Feast.!Resister / VoL 56. No. 205 I Wednesday,October 23. 1991. I Rules and Regulations 54~57

50 CF~Part 17

RIM 1O1$-A842

EndangeredandT~.a~d~1sandPlantsthe RazorbasliSuoliss(Xyra.chsntoxanus)DM.nsliwdToB. an Endsngsr.dSpd,sAOENCV~Fishand Wildlife Servica~Interior.ACTION: Final rule.

surany TheU.S.Fishand WildlifeServicedetermine,therazorbacksucker(Xyrauchen tnxaner) tobe anendangeredsped..~adertheauthorityof the EndangeredSped..Act of1073,asamended. flils natI~fish I. found Inlimitednumberadn’oughouttheColoradoRIverbasin.Little evidenceofnatural recruitmentha.beenfound Inthe past30y..r.. anduwuber,of adult

fish captured In the ~ut1O yearsdemonstvat*.ilawltwardtrendrelative

54958 Federal Register / Vol. 56, No. 205 I Wednesday,October 23, 1991 / Rules and Regulations

tohistoric abundance.Significantchangeshaveoccurredin razorbacksucker habitat throughdiversionanddepletionof water,introductionofnormative fishes,and construction andoperation of dams. Further changesareanticipatedas theseactivities continue.Listing therazorbacksuckerasendangeredwill affordthis speciesfullprotectionundertheEndangeredSpeciesActEFFECTIVE DATE.~November22, 1991.ADDRESSES: The completefile for thisruleis availablefor inspection,byappointment,duringnormalbusinesshours at theU.S. FishandWildlifeServiceField Office, 2060AdministrationBuilding 1745 West 1700South.Salt Lake City, Utah 84104—5110.FOR FURTHER INFORMATiON CONTACT:PatriciaA. Schrader,FishandWildlifeBiologist, U.S. Fish and Wildlife Service,529—25½Road, suite B—1l3, GrandJunction. Colorado 81505/6199,(303)243—2778.SUPPLEMENTARY INFORMATION:

Background

The razorback sucker was describedby Abbott (1881)fromasinglemountedspecimencapturedfrom the ColoradoRiver. He placed it in the genusCatostomus.but Eigenmannand Kirsch.after further study, assignedit to its owngenus,Xyrauchen(Kirsch 1889). Alsoknownas the humpback sucker, theadult razorback sucker is readilyidentifiable by the abrupt sharp-edgeddorsal keelbehind its headand a largefleshy subterminal mouth that is typicalof most suckers.Adult fish are relativelyrobust, often exceeding3 kg (6 lbs.) inweight and 600 mm (2 ft.) in length.Although traces of the developingkeelhave beenobservedexternally on somecultured specimensas small as 85 mm(3.3 in.) (Snyder and Muth 1990).thedorsal keel of juvenile razorbacksuckersmay not be obvious in otherindividuals, making them difficult todistinguishfrom othersuckerspecies.

Therazorbacksuckerwasonceabundantthroughout5,835kin (3.500ml.)of theColorado River basin,primarily inthe mainsteinandmajor ~1butariesInArizona, California, Colorado,Nevada,New Mexico,Utah. andWyoming andin the Statesof Baja California Norteand Sonoraof Mexico (Ellis 1914,Minckley 1973).The Colorado Riverwasdivided into upper and lower basinsatLeeFerry,Arizona (approximately 14km (9 ml.) below Glen Canyon Dam), bythe Colorado River Compactof 1922.Therearemany accountsof razorbacksuckersduring early settlement of thelower basin (Gilbert and Scofleld 1898,Minckley 1973)anda significant

commercialfisheryfor themexistedinsouthernArizonain theearly1900’s(HubbsandMiller 1953, Miller 1964).Intheupperbasin,Jordan(1891)reportedrazorbacksuckersto be very abundantat GreenRiver, Utah, in 1889.Residentsliving along the Colorado River nearClifton, Colorado,observedseveralthousand razorback suckersduringspringrunoff in the 1930’sand early1940’s (accountin OsmundsonandKaeding 1989a).

in recent times, razorback suckerdistribution has beenreducedto about1,208 km (750 iiii.) in the upper basin(McAdaand Wydoski 1980, FloldenandStalnaker 1975,EcologyConsultants1978).In the lower basina substantialpopulationexistsonly in Lake Mohave,but they do occurupstreamin LakeMead and the Grand Canyon anddownstreamsporadicallyon themainstemand associatedimpoundmentsand canals (Marshand Minckley 1989).Marsh andMinckley (in press)estimatedapproximately60,000adultrazorbacksuckersstill occurin LakeMohave, and LaniganandTyus (1989)estimatedthat758 to 1,138razorbacksuckersstill inhabit the upper GreenRiver. In theupper Colorado Riversubbasinmost razorback suckersoccurin the Grand Valley area (Valdez et al.1982), Observationsin other areasarespottyand inconsistentand aregenerally viewed as incidental captures.The number of adult capturesin theGrand Valley had declinedappreciablysince1975(OsmundsonandKaeding1991).No significantrecruitmentto anypopulation has beendocumentedinrecentyears (Tyus1987a.McCarthyandMinckley1987, OsmundsonandKaeding19894

Informationon behaviorand habitatneedsof the razorback sucker is limited.Until recently,it has not beena majorobjective of most upper basininvestigationsandit is rarely collectedin fisheriesInvestigationsdirectedat thethreeendangeredColoradoRiverfishes:The Coloradosquawfish(Ptychocheiluslucius); humpbackchub (Gila cypha);andbonytailchub (Cueelegans).However, information has beenaccumulatedIn conjunctionwith otherstudies,andsomespecificstudieshavebeenconducted.

in 1981, the U.S. Fish and WildlifeService(Service)andthe Arizona Gameand FishDepartment beganareintroductionand monitoring programin historic razorback sucker habitats ofthe Gus, Salt, and VerdeRivers. TheStateof California initiated a similarefforton theColorado River mainstemin 1986 (Minckley et al. in press). In thepast10 years, over 13 million razorbacksuckerswere stockedin 57 sites in

Arizona, primarily in the Verde, Gila.andSalt Riversandtheir tributaries(DuaneShroufe,Director,ArizonaGameandFishDepartmexit,in Iitt., 1990).Recapturesfrom thesestockingeffortshavebeenscarcebecausemostfishstockedwerefry (whichnormallyexperiencehigh attrition), stockedfishwere heavilypreyed upon. and therewere inadequatesurvey efforts for thelarge reintroduction area(Brooks 1986).There are indications that populationsare being establishedin isolatedhabitats and in theuppermostreservoirsof thedrainages beingstocked(DuaneShroufe,Director. Arizona Game andFish Department, in iitt., 1990).

Someadult razorbacksuckersmigrateconsiderabledistancesto specificareasto spawn(Tyus1987a,Tyusand Karp1990).Spawningoccursin the lowerbasin from January through April (Ulmer1980,LanghorstandMarsh 1986, Mueller1989).In the upper basin, ripe razorbacksuckerswere observedin suspectedspawning areasin the GreenRiver fromApril 20 to June14, from 1981 to 1989(Tyus 1987a,Tyus and Karp 1990).Osmundson and Kaeding (1991)suinniarized capturesby variousinvestigators of razorback suckersin theGrand Valley. and report that 40 of the42 runningripe adults captured werecaptured betweenMay 24 and June 17.Water temperaturesduringspawninginthe lower basin ranged from11.5—18°C(52.7-64.4°F)(Douglas1952. Ulmer 1980.Langhorst and Marsh 1986)whiletemperaturesrecordedin the upperGreenRiver ranged from 9—17°C(48.-63°F)(Tyusand Karp 1990). Spawning isusually accomplishedovergravel barsthat aresweptfreeof silt by currentsand severalmalesaccompanya singlefemale (Jonezand Sumner 1954.Uliner1980).In Lake Mohaveand SenatorWash Reservoir.spawningtakes placeon gravelbars sweptcleanby waveaction (Ulnier 1980,Bozeket al. 1984).Tyus (1987a)collectedripe adults overcoarsesand substratesandin th~vicinity of gravel or cobble bars,butdirect observation of spawningwasnotpossiblebecauseof high turbiditiesprevalent during that time of year. InSenatorWash ReservoirandLakeMohave. the eggsapparently settledonto gravel and into intersticessweptcleanby the spawningactivity-, larvaeremained in the gravel until swim-up(Uliner 1980,Mueller 1989).

A number of investigatorshavecollectedviable fertilized eggsandlarvae in the areasof observedspawning activity (Bozeket a!. 1984,Ulmer 1980,Marshand Langhorst1988,Tyus 1987a),but few have collectedlarvae larger than 14 mm (0.8 in.) in the

Federal ~egister I Vol. 56, No. 205 I Wednesday,October 23, 1991 I Rules and Regulations 54959

wild. This indicateslittle or nosuccessfulrecruitmentof wild razorbacksuckers(Tyus 1987a).MarshandLanghorst(1988)recoveredlarvaeup to20 m’i (0.8 in.) total lengthin anisolatedbackwaterin LakeMohavewherepredatorshadbeenpreviouslyeradicated,andgrowthto 20 cm (7.9 in.)wasreportedfor juvenile razorbacksuckersin the samelocation(Minckleyet aL in press).However, thesefishdisappearedwithin amonthfollowingreinvasionof thebackwaterbypredators.Most investigatorshavereportedconcentrationsof carp(Cyprinuscarpio).greensunfish(Leponilscvanelius),bluegill (Lepornismocrochirus).channelcatfish(Ictaluruspunctatus),andlargemouthbass(Micropterussalnioides)in razorbacksuckerspawningareas(JonezandSumner1954, MarshandLanghorst1988,Ulmer1980, Bozeket al. 1984).Larvaeandlargerrazorbacksuckershavebeenfoundin stomachsof predatoryfishessuchasgreensunfish.warmouth(Lepornisgulosus).channelcatfish.flatheadcatfish(Pylodictisolivaris),andthreadfinshad(Dorosornapetenense)(MarshandLanghorst1988.Langhorst1989,Brooks 1986).

Habitatneedsof youngandjuvenilerazorbacksuckersin the wild arelargelyunknownbecausetheyrarelyhavebeenencounteredby researchers,particularlyin nativeriverine habitats(Tyus1987a).MarshandLanghorst(1988)observedthat larval razorbacksuckersin LakeMohaveremainednearshoreafterhatchingbut either disappearedormigratedto depthsin excessof 15 m (49ft.) within a few weeks.Most juvenileshavebeencollectedfrom irrigationcanalsin southernCalifornia andArizona (MarshandMinckley 1989).Substantialnumbersof razorbacksuckershavebeenrearedthroughthejuvenileandadult stagesin hatcheries(Toney1974, Harnman1985)andinisolatedponds(Langhorst1989~OsmundsonandKaeding1989b),providing some information ongrowthratesandfood habits.

Dietsof razorbacksuckerlarvaehavebeenstudiedin LakeMohave (MarshandLanghorst1988)and underexperimentalconditions(Papoulis1988,Tyus andSeverson1990).LarvaefromreservoirsselectedBosmjnaspp.(Cladocera) and avoided Copepoda,while larvaefrom backwatersor LakeMahaveselectedBosmincrandavoidedRotifera(MarshandLanghorst1988).Dietarystudiesin controlledconditionsndicatedwide differencesin theirresponseto commercialfish foods(TyusandSeverson1990).Information is notavailableon food habitsof razorback

suckerlarvaefrom naturalriverinehabitats.

Only limited informationhasbeenaccumulatedon thefood habitsof adultrazorbacksuckers,primarily dueto theirrarity andprotectedstatusunderStatelaw. Marsh(1987)examinedthestomachsof 34 adult specimensfromLakeMohaveandfoundcontentsdominatedby planktoniccrustaceans.diatoms,filamentousalgae,anddetritus.JonezandSumner(1954)reportedmidgelarvaeas thedominantfood item in theirstomachanalysisof LakeMohaverazorbacksuckers.Theyalso reportedalgaeas themost commonfood itemfoundin razorbacksuckerstomachsfrom LakeMead,followedby plankton.insects,anddecayingorganicmatter.Vanicek(1967)examinedeight adultrazorbacksuckerstomachsfrom theGreenRiver andfoundthempackedwith mud or claycontainingchironomidlarvae,plant stemsandleaves.

Usingscales,Minckley (1983)estimatedannualgrowth ratesin thewild LakeMohavepopulationto belessthan 10 mm (0.4in.) per yearafter theirseventhyearof life. Recently,researchershavedemonstratedtheinadequaciesof usingscalestodeterminetheageof razorbacksuckersandhaveshownthatmost razorbacksuckerscapturedin recenttimesaremucholderthnn their scaleswouldindicate(McCarthyandMinckley 1987).Usingsectionedotoliths, McCarthyandMinckley (1987)computedtheagesofLakeMohaverazorbacksuckerscollectedin 1981—83to be24 to 44 years.Eighty-ninepercentof the70 fishsampledwereestimatedto havehatchedprior to or coincidentwithimpoundment.Disappearanceofrazorbacksuckersfrom lower basinreservoirs40 to 50 yearsafterimpoundmentwasdocumentedbyMinckley (1983).McCarthyandMinckley (1987)predictedthe LakeMohavepopulationis following thistrend andmaybeextirpatedbefore theyear2000. Tyus (1987a~concludedthatrazorbacksuckersin theGreenRiverweresubstantiallysmallerandyoungerthan thosefound in the lower basin,butno recentrecruitmentto theadultpopulationwasevident.

Adult razorbacksuckersaremorevulnerableto capture during theflspawningseason.Tyus (1987b)reportedthemto be10 times more prevalent instandardizedelectrofishingcollectionsduring the spring than during theremainder of the year. During spawningseason,razorbacksuckershavebeenfound in runswith coarsesand,gravel.and cobble substrate; floodedbottomlandsandgravelpits; andlarge

eddiesformedby floodedmouthsoftributarystreamsanddrainageditches(Tyus 1987a.OsmuñdsonandKaeding1989a).Tyus (1987a)trackedsix radio-implantedadult razorbacksuckersfor 2years.andfoundthat they utilized themain channelof the GreenandDuchesneRivers.During non-breedingseason,thefish were found in depthsof0.6 to 3.4 m (2.0 to 11.0ft.), usedsandorsilt substrates,andwatervelocitiesof0.1 to 0.6 m persecond(0.33 to 2.0 ft. persecond).Razorbacksuckersalsoselectednearshorerunsduring thespring,but shifted to relativelyshallowwatersoff mid-channelsandbarsduringthesummermonths.Exceptforspawningmigrations,razorbacksuckersarefairly sedentary,movingrelativelyfew kilometersoverseveralmonths(Tyus 1987a,Tyus andKarp 1990).Valdez andMasslich(1989)tracked17razorbacksuckersthroughoutthewinteron theGreenRiver. Theyfound thatmostof the radio-telemeteredfishmovedlessthan5 km (3 mi.) throughoutthewinter. Theyalsoreportedlocalizeddiel movementpatternsthat increasedwith fluctuatingflows which theyattributedto changesin watervelocities.Theradio-telemeteredrazorbacksuckersusedslow run habitats,slackwaters,andeddies.Theyselecteddepthsof 0.6 to 1.4 m (2.0 to 4.6 ft.) andvelocitiesof 0.03 to 0.33m persecond(0.1 to 1.1 ft. persecond).OsmundsonandKaeding(1989a)reportedtheyear-roundmovementandhabitatuseof oneto fourradio-telemeteredadultrazorbacksuckersovera3-yearperiodin theGrandValley regionof the upperColoradoRiver. They reportedthatpools andslow eddyhabitatswerepredominantlyusedfrom NovemberthroughApril, runs aridpools from Julythrough October, runs andbackwatersduring May, and backwatersandflooded gravel pits during June.Selectionof habitats of various depthschangedseasonally:useof relativelyshallow wateroccurred duringspringanduseof deepwaterduring winter.Meandepthswere0.9 to 0.99m (3.0—3.3ft.) duringMay andJune,1.62to 1.65 rn(5.3—5.4ft.) from August throughSeptember,and1.83 to 2.18 m (6.0—7.1 ft.)from NovemberthroughApril.

The razorbacksuckerwasproposedfor listing asa threatenedspeciesonApril 24, 1978,in theFederalRegister(43FR 17375).Theproposalwaswithdrawnon May 27, 1980, in accordancewithprovisionsof the1978amendmentstothe EndangeredSpeciesAct (Act) of1978, asamended(18U.S.C. 1531etseq.).TheseprovisionsrequiredtheServiceto include critical habitat in thelisting of mostspeciesandto complete

54960 Federa’ Register / VoL 56, No. 205 / Wednesday.October 23, 1991 / Rules and Regulations

thelistingprocesswithin 2 yearsorwithdraw theproposalfrom furtherconsideration.TheServicedidnotcr’mplete thelisting processwithin 2years.

A petitiondatedMarch14. 1989, wasreceivedfrom theSierraClub, NationalAudubonSociety,The WildernessSociety,ColoradoEnvironmentalCoalition.SouthernUtahWildernessAlliance,andNorthwestRiversAllianceon March15. 1989. ThepetitionrequestedtheServiceto list therazorbacksuckerasanendangeredspecies.A positivefmding on thispetitionwasmadein June1989 andsubsequentlypublishedby theServicein theFederalRegisteron August 15,1989 (54 FR 33586).This noticealsostatedthat astatusreviewwasinprogressand that the Servicewasseekinginformationuntil December15,1989.A proposedrule to list therazorbacksuckerasendangeredwaspublishedin the FederalRegisteronMay 22, 1990 (55 FR 21154).A publichearingwasheld on August14, 1990, inFarmington,NewMexico.

Summaryof CommentsandRecommendations

In the May 22, 1990. proposedrule (55FR 21154) and associatednotifications,all interestedpartieswererequestedtosubmitfactualreportsor informationthat might contributeto thedevelopmentof a final rule. Theinitial commentperiodclosedon July 23, 1990, but wasreopenedon July 27 andclosedonAugust27, 1990(55 FR 30727).Appropriate Stateagencies,countygovernznentg,FederalAgencies,scientificorganizations,and otherinterestedpartieswere contactedandrequestedto comment.Newspapernoticesinviting generalpublic commentwerepublishedin the following papersbetweenJune7 andJune14, 1990DenverPost.Colorado;RockyMountainNews,Colorado;DailySentinel,Colorado: DurangoHerald,Colorado:NorthwestColoradoDailyPress,Colorado; Times Independent.Utah;VernalExpress,Utah;SumAdvocate,Utah;Salt Lake City Tribune.Utah;DeseretNews,Utah; SouthernUtahNews,Utah.,OgdenStandardExaminer,Utah;andCasperStarTribune.Wyoming. Newspapernoticeswerepublishedon June21, 1990,in thefollowing papers:MohaveMiner,Arizona;Mohave Valley News.Arizona;andFarmingtonTimes,NewMexico.Sixty-two written andeighteenoralcommentswerereceived(includingduplicates from severalcommenters]andarediscussedbelow.Comments(sometimesseveralfrom anorganization) were receivedfrom ii

Federaland 7 Stateagencies,10 localgovernments,and47 privateorganizations,companies,andindividuals.Forty-onecommentssupportedlisting, twenty-fourcommentswereneutraLand ninecommentswereopposedto Listing.

A public hearingwasrequestedandheldin Farmington,NewMexico,onAugust14, 1990.Approximately60peopleattendedthepublic hearingand18peoplepresentedoralstatements.

It should be notedthat manycommentorssurfacedissuesorquestionsthatconcernedthe razorbacksuckerbut that were not pertinent to thetwo decisionsthatarethe subjectof thisrulemaking,I.e.,whetherthe razorbacksuckermeritslisting andwhethercritical habitat should be designated.Predominant amongtheseconcernswasthe potential impact of the proposedAnimas-LaPlataProjecton the Ani~nasRiver and the razorback sucker, andthepotential impact of listing and/or criticalhabitat designation on the proposedAninias-LaPlataProjectand futurewater development.Copies of theseletterswere referredto the appropriateServiceoffices. Othercommentorsraisedquestionsregardingthespecificsof how thespecieswould be protectedor reccveredand theimpacts likely toensue,for exampTe,the impactofspecieslistingon agriculturalpractices.operationof federallycontrolleddams,recreationalopportunities, and otherhuman activities; whetherstockingofnonnativefisheswould be impactedbylisting theextentof the species’rangethatwould be protected;the degreeofState.Federalpartnershipin species’protection; the needfor additionalresearchon the species;theuseofhatcheriesto recover thespecies;andhow critical habitat designationmightrestrictcurrentwater-relatedmanagementpractices.

Though suchconcernsareunderstandable,theyonly canbeaddressedafter thespeciesis listed. TheAct’s amendmentsof 1982madeit clearthatdecisionsto list a speciesmustbemadesolelyonbiologicalconsiderations.and that economicorother nonbiological factorswerenot tobe takenunderconsiderationIn thedecisionof whether to list. However.economicconsiderationsarerelevantifcriticalhabitat Is designated.Specificson how the specieswould be protectedand the impactsof suchprotectionaremoreproperlyaddressedon a case-by-casebaais after the speciesis listed. i.e..duringthe courseof Section7consultationandas specificrecoveryactionsare proposed.

Written andoral commentspertinentto this rulemakingthat wçre receivedduringthecommentperiods arecoveredin the following summary. Commentsofa similarnatureorpoint aregroupedinto anumberof generalissues.Theseissuesandthe Service’sresponsetoeacharediscussedbelow.

Issue1: All coinmentorswhosupportedlisting therazorbacksuckersupportedlisting it asendangered,excepttwo Regionsof the BureauofReclamationandthe Stateof Nevada.TheBureauof Reclamationrecommendedlisting therazorbacksuckeras threatencdthroughoutitsrange.The Stateof Nevadarecommendedthreatenedstatusin thelower basin andendangeredstatus inthe upper basin.The BureauofReclamationstatedthat listing therazorbacksuckerasendangeredcouldjeopardizeordelaypositive programsinitiated in the upper and lower basins.Theystate that listing thespeciesasthreatenedwould allow more activemanagementof thespecies.

Response:According to sectioa~3 ofthe Act, a threatenedspeciesis definedasanyspecieswhich is Likely to becomeanendangeredspecieswithin theforeseeablefuturethroughoutall ó~rasignificantportion of its range.Anendangeredspeciesis definedas anyspecieswhich is in dangerof extinctionthroughoutall or a significantportion ofits range.After reviewingthe biologicaldata,theServicefinds that therazorback suckeris dearly in dangerofextinctionthroughoutall ofits range.dueto its greatlyreducedrange,theextensivealterationof its naturalhabitats throughimpoundmentandalteredflow and temperatureregimes.its apparent Inability to recruitsuccessfullyin thewild, andtheintroduction of noanativefish species.Therefore the razorback sucker qualifiesas endangered.

Issue2: Oneindividual representingwaterdevelopmentinterestsstatedthatthe razorback suckershouldnot belisted asthreatenedor endangeredintheUpperC~,loradoRiverBasinbecausehe believestherazorbacksuckersin theupperbasinareadistinctsubpopulation.and that nodata areavailable to indicate theupper basinpopulation hasexperienceda seriousdecline.This Individualalsostatesthatthe RecoveryImplementationProgramfor EndangeredFishSpeciesIn theUpper Colorado RiverBasIn(RecoveryImplementationProgram)is adequatefor recoveryofthe razorbacksuckeraridListing would not provideany additionalbenefits.

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Response:The Servicehasdeterminedthat the razorbacksuckeris in dangerofextinction throughoutall of its range,whichincludestheupperandlowerbasins.This rule presentsinformationon the rarity of andthreatsto razorbacksuckersin theupperbasin(seeFactorsA. C. andE, and‘Background”).FactorD and“Available ConservationMeasures”discussthecapabilitiesandlimitationsof theRecoveryImplementationProgramin protectingtherazorbacksuckerandthe additionalbenefitsprovidedby listing the species.

Issue3: Fourteencommentorsexpressedconcernaboutcritical habitatdesignation.Tencommentorssupporteddesignationof critical habitat;fourcommentorsopposeddesignatingcritical habitator including areaswithincritical habitat that might adverselyimpacttheir economicinterests.Amongthecommentorssupportingcriticalhabitatdesignation.the followingreasonsor concernsweresurfaced:

a. Five commentorsbelievedcriticalhabitatwascapableof beingdeterminedand/orwould providehabitatprotectionbenefitsto thespecies.

b. Two commentorsthoughtit wouldlimit theareathatwould needto beevaluatedin determiningimpactsto thespecies.

c. Two commentorsthoughtit wouldhelpin protectingagainstfurtherintroductionof nonnativefishes.

d. Onecommentorthoughtconservationmeasurescouldnot beimplementedwithout suchdesignation.

e. Onecommentorquestionedwhetherdesignationof critical habitatwould precluderestorationefforts.

Response:Thereappearsto besomemisunderstandingregardingwhatdesignationof critical habitatmeans,andwhatbenefitsdesignationof criticalhabitatmight provide for therazorbacksucker.

Under section 3 of the Act, criticalhabitat is definedas “(I) the specificareas within the geographicalareaoccupiedby thespeciesat the time it islisfed * * ~, on which arefoundthosephysicalor biological features(I)essentialto theconservationof thespeciesand(II) whichmay requirespecialmanagementconsiderationsorprotection; and (ii) specificareasoutsidethegeographicalareaoccupiedby thespeciesat the time it is listed * , upona determination by the Secretarythatsuchareasareessentialfor theconservationof the species.”“Designation”meansidentificationofcritical habitatvia rulemaking.Economicand any other relevantimpactsmust be taken intoconsiderationprior to designationof

critical habitat.After critical habitathasbeendesignated,FederalAgenciesmustinsurethat their actionsarenot likely toresultin thedestructionor theadversemodificationof this habitat,persection7(a)(2)of theAct.

Critical habitat is not alwaysdesignatedfor a listedspecies.It is notdesignatedat the time of specieslistingif it is not determinable(i.e., if thebiological needsof thespeciesarenotwell knownenoughto permitidentificationof criticalhabitator ifsufficientinformationis not availabletoperformthe requiredimpactanalysis).Itis not designatedif it is not prudent(i.e.,if designationwouldincreasethe threatof takingorvandalismor it would not bebeneficial to thespecies).The “CriticalHabitat” sectionof this rulemakingexplainswhy critical habitatdesignationis considerednotdeterminablefor the razorbacksuckeratthis time.

With regardto thereasonsorconcernssurfacedby commenterssupportingcritical habitatdesignation:

(a)Becauseit is determinableand/orwouldprovidehabitatprotectionbenefits:The Servicedoes not findcritical habitatto bedeterminableatthis time for thereasonsexplainedinthe“Critical Habitat” sectionof thisrulemaking.TheServicewill reviewexistingdata~andtheprotectionsprovidedby listing thespecies,theRecoveryImplementation Program,andother activities to determinewhetherdetermination and designation of criticalhabitat would provide habitat benefitsover and aboveth~protection providedto the razorback sucker followingspecieslisting.

(b) Becauseit wouldlimit theareaofevaluation:Designationof criticalhabitat highlights specific areaswherespecialmanagementconsiderationsorprotectionsare needed;however, it doesnot limit the area of evaluation fordetermining impacts to a listedspecies.Once a speciesis listed, It is protectedthroughout its range. Evenif criticalhabitat wasdesignatedsuchthat it wascoincidentwith the razorback sucker’scurrent range. proposedFederal actionsthat would alter flows or water qualityupstream of this habitat would still needto be evaluated.

(c) Becauseit wouldprotectagainstfurther introductionofnonnativefishes:At this time, it is not clear whetherdesignationof critical habitat woulddeter future stocking of nonnative fishesbeyond anydeterrent resultingby listingthe speciesas endangered.This pointwill be examinedduring the reviewofdata and existing protectionsfollowingspecieslisting. As noted under Factor D.the Servicecan limit the introduction of

nonnativespeciesthroughagreementswith the Statesor by withholdingFederalfunds_orfish from Federalhatcheriesfor stockingproposalswithpotentialto adverselyimpacttherazorbacksucker.

(d) Becauseconservationmeasurescouldnot beimplemented:It is notnecessaryto designatecritical habitat inorderto implementconservationmeasures.Conservationmeasures.which areusedto avoidjeopardytolistedspecies.arecurrently providedinbiological opinionsfor threespeciesofendangeredfish in theColoradoRiverbasinwhichdo not havecritical habitatdesignated.

(e) Whetherit wouldprecluderestorationefforts within existinghabitat: If critical habitatwere to bedesignated,only federallyauthorized,permitted,or fundedrestorationeffortsthatwoulddestroyor adverselymodifycritical habitat would be precluded.Becausethe purpose of any restorationeffort would be to benefit the speciesand/orhabitat,it is unlikely thatdesignationof critical habitat wouldpreclude restoration efforts.

Issue4: One county in Utah statedthat the introduction of the river otterinto the Colorado River could.beathreat to razorback suckers.

Response:The river otter’s historicrange included the Colorado River andits tributaries in Utah and Colorado.Riverotters and native fishescoexistedhistorically. The Utah Division ofWildlife Resourcesrecently prepared anenvironmental assessmentthatexaminedpotential conflicts betweenthe reintroductionof the river otterandthe rareandendangeredfishesin theColoradoRiversystem.It concludedthat reintroducingtheriver otterwouldnot haveasignificantimpacton rareandendangeredfish species.Dietstudiesconductedin Coloradofoundthat crayfishandchannelcatfishcompriseda majorportion of theriverotter’sdiet. If anegativeimpacton rareandendangeredfishesis detected,riverotternumberscouldbecontrolled.

lssue5: The DenverWaterDepartmentstatedthat theTwo Forksproject underwent section7 consultationandwasfoundnot to bea threattorazorback suckers.

Response:Thesection7 consultationconductedfor theTwo Forks projectwasfor three Colorado River fishescurrentlylistedasendangered:TheColoradosquawfish;humpbackchub:andbonytail chub.The razorbacksucker was a candidate for Federallisting at the time of the subject section7 consultation. Candidate speciesreceiveno legalprotectionunderthe

si~ FederalRajlser / VoL 56, No. 205 / Wednesday,October 23, 1991 I Rules and Regulations

Act, andthe razorbacksuckerwasnotaddressedin the biological opinionissuedfor the Two Forks project.Therefore,theServicehasnotdeterminedwhether the Two Forksprojectis likely to jeopardizethecontinuedexistenceof therazorbacksucker.

Issue6: Onefarmbureauaskedthatadverseimpactsto privatepropertyownersbe consideredduring the listingprocess.

Response:Only biological factors maybeusedin our decisionon whether tolist a species.

Issue7: Severalcomrnentorsaskedwhether the razorback suckersstockedin thelower basinduringthelast10yearswouldbeconsideredendangeredif thespecieswere listed.Also, oneFederalAgencyrecommendedthat therazorbacksuckersstockedin the Gila.Salt, and Verde Rivers be designatedasan experimental population.

Response:All razorbacksuckers,regardlessof their origin or wheretheyoccur,would befully protectedunderthe Act upon listing. The Servicecannotdesignatean existing naturally.occurring population as experimental.Oncethe razorbacksuckeris listed,anyfuturereintroductionor augmentationwould requireapermit,or a rulecoulddesignatethestockedfish as anexperimentalpopulationif thefuturereintroductionsiteis unoccupiedhabitatwithin historic range.

Summaryof FactorsAffecling theSpecies

After athoroughreviewandconsiderationof all informationavailable, the Servicehas determinedthat the razorbacksuckershouldbeclassified as an endangeredspecies.Proceduresfound at section4(a)(1)ofthe Act and regulations(50CFRpart424)promulgatedto implementthelisting-provisionsof theAct werefollowed. A speciesmaybedeterminedto be anendangeredorthreatenedspeciesdueto one or moreof thefivefactorsdescribedin sectimi4(a$1).Thesefactorsandtheirapphnatlontothe razorback sucker (Xyranch~ntexanus)areasfollows:

A. ThePresentor ThreatenedDestruction,Modification,orCurtailwentof It~Habitat or Range

OnceabundantandwidelydistributedthroughouttheColoradoRiverbasin,the razorbacksuckernowinhabitsapproximately25 percentof itsoriginalrange.Therazorbackisconsideredrare,andof the fourrareandendangeredlarge-rivernativeColoradoRiverbasinfishes,only the bonytailchub(do elegarm)is consideredless

common(McAda 1987). In the LowerColoradoRiverBasin, the razorbacksuckeroccursin substantialnumbersonly in Lake Mohave,in Arizona andNevada.Thesefish arethoughttorepresentthe largest remainingpopulation in the basin (Minckley 1983)but areexpectedto declinein numbersas they dieand arenot replaced.Razorbacksuckersare very rare andsporadic in the Colorado River,reservoirs,andcanalsdownstreamofDavisDam (Marsh and Minckley 1989).In the UpperColoradoRiverBasin,razorbacksuckersarerarein the upperGreenRiver, Utah;lower Yampa River,Colorado(Tyus1987a,Tyus andKarp1990); andmainstemColoradoRivernearGrandJunction,Colorado(KaedingandOsmundson1969).Therazorbacksucker is very rare throughouttheremainingwarmwaterreachesof theGreen.SanJuan,andupperColoradoRivers. Small numbersalso occur in theColorado, Dirty Devil, and SanJuanarmsof Lake Powell (PersonsandBuildey 1962, McAda1987,RobertsandMoretti 1989).

Since1910, 15 damshavebeenconstructedon the lowerColoradoRiverand its major tributaries,theGila.Verde,andSalt Rivers.Thesedamshave dewatered,cooled,or impoundedmostof thelowerbasinsystemso thatlittle naturalriverinehabitatexiststoday. GlenCanyonDamhasreducedwater temperature.for 384km (238mr.)throughtheGrandCanyon.Spawninghas beenobservedin severalreservoirsin thelower basin(JonesandSumner1954,Loadermilk1985)andrazorbacksuckerlarvaehavebeencollectedinLake Mohave, Lake Havasu,SenatorWashReservoir,andtheCentralArizona Projectcanal(Bozeket aL 1984.MarshandLanghorst1988.MarshandMinckley1989).However,only fourjuvenilerazorbacksuckers(33to 54 mm.or1.3 to 2.1 in.) havebeencollectedfrom LakeMokavesincethe1960’s.whith indicat~insufficientrecruitmentto thepopulation(Ifarth andMirw*Ia.y1989).In theupperbasin.Lake PowellandFlamingGorgeReservoirhaveimpounded500km (310mi.) ofrazorbacksuckerhabitatandloweredwater temperaturesin another106km(65ml.) of the Colorado and GreenRivers.Otherupperbasinreservoirsalsohavealterednaturalflow andtemperatureregimes.Thelast reportofjuvenilerazorbacksuckerscoLlectedfromtheu~ ColoradoRiverwasthatof Tabs etaL (1965)who collectedeightindividuals90-fl5mni (3.5-4.5 in.) inlengthdownstreamof Moab,Utah,during1962—1984.

Darns anddiversionsalsoobstructrazorbacksuckermigration.Although

little is knownof the locationofrazorbacksuckerspawningareaspriorto the constructionof thesefacilities, itis believedthatthey haveobstructedaccessto or impoundedonceimportar.fspawningareas.Early investigatorsfrequently referred to spawningconcentrationsin small tributariesin thelower basin(Jordan1891,HubbaandMiller 1953).More recently,Tyus (1987a)and Tyus and Karp (1990)observedconcentrationsof razorbacknx±ersnearthreesuspectedspawningareasintheupperGreenRiver andlower YampaRiver. Uliner (1980)alsoobservedspawningin Senator Wash Reservoirand Mueller (1989)did so in thetailwaters of HooverDam.Spawninghas beenobservedin Lake Mesd andLake Mohave (Jonesand Sumner1954.Minckley 1983, LanghorstandMarsh1988).Radio-trackingandrecaptureoftaggedrazorbacksuckersdemonstratesthat somefish migrateconsiderabledistancesto SpaWn.Tyue (1987a)recaptured21 adult razorbacksuckersinsuspectedspawningareasthathadbeenpreviously taggedin otherlocations,overa period of 8 years.Ulmer(1980),utilizing SCUBAgearandsonic tags.followed five adult razorbacksuckersinSenatorWashReservoirto two specificareas where congregationsof spawningrazorback suckerswere observed.

Storageanddiversionof naturalflowshave resulted in an 18 percent reductionin meanannualdischargeat theGreenandColorado riverconfluence26 km (16ml.) upstreamofLake Powell(U.S.GeologicalSurvey(USGS)flow records,1906-1982).Storageof high flows duringthespringandreleasesof morewaterduring the remainderof theyearhavereducedspring runoffby 28 percentinthe GreenRiverand37 percentin theColoradoRiverduringMay andJune(USGSflow records,1906-1982).Reductionof thesehigh springflows hasalteredthenaturalfloodingcycleandreducedtheareaof off-streamhabitatsusedby razorbacksuckers(McAda1977, OsmundsonandKaedlngtool).Tyus andKarp(1989)believedthatflooding of bottomlandduringspringrunoff wasimportantto adultsandrearingof young.OnmundsonandKaeding(1991)suggestedthat floodedbottomlandsin theGrandValley werehistorically theprimaryspawninghabitats.Thelack ofrecruitment ofrazorbacksuckersin theupper basinmay be associatedwith lossesof theseinundatedhabitats(OsmundsonandKaeding1989aand1090.TynsandKarp1989). -

Dam operationsalsocancausechangesin daily flow regimes.Peakingpoweroperationsat FlamingGorge

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produceda400percentincreasein dailyflow fluctuationsat Jensen.Utah (USGSflow records,1906—1982J.Tyus and Karp(lg8gJrecommendlow. stableflows forrazorback suckersduringsummer,fall,and winter, after finding that suchflowsare necessaryfor growth and survivalofyoungnative fishes.Stable flowsthroughice breakupalsowereimportantfor overwintersurvivalof youngandadultnativefishes.

Cooler water temperatures.as a resultof dam operations, may have excludedtherazorbacksuckerfrom portions of itsoriginal range(Vanicek 1967).Bulkleyand Pimentel (19831 showedthat adultrazorback suckerspreferredwatertemperaturesbetween22.—25’C (71.8-.77’F) andavoidedwatertemperaturesbelow14.7C(58.5’F) andabove27.4’C(81.3W).Whereaswintertemperaturesdrop well belowthis reportedpreferencerangethroughout most of occupiedrazorback sucker habitat. summertemperaturesaregenerally within thepreferred range. During the day, riverinetemperaturescanvarygreatlybetweenoff-streamandmainstreamhabitats.Grabowski and Hlebert(1989)recordedsummerand fall water temperaturesinbackwatersof the GreenRiver to be 2.5to 3.~C(4.5 to 6.811warmer than themainstream. While water temperatureisdynamic and influencedby manyvariables,therearetwo reachesof theGreenandColoradoRiverswherespringandsurnxner temperatures areclearly belowthe preferredrange ofrazorback sucker.Thesereachesoccurdirectly belowFlamingGorgeReservoirfor 105 km (65ml.)wheresummertemperaturesaveragelessthan 15’C(59W)(USGSWater ResourceData),andbelowLake Powell for 384 km (238an.)wheresummerwater temperaturesrarelyexceed15C(59fl (CarothersandMinckley 1981). Razorbacksuckershaverarelybean capturedin thesereachessincecompletion of thesedams(Vanicek1967. Carothers and Minckley1981).

The alteration of temperaturescausedby theconstructionandoperationofdamsalsomay affect incubationtimeandsurvivalof razorbacksuckerembryos.Incubationtime to hatchingvariesinverselywith water temperature.with longerhatchingtimesrequiredatlower temperatures.Gustafson(1975)reported that55 dayswere requiredat20C (08F1.while Bozeket at. (1984)reportedthe following incubationperiods:19.4daysat b.C (50’F!; 11.1days at 15C (597J~and 6.8 daysat 20C(88W).Marsh (1985)found it required 9Jaysfor larvaeto hatchat 15’C (59W).ind 3.5 daysat25C (77F).Mostinvestigatorsreportedpoorhatching

successat temperaturesbelowI5’C(59’?)andtotal mortality of eggsbelow1O’C (50’?). However,Bozekci al. (1984)notedonly slightly lower survivalratesat io’C (50’?)thanat 15 and213’C (59and68’?).

Alterationof razorbacksuckerhabitatwill likely continuebecauseseveralmajorreservoirsandwater diversionsarein theplanningprocessor areunderconstruction (e.g..Anirnas-LaPlataProject,Muddy CreekReservoir.SandstoneReservoir,CentralUtahProject).Furtherlossof floodedbottomland habitat importantforspawningis likely to occuraslandownerscontinuedikin~theColorado River.particularlyin theGrand Valley. Other,lessdirectinfluencessuchasdecreasedflow.alteration in streamhydrology.increaseddissolvedsolids,alteredtemperatures,andotherwater qualitychangesmayadverselyaffect therazorbacksuckerby reducingordegradingits habitat,interruptingspawning,andincreasingcompetitionfor food andspaceby creatingconditionafavorableto nonnativefishspecies.Developmentactivitiesthatmost threatentherazorbacksuckeroccurin theupperbasinwheremost oftheremainingriverinehabitatsoccur.Since1980,theServicehasconductedconsultations,.ndersection7 of theActonover100federallyfundedorregulatedprojectsin theupperbasinthat involvedwaterdepletions.Severaltransbasindiversionsareplannedor areunderconstruction.Themostprominentis theCentralUtahProjectwhichwoulddivert166,000so. ft. of waterfrom theGreenRiverto the BonnevilleBasin.

B. Overutilizotionfor Convrrercial,Recreotloiwil,Scientific,orEthzcationaiPurposes

Thoughonceextensivelyusedforfood when availablein largenumber(Minckley 1973).the razorback

8~rL~~r~

no longerabundantandmarketsarenolongerengagedin suchenterprises.Inthe lowerbasin,therewereonceenoughrazorbacksuckersto supportacommercialfishery(HubbaandMiller1953)butail Stateswithin itscurrentrangenow have1awsthat protectit fromharvest(Mlnckley at al. in press).Therefore,overutilizatkmis notconsideredto be a threattoday.

C. Diseaseor Predation

There is onevidencethatdiseaseis asignificantfactorin thecurrentstatusofthe razorbacksucker.However.Minckley (19831reportedmanyoldindividualscapturedin LakeMohavowereblind in oneor botheyesandshowedothersignsofdiseaseor injury.

Several investigatorshaverecentlyisolatedpethogensfromrazorbacksuckers,but re haveconcludedthatthey wereaseriousthreatto theexistingstocks(MpoameandRinne1983,Flagg1982).

Severalresearchershaveobservedpredationof razorbacksuckereggsandlarvaeby carp.channelcatfish,smallmouth bass(Micropterusdolomieui).largemouthbase.bluegill.greensunfish,andradeersunfish(Lepomismicroiophus)(JonesandSumner1954,Ulmer1960,Langhorst1989, Marsh andLaughorat1988).Otherresearchershypothesizedthatpredationis amajorcauseunderlyingtheLackofrecruitmentto theadultrazorbacksucker populationthroughoutthe basin(McAda andWydoski1960,Mlnckley1983, Tyns1987a).Loudennilk(1985)observedthatyoungrazorbacksuckerLarvaeinhabitedtheupperwatercolumnfor the first fewdaysafterswim-up andexhibitednodefensivebehaviorfrompotentialpredators.MarshandLanghorst(1988)foundlarval razorbacksuckersin LakeMohavesurvivedlongerand grewlargerin theabseiu*bfpredators.MarshandBrooks11989)demonstratedthatchannelcatfishandflatheadcatfishweremajorprpdatorsofrazorback suckersstockedinto theCilaRiver. Theyconcludedthatpredationbythesefish hadpotentialto resultin totallossof thosestocks.Laughorst (b989)reported channelcatfish andlargemouthbasspredation on juvenile razorbacksuckersaveraging171mm (6.7in.) totallengthstockedin isolatedcovesalongthe ColoradoRiverin Califosnia.Twoadditional predaceousspecies,thewalleye (SIth,stedioirvitrenm)andnorthern pike (E.aaxhscñzs)haverecentlybecomeprominentinhabitantsof theGreenRiver(TyusandBeard1990).

Thoughnmmatlvefish specieswereand are introducedby man,theabilityof thesenormativefish to survive andbecomeestablishedhi theColoradoRiverbasinis, in part.doeto thealteration of naturalrjwcrw habitatdescribedunder Factor A. Alterationofhistoric flow regimesandconstructionof reservetrshaserestedfavorableconditions for some~inatlve flakes(Seethaler197$,McAdaandKeeding1989, Minekley 1963).Thusthe threatofpredationis. to someextent,associatedwith habitat modification.

D. TheInadequacyofF.zfstingRegulatoryMechanisms

AsdiscussedIn FactorsA andC. therazorbacksuckerhasdeclinedsubstantiallyin thepast60 yearsbecaua. of major alterationsin its

54964 Federal Register I Vol. 56, No. 205 / Wednesday,October 23, 1991 I Rules and Regulations

habitat,dissectionof theriver systemwith dams,andthe introductionof manynew speciesto the ecosystem.Althoughthe razorback sucker has beenincludedon the protectedlist of all ColoradobasinStates,exceptWyoming (wheretheyareextirpated)andNewMexico(though evidencesuggeststhe specieswasprobablyhistoricallynativeto theState, no specimen-substantiatedrecordsof razorbacksuckerexist inNewMexico) (Minckley et ci. in press).it hascontinuedto decline. It ispresently oneof the most endangeredfishesin theColoradoRiverbasin(Minckley1983, Tyus 1987a).

Most State regulations protect therazorbacksuckerfrom takeandpossession.They do not, however,addressthemajorproblemsof habitatdestruction or the introduction ofcompetitiveandpredaceousspecies.AllStatesprohibit transportation andstocking of any fish specieswithoutprior consentof the respectiveStateagencies.Stateagenciesdo, however,introducenewspecieswhich maycompetewith or prey upon theendangeredColorado River fishes.TheServicehas an Informal agreementwiththeStateof Coloradoto review allstockingproposalsin the Colorado Riverwithin Colorado. The Serviceisattemptingto developa similararrangementwith theStateof Utah.However,Serviceagreementswith otherStateswith habitats occupiedbyrazorback sucker have not beenformulated.The Servicecan, to someextent, influenceStatestocking actionsby withholdingFederal fundsor fishfrom Federal hatcheriesfor stockingproposalswith potential to adverselyimpacttherazorbacksucker.

Statewaterquality andstreamfiowregulationsdo not assignstringentcriteria to waters inhabited by therazorback sucker. Regulations permitdesiltingand coolingbecausesuchwaterquality changesare generallydeemedbeneficial. However, therazorback sucker and other native fishspeciesare adapted to the ColoradoRiver’s highly turbid, turbulent,andwarm conditions.Most Federalregulations also considerwaterclarity,low temperatures. and “purity”desirable waterquality standards, andtheyassigncriteria that enhanceorpreservetheseconditionseven thoughthey may not provide thebestconditionsfor native ecosystems.Waterdischargesassociatedwithdevelopment,such as oil and gas.maynot haveadequateregulationsto assurethat water quality standardsaremet.

The presenceof any oneor all of theother listed Colorado River fishesin the

samereachesas the razorback suckerdoes not necessarilylend adequateprotectibnto the razorbacksuckerbecauseits life history and habitatrequirements are different than thoseoftheotherspecies(TyusandKarp 1989).Although FederalAgenciesaremandatedto consider the other listedfishesrelative to their actions, they werenot mandatedto do so for the razorbacksucker.Therefore, unlessthe razorbacksuckeris listed,FederalAgenciesmaytake actions and implement programswhich avoid jeopardy to otherendangeredfisheswhile adverselyaffecting the razorback sucker.

The RecoveryImplementationProgramhasa goalof managingtherazorback sucker so that it doesnotneed the protection of the EndangeredSpeciesAct. The managementgoaladoptedby theRecoveryImplementation Program for therazorback sucker is to establishandprotectself-sustainingpopulationsandnatural habitat. Substantial funds andresourceshavebeenprovidedby theRecoveryImplementation Program tomeet the goalsfor this and other listedColorado River fishes.Although actionsby theRecoveryImplementationProgramwill providebenefitsto therazorback sucker, theseactions alonedonot provide permanentprotectionbecausetheReco~eryImplementationProgramis not aregulatorymechanism.Instead,it is acooperativeeffort agreedto by public and private entities thathave an interest in how the UpperColorado River Basin and its resourcesaremanaged.The CooperativeAgreement that binds theseparties maybe amended or terminatedby agreementof the parties,or anyparty maywithdraw upon written notice. Section7of the Act requires that all FederalAgenciesinsure that any actionauthorized, funded, or carried out bysuchagencyis not likely to jeopardizethe continued existenceof anythreatenedorendangeredspecies.TheRecoveryImplementationProgramdoesnot have the force and effect of law tomandatethat the effectof any Federalaction on the razorback sucker beconsidered.And finally, the RecoveryImplementation Programonly appliestothe upper basin (excluding the SanJuanRiver). and therefore doesnot protectthe speciesthroughout its range.

E. OtherNaturalor ManmadeFactorsAffectingIts ContinuedExistence

Of great concern is the fact thatsignificant recruitmentof young fish tothesepopulations has not been evidentfor at least30 years,There isconsiderableevidencethat existingpopulations arecomposedprimarily of

old individuals that are slowly dying off(McCarthyandMinckley, 1987,Tyus1987a).Only a fewnaturally reproducedjuvenileshavebeenreportedfrom LakeMohave, the Colorado River, and off-streamcanalsystemsdownstreamofLake Mohave (Marsh and Minckley1989)and from the GreenRiver (Holden1978) in thepast15 years.

The introduction and establishment ofnonnativefish speciesinto theColoradoRiver systemis believed by manyresearchersto have negativelyimpactedthe razorback sucker.Tyus et a!. (1982)recorded 42 speciesthat havebecomeestablishedin the upper Colorado Riverbasin, and Minckley (1979) listed37nonnative speciesin the lower basin.Many of thesemay be innocuousorinhabit areasnot occupiedby razorbacksuckersbut severalareconsideredseriouscompetitors or predators(Minckley 1983,Loudermilk 1985). Inaddition to direct predation (seeFactorC), competition may result in negativeimpacts to the razorback sucker,butimpacts from competition are moredifficult to detect than predationimpacts. Although theseinteracti~sarenot fully understood,normativefishspeciesare hypothesizedto impacttherazorback sucker due to theirconsiderablenumbers, the sharing ofcommonfoods,and occupation of thesamehabitats (Jonezand Sumner 1954).

The threat of competition continuesasnonnative speciescontinue to beintroduced and their rangescontinue toexpand. The triploid grasscarp(Ctenopharyngodonide/la) has beenlegalized’ for importation into Californiaand Arizona. In the lower basin, twotilapia species(Tilapia spp.) havebecomeestablished,and, along with thefiathead catfish,have becomethedominant fish speciesin the lowerColorado River(W.L Minckley. ArizonaState University. pers.comm.1989).Therainbow smelt (Osmerusmordax)recentlyhas beenproposedforintroductioninto Lake Powell(Gustavesonet al. 1990).

MarshandLangborst(1988)studiedfood availability and consumptionbylarval razorbacksuckersin LakeMohaveand found that larval razorbacksuckersconsumeda varietyof thezooplanktersavailablein the area.Papoulias(1986) found, underexperimental conditions, that food itemsneededto bepresentat a densityof 10organismsper liter within 10 daysofabsorption of the yolk sac. Deathoccurred at about 20—30 daysof ageifinsufficientnumbersof zooplanktonwere present.Marsh and Langhorst’s(1988)researchon LakeMohaveshowedanaverageof 1.5 zooplanktersper liter,

FederalRegister1 Vol. 56~.No. 205 / Wednesday,October 23~1991 / Rules aid Regulations 54965

andthey reportedthedisappearanceoflarvaeat about20 daysof age.Papoulias’(1986)resultsindicatelowavailability of foodorganismsmayexplain the absenceof fishesgreaterthan 10.6mm(0.4 iflj4nr LakeMohave.l-Ia’wever.MarshandLanghurst(1988)report thatlow availabthtyof larvalfoodsdoesnot accountfor the apparenttotal mortality of larvaein LakeMohave.

IntercrossingbetweenrazorbacksuckersandfIannelmouthsuckers(Catostoriruslatipinnth)was firstreportedby Hubba andMiller (1953).Vaniceket aL (19;0)andHolden(1973)reportedahigh incidenceofintercrossingbetweenrazorbackandflanrielmotrthsuckersin theupperbasin.Theyfound ratiosof 16 intercrossesto~3razorbacksuckersand40iritercrossesto 53 razorbacksucker,,respectively.McAdaandWydaski(1980} reported8razorbacksuckerxflannelmouthsticker intercrossescollectedwith 95 razorbacksuckersintheupperbasin.All of the abovereportsof intercrossingwerebasedonanexaminationof morphologicalcharacteristics.Thereportsofintercrossingare suggestive,but notconclusive,evidencethat intercrossingmay beathreatto thespecies~Therefore,until additionalscientificdataaregathered.it is prematuretoconcludethat intercrossingi asignificant threatto thespecies.Recentelectrophoretinanalysesof LakeMohave razorbacksuckersrevealedlessthana5percentincidenceoffiannelmouthsuckergenes~andBulb etal. (19871consideredthis level ofintrogressionto be insignificant.

A pre-impoundmentpoisoningprojectin theGreenRiverwhereFlamingGxgeReservoiris now locatedis oftencitedas at leastapartial causefor theLossofnativefishesimmediatelydownstreamof thereservoinWhilemanyrazorbacksuckerawereundoubtedlylost,acomparisonof fish speciescompositionin Dinosaur~ational Monumentbeforeandafter theprogram~nns et al.19~l.VanicekandKramer1990,Vanicaket sI.1970)supportsthepressuethattheeffectof thepoisoningwasshort termandnot responsiblefor thecurrentstatusof the razorback sucker.A similarpre-impoundmentstudyandtreatmentprogramwasconductedon theSanjuanRiverin NewMexicowhereNavajoReservoiris located.No razorbacksuckerswerecotiectedbeforeor alterthetreatmentprogramIPtatania1990).

TheServicehascarefullyassessedthebestscientificandcomzosrcialinformationavailableregardingthepast.present,andfuturethreatsfacedby the

razorbacksackerin determiningtomake thi, rule final. Basedon thisevaluation,thepreferredactionis to listtherazorbacksuckerasendangered.Endangeredstatus,whichmeansthatthespeciesis in dangerof extinctionthroughoutall ora significantportion ofits range,is sppvc,piiatefor therazorbacksudierbecauseof its greatlyreducedrange.theextensivepartitioningof its rangeby dams,theextensivealterationof its naturalhabitatsthroegnimpoundmentandaltered flow and temperatureregimes.itsapparentinability to recruitsuccessfullyin thewild, andtheintroductionof nonnatire fish species.Adecisionto takenoactionwouldconstitutefailure to properly classify therazorbacksuckerpursuantto the Actandwouldexcludetherazorbacksuckerfrom protectionprovidedby theAct. Adecisionto determinethreatenedstatus,whichmeansthespeciesis likely tobecomeendangeredwithin theforeseeablefuture,would notadequatelyreflect the statusof therazorback sucker.Thesmallnumberofold fish thatcurrentlyrepresentthevirtually rionrecruitingpopulationindicate the razorback suckeris indanger of extinction throughoutitsrangeCritical habitat is not beingproposedfor thereasonsstated below.

Critical Habitat

Section4~aX3jof the Act, asamended,requiresthat,to the maximimi extentprudentanddeterminable,theSecretarydesignatecritical habitatat thetime thespeciesis determinedto be endangeredor threatened.In theproposedrule, theServiceindicatedthat thedesignationofcritical habitatwagnot determinableorprudentat that time for therazorbacksucker.Howe~’ei’,severalconimeatersrespondingto theproposedrulerecommendedthatcritical habitatbedesignated.Anotherdevelopmentsios~uthe proposedrulewaspublishedwasacourtdecismn(~JartMrnSpottedOwl v.Lujan) regardingthedes~nationofcritical habitatfor thespottedowLThatdecisionhascausedtheServicetoscruisnizeitscritical habitatfindingsmoreclosely.TheServicefindsthatcriticalhalitat for therazorback suckeris notpresentlydeterminable..TheServicewill reexa~impthequestionofwhethercriticalhabitatdesignationisprudentduringtheperiodthattheServiceis attemptingto determinecritical habitat

Critical habitatis definedin section3(5~A)of theAct asthespecificareagwithin thegeographicalareacurrentlyoccupiedby aspecieson whicharefound thosephysical or biologicalfeaturesessentialto theconservationof

thespeciesandthatmayrequirespecialmanagementconsiderationsorprotection.Provisionsalsoare includedfor designatingcritical habitat outsideareascurrentlyoccupied.Designationsof critical habitat must bebasedon thebestscientificdata availableandmusttakeinto considerationtheeconomicand other relevant impactsof specifyinganyparticularareaas critical habitat(Section4(bl(2J).

The Service’sregulations(5C1 CFR424.12(aytZfl state that critical habitat isnot determinable if mformationsufficientto performrequiredanai~seaof theimpactsof the designationislackingor if the biological needsof thespeciesarenot sufficiently well knownto permit identificationof anareaascriticalhabitat.Thoughit is likely thatthere are areasveryimportant to therazorback sucker,we are unabletoadequately determineat this time thepreciseconstituentelementswithinspecificareasthat areessentialto itssurvivalandrecovery.Asnotedearlier.thereis limited informationon thespecifichabitat needsof’ the razprbacksucker.Though habitat occupiedby therazorbacksuckerhasbeenideatifiedandspawninghasbeendocumentedinseveralareas,it is questionableastowhethertheseareasareadequatelymeetingthe life history needsof therazorbadcif therehasbeenlittle ornorecruitment.Therazorbacksuckercarmmperpetuateitself in the wild ifthereis little or no recruitmentto theadult population.It would not be in thebestinterestof thespeciestoidentify oruse the characteristicsof existinghabitats as the basisfor critical habitatwhen we are unableto’ identify thosespecificareasandprecisehabitatcharacteristicsneededto bring aboutrecruitment.Hence,theServicefindsthat criticalhabitat isnot determinableat this time.

Section4(b)(~)~C)further indicatesthat a concurrentcritical habitatdeterminationis not required,andthatthefinal decisionondesignationmaybepostponedfor I addItionalyearfrom thedate of publicationof theproposedrole.if theServicefindsthatapromptdetermination of endangeredorthreatenedstatusI, essentialto theconservationof the speciesinvolved.The Serviceconsider,thata premp’tdeterminationof endangeredstatusforthe razorbacksuckerisessential.As aproposedspecies,therazorbacksuckerwould be eligible only for thelimitedconsiderationgivenundertheconferencerequirementof section7(a)(4)oftheAct asamended.Thisdoesnot requirealimitation ontheconimitinentof resourceson the part .1

54966 Federal Register I Vol. 56, No. 205 I Wednesday,October2~,1991 / Rules and Regulations

concernedFederal Agenciesorapplicantsfor Federalpermits.Therefore,to ensurethat the fullbenefitsof Section7 andotherconservationmeasuresundertheActwill applyto therazorback,-s~,tcker,prompt determinationof endangeredstatus is essential.

Pursuant to section4(b)(6)(C)(ii) of theAct, asamended,it critical habitat is notdeterminableat thetime of listing,within 2 yearsof the proposedrule theSecretarymust designatecritical habitatto themaximumextentprudenton thebasisof whateverdataareavailableatthat time. Thatdeterminationwill bedue for the razorback sucker on May 22,1992.

Available Conservation MeasuresConservationmeasuresprovided to

specieslistedasendangeredorthreatenedunder the Act includerecognition,recoveryactions,requirements for Federal protection, andprohibitions againstcertain practices.Recognition throughlisting encouragesandresultsin conservationactionsbyFederal, State, and private agencies,groups,and individuals. The Actprovides for possibleland acquisitionand cooperationwith the Statesandrequires that recovery actions be carriedout for all listedspecies.Theprotectionrequiredof FederalAgenciesandtheprohibitions againsttaking and harm arediscussed,in part, below.

Section7(a)of the Act, as amended,requires Federal Agenciesto evaluatetheir actionswith respectto anyspeciesthat is proposedor listed as endangeredor threatened and with respect to itscritical habitat, if any is beingdesignated.Regulationsimplementingthis interagencycooperationprovisionof theAct arecodifiedat 50 CFR part402. Section7(a)(2) requires FederalAgenciesto insurethat activities theyauthorize,fund, or carryout arenotlikely to jeopardizethecontinuedexistenceof a listed speciesor todestroy or adverselymodify its criticalhabitat. if a Federal actionmay affectalisted speciesor its critical habitat, theresponsibleFederal Agencymust enterinto formal consultation with theService.

The Green and Colorado Rivers havebeen extensivelydevelopedthroughseveralFederal programs for powergeneration, floodcontrol, salinitycontrol, andirrigation.As a result,manyFederalAgenciesareinvolved withactivities which may affect therazorback sucker.Flow conditionsin theGreen and Colorado Riversareinfluenced by powergeneration andflood control at severalBureauofReclamationprojects. Power generated

by the Colorado River StorageProjectreservoirsis marketedby theWesternArea Power Administration, whosemarketing program has considerableinfluenceon dischargesfrom thosereservoirs.OtherBureauof Reclamationprojects involving diversions andstoragefor irrigation or municipalandindustrial usesand salinity control arein various stagesof planning~construction,or operation.The SoilConservationServicehas salinitycontrolprogramswhich affectflows andwaterquality in the Colorado Riversystem.The Corps of Engineerswouldconsider the razorback sucker in theiradministration of Section404of theCleanWater Act, and theEnvironmentalProtectionAgencyalsowouldconsiderthe fish inadministrationof theCleanWaterAct.theNationalEnvironmentalPolicy Act,and other pollution and pesticidecontrolprograms. SeveralFederal land andresourcemanagementagenciesincluding the National Park Service, theU.S.Forest Service,and theBureau ofLandManagement would have toconsider the needsof the razorbacksucker in programs under theirjurisdiction.

The interagencyRecoveryImplementation Programcoordinates therecovery of currently listed species(Colorado squawfish,humpback chub.andbonytail chub)andthe managementof therazorback sucker in the upperbasin, excluding the San Juan River. TheRecoveryImplementation Programconsiders therazorback sucker animperiled speciesthat may requirelisting in the futureunless actions aretaken to reverse its downwardpopulationtrend.Listing the razorbacksucker asendangeredwill give it equalstatuswith the other threelisted speciesin theRecoveryImplementationProgram’s recovery efforts.

Listing the razorback sucker asendangeredwould influencethestockingof normative fish speciesandthe managementof recreationalsportflshingin asimilar mannerastheother threelisted fish speciesin theColorado River basin.If a stockingorsportfishing program involved Federalfunds or permits, or receivedfish fromFederalhatcheries,the action would bereviewed under section7 of the Act. Inaddition, control of normative fishesisan elementof theRecoveryImplementation Program. This programwould confinestocking of nonnativefishesto areaswhere no conflict withendangeredfishescanbe demonstrated.When feasible and effective,normativefisheswould be selectively removedfrom areasconsideredessential torecovery of the listed species.

Participantsin theRecoveryImplementationProgramalsowouldreview State sportflshing practicesandregulationsfor compliancewith Federallaw andimpactson endangeredfishspecies.As noted previously, theServicehasan informalagreementwiththeStateof Coloradoto reviewallstocking proposals, and is seekingasimilar arrangementwith the StateofUtah.

The Act, andits implementingregulationsin 50 CFR 17.21,setforthaseriesof generalprohibitionsandexceptionsthat applyto all endangeredwildlife. Theseprohibitions, in part.makeit illegal for anypersonsubjecttothejurisdiction of the UnitedStatestotake (includes harass, harm, pursue.hunt, shoot,wound,kill, trap,or collect;or attemptanyof these),importorexport, ship in interstatecommerceinthe courseof commercialactivity, or sellor offer for salein interstate or foreigncommerceany listed species.It also isillegal to possess,sell,deliver, carry,transport,or ship anysuchwildlife thathas beentaken illegally. Certainexceptionsapply to agentsof the.~tService and Stateconservationagencies.

Permits may be issuedto carryautotherwiseprohibited activities involvingendangeredwildlife speciesundercertain circumstances.Regulationsgoverningpermits areat 50 CFR17.22and17.23.Suchpermitsareavailableforscientific purposes,to enhancethepropagation or survivalof the species,and/or for incidental take in connectionwith otherwiselawful activities. In someinstances,permits may be issuedfor aspecifiedtime to relieve undue economichardshipthatwould be suffered if suchreliefwere not available.With respectto the razorback sucker, it is anticipatedthat few, if any, trade permits wouldeverbe sought or issued,sincethespeciesis not in trade or commonin thewild. Requestsfor copiesof theregulationson animalsand Inquiriesregardingthem may be addressedto theOffice of ManagementAuthority, U.S.Fish and Wildlife Service,room 432,4401N. Fairfax Drive, Arlington,Virginia 22203,(703)358—2093;FTS 921—2093.National EnvironmentalPolicyAct

The Fish and Wildlife Servicehasdeterminedthatan EnvironmentalAssessment,asdefinedunder theauthorityof the National EnvironmentalPolicy Act of 1969,neednot be preparedin connectionwith regulationsadoptedpursuant to section4(a) of theEndangeredSpeciesAct of 1973, asamended.A notice outlining the

Federal Register / Vol. 56, No. 205 / Wednesday, October 23, 1991 / Rules and Regulations ~

Service’s reasonsfor this determinationwas published in theFederalRegisteronOctober 25, 1983 (48FR 49244).

ReferencesCited

A completelist of all referencescitedherein, aswell asothers, is availableupon request from the Service’sUtahField Office (seeADDRESSEsabove).

Authors

This rule waspreparedby Pit.,Schrader,U.S.Fish andWildlife Service(seeFORFURThER,NFORMATIONcoNrsc’r above),with assistancefrom

D.L Archer, formerly with theU.S. Fishand Wildlife Service.List of SubjectsIn 50 CFR Part17

Endangeredandthreatened species,Exports, Imports, Reporting andrecordkeepingrequirements,andTransportation.RegulationPromulgation

PART 17—fAMENDED)Accordingly,part17, subchapterB of

chapter 1, title 50 of the Codeof FederalRegulations,is amendedas setforthbelow:

1. The authoritycitation for part 17continuesto readasfollows:

Authodty 16 U.S.C 1361-1407:16U.S.C.1531-1544:16U.S.C.4201-4245;Pub.L 99-625. 100Stat. 3500, unlessotherwisenoted.

2. Amend * 17.11(h) by adding thefollowing, in alphabeticalorder under“FISHES,” to the List of EndangeredandThreatenedWildlife:

* 17.11 Endeng.rsdand threatenedwildUfe.• a * a *

(h) a a a

Dated: October15, 1991.RIchard N. Smith,ActingDirector, Fish andWildlife Service.[FR Doc.91—25471Filed 10—22—01; 8:45am)SILUNOcOca 431G-S&-~

Species

Historic range

Vertebrate

P0~rs Status When listedendangeredor

ttweatenedt

SPec’a~rulesCommonname Scientific name

FISHES

~uCker•razorbacli .... Xyrauche.tte.xanus . U.S~A.NV.

(AZ, CA. CO. NM, Entire ........ EUT, WV), Me~oco.

447 NA NA