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Fish Habitat Relationships Technical Bulletin
April 1995
Number 18
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Resident Trout and Movement:
Consequences of a New Paradigm
Michael K. Young
Rocky Mounluin Forest and Range Experiment Station
222 S. 22nd Street,
Larnmie. Wyoming 82070
Abstract
Trout living in streams have been tholight to move
very llttle thr.oughout their entire lives. Recent
research has demonstrated that adrill browr~trout,
Colorado River ctitti~roattr0~11,brook trout, and
rainbow r m t wcx-c far more mobile than previously
bclicvcd. The rrlobility of trout h;u probably affected
esli~natesof flsh abundance, pcrreptions of habitat
quality, and the delineation of populations, and
co~rldnullify the desired outcome of reslricrive
angling regulations. Also, by fragrncr~tfng
streams
wc may be reducitig the probability of pcrslstence of
native trout poptilatlons by restricting moverrrent
; ~ n dthus rcstrlcting population size.
USDA
Forest Scrvicc
Restricted Movement:
The Prevailing Paradigm
Unlike their anadromous relatives, streal-n-rcsldent
trout are often considered to he rslativcly irnrnobile. For cxarnple, Northcote (1992) stated that
the "home ranges for [such] yearling arid older.
salrnonids are ... usually a few tens or I-r~ctcrs."
The
notion of restricted movement of stream-dwellina
trout has persisted for over 50 ycars (Hoover and
Johnson 1937; Gerking 1959), and has been
applied to trout species as tlifti-:r-cntas cutthroat
trout (Oncorhynchus clarki) (Miller 1'357;
Heggenes et al. 1991) and brown Irout (Salrno
trutta) (Stefanich 1952; Bachman 1 984).
Forest Service Fish Habitat Relationships Program Leaders
or Representatives
FHR Currents Purpose
The USDA Forest Service Fish
Habitat Relationships Program
was established to further the
development of fisheries
technology and transfer this
technology to fleld biologists.
With ever increasing demands
for natural resources, protection
and management of aquatic
communities requires biologisb
to be knowledgable of current
research findings and state-ofthe-art techniques. The purpose
of FHR Cumnts is to provide a
vehicle to quickly disseminate
information important to fieldlevel biologists in the USDA
Forest Service.
National FHR Program
Region 8
Jeffrey L. Kerstmer
Washin ton Offlcr
Plrh 61 k'lldllfe Department
Utah Slate Universily
Logan, UT 84322-5210
Clndy A. Wllllams, Southern Kegion
Wildlilk, Fish Rr Bo~anyStall'
1720 Peachtree Rti.
N.W. Atlanta. GA 30367
Region 9
Rcgion 7
Kathy Moynan, Northern Rcgion
(Anadromous Flsh Pmgram)
Nez Perce Nat~onalForcst
Routc 2, Box 475
Gran~evllle.ID 83530
B r i m Sanborn, Northern Region
(Kesldenl Fish Program)
Dccr-lodjit! National Forest
Federal k u l l d h Box 400
Butte, MT 597&
Region 2
R. Nick Schmal, Rocky Mountain Rcgion
Wildlife. Flsh & Botanv Staff
IJniv. of W orning, c o i e g e of Agriculture
PO. Box 3&4
Laramie. WY 82071-3354
Bnh H o l l l n p w n r t h , Northcast Rcglon
IJSDA Forest Scrvlcc
310 W. Wlsconsln Ave.
Mllwaukee. WI 53203
Region 10
Ron Dunlnp, Alaska R c ~ i o n
Wildlife, Fish Rr Botany StaK
Fcticral Officr B u j l d i n ~ Box
.
21628
Juneau, AK 99802- 1628
Intermountain/Nor them Region
Kerry Overton. Fish Rrscarch Work Unit
Intcrmo~tntalnRrwarch Statlon
316 E. Myrtle St.
Boise, ID 83702
Associates
Submissions:
If you wish to submit a paper for
publication in FHR Currents.
please contact the following
people for information and
guidelines:
Jerry Bobe Karen Kenfield
Txhnical dltors
(707) 441-3669
B
Six Rivers National Forest
Fisheries Department
1330 Bayshore Way
Eureka, CA 95501
Region 3
Glcntn Chcn
Bryce Rickel, Southwest Region
Wlldlifc, Fish & Botany Staff
Federal R u l l d l n ~
51 7 Gold Avel. S.W.
Albuquerque, NM 87102
Fishcrlcs Blnlogist/Mnn~toriwSpecialist.
USDA Forest Scrvlcc
Fish Xr Wildllfe Deparlmenl
Utah State UniversiLy
Logan, UT 81322-5210
Region 4
Frcd Mangum
Aquatic Ecosystem Ar~alysisLab
105 Pagc School
Rrigharn Ynurig U ~ i i v r r s ~ t y
Pmvo. U T 84602
Seona L. Brown, Intermountain R e g ~ o n
Wildllfe, Flsh & Botany Staff
3 2 1 25th St.
Ogden, U'S 84401
Region 5
Jerry Buberg, Pacific Suuthwest Kegion
(Anadromous Flch Prograin)
S L Kivers
~
Na~ioiialForest
1330 Bayshorc Way
Art work by:
Jerry Boberg,
Six Rivers National Furcst
Ken Roby
Hyrlmlo~lst.USDA Fnrwt Scrvicc
k'aciflc Soulhwest Experinien~Slauon
PO. Box 245
Rcr~kclry,CA 94701-0245
Eurcka, CA 9.5501
JrtTrry Kririer, Pacifk Southwesl Region
(Kesldent Plsh P r n ~ r a t n )
Lake 'lahoe Hasln Managcmcnt Unlt
870 Emerald Bay Kd.. Sulle 1
South Lake Tahoe. CA 96150
Region 6
Deborah Konnoff, Padflc Northwcst Rcgion
Wildlife, Fish Pr Botan StaK
1133 SW. 1st Aw., PO. %ox 3623
Portland. OR 97208
Larry Schmidt
St~wm
Systcrns Technology Ccntcr
USDA Forcst Scrvlcc
Rock Mountain Exprrirl~entS~atiorl
240
Prospect
Furl Collins, C O 80526-2098
3;
Mark Vinson
drologist/Mo~~itorirlSpeclalist,
U ~ D Borcaa
I
u l Land f i a r ~ a ~ e r n e ~ i t
Flsh KL Wlldllfr Departrncnt
IJtah Statc IJn~vcrsity,
Logan, U'T 84322-5210
H
FHR Currents
Unfortunately, the methods used In movement
studies favor relocating immobile fish (Gowan et
al., in press). The procedure for most studies was
to mark fish in relatively short reaches of strcarns,
return to these same reaches wceks to a year later
to resample them, thcn discuss only the recapture
of marked fish. Usually few if any areas outside
the selected reaches were sampled. Because most
marked fish that were recaptured carnc from the
reaches where they were originally marked, the
authors considered this evidence for a lack of
movement. But they typically railed to address the
fate of the 15 to 90% of marked fish that were
nevcr recaptured, or attributed their absence to
mortality or lost marks. Studies employing other
techniques, such as direct observation, werc
handicapped because fish were not followed
during all seasons or at night (e+, Bachrnan
1984). Until the last fivc years, potentlal movement had beer) inadequately evaluated.
- - -r
New Views of Movement
Recent research in the Midwest and the Rocky
Mountains has disputed the paradigm or irnmc>hility of stream-dwelling trout. Clapp et al. (1990)
and Meyers et al. (1992) used radiotelemetry to
rnnnltor the positions of large brown trout in
Michigan and Wisconsin, and observed seasonal
movements or over 30 km. Similarly, Young (in
press) implanted transmitters in over 50 adult
brown trout in tributaries of the North Platte h e r
in Wyoming. I observed fish moving as far as 96
km and hypo(.hesized that fish began spawning
migrations from the river to the tributaries in late
July, wintered in the tributaries (often in deep
pools), and returned to the river during spring
high flows (Figure 1). Young (in review) used the
same technique to monitor much smaller Colorado River cutthroat trout (0.c. pleuliticus) and
sprlng-sumnicr r r ~ u v c r r ~ e rinrn
~ t \ rivrr
+ .;~~rnm~r,-fall
m o v e m c n ~ sInlu rribulnrlcs
........
Figure 1. Brown trout movcrncnts in the North Platte River drainage. The dotted line represents
hypothesized summer-fall movcrnents into the tributaries, and thc dashed line represents hypothesizcd spring-summer moverncnts into the river. Small letters rcprcsent observed movements of
three brown trout: fish "a" movcd 23 krn, fish "b" moved 66 km, and fish "c" moved 96 krn.
Page 7
J
FHR Currents
detected movements averaging over 300 rn (and
up to 2.4 km) in mid-summer. Twenty-four-hour
observations of both species revealed nurnerous
movements of over 100 m and tip to 1.1 km
(Young, unpublished data). Using twcl-way lish
traps to monitor movement, Riley et al. (1992)
observed extensive, continuous movements of
brook trout (Salvellnus fontinalis) in mid to late
summer in small Colorado strearns. Investigations
of these species, as well as rainhow trout (0.
mykiss) in Idaho (Middle Fork Salmon River,
Bjornn and Mallet 1964; Silver Creek, Young,
unpublished data), continue to dcrnnnstratc that
movement is far more commonplace among adult
trout than previously believed.
Consequences of
Movement
Many aspects of resident trout biology implicitly
rest on the assumption of immobility. If this
assumption is invalid, it challenges several teneLs
of current trout management and research.
Special regulations.-Restrictive regulations are
usually d e s i ~ n c dto rcduce harvest of some or all
of a trout population. These regulations presume
that the protcctcd groups will remain within
designated stream reaches. But this presunlption Is
not always correct; Clapp et al. (1990) noted that
some large brown trout, originally tagged in a nokill scctlon of the South Branch of thc Au Sable
River, spent most of their time in a standarclregulation reach. In Wyoming, a slot limit has
protected 254-406 rnrn trout i r ~the North Platte
Rwer since 1982 (Mike Snigg. Wyoming Game
and Fish Department, personal comrnunicatinn) ,
and t.his may have led to irw-eases in the abundance of spawning adults in the tributaries during
the spawning run. The trlbutaric:~,however, are
under standard regulations, and fluvial fish are
unprotc:ctcd once t h y cntcr the Iributarles (often
as early as July). If anglers harvest thcsc large: fish
in the tributaries (arid anecdotal evidence suggests
that they do), future gains to the owrall populatjon may be limited.
Page 2
Up- and downstream effects.-Another belief is the
overriding importance or local habitat on fish
populations. For example, structural rehabilitation
has been thought to increase the abundance of
trout in a treated reach by incrcaslng survival, but
this assumption has never been verified. In contrast, Riley and Fausch (in press) attributed the
increased abundance of trout In structurally
enhanced reaches of six Colorado strearns to
greater retention of mobile fish arriving from
outside the treated reaches. This irnplies that the
absence of a critical habitat outside an "enhanced"
reach rnay be responsible for suboptimal trout
densities within the reach. Consider that suitable
edge habitat for fry of Colorado River cutthroat
trout was usually unoccupied unless spawning
habitat was nearby (Bozek 1990).
The possibility of fish movement is frequently
ignored when building in-stream structures not
,
intended to enhance trout populations ( e . ~ .water
diversions or dams). One consequence is that fish
may be blocked from seasonally critical habitats
up- or downstream (eng.,spawning or overwintering sites). Alternatively, such barriers may
cause the extinction of mobile life history forms,
and if these forms are genetically distinct, thelr
genetic contribution to the population will be lost.
A gcnetic contribution to mobility Is plausible but
speculative (Jonsson 1985; Northcote 1992).
Regardless, these structures fragment populations
that then run a greater risk of extinction without
the opportunity for natural recolonizalion.
Up- and downstream effects are not limited to
physical disruptions. The stocking of non-native
trout has led to the eventual loss of many indigenous trout populations, except where barriers
prevented nligratlon of the invading species (see
Young 1995). For example, a single stocking of
brook trout in a headwater lake apparently led lo
their eventual replacement of Colorado River
cutthroat trout in most of the Battle Creek, Wyoming watcrshcd, except whwc a pollutcd strcarri
prevented their invasion into t~npollutedtribt~tarir:s (Eiscrmarl 1958). Iroriic:ally, the relalivcly
rapid spread of introclucecl populations was
apparcr~tlydisrt:prdcd as cvidcnce that trout wcrc
mobile.
FHR Currents
Sampling fish abundance and population
charactcristlcs.-Most estimates of fish abundance
in streams are derived from one or. a few short.
reachcs of a stream, typically only once cacti year
(or less often). Movement of fish through these
reaches would render counts suspect, in part by
violating an assumption of mark-recaplurc cstirnat.c:s. Decker and Ernian (1992), after rr:peatedly
electrofishing adjoining reaches uf one stream
throughout a summer, noted that the abuntlance
of several trout species varied asynchronously.
They attributed this variability to species-specific
movements, and questioned the value of one-time
sampling for estimating fish abundance. Over 50
years earlier, Shetter and Hazzard (1 938) similarly
concluded that "populations of slrearn fish are
relatively unstable in specific a n a s of a strearn
durlng the summer months, and ... calculations of
stream populations from counts made on one or
two short sections of stream at only one period of
the year are riot reliable." Long-term modelling of
population fluctuations (Platts and Nelson 1988)
or community composition (Ross et al. 1985) are
especially sensitive to annual or specics-speclfic
variation in mobility. Even one-time basin-wide
inventories cannot account for trout rnobility.
Herger et al. (in review) perlorrued two basinwide surveys one month apart on each of two
streams, and noted that the redjstribution o l
Colorado River cutthroat trout led to different
estimates of habitat-specific dcmsities and overall
trout abundance within each stream.
This unrclhbility can extend to other killds of
sampling. For example, meristic and tnorphornclric analyses were used to determine the gcmetic
purity of Colorado River cutthroat trout from two
trlbutaries and the mairistcrn of the North Fork
Little Snake River in southern Wyoming (Binns
1977). Ttie analyses indicated that fish in the
rnainstem were genetically purc:, fish from
Harrison Creek werc obviously contaminated by
hybridization, and fish from Greer~Timber Creek
were assutnecl to be intermediate. However, in
rrlnvcrnent studies conducted In 1992 (Young, in
review), a single radio-tagged adult occupied all
three locations within 23 days. Mnreovcr, nearly
all the fish origjxially captured in 14arrison Creek
and Green Timber Creek eventually riiigratecl to
the North Fork Little Snake River and could have
been thought to represent the putatively isolated
populations in any of the three streams. Because of
the potential seasonal and annual variability in
populat.iori cornposition, we should consider the
consequences of one-lime sampling for describing
population genetic structure (Fausch and Young,
in press).
Habitat modelling.-Modelling may also be
confounded by trout movement. Many habitatbased models, constructed from physical or
biological data often collected at a singlc point in
time, attcrnpt to predict the abundance or biomass
of salmonids (see Fausch et al. 1988 for examples). The inability to incorporat.c! temporal
variation in stream characteristics has been
recognized as a shortcoming of such models i.e..
habitat characteristics change seasonally without
apparent concurrent changes in fish abundance
(Ccmdcr and Annear 1987). Yet rarely consicicrcd
is the potential temporal variation in fish abundance produced by mobility, which could add
st~bstantiallyto the unexplained variation in such
models. Additionally, that species ( e , ~ .brown
,
trout) may riot be in feeding positions when
sarr~plcdby electrofishirq (Young, personal
observation) may further degrade the performance
01thesc: models.
Arbitrary definition of populations.-Perhaps
because or a perceived lack o f mobility in fishes,
biologists often attempt to geographically, but n o t
biologically, define populations. That is, we often
designatc the trout in a srnall strearn as a singlc
population (in a sense, isolated by irrirnobility).
Yet rarcly is this designation merited, becauso
trout may imrnigratc to the small slreani (to
reproduce, feed, or escape floods) or emigrate
frorn it (to overwinter or escape desiccation), That
far.
the rangc of a single population may Incl~~dc:
more waters than the "type loc:ationUis consister-it
with thc crnerging conccpt of rnetapopul;ltic-)~~s.
Metapopulatioris consist o l a cullcction of silt)populations that are linked by immigration a r d
e r n i p t i o n (Hanski and Gilpin 1991). Thc inciividual suhpopulations may thrivt!, suffer losses of
gericlic variation, or go extinct, but individuals
from other sukpopulations wit.kiin the
Page 3
FHR Currents
metapopulation can contribute to the growing
subpopulations, restore genetic variation to small
subpopulations, or found new s~~bpopulations
after extinction. To persist, metapopulations must
consist of periodically mobile individuals in
habitats without contjnuous barrjers to movement
(Gilpin 1987). Whether metapopulatior~theory
explains trout population structure remains to be
investigated, but it seems likely that most populations of salrrionitls have been founded by mobile
individuals from large populations (cf. Milner and
Bailey 1989).
Conclusions
A new paradigm for stream-dwelling trout. considers (but does not mandate) mobility as one of the
possible responses to food, growth, cornpctition,
predation, environmental disturbance, and daily
and seasonal cycles. Movement may be minimal
under somc circumstances e.g.,abundant
macrolnvertebrates, complex habitats, and environmental stability (cf. Bachman 1984). But
because most streams are spatially and temporally
heterogeneous, trout may elect to rnove frequer~tly
and extensively. The challenge for managers and
rescar.chcrs is to recognize when and where
movement will be advantageous or necessary for
maintaining wild trout populations.
Literature Cited
Bachrnan. R.A. 1984. Foraging behavior of frcc-rar~girigwild
and halchery brown lrout In a slrearn. rl'ransactlons of the
Amcr~canFlshcrics Socicty 11 3: 1-32.
Elms. N.A. 1977. Present status of Indigenous populations of
cr~tthrnatt r o ~ ~Safrno
t.
clnrkl, in sotlthwcst W y o r r ~ i r ~ ~ .
Wyoming Garr~carid Fish Department, Cheyen~ie,pisherles
'I'cchnlcal Rrlllctin 2.
Bjormn. T.C., and J. Mallet. 1964. Movements olpla~itedand
wild lroul in an Idaho rlver syslem. Transactlons of thc
Ari~cl-icariFisheries Society 93: 70-76.
Bozck, M.A. 1990. Generality of habital models for Colorado
Klver culthroat trout fry and the Influence of adults on
habitat choiw arid behavior. Doctoral dissertaliur~,'IJn~versi~y
of Wyoming, Laramle.
Page 4
Clapp, D.F., R.D. Clark, Jr., and J.S. Diana. 1990. Range,
activity, and habitat of large he-ranging brown trout in a
Michigan stream. l'ransactlons of the American Fisheries
Socicty 119:1022-1034.
Condcr. A.L.. and T.C. Anncar. 1987. Test ofweighted usable
area estimates derived h n a PHABSIM model Tor instream
flow str~dlcson trout streams. North American Journal of
Fisheries Management 7:339-350.
Decker. C.M.. and D.C. Erman. 1992. Short-term seasonal
rhdi1f.y~
- in composition and abundance of flsh In S a-~ e h e n
Creek. Callfornia. Transactions of the American Fisheries
Society 121:297-306.
Eiscrman, F. 1958. A fisheries survey of the Little Snake River
drainage. Wyomlng Game and Flsh Commlsslon, Cheyenne.
Flshcrles Technical Rcport 6.
Fausch, K.D., C.L. Hawkes, and M.G. Parsons. 1988. Models
that predict standing crop of stream fish rrom habitat
variables: 1950-85. USDA Forest Servke, P a c l k Northwest
Rcscarch Station, Portland, Oregon. General Technical Rcport
PNW-CTR-213.
Fausch, K.D., and M.K. Young. In press. move men^ or
resldenl stream flshcs and managing ESU'S: a carltinnary tale.
In Proceedings of the confcrcncc on cvolutiori arid thc! aqrlatir
ecosyslem: deflnlng unlqr~eunits in population conscrvatlon.
Arlicricar~Fisheries Society, Belhesda, Maryland.
Ccrking, S.D. 1959. Thc restricted movement of flsh populatlons. Blologlcal Rcvlew 34:221-242.
Gllpln. M.E. 1987. Spatlal stnlctrlrc and p o p ~ ~ l a t l ovulncrn
ability. Pages 1 2 5 1 4 0 In M.E. Soule', editor. Viable populations for ronservallon. Cambridge University Press, Cambridge.
Guwari, C . , M.K. Young, K.13. Pausch, and S.C. Kiley. In
press. Thc rcstrictcd movcmcnt of strcarn-~.csidcntsalrnonids:
a pa~wllgmlost? Canadiari Journal of Fisheries arid Aquatic
Sciences.
IIanski, I., and M.Gilpin. 1991. Metapopulat~ondynamlcs:
brlef hlstnry a n d conceptual domain. Biological Jourml of the
Lir~rieanSociety 42:3-16.
H c ~ ~ c n cJ..
s ,T.C. Nor~hcotc,and A. Pctcr. 1991. Spatial
stability of cutthroat rruut ( O n c o r f ~ y ~ ~ cclarki)
t ~ u s in a small.
coastal strcarii. Car~adianJournal of Fisheries and Aquatic
Sdences 48:757-762.
I Ierger, L.G.. W.A. Hubert, and M.K. Young. In rcvlew.
Evaluation uP a basin-wide invenlory of culthroat trout
habltat In small tnotmtaln strcarns. Nnrth Amcricarr J o ~ ~ r n a l
o l Fisheries Managemenl.
Hoover,, E.E., and M.S. Johnson. 1937. Migralion and
depletion 01slocked brook trout. Transactlons of the
FHR Currents
Arncrlcan Flsherles Society 67:224.227
Jonsso~i,B. 1985. Llre hislory pattclrns of freshwaler redden1
and sea-run mlgranl brown tsot~tIn Norway. Transaclioris of
Lhe Americari Fisheries Socle~y114:82-194.
Meyers, L.S., T.F. Thucmler, and G.W. Ko~mcly.1992.
Seasonal movemenls ol-brown trout In norlheast Wiscurisi~~.
North Amcrican J o ~ ~ r nor
a l Fisheries Management 12:43344 1.
Mlller, R.B. 1957. Permanence and size or h u ~ n tc!rritory
r
in
stream-dwelling culthroat trout. Jot~rnnIof the Flsherles
Research Board o l Cariada 14:687-691.
Milner, A.M., a ~ i dR.G. Bailey. 1989. Salrnonid colonl7atlon
of ncw streams in Glacicr Bay National Park. Alaska.
Aquaculture and Fisheries Mana~crncnt20: 179-192.
Norlhcote, T.G. 1992. M l p t l o n a r ~ drcsidcnry In strcatn
sal~iio~iids:
some ecolo~lcalconsitlcrations and evoluHunary
conscqtmnces. Nordic Journal of Freshwa~erResources 67:517.
Plalls, W.S., and R.L. Nelson. 1988. Fluctuations In tlmul
populations and h e i r implications for land-use evalualions.
Norlh American Jot~tnalor Fisheries Mariagrrnrnt R:333-345.
t
Riley, S.C.. and K.D. Fausch. Iri prrss. T r o l ~ population
response to habitat crihancemen1 In six nor-rhcrn Colorado
strcams. Canadlari Journal of Flsherles and Aquatic. Scicnrrs.
Riley, S.C., K.D. Fausch, and C. Cowan. 1992. Movernen~ol
brook trout (Salvelir~usfontir~allr)I n Four small subalpirie
slrea~nsin ~iorthcrnColorado. l h l u g y of Frcshwatcr Fish
1:112-122.
Ross, S.T.. W.J. Matthews, and A.A. Ecticllc. 1985. Perslstence or stream nsh assemblages: efrecls or erivirorirricrital
changc. Alncrlcan Naluralis~126:24-40.
Shetter, D.S., and A.S. H a n a r d . 1938. Sprcies composltlon by
age groups and stabllily o l Ilsh populations In secllons or
three Michlgan (rout strea~nsd ~ ~ r l nhe
g summer of 1937.
Trarisactions of thc American Fistierics Society 6R:281-302.
Stcfanich. F.A. 1952. 'l'he population and mowmen1 or nsh in
Prickly Pear Creek, Montana. Transactions ul thn American
Fishcrles Soclety 81:260-274.
You~ig.M.K.. tcchnlcal edltur. 1995. Conscrvatlon assessmen1
for Inland cutthroat trout. USDA F o r e s ~Service, Rocky
Mountain Forest and RanRe Bxperirncnt Statlon. Port Collins,
Colorado. General Technical Report RM-Grl'K-256.
Younp,. M.K. In press. Browri trout rnohlllty In sou~h-central
Wyoming streams. Canacllan Journal of Zoology.
Young, M.K.
111scvicw. Tclcmet~y-determir~rd
niovcrnrnt and
habitat use of Colorado Kivcr cutthroat trout (Oncork~yr~cttus
clilr.ki plrurltlcc~s).Canadlan Journal of Fishrr.ics and Aquatic
Sciences.
Page 5
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ry
U.S. 1)rpnrtmrnr nf Agrirult~tir.Wnqhlngron. D.C. 20250, nr roll (202) 720-7327 (vadrtv)
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or- nny prodlrct or, service to rl~eexcl~rsior~
of others that may be strltoblr.
rndorsrrr~rrltor appr-ovsl Iry rtw 11 S. Drpnrmrnl o[Agrlc~tlt~we