DISTRIBUTION, RELATIVE ABUNDANCE

AND HABITAT UTILIZATION OF THE
ARCTIC GRAYLING (Thvmallus arcticus )

IN
THE UPPER BIG HOLE RIVER DRAINAGE, MONTANA

JUNE 21 TO AUGUST 28, 1989

Final Report - November 1990

by

Geoffrey A. McMichael

Montana Natural Heritage Program
1515 East Sixth Avenue
Helena, Montana 59620

for the

U.S. Forest Service - Beaverhead National Forest

Bureau of Land Management - Butte District Office

Montana Department of Fish, Wildlife and Parks

Montana Cooperative Fisheries Research Unit

November 7, 199©

© 1990 Montana Natural Heritage Program

This document should be cited as follows:

McMichael, G.A. 1990. Distribution, relative abundance and habitat utilization of the Arctic grayling
ffhymallus arcticus) in the upper Big Hole River Drainage, Montana. June 21 to August 28, 1989.
Montana Natural Heritage Program. Helena, MT. 40 pp.

CONTENTS

List of Figures. . iii

List of Tables iv

Acknowledgements ...................... v

Summary. ... . ......... 1

Introduction ..... . 5

Study Area and Methods ................... 6

Results and Discussion ............. 12

Distribution and Abundance of Fishes ... 12

Growth of Young-of-the-Year Fishes . 14

Habitat Utilization by Young-of-the-Year Arctic Grayling . 17

Macrohabitat Utilization ................ 17

Microhabitat Utilization ................ 26

Depth and Velocity 26

Cover. 26

Substrate 2 9

Temperature. ....................... 29

Flows 31

Stomach Content Analysis ............ 31

Movements of Young-of-the-Year Arctic Grayling ...... 38

Conclusions and Recommendations 39

Literature Cited ... ............. 41

li

LIST OF FIGURES

Number Page

1 Map of the upper Big Hole River drainage, showing
sample sections where electrof ishing surveys

were conducted 7

2 Mean length of young-of-the-year Arctic grayling,
mountain whitefish, and brook trout versus date . . . 16

3 Depth (ft) isopleths for macrohabitat area 1 19

4 Depth (ft) isopleths for macrohabitat area 2a . . . .20

5 Depth (ft) isopleths for macrohabitat area 2b . . . .21

6 Depth (ft) isopleths for macrohabitat area 3. .... 22

7 Depth (ft) isopleths for macrohabitat area 4 2 3

8 A Frequency of depth measurements in macrohabitat

areas
B Frequency of depth measurements at capture sites. . . 27

9 A Frequency of velocities for macrohabitat areas

B Frequency of velocities at capture sites. ...... 28

10 Gauge height (ft) versus streamflow discharge (CFS)

for the west channel of the Big Hole River .32

11 Gauge height (ft) versus streamflow discharge (CFS)
for the east channel of the Big Hole River upstream

of the mouth of Steel Creek 33

12 Gauge height (ft) versus streamflow discharge (CFS)
for the east channel of the Big Hole River
downstream of the mouth of Steel Creek. ....... 34

13 Gauge height (ft) versus streamflow discharge (CFS)

for Swamp Creek . ....... 35

14 Percent volume of stomach contents of 6 to 10 inch
Arctic grayling and brook trout made up by various

food items .36

15 Percent volume of stomach contents of 10 inch and
larger Arctic grayling and brook trout made up by
various food items. ... ..... 37

in

LIST OF TABLES

Number Page

1 Physical characteristics of sample sections

in the upper Big Hole River basin. ........ 8

2 Total number and relative abundance of Arctic
grayling and brook trout captured by
electrofishing in the Big Hole River drainage,

June 21 - August 28, 1989 13

3 Mean and range of total length of YOY Arctic
grayling, mountain whitefish, and brook trout
in the Big Hole River drainage, July 6 to

X"iCiy v4.)Z> U Z O > X!?0 J? « s a m o s o a a o o o o a » o o a , 1 Z~i

4 Habitat features for YOY grayling collected
in grids, electrofishing upstream,
electrofishing downstream, and adjacent
macrohabitat areas on the east channel

of the Big Hole River 25

5 Frequency of cover types within a 3.28 square
foot area centered on capture sites of YOY
grayling within the larger macrohabitat

6 Maximum daily water temperatures recorded on the
Big Hole River and its tributaries, June 2 6 to
August 22, 1989 30

IV

ACKNOWLEDGEMENTS

The Montana Natural Heritage Program, through Dave Center,
and the U. S. Forest Service and Bureau of Land Management's
Challenge Cost Share Programs provided funding for this study.
The Montana Department of Fish, Wildlife and Parks, through the
Bozeman and Dillon offices, provided field and computer equipment
as well as some personnel for the project. Gary Senger was very
helpful in the field and generated the isopleths for this report.
Brad Shepard, Montana Department of Fish, Wildlife and Parks,
provided ideas, suggestions and overall guidance for this study.
Bob McFarland, Montana Department of Fish, Wildlife and Parks,
aided in the computer analysis of data and the generation of this
report. Kal Caya at Montana State University provided comments
on the final draft.

v

SUMMARY

This study focused on the distribution, relative abundance, and
habitat utilization of native Arctic grayling ( Thymallus
arcticus ) and possible dietary competition between grayling and
introduced brook trout ( Salvelinus fontinalis ) in the Big Hole
River and its tributaries along a 26 mile reach of the river near
the town of Wisdom, Montana. The continuing decline of the Big
Hole River Arctic grayling population, the last remaining
population of fluvial grayling in the lower 48 United States, has
led to increasing concern and has made studies such as this
particularly important for the future management of this
population.

Electrofishing was used to determine the distribution and
relative abundance of young-of-the-year (YOY) Arctic grayling.
Arctic grayling, brook trout, and mountain whitefish ( Prosopium
williamsoni ) were measured and weighed and released in the area
where they were captured. Stomach samples were collected from 47
grayling and brook trout with the gastric lavage technique. In
areas where large concentrations of YOY grayling were captured
macro- and microhabitat measurements were made to quantify the
grayling's preferences with respect to habitat. Three different
methods of electrofishing were used to determine preferred sites
of grayling. The first two used a Coffelt BP-1C backpack
eiectrofisher in upstream and downstream directions in
•intensive-use areas' that had been previously located. The
third method utilized a series of stationary electrofishing
grids. Microhabitat data derived through these three methods
were compared to determine whether the method used affected
capture site parameters.

Microhabitat sites were quantified with respect to depth,

velocity, substrate, cover, and proximity to riffles where
grayling spawning may have occurred. Macrohabitat areas were
measured to develop an index of availability for habitat
parameters such as depth, velocity, substrate, and cover. These
macrohabitat areas were located in areas that contained large
concentrations of YOY grayling and may not represent the true
habitat availability.

The east channel of the Big Hole River below the town of
Wisdom had the highest concentrations of YOY grayling of the ten
sections surveyed. The west channel of the river, also below
Wisdom, and an irrigation ditch above Wisdom also supported
relatively high densities of these YOY fish.

Young-of-the-year Arctic grayling increased in mean total
length (TL±SD) from 2.52 (+.08) inches on July 6 to 4.08 (±.24)
inches on August 28, 1989. This growth rate is quite similar to
that presented by Skaar (1989) for this same area in 1988.
Condition factors for age I and older grayling averaged 1.10
(±.20) which is higher than that reported for 1988 (Skaar 1989)
and much higher than that reported for 1979 (Liknes 1981) . This
result indicates that the individual fish were in better
condition in 1989 than they were in either 1979 or 1988.

Macrohabitat areas selected by YOY grayling were typically
one riffle-pool-riffle complex and could be characterized as
having sloughing banks, being in close proximity to relatively
•clean 1 substrate materials, having at least one pool in excess
of 1.5 feet in depth, and having abundant cover (usually in the
form of aquatic vegetation). Orange-colored 'spawning flags',
marking the locations where Montana Department of Fish, Wildlife
and Parks personnel captured spawning grayling in late April and
early May of 1989, were often in close association with the
macrohabitat areas where large concentrations of YOY grayling
were captured.

Microhabitat areas selected by YOY grayling averaged
slightly deeper and had higher velocities than the surrounding
macrohabitat areas. Cover was typically within one foot of a

capture site and was most often (80%) aquatic vegetation.
Aquatic vegetation and soil clumps were used in higher proportion
than they occurred, while pools were used in lower proportion

than they occurred. Substrate at microhabitat sites was
•cleaner 1 (less silt) and of larger particle size than was
available in the larger (adjacent) macrohabitat units.

The three electrof ishing methods produced differences in
locations where YOY grayling were collected relative to upstream
or downstream riffles within microhabitat areas. The fish
collected while moving in an upstream direction with the backpack
electrofishing unit were closer to the upstream riffle than fish
collected with either of the other two methods. The same type of
relationship was true for the fish collected while moving
downstream, in that they were collected closer to the downstream
riffle, while the fish collected in the grids were intermediate
in distance between the two riffles. This suggests that the two
methods requiring the samplers to enter and move about in the
water may displace the fish from their selected habitats and that
the fish collected with the grid method probably provide the most
reliable data with respect to microhabitat utilization. This
result also indicates the results presented by Skaar (1989) may
be biased and need to be re-examined.

Age I and older grayling in the Big Hole River appear to
select a higher proportion of surface food items than do brook
trout in the same areas. Stomach content analyses showed very
little dietary overlap between the two species which indicates
there may be little competition for food between the two species
during the summer months. There were no YOY grayling found in
the stomach samples from brook trout, however, few stomach
samples were obtained early in the study when grayling fry had
recently emerged and would be most vulnerable.

Young-of-the-year Arctic grayling showed a high fidelity for
specific riffle-pool-riffle complexes. The proximity of YOY
grayling to known spawning areas, as well as the lack of movement
for the majority of recaptured YOY grayling suggests that these

fish are fairly stationary through at least their first summer.

The Arctic grayling population of the Big Hole River is
continuing a decline that threatens their continued viability.
More work is needed to understand why this population has
declined so drastically. Studies of the distribution, habitat
use (throughout the year) , interspecific competition, predation,
thermal tolerances, and land and water uses in the Big Hole
Valley that affect the grayling are examples of the work required
to help managers understand and remedy the factors causing the
demise of this unique and threatened fishery.

INTRODUCTION

The continued decline of the only known population of
fluvial Arctic grayling ( Thvmallus arcticus) in the lower 4 8
states has caused increasing concern. Liknes (1981) cited
dewatering, overharvest, and competition with brook trout
( Salvelinus fontinalis ) as the principle factors that may be
contributing to the decline of the Arctic grayling in the Big
Hole River. The severe drought conditions (low water and very
high water temperatures) in the Wisdom, Montana section of the
Big Hole River during the summers of 1987 and 1988 appear to have
seriously impacted the grayling population there. From Fall 1986
to Fall 1989 the linear density of age I and older grayling in
the Big Hole River declined from about 35 per mile to
approximately 18 per mile (R. Oswald, pers. comm.).

The Montana Natural Heritage Program, the Montana
Cooperative Fisheries Unit, the Montana Department of Fish,
Wildlife and Parks (MDFWP) , and the U.S. Forest Service, through
a cooperative effort, provided funding, equipment, and logistical
support for a study of the Big Hole River grayling. This study,
which began in the Spring of 1988, emphasizes the early-life
history requirements and habitat preferences of young-of-the-
year (YOY) Arctic grayling in the upper Big Hole River and its
tributaries near the town of Wisdom, Montana.

The first portion of this study was conducted through the
summer of 1988 and provided information on the distribution and
habitat utilization of YOY Arctic grayling (Skaar 1989) . This
report presents the results of the continuation of the 1988 study
and focuses again on the distribution and habitat preferences of
YOY grayling as well as the possibility of interspecific
competition for food between Arctic grayling and the non-native
brook trout.

STUDY AREA AND METHODS

Electrof ishing with three types of systems was conducted on
the Big Hole River and associated tributaries from June 21 to
August 28, 1989 to collect information on the distribution and
relative abundance of grayling and in an attempt to locate areas
with high densities of YOY Arctic grayling for later habitat
measurements. Ten sample sections (Fig. 1) , ranging in length
from 0.18 to about 5 miles, were electrof ished from one to
several times. Streamflow discharge ranged from about 2 cubic
feet per second (CFS) in the smaller channels and tributaries in
late July and August to about 70 CFS in the mainstem of the Big
Hole River during high flows in late June (Table 1) .

Two mobile electrode electrof ishing systems and a series of
stationary grid-type electrofishing units were used throughout
the study. Three people operated the boat system, which
consisted of a plastic flat-bottom boat (Coleman Crawdad model)
equipped with a 120 volt gasoline-powered generator and a Harvey
Leach rectifying unit with an attached negative electrode and
mobile positive electrode. A Coffelt BP-1C backpack
electrofishing system was used in areas where the boat system was
not applicable (where the water was too shallow) . Electrofishing
grids were constructed to sample microhabitat utilization by YOY
grayling in a manner similar to that described by Bain et al.
(1985) . All electrofishing systems were operated with direct
(DC), non-pulsed current ranging from 75 to 500 watts. The boat
system was used early in the season when higher discharges were
present and for the majority of the sampling on Swamp Creek
(sections A and B) and the Big Hole River proper (sections C,D,
and I) where flows were seldom below 10 CFS. Electrofishing
always proceeded downstream with the boat system, as the primary
purpose in using the boat system was to quantify distribution and
relative abundance of fishes and habitat measurements were not
made in areas that were sampled with only the boat system.

/

E-- 8 "'"-cs »«wJ'!iTfle«m

Figure 1. Map of the upper Big Hole River .drainage, showing
sample sections where electrofishing surveys were
conducted .

Table 1. Physical characteristics of sample sections in the
upper Big Hole River basin and dates of sampling.

Electrofishing
Stream/ Length Gradient

Sample Section (miles) (%) Date(s) Flow (CFS)

Swamp Creek

A: Upper

B : Lower

2.0

~ .30

6/21

~ 35 (est)

1.9

.28

6/22,
7/11,

7/6,
8/1, 8/2

8-35

3.49

.25

6/26,
7/18

7/12,

26-70

Big Hole River

C: Below Wisdom
(West Channel)

D: Above Wisdom -5.0 .26 6/27, 7/19 15-50 (est)
(Clemow-Wisdom)

E: Below Wisdom ~ 5.0 <.25 6/28 70 (est)

(Pintlar Cr.-
Squaw Cr. )

Fs Below Wisdom -1.0 - .25 7/13 20

(Upper last
Channel)

G: Below Wisdom 2.83 .27 7/17, 8/3, 2.5-30
(Lower East 8/7-10, 8/14-18,

Channel) 8/21, 8/28 *

H: Above Wisdom - 3.0 ~ .25 7/24 25 (est)

(Twin Lks Rd.-
Clemow Rd. )

Steel Creek

I: Highway 278- 1.39 .36 7/26-27 10 (est)

Campground Rd.

Irrigation Ditch

J: Cal Erb's Ranch .18 .18 7/14, 7/21 2 (est)
(formerly

McDowell • s)

* Small sub-sections sampled only on most days.

8

The backpack system was used primarily in side channels,

irrigation ditches and smaller tributaries of the Big Hole River
where flows seldom exceeded 15 CFS. Backpack electrof ishing
proceeded in an upstream direction when data were collected for
distribution and relative abundance. Electrof ishing proceeded
both upstream and downstream while marking locations for later
microhabitat measurements. Samplers would move as quietly as
possible and stab the electrode in the water in an attempt to
avoid displacing the YOY grayling. We immediately marked
locations where specimens were captured for later habitat
measurements. Different colored rocks were used to differentiate
between sites where fish were captured: 1) while backpack
shocking upstream, 2) while backpack shocking downstream, or 3)
in a grid apparatus. The grid system was used in areas where we
had captured large numbers of YOY grayling to try to determine
whether the fish captured with each backpacking system had been
displaced. The six grids, ranging from three to 12 square feet
in size, were typically set in appropriate habitat from 12 to 7 2
hours before the power supply was turned on. A netter was
positioned downstream of the grid (often on the streambank) and
remained motionless for 3 seconds to two minutes until the
person operating the power supply (either in the boat downstream
or on the bank) about 50 feet away supplied power to the grid.
The netter then rushed forward and netted the fish as they were
stunned in the area inside the grid. If YOY grayling were
captured, then each spot was immediately marked with one of the
aforementioned colored rocks for later microhabitat measurements.
In addition to Arctic grayling and brook trout, YOY mountain
whitefish ( Prosopium williamsoni ) and rainbow trout ( Oncorhynchus
mykiss ) were netted and placed in a live car until they were
measured to the nearest 0.1 inch in total length (TL) and weighed
to the nearest 0.01 pound. Lengths and weights were converted to
metric units and condition factors (K) were calculated using the
following equation:

(weight in grams) x( 100, 000)

K =

3
(length in mm)

Macrohabitat parameters were quantified in areas where
relatively high numbers of YOY grayling were captured (referred
to as "intensive-use areas" by Skaar (1989)) to characterize the
general habitat the YOY grayling were using. Four locations were
selected as macrohabitat areas on the lower section of the east
channel of the Big Hole River (section G) where large numbers of
YOY grayling were captured. Transects were established
perpendicular to the direction of flow and were spaced from five
to 20 feet apart. Depth, velocity, substrate, and cover were
quantified at 1.0 foot intervals along each transect except in
some isolated backwaters where measurements were taken every 3 .
feet. Depths were measured to the nearest 0.1 foot with a yard
stick affixed to a wooden handle and velocities were taken at 0.6
total depth using a type AA flow meter (Price model) and rod.
Substrate composition was visually established using the standard
size categories of silt (<0.0024 in.), sand (0.0024-0.0787 in.),
small gravel (0.0787-0.236 in.), large gravel (0.236-2.52 in.),
and cobble (2.52-9.84 in.). No boulders (>9.84 in.) were found
in measured areas. Embeddedness was also visually estimated by
examining cobbles and large gravel particles at each increment of
the transect for the percentage of the particle that was embedded
in the fines. Cover types were characterized, if present, at
each point along the transect as aquatic vegetation, terrestrial
vegetation, soil clump (from eroding streambanks) , pool (over 2.0
feet deep) , bank, and debris.

Microhabitat measurements were taken from one hour to two
weeks following capture under flow conditions that were not
different by more than 20%. The area inside of a 3.28 square
foot area centered on the capture site was quantified with
respect to depth, velocity (at 0.6 depth and bottom), substrate,

10

embeddedness , cover, distance to cover, and proximity to both

upstream and downstream riffles. The capture sites for fish
captured while backpack shocking upstream, backpack shocking
downstream, and using grids were treated, in most cases,
separately in this report to determine whether capture method had
an affect on the capture site parameters.

Pocket thermometers were used to measure water temperatures
at random locations and times of day to the nearest degree
Fahrenheit. Streamflows were measured every other week at each
of four gauge stations using the type AA current meter. Gauge
heights were recorded at least once each week at each location.
Staff gauges were located on Swamp Creek at the bridge on the
North Fork of the Big Hole Road (section B) , on the west channel
of the Big Hole River (on the west bank) approximately 0.3 miles
downstream of the Wisdom Bridge (section C) , on the upper portion
of the east channel of the Big Hole River about 50 yards upstream
of the confluence with Steel Creek (section F) , and on the lower
portion of the east channel of the Big Hole River about 0.75
miles downstream of the confluence with Steel Creek (section G) .

To investigate possible competition for food items between
brook trout and Arctic grayling stomach samples were collected
from 35 brook trout and 12 Arctic grayling using the gastric
lavage technique discussed by Light et al. (1983) . These samples
were then pooled into the following categories; 1) brook trout 6-
10" TL, 2) brook trout >10" TL, 3) Arctic grayling 6-10" TL, and
4)Arctic grayling >10" TL. Stomach contents were then sorted
into the following classifications with the aid of a dissecting
microscope: mayfly, caddisfly, stonefly, scud, aquatic beetle,
terrestrial insect, leech, worm, fish, cranefiy, and
unidentified. Percent composition of the identified matter was
calculated for each category (except 'unidentified') by number
and volume.

11

RESULTS AND DISCUSSION

Distribution and Mmndance of Fishes

The highest concentrations of YOY Arctic grayling were
located in the east channel (Steel Creek channel) of the Big Hole
River below the town of Wisdom (section G; Table 2) . The highest
densities in this area occurred from the confluence of Steel
Creek downstream for approximately 2.5 miles. Notable
concentrations of YOY grayling were also found in the west
channel of the Big Hole River below Wisdom (section C) and in an
irrigation ditch on Cal Erb's (formerly McDowell's) ranch just
upstream from Wisdom (section J) . Relatively few YOY grayling
were captured on Swamp Creek (section B) , Steel Creek (section
I) , the Big Hole River upstream of Wisdom (section D) , and the
upper east channel of the Big Hole River below Wisdom (section
F) . Age 1+ Arctic grayling, though very sparse in general, were
most numerous in sections C and G, following a similar pattern of
distribution as that of the YOY grayling. No grayling and only
11 brook trout were captured in approximately 5.0 miles of river
between Pintlar Creek and Squaw Creek in an area that was
severely dewatered during the summer of 1988.

Though not quantified in many cases, the higher densities of
YOY grayling were found in similar habitat, and in close
association, with YOY mountain whitefish indicating they may
exhibit similar habitat preferences during their first summer of
life. Young-of-the-year brook trout were most plentiful in Steel
Creek (section I) and in the lower section of Swamp Creek
(section B) . They were also relatively abundant in the lower
east channel of the Big Hole River (section G) , however the
linear densities should be interpreted cautiously as they include
multiple samplings in some circumstances which may give a
misleading impression overestimating the actual relative density
in a given section.

Adult brook trout were most numerous in lower Swamp Creek

12

(section B) and in the west channel of the Big Hole River below
Wisdom (section C) . Rainbow trout were very rare throughout the

Table 2. Total number and relative abundance of Arctic Grayling
and brook trout captured by electrof ishing in the Big
Hole River drainage, June 21 - August 28 , 1989.

Number captured (number/ 10 00 ft of stream) *

Arctic grayling

brook trout

Stream/

section YOY <9 in >9 in YOY <6 in >6 in

Swamp Creek:

A: 0(0)
B: 14(1.4)

Big Hole River:

C: 100(5.4)

0(0) 0(0)
9(0.9) 0(0)

0(0)** 17(1.6) 61(5.8)
100(9.9) 17(1.7) 181(18.0)

9(0.5) 8(0.4)

0(0) 3(0.1)

0(0) 0(0)

3(0.6) 0(0)

495(33.1) 39(2.6) 5(0.3)

0(0) 1(.06) 0(0)

11(0.4)
0(0)
6(1.1)

D:
E:

F:
G:
H:

Steel Creek:

I: 6(0.8) 3(0.4) 0(0)
Irrigation Ditch:

J: 10(10.0) 0(0) 0(0)

2 (0.1)
3(0.1)
0(0)
0(0)
109(7.3)
4(0.3)

1(.05) 124(6.7)

1(.04) 58(2.2)

0(0) 11(0.4)

0(0) 5(0.9)

7(0.5) 67(4.5)

0(0) 9(0.6)

200(27.3) 0(0)

0(0)

0(0)

5(0.7)

1(1.0)

* = Several sections were sampled more than once, see Table 1.
** = Sampled prior to the time when YOY brook trout were large

enough to be vulnerable to our collection methods.
Note: Number per pass would not be appropriate because passes
varied with respect to intensity, method, and duration.

13

entire study area and were captured in only sections C (1) , D
(1) , E (1) , and G (1) . Skaar (1989) found higher concentrations
of rainbow trout in the Big Hole River and Governor Creek about
15 miles upstream of the 1989 study area and theorized that the
rainbow trout present in the Wisdom area had drifted down from
this upstream area.

Burbot (Lota lota ) , longnose dace ( Rhinichthy s cataractae ) ,
longnose suckers ( Catostomus platvrhynchus ) , white suckers (C.
commersoni ) , and mottled sculpin (Cottus bairdi ) were captured in
differing densities throughout the study area but were not
quantified (see Skaar (1989) for relative abundance and
distribution of these species) .

In most cases the distribution and relative abundance of
both Arctic grayling and brook trout in 1989 were very similar to
those reported by Skaar (1989) with the notable exception of the
lower density of YOY grayling in the lower portion of Swamp
Creek. This may have been due in part to the higher discharges
present in Swamp Creek in 1989 that may have lowered our capture
efficiency for these small fish.

Growth of Young-of-the-Year Fishes

Young-of-the-year Arctic grayling increased in mean total
length (TL+SD) from 2.52 + .08 in. on July 6 to 4.08 + .24 in. on
August 28, 1989 (Table 3, Fig. 2). These lengths are very
similar to those found by Skaar (1989) for the same area in 1988
but, as Skaar (1989) pointed out, these are much larger than the
lengths reported by Liknes (1981) for YOY grayling in the
tributaries of the Big Hole River in 1979. Liknes (1981)
reported mean TLs of 2.17 + .22 inches for the period of July 11-
15, 1979, while Skaar (1989) found that for the period of July
12-14, 1988 the grayling were 2.68 + .19 inches in mean TL. For
the period of July 11-14, 1989, 80 YOY Arctic grayling sampled in
four areas of the Big Hole River showed a mean TL of 2.55 + .15
inches. The size differences between these years may be related
to water temperatures.

14

Table 3 . Mean and range of total length of YOY Arctic

grayling, mountain whitefish, and brook trout in the
Big Hole River drainage, July 6 to August 28, 1989.

Grayling Whitefish Brook Trout

Mean Rng. N Mean Rng. N Mean Rng. N

Date (±SD) (±SD) (±SD)

Jul 6 2.52 2.4- 5 2.63 2.5- 26 2.54 1.9- 85

(0.08) 2.6 (0.11) 2.9 (0.26) 3.1

Jul 11-14 2.55 2.1- 80 2.83 2.3- 9

(0.15) 3.0 (0.23) 3.0

Jul 17-20 2.80 2.4- 101 2.92 2.4- 39 2.66 2.1- 33

(0.19) 3.2 (0.24) 3.6 (0.41) 4.5

Jul 21-24 2.69 2.3- 9 3.35 3.0- 17 2.63 2.6- 4

(0.19) 3.0 (0.19) 3.6 (0.05) 2.7

Jul 26-27 3.06 2.9- 5 2.73 1.7- 67

(0.15) 3.2 (0.66) 4.6

Aug 1-3 3.42 3.0- 203 3.43 2.9- 60 3.11 2.7- 25

(0.18) 3.8 (0.22) 4.1 (0.22) 3.6

Aug 7-10 3.68 3.0- 144 3.49 3.0- 52 3.11 2.2- 58

(0.19) 4.1 (0.19) 3.8 (0.41) 3.9

Aug 14-16 3.70 3.3- 19 3.53 3.0- 12

(0.22) 4.1 (0.25) 3.9

Aug 17-21 3.90 3.3- 33 3.64 3.1- 7 3.40 3.0- 5

(0.28) 4.4 (0.33) 4.0 (0.22) 3.5

Aug 28 4.08 3.7- 55 3.69 3.2- 33 3.71 3.5- 8

(0.24) 4.7 (0.19) 4.1 (0.16) 4.0

15

4.6

TOTAL LENGTH (IN)

4.0 h

LZ3 GRAYLING □ WHITEFISH

BROOK TROUT

7/6

7/11-
14

7/17-
20

7/21-

24

7/26- 8/1-
27 3

DATE

8/7-
10

8/14-
16

8/17-
21

....

/
/
/"

*'/

/
/

/
/

*

8/28

Figure 2. Mean length of young-of-the-year Arctic grayling

(NM654), mountain whitefish (N=255) , and brook trout
(N=285) versus date for the Big Hole River and its

tributaries, July 6 to August 28, 1989.

16

Mountain whitefish appeared to grow more rapidly than
either grayling or brook trout between July 6 and 24, after which
grayling grew more rapidly and surpassed whitefish in mean TL.
Young-of-the-year brook trout grew relatively slowly and showed a
greater variation (some very small age 1+ may have erroneously
been included in the calculation of YOY mean TL) . Skaar (1989)
reported very similar growth rates for both Arctic grayling and
brook trout in these waters during the summer of 1988.

Condition factors (K) were calculated for 4 6 age 1+ Arctic
grayling captured during July and August, 1989 in the study area
for comparison with the condition factors reported for the same
waters by Liknes (1981) for 1979 and by Skaar (1989) for 1988.
For grayling between 6.4 and 13 inches TL the mean K value (±SD)
was 1.10 (±.20). This was higher (the fish were in better
condition) than those measured by either Liknes (1981) [K=0.95
+.08] or Skaar (1989) [K=1.06 ±.11]. Flows were slightly higher
and temperatures were slightly cooler during the summer of 1989
than they were during the same period of 1988 which may help
explain the healthier individual fish. One could also speculate
that with the much reduced densities of age 1+ grayling since
1979, the grayling that survive to age I have considerably less
competition for food and space, if food and space are limiting.

Habitat Utilization by Young-of-the-Year Arctic Grayling

Macrohabitat Utilization

The east channel of the Big Hole River (section G) was
chosen for habitat measurements due to the high densities of YOY

Arctic grayling found there. Four areas were intensively
measured with respect to depth, velocity, substrate, and cover to
develop an index of availability for these parameters in an
attempt to determine whether YOY grayling were selecting habitat
types in proportion to their occurrence.

Seventeen YOY grayling were captured in macrohabitat area 1
(Fig. 3) which was located approximately 2 00 feet upstream of the
•intensive-use area C 1 described in Skaar (1989) and was in an

17

area marked by two orange-colored • spawning flags • which were
placed by MDFWP personnel at locations where adult spawning
grayling were captured during electrof ishing in late April and
May, 1989. The presence of large concentrations of YOY grayling
in areas where spawning grayling were captured suggests a high
site fidelity of YOY grayling to the areas in which they were
spawned .

Area 2 (a and b) (Figs. 4 and 5) consisted of one long
riffle-pool-riffle sequence and was located approximately 500
yards upstream of area 1. Area 3 (Fig. 6) was actually the
downstream end of a very long riffle-run-pool-riffle complex of
which area 4 (Fig. 7) was the upstream portion. These are
presented primarily to show the location of YOY grayling capture
sites that resulted from the downstream run with the backpack
shocker. Most of these fish were captured in a small sidewater
pocket immediately upstream of a shallow riffle. Though herding
was not directly observed in this case, it seems likely that the
fish were driven from the pool-run habitat upstream of the
capture sites. No YOY grayling were captured with either the
grids or the backpack shocker while moving in an upstream
direction in this general area. Area 4 was upstream of, and
separated from, area 3 by a 140 foot long shallow run. There
were no YOY grayling collected in this run area, as the grayling
were probably driven out while the electrof ishers were walking
through the area. Grids set in this shallow run also yielded no
YOY grayling. The upper boundary of area 4 was located on a
riffle that adult grayling may have spawned on during the Spring
of 1989, however no "spawning flag' was visible in the area
(livestock in this area had eaten or displaced many of our
flagging markers and may have made the • spawning flags ' less
visible) .

Typically, the fish captured while electrof ishing in an
upstream direction were concentrated in areas that: 1) provided
some type of cover, and 2) acted in some way as a visual barrier
to further upstream movement. These areas were usually

18

o 6 <,a

Figure 3. Depth (ft) isopleths for macrohabitat area l on the
lower east channel of the Big Hole River below
Wisdom. YOY grayling that were captured while moving
upstream, moving downstream, and in the grids are
marked by triangles (a), circles (•) , and squares
(■), respectively. Letters along streambanks denote
transect points.

19

Figure 4. Depth (ft) isopleths for macrohabitat area 2a (lower
portion) on the lower east channel of the Big Hole
River below Wisdom. YOY grayling that were captured
while moving upstream, moving downstream, and in
grids are marked by triangles (*) , circles (•) , and
squares (») , respectively. Letters on streambanks
denote transect points.

20

£ ,0

*k-"" f

ft

Figure 5. Depth (ft) isopieths for macrohabltat area 2b (upper
portion) on the lower east channel of the Big Hole
River below Wisdom. YOY grayling that were captured
while moving upstream, moving downstream, and in
grids are marked by triangles (a) , circles (•) , and
squares (■), respectively. Letters on streambanks
denote transect points.

21

4= UfSTfieA*) ClT

•ft

N

Figure 6. Depth (ft) isopleths for macrohabitat area 3 on the

lower east channel of the Big Hole River below Wisdom.
YOY_ grayling that were captured while moving upstream,
moving downstream, and in grids are marked by
triangles (a), circles (•), and squares (■) ,
respectively. Letters on streambanks denote transect
points.

22

» = ^R,X) (4-)

Figure 7. Depth (ft) isopleths for macrohabitat area 4 on the

lower east channel of the Big Hole River below Wisdom.
YOY grayling captured while moving upstream, moving
downstream, and in grids are marked by triangles (a) ,
circles (•) , and squares (■) , respectively. Letters on
streambanks denote transect points.

23

depressions in the streambed immediately below a shallow riffle.
These types of capture sites indicate that these fish may have
been 'herded* upstream into these areas from habitat they
actually preferred. In similar fashion; fish captured while
electrofishing downstream tended to be concentrated in areas that
provided them with cover and occasionally that served as some
sort of visual barrier to further downstream movement. Whether
the shallow riffles were actually visual barriers, or whether the
grayling did not feel secure crossing them is not known, but they
rarely would move through these riffle areas.

For 33 YOY grayling captured in grids, the mean distance to
the nearest upstream riffle was 74.5 ft, while the mean for the
fish collected while electrofishing upstream (sample of 35) was
only 39.2 ft (Table 4). The YOY grayling collected while moving
downstream (sample of 42) were an average of 158.5 ft below the
nearest upstream riffle. A similar, though inverse, relationship
is seen in the values presented for the distances above the
nearest downstream riffle, the grid fish are intermediate in
distance while the fish collected while moving downstream are
closest and the fish collected while moving upstream are furthest
from the downstream riffle. This indicates that these YOY
grayling may have been displaced by the presence and movement of
the electrofishers and that the grid method may provide more
accurate results with respect to microhabitat information.

The typical macrohabitat area parameters that appeared in
all 'intensive-use areas' were, 1) a sloughing outside bank,
providing soil clumps of varying size and age, 2) at least one
pool area with depths in excess of 1.5 ft, 3) presence of
extensive mats of aquatic vegetation, 4) proximity to a riffle
with relatively loose substrate particles that may have served as
spawning habitat for adult grayling, and 5) streambanks.

24

Table 4. Habitat features for YOY grayling collected in grids

(N=33) , electrof ishing upstream (N=35) , electrof ishing
downstream (N=42) , and macrohabitat in adjacent areas
(N=1311) on the east channel of the Big Hole River
below Wisdom, August, 1989.

Grid

Upstream Downstream

Macrohab .

Variable

Mean Rng. Mean Rng. Mean Rng. Mean Rng.

Depth (ft) 1.32 .54-

2.58

,98 .38- 1.10 .42-
1.67 2.08

.83

0.0-

3.10

Mean Vel
(ft/s)

,78 .10-
1.84

.59 0.0-
2.18

32 0.0-
1.50

,29

0.0-

2.35

Bottom
Vel (ft/s)

Dist to
Cover (ft)

,56 0.0-
1.50

.46 0.0-
1.80

.27 0.0-

1.47

1.02 0.0- 1.16 0.0- 1.43 0.0-

6.50

4.00

Embedded- 40.75 20- 52.43 25- 44.16
ness (%) 70 100

Substrate

4.50

20- 69.45 20-
75 100

Silt (%)

8.33

5-
30

13.86

5-
50

18.45

5-

50

27.

,86

0-

100

Sand (%)

14.54

5-
60

30.71

5-
80

19.76

5-

70

28.

,51

0-

100

Small
Grav (%)

12.58

5-
30

11.86

0-
50

12.38

5-
30

8.

,72

0-

100

Large
Grav (%)

34.39

5-

70

30.57

0-

65

31.54

5-
65

27,

,37

0-

100

Cobble
(%)

30.15

0-

60

13.00

0-

40

17.62

0-

55

6,

,87

0-

100

Dist to
Upstream
Riffle (ft

74.47
■)

8-

215

39.24

5- :

201

158.48

16-

321

Dist to
Downstrm

Riffle (ft

159.59
■)

56-

261

191.08

15-
375

85.79

10-
300

"

"

""

25

supporting permanent perennial grasses and sedges. Mean depth and
velocity for the macrohabitat areas were 0.83 ft and 0.29 ft/s,

respectively. These mean depths and velocities are slightly less than
the means for these parameters measured at the capture sites.

Microhabitat Utilization

Depth and Velocity

Habitat preference is exhibited when fish utilize a particular
habitat variable with greater frequency than it is available (Bovee
1986) . Young-of-the-year Arctic grayling utilized deeper areas of the
Big Hole River with a frequency slightly higher than availability
(Figs. 8 and 9). They also selected higher velocity areas (Figs. 10
and 11). Availability was determined by measuring at 1,311 points
along transects in macrohabitat areas. Since these areas may have
been of higher quality and of different composition than in unused
surrounding macrohabitat areas, these determinations of preference may
be inaccurate. Random sections of stream were not measured to develop
a true index of availability.

Cover

The average distance from a capture site to the nearest cover for
grid-captured YOY grayling was 1.02 ft. Aquatic vegetation was the
cover type closest to 80% of these sites (Tables 4 and 5) . Skaar
(1989) reported similar findings for these measures of 0.92 ft and
86%, respectively. Rannunculus aquatilis and Elodea canadensis were
the primary species of aquatic vegetation (Skaar 1989) . Other cover
frequencies were also similar to those reported for the same area in
1988 by Skaar (1989) . Aquatic vegetation and soil clumps were
utilized in slightly higher proportion than they occurred, while pools
were utilized in slightly lower proportion than they occurred.
Debris, terrestrial vegetation, and banks were used in approximate
proportion to their occurrence.

26

a; availability

U)

u

z
111
I

£t

D

o
o
o

u.

>

o

z

ID
D

1U
DC

u.

240

aoo

ISO

ISO

eo

■no

b; use

30

25

20

IT"! 1 I [ 1 1 1 1 I 1 1 1 r i 1 1 I 1 I 1 1 1

l 1 1 J 1 l l I J l 1 1 11 1

m
oc

3
f-

<

o

u.
o

U 15

z
111

3
O
Ul

a.
u.

10

Jjg 3_i..J I 1 1 1 1 I 1 1 1 r

O .83

C

■4

O.BB H

r

H

N
>

O.S H

H

z

.33 H

z

D

m

O.IB-' x

O . 5

1.5 2 2.5

DEPTH (FT)

3 . 5

o

A

Figure 8. A. Frequency of depth measurements in macrohabitat
areas of young-of-the-year Arctic grayling in the
Big Hole River.

B. Frequency of depth measurements at capture sites of
young-of-the-year Arctic grayling in the Big Hole
River.

27

A; AVAILABILITY

ui
u

2
IU
I

a.

3
U

o
o

U.

>

o

2
UI
3
O
UJ
I
IL

ISO

120

so

so

30

'R5j ' [ ' ' ' | ' > ' | i i I [ 1 I l | I I I | I I I | I l I | I l l | I I [

IU

DC
3
h
Q.
<
U

lL

o

y
u

2
111
3

III
It
lL

30

25

20

as

10

BS USE

| l I l | I II | l I I | I I I | I I I | I II | l I l I l I'll a

— O.B3

O .66

O.S

— 0.33

■ — O . IB-

C
H
H

r

H
N
>

■^

H

o
z

H

z

D

m
x

Figure 9. A. Frequency of mean velocities for macrohabitat areas

of young-of-the-year Arctic grayling in the Big Hole
River.

B. Frequency of mean velocities at capture sites of

young-of-the-year Arctic grayling in the Big Hole

River.

28

Cover Type

Capture Sites (%)
(Use)

Aquatic Vegetation

80

Pool

11

Soil Clump

4

Debris

1

Terrestrial Veg.

1

Bank

2

Table 5. Frequency of cover types within a 3.28 square foot area
centered where young-of-the-year Arctic grayling were
captured with electrofishing grids and of cover types
within the larger macrohabitat areas on the Big Hole

River.

Macrohabitat (%)
(Availability)

75

19

1

2

1
1

Substrate

Silt comprised 27.86% of the substrate materials in the
macrohabitat areas and only 8.33% in grid-capture sites (Table 4).
Embeddedness was lower and the percent substrate composition made up
by larger particles (large gravel and cobble) was higher at grid-
capture sites than in the adjacent macrohabitat areas, indicating a
possible preference for clean substrate with larger particles.

Temperature

Stream temperatures were only randomly recorded and were not
always taken when the water temperature was at its daily maximum,
therefore the data in Table 6 are presented only to provide a very

general thermal trend through time. The highest maximum daily water

temperatures occurred from the end of July through the first week of
August and appear to be lower, in general, than temperatures recorded
in the same area in 1988 (Skaar 1989) . No thermally induced mortality
was observed.

29

Table 6. Maximum daily water temperatures recorded on the Big

Hole River and its tributaries, June 26 to August 22, 1989.
Temperatures from a USGS station at the Wisdom Bridge are shown
in brackets (only data available at press time was for June
1989) .

Date Time Sample Section Temperature ( F)

C 64 [64.4]

E 64 [68.4]

B 63

C 70

F 64

G 64

C 66

D 70

H 68

F 68

I 72

B 65

G 67

G 68

B 72

G 75

G 60

G 66

June

26

1900

June

28

1425

July

11

1200

July

12

1505

July

13

1230

July

17

1645

July

18

1410

July

19

1345

July

24

1255

July

25

1420

July

26

1200

August 1

1230

August 3

1435

August 7

1345

August 8

1415

August 9

1645

August 21

1530

August 2 2

1513

30

Flows

Streamflow discharges were much higher in the upper Big Hole
River drainage during the summer of 1989 than they were the previous
summer. Figures 12 through 15 present the range of flows recorded at
each of four staff gauge sites with 95% confidence limits.

Stomach Content Analysis

Arctic grayling in the Big Hole River and its tributaries appear
to select different types of food items than the brook trout in the
same areas during the summer months. Grayling between 6 and 10 inches
(N=9) had stomach contents consisting of 32% mayflies by volume while
brook trout of the same size (N=3 0) showed 23% of their contents to be
made up of a variety of fish (Fig. 16) . Grayling also tended to
utilize other organisms present on the water surface, such as stonefly
adults and terrestrial insects , in much greater proportion than did
brook trout. Larger grayling (>10") (N=3) showed a more dramatic
preference for surface food items (adult mayflies, caddisflies,
stoneflies, and terrestrial insects) than did similarly sized brook
trout (N=5; Fig. 17). Subsurface food items such as fish, leeches,
and cranefly larva comprised the majority of the diets of larger brook
trout .

Arctic grayling in the upper Big Hole River drainage seem to show
a strong preference for surface food items while brook trout consume a
larger proportion of subsurface items, indicating that there may be
little direct competition for food between the two species during the
summer months. This situation may change considerably during the
winter months when surface food items probably become less available.
Of the fish found in stomachs of brook trout none could be positively
identified as grayling fry or YOY. The majority of the fish present
in the stomach samples

31

2.3

h

h

I
S
H

UJ

I

UJ

D
<

T-r-i — r*r

i — i — I — i — r

s. i

1 .3

i .a

TT-j-r-T-^r

1.7 tjJll_J-_J_J-^_J__J_J__^^

J I L_J_

26 3B -46 SB SB

FLOW (CFS)

J I I L

76

Figure 10. Gauge height (ft) versus streamflow discharge (CFS)

for the west channel of the Big Hole River below Wisdom. Dashed
lines represent 95% confidence limits.

32

2.7

UI

D
<

t — I — i — r

b a.s

h

l
o

H
UI
I

2.3

2. 1

1.8

J_U__L

r -- r ™- 1 ^ 1 ^ T _ T

>^ " « "
• % „ ..... .^c . ..«.......,„*...

9 y^

a ^^^ *

° * ' " * * * * \ ° " ° * * - ° ' J.X" ° " '• * ' ** ' *.»**«»* "« „ ffl a 8 „ . m , . .

v _/^ *> -

a» >^ «s» ° *

* * ^^ *

* >*^ *»

." * » .

«* .

J 1 I L

J 1 L_L

J L L

lO

20
FLOW (CFS)

30

«40

Figure 11. Gauge height (ft) versus streamflow discharge (CFS)

for the east channel of the Big Hole River immediately upstream
of the mouth of Steel Creek. Dashed lines represent 95%
confidence limits.

33

h

lL

h

I

e

H

ai
I

UJ
CD

3
<

1 .6

1 .-4

i .a

i — i — | — | — j — , — r

i i |~~i — i — i — | — i — r~i — [ i - j—p -

o.s

0»6

FLOW (CFS)

Figure 12. Gauge height (ft) versus streamflow discharge (CFS)

for the east channel of the Big Hole River below the mouth of
Steel Creek. Dashed lines represent 95% confidence limits.

34

i .7

SO

FLOW (CFS)

Figure 13. Gauge height (ft) versus streamflow discharge (CFS)
for Swamp Creek at the North Fork Road Bridge. Dashed lines
represent 95% confidence limits.

35

p

E
R
C
E
N
T

O

F

V
O
I
U
M

MAY CAD STN SCUD AQBTL TER LCH WRM FSH

FOOD ITEM

CRN

Figure 14. Percent volume of stomach contents of 6 to 10 inch

Arctic grayling and brook trout from the Big Hole River and its
tributaries made up of various food items.

MAY=Mayfly, CAD= Caddisfly, STN=Stonefly, SCUD=Amphipod Crustacean,
AQBTL=Aquatic Beetle, TER=Terrestrial Insect, LCH=Leech, WRM=Worm,
FSH=Fish, CRN=Cranefly

36

p

E
R

C
£
N
T

O

F

V

o

L
U
M
E

MAY GAD STN SCUD AQBTL TER LCH

FOOD ITEM

WRM FSH CRN

Figure 15. Percent volume of stomach contents of 10 inch and

larger Arctic grayling and brook trout from the Big Hole River
and its tributaries made up of various food items.

MAY=Mayfly, CAD=Caddisf ly, STN=Stonef ly f SCUD=Amphipod Crustacean,
AQBTL=Aguatic Beetle, TER=Terrestrial Insect, LCH= Leech, WRM=Worm,
FSH=Fish, CRN=Cranefly

37

of brook trout were, in approximate order of abundance, sucker fry,
adult longnose dace, and YOY mountain whitefish. Though brook trout
predation on grayling fry has been documented (Nelson 1954) , it was

not seen in any of the samples collected in this study. The stomach
pumping portion of this study began when the YOY grayling were
approximately 2.5 inches long, which may be beyond the size that would
be consumed, though many of the dace and whitefish were larger than
this.

Movements of Young-of- the- Year Arctic Grayling

The « spawning flags • placed in locations where MDFWP personnel
captured spawning grayling during the Spring of 1989 were often close
to the areas where large concentrations of YOY grayling were found.
Spawning typically took place on "riffle areas with clean surface
gravel which appeared 'bright 1 near pool or run habitats" (Shepard and
Oswald 1989) . The flags that marked these areas were often on riffles
immediately upstream or downstream of the capture sites (which were
often in pool or run habitats) , thus it seems likely that grayling
reared in an area stay in that area through at least their first
summer. Work by Kaya (1989) showed that Big Hole River Arctic
grayling fry exhibited the greatest tendency to remain stationary
(maintain their position with respect to linear flow) in an artificial
stream current of four populations he examined.

Twenty-nine YOY grayling were marked in one area (in section G)
of which 11 were later recaptured. Nine of these were recaptured in
the same general area about three weeks later and two were recaptured
approximately 100 feet upstream three days after initial capture.
This supports the idea that these fish are loyal to a given area
(which may be as large as one riffle-pool-riffle complex) . Direct
observation suggests there may have been some daily movement among the
YOY grayling within an area. It appeared that the fish would remain
in or near aquatic vegetation in pool or run areas until about 1000
MDT (when water temperature reached about 59 F) when they would move
upstream closer to riffles to begin surface-feeding on small mayfly
spinners. This daily type of movement was supported, though not

38

conclusively , by capture in grids.

Conclusions and Recommendations

The Arctic grayling population in the Big Hole River system has
been detrimentally impacted by an unknown combination of factors in
the recent past. Changes in water use, land use, and the introduction
of non-native species are among the factors which could have
contributed to an overall decline in the grayling population. The
isolation of factors that may be contributing to the decline of this
population is difficult in a system as large as the Big Hole River
drainage. Studies such as this, which focus on the present
distribution of, and habitat utilization by, a particularly sensitive
segment of the population (the young-of-the-year) are important and
useful in that they add to the base of knowledge available for future
management decisions and serve as pieces in the puzzling question of
why this population is so rapidly declining.

Work by Skaar (1989) , Shepard and Oswald (1989) , Liknes (1981) ,
and Kaya (1989) has brought forth information on the distribution,
habitat utilization, and behavior of these fish. Much more work is
needed however before the problem of the declining grayling can be
remedied. The Montana Department of Fish, Wildlife and Parks has
collected fertilized eggs from one spawning season (1988) and planted
the fry in a mountain lake for future brood stock of Big Hole River
Arctic grayling in the event that they are needed to restock or
supplement the population in the Big Hole River. This type of
management may be largely ineffective, however, until the problems
within the system are identified and steps are taken to lessen their
negative effects.

Laboratory studies on interspecific competition between grayling,
brook trout, and brown trout will help to clarify the role of
introductions of brook trout and brown trout in the decline of the
grayling. Thermal studies concerning the tolerances of all life
stages of grayling as well as continued field studies, particularly
those focusing on the winter habitat use of the grayling and the other
saimonids and land and water use in the Big Hole River Valley, are

39

needed to make the information available for future managers more
complete.

LITERATURE CITED

Bain, M.B., J.T. Finn, and H.E. Booke. 1985. A quantitative method
for sampling riverine microhabitats by electrof ishing. N. Am.
Jour. Fish. Mgt. 5:489-493.

Bovee, K.D. 1986. Development and evaluation of habitat

suitability criteria for use in the Instream Flow Incremental
Methodology. Instream Flow Information Paper 21. U.S. Fish and
Wildl. Serv. Biol. Rep. 86(7). 235 pp.

Kaya, CM. 1989. Innate differences in behavioral responses to water
current of Arctic grayling from fluvial and lacustrine
populations in Montana. 119th Annual Meeting of the American
Fisheries Society, Anchorage (abstract) .

Light, R.W. , P.H. Alder, and D.E. Arnold. 1983. Evaluation of
gastric lavage for stomach analyses. N. Am. Jour. Fish. Mgt.
3:81-85.

Liknes, G.A. 1981. The fluvial Arctic grayling ( Thymallus

arcticus) of the upper Big Hole River drainage, Montana. M.S.
Thesis, Montana State University, Bozeman. 59 pp.

Nelson, P.H. 1954. Life history and management of the American

grayling ( Thymallus signifer tricolor ) in Montana. Jour. Wildl.
Mgt. 18(3) :324-342.

Shepard, B.B., and R.A. Oswald. 1989. Timing, location and

population characteristics of spawning Montana Arctic grayling
( Thymallus arcticus montanus [Milner] ) in the Big Hole River
drainage, 1988. Montana Department of Fish, Wildlife and Parks,
Bozeman. 38 pp.

Skaar, D. 1989. Distribution, relative abundance and habitat

utilization of the Arctic grayling ( Thymallus arcticus ) in the

upper Big Hole River drainage, Montana July 5 to September 8,
1988. Report for the Montana Natural Heritage Program, Helena.
53 pp.

40

© 1990 Montana Natural Heritage Program

This document should be cited as follows:

McMichael, G.A. 1990. Distribution, relative abundance and habitat utilization of the Arctic grayling
(Thymallus arcticus) in the upper Big Hole River Drainage, Montana. June 21 to August 28, 1989.
Montana Natural Heritage Program. Helena, MT. 40 pp.