 was 13.7o C, and pressedby otherfactors should be investigated. the maximumwater temperature was 24o C. In Vincent(1962) believed rhat interspecificcom- this area,the gradientvas 0.29percent, rubble petitionwith exoticswould manifest itself in 40 and gravelconprised 85 percentof the substrate years.However, brook trout wereintroduced into andtotal shoreline cover was approximately 261 the upper Big Hole drainagearound 1929 and m'/km of stream.Transplant sites having similar havenot eliminatedthe Arctic grayling.Perhaps physicalhabitat characteristics to theseshould this portion of the river is optimalhabitat for Arc- be sought,while areasmore like Section3 should tic grayling and they havethus beenable to hold beconsidered les" desirable. Hor,rerer.5inae 16y their own againstthe introducedcompetitors. Arcticgrayling were found in the river nearSec- Nevertheless,this indicatessuitable locations tion 3, is shouldbe consideredsuirable habitat with brook trout also might be considered, for use at somepoint in their life history. although as less desirablesites.

ReferencesCited Henshall,J. A. 1906.A lisr of the fishes of Monkna. Bnll. Univ. Mont.34:l-12. Aagaard,F. C. 1969.Temperarure ofsurface watersin Mon- Hile, R. 1941.Aee and growrh o{ the rock bass,zlnbloplnes tana. U.S. Geol.Survey and MontanaFish Game rupesrris (Rafinesque),in Nebish Lale, Wisconsin. Comm. Trans. Wis. Acad. Sci. Arls. Lett. 33:189-337. AmericanPublic HeahhAssociation. 1976. S|andardmethods Leopold, L. 8., and W. B. Lansbein. 1966.Rirer meanders. lor the examination oi waler and wasl€{ater, l4 ed. Sci.Aner.214:60-70. Amer. Pub. HealthAs!n., Washingron, D.C. Lund,J. A. 1974.The reproduclionof salmonidsin rhein- Bagenal,T. B., and F. W. Tescb.l9?8. Age and gro{rh.1r lets ofElI Lake, Montana.Montana StateUniversitv. T. B. Bagenal(ed.).Meihods ofassessnent offisl pro- Thest. ducrion in fresb waters,3ed. BlackwellSci. Pub., Ox Lund, R. E. 1979.A uler's guide ro MSUSTAT an intersc- ford and Edinburgh,Great Britain. Pp. l0l-136. tiye sktislical analysispackage. Dept. Math. Sci.Mon- Bishop,F. G. 1971.Observations on spawninghabns of the tana State Unir€rsny. Arclic grayling.Prog. Fisb Cult.33:12-I9. National Oceanic and Atmosphe.ic Adminislration. l9?7. Brett, J. R., J. E. Shelbourn,and C. T. Shoop. 1969.Crowth Climdrologi.alDd ls: Vontana.80:5-8. rate and bodr composilion of fingerling sockeye l9?8. Clinarological Data: Montana. s non, Oncorhynchus nerIo, in relation to 81:5-8. 1979. ClimatologicalDarar Montana. 82:5-8. remperarureand ration size. J. Fish. Res. Bd. Can. 26:2363-2394. Nelson, P. H. 1954. Life history and nanagement of the B.own, C. J. D. 1938.Obserrations on the life history and Anerican grayling (Thyna us sisnifer tricolot) in breedinghabns of the Monranagrayling. Copeia Montana. J. Wild. Msnt. l8:324-3,12. 1938;123'126. Nie, N. H., C. H. Hull, J. G. Jenkins,K. Steinbrenner,and Deacon,J. E., G. Koberich,J. D. Willians, S. Contreras, D. H. Benr. 1975.Statistical paclage for the social and other nenbers of rhe EndangeredSpecies Con sciences,2 ed. McGraw,Hill,Inc., New York. mitt€eoirhe AmericanIish€ries Society.l9?9. Fishes Pelerman, L. G. 1972. The biolog1 and population of North Anerica endangered,threalened or of special characte.isticsof the Arclic grayling in Lake Agnes, concern: 1979. Fisheries4129,44. Montana.Montana State University. Thesis. Everett,R. J., and F. W. Allendorf. 1985.Population senetics Perere,J. C. 1964.Age and gro{th studies and analysisof ofArcric grayling: Crebe Lake, YellowstoneNationai bottom 6anrplesin connectionwith pollulion studies. Park. Pop. Cen. Lab. Rep.851I, Unirersity of Fed.A;d Proj. F-23-R-6,Job. no. I and II. Mon!. Depi. Montana. Fish Game,Helena.

128 Liknesand Could Peterson,N. 1974.Sourhwestern Monlana FisheriesStudy- Wells,J.D., andB. J. Rehwinkel.t980. Southwest Monrana Fed.Aid Proj. F-9-R'22,Job. no. I-b. N{ont.Dept. Fish fisheriessiudy. Ied.Aid Proj.F'9R27,Job no. I-b. Game,Helena. Mont. Dept. Fish Wild. Parks,Helena. Ricket,W. E. 1975.Conpulalion and interpretationof Wentworth, C. K. 1922. Gradesand classlerns for claslic biologicalstatistics of fish populations.Dept. Env, sedim€nrs.J. Ceol. 30:37?-392. fish Ntar. Serv. Bull. l9L 0ttawa, Canada. Wojeik, F. J. 1955.Life history and rnanasenenlof the gray- Scotr,W. 8., and E. J. Ctossman.1973. Fresh{ater fishes ling in inreriorAlaska. University ofdaska, Fairbanks. of Canada.Fish. Res. Bd. Can.Bull. 1984.Ottawa, Thesis. Canada. Wurlsbaush, W. A., nnd C. E. Davis. 1977. Effects of Snedecor, G. W., and W. C. Cochran. 1967. Sudsrical temperatureand radon level on the growth and iood nethods,6 ed. Iowa St. Univ. Press,Ames. conversionefficiency of Salno galrdnea, Richardson. Vincent, R. E. 1962.Bioseog.aphical and ecolosicalfactors J. Fish Biol. I l:8?-98. contribuiing !o th€ decline of Arctic grayling, Thlmallus arcticus(Pallzs), in Michiganand Montana. University of Michigan. Diss€rtation.

Receired 9 April 19B6 Accepted,for publication 5 Noaember 1986

Distribution,Habitat and PopulationCharacteristics of FluvialArctic Grayling t29