CHAPTER II
LIFE HISTORY OF THE GRAYLING
(Thymallus arcticus) IN BEAUFORT SEA
DRAINAGES IN THE YUKON TERRITORY
M. de BRUYN
P. McCART
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ERRATA- VOLUME FIFTEEN
TABLE OP CONTENTS
line 2:
line 24:
"LANDS" should read "LAKES"
"SPRING TIED" should read "SPRING FED"
Chapter I
p.l7, COMMENTS,
line 3:
p.49, Conductivity:
p.l41, COMMENTS:
p.l52, Sample
locality:
p.l54, Sample
locality:
"large on" should read "large one"
"7200" should read "200+"
"0 ygen levels" should read "Oxygen levels"
"3 1/2 m" should read "3 1/2 miles"
"2 mi" should read "2 miles"
Chapter II
p.3, line 21:
p.4, line 12:
p.7, line 17:
p.S, line 8:
p.22, line 12:
p.22, line 14:
p.23, line 13:
p.27, line 9:
p.27, line II:
p.28, line 4:
p.30, line 2:
p.38: Delete references:
"Aquatic Environments Limited, Winter Data Report" shoud read
"Chapter I of this volume"
"60 F" should read "15 C"
"the fish had been aged" should read "the ages of the fish had been
determined"
"For the purpose of aging" should read "To determine age"
"ration (Table IV). the sex" should read "ratio (Table IV). The sex"
"the Age" should read "the age"
"fecudnity" should read "fecundity"
"Probably" should read "Probable"
"the occurance" should read ", and the occurrence"
"downstream" should read "upstream"
"Craig, 197 3" should read "Chapter III of this volume"
"Aquatic Environments Limite!!!. 1973 .... "
"Craig, P.C. 1973 ... ."
Add references:
"Brown, J .E. 1970. Permafrost in Canada- Its influence on northern
development. Univ. of Toronto Press, Toronto."
"Duncan, D.B. 1955. Multiple range and multiple F tests.
Biometrics, II: 1-42."
)
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TABLE OF CONTENTS
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Page
1.0
INTRODUCTION
1
~.0
DESCRIPTION OF THE STUDY AREA
1
.1
Physiography
1
.2
Streams
2
.3
Lakes
4
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3.0
MATERIALS AND METHODS
5
4.0
RESULTS AND DISCUSSION
8
.1
Distribution of Grayling in the Study Area
8
.11
Firth River
9
.12
Babbage River System
10
.13
Other Mountain Streams
11
.14
Tundra Streams
11
.15
Lakes
12
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.2
Age & Growth
~~-
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.21
First Year Growth
13
.22
Growth of Older Fish
16
[
.23
Comparison with Growth in Other Areas
21
.3
Age at Maturity
21
.4
Sex Ratios
22
[
.5
Egg Size, Fecundity and Frequency of Spawning
22
,6
Spawning Period
25
[
.7
Fry Emergence
26
.8
Spawning and Rearing Areas
27
.9
Movements in Streams and Overwintering Areas
29
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~--'\..,.__
______
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.10
Food Habits
35
.11
Parasites
37
LITERATURE CITED
38
Following page
PLATES
39
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LIST OF FIGURES AND TABLES
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Follows Page
Figure 1.
Map of the study area showing the location of streams
and lakes.
number.
[
[
[
Unnamed waterbodies have been assigned a
Black triangle indicates location of sam-
pling site at the head of the Firth River Delta.
Figure 2.
Location of spring-fed aufeis fields in the study
Table
1.
Distribution of fish species in lakes examined during
the Yukon Territory, 1972.
Figure 3.
[
Figure
4.
Fish sampling sites.
Distribution of grayling in samples.
captured.
Closed circles
12
th~-year
Figure 5.
Open circles are those at which young-ofwere taken.
Comparison of late summer growth of fry from Stream
1000 and Trail River.
[
16
Temperature at the two study
sites also shown.
Figure 6.
Comparison of age-length relationships determined
20
from both scales and otoliths for grayling from the
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10
are sites at which adult and juvenile grayling were
[
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4
fisheries investigations in Beaufort Sea drainages in
[
[
4
area.
[
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2
Lower Firth River.
Figure 7.
Comparison of age-length relationships determined
from both scales and otoliths for grayling from
Trout Lake.
[
[
iii
20
[
[
Follows Page
Figure 8.
Comparison of growth rates of grayling from the
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22
Firth River, Trout Lake 100 with those of other
[
populations from Alaska and the Canadian Arctic.
Figure 9.
Numbers of males and females in various size classes
24
in samples from three localities in the Yukon
Territory.
Figure 10.
[
Seasonal development in egg size for mature grayling
26
[
from three locations on the Yukon North Slope.
Figure 11.
[
Probable spawning areas for grayling along the
Yukon North Slope.
28
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1.0
INTRODUCTION
The grayling (ThymaZZus aratiaus), an important sport fish,
is one of the most widely distributed species in the Western
Arctic (Plate 1).
This report describes the distribution and
life history of the species in Beaufort Sea drainages of the
[
[
[
[
Yukon Territory.
These studies are part of the efforts being
expended to determine the ecological impact of the construction
and operation of the gas pipeline proposed by Canadian Arctic
Gas Study Limited.
The studies were conducted through Northern
Engineering Services Limited.
They were concentrated on streams
and lakes along the proposed pipeline route from the AlaskaYukon border east to the Yukon-Northwest Territories border.
[
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2.0 'DESCRIPTION OF THE STUDY AREA
The study area and the names of the major drainages are shown
in Figure 1.
.1
Physiography
There are three major physiographic divisions within the study
area:
[
1.
[
[
[
The Arctic Coastal Plain including the zone between
the Beaufort Sea Coast and the 500 feet contour to
the south.
In the study area, the plain is very narrow
ranging from less than 5 miles in the vicinity of Fish
Creek to little more than 18 miles in the vicinity
[
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of the Walking River.
[
The topography of the plain
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in the study area is somewhat rolling, not nearly as
level as it is further west in Alaska (eg. in the vicinity
of Prudhoe Bay).
[
In the more level areas drainage is
poor with extensive marshy areas and shallow, often
[
undrained lakes and ponds.
[
2.
The Arctic Foothills include the area between approximately
the 500 feet and 2500 feet contours.
typically rounded.
[
The hills are
Drainage is good and there are a
[
number of small lakes scattered throughout the area.
3.
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The Arctic Mountains including in our area, from west
to east, the British, Barn and a small portion of the
Richardson Mountains.
There are few lakes within the
[
mountains but a number of important streams originate
there.
.2
[
[
Streams
In this area, the streams important to grayling can be placed
[
in two general categories, Mountain Streams and Tundra Streams.
[
Mountain streams originate in the Arctic Mountains and flow northward,
[
through the foothills and across the coastal plain to enter
the Beaufort Sea.
These are generally large streams, frequently
braided, both in their headwaters and near their mouths (Plate 2).
Water
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Lake 104
Lake 103
Firth Lake
Lake 107
Lake 108
Lake 105
Lake 110
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Lake 100
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Bloomfield Lake
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Lake 102
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Lake 106
Lake 109
Lake 101
~ Trout Lake
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Figure 1. Map of the study area showing the location of streams and lakes.
Unnamed water bodies have been assigned a number. Black triangle indicates
location of sampling site at the head of the Firth River Delta.
.
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----------- - - - - - -
levels fluctuate considerably both during the spring and early
summer when snow melt occurs and later in the
summ~r
fall as the result of rainstorms in the mountains.
the mountain streams become quite turbid.
and early
During freshets
There are major springs
on some of the mountain streams (Fish Creek, the Firth and Babbage
Rivers, Joe and Canoe Creeks) and segments of these streams,
in the vicinity of perennial springs, flow throughout the winter
(Plate 3).
Such springs can often be identified by the large
areas of aufeis (layered ice) which form downstream during the
winter and may remain throughout the summer (Plate 4).
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Spring
areas are often important to spawning and overwintering fish
(Craig, 1973).
The locations of some important springs and extensive
aufeis areas are indicated in Figure 2.
Some mountain streams
in our area are apparently without drainage from perennial springs.
These include the Blow and Trail Rivers.
Tundra streams are typically small streams which originate in
the foothills or the Arctic Coastal Plain.
"'
Their primary sources
of flow are melt-water, runoff and lake drainage.
In our area,
-,:
only one perennial source of groundwater has so far been identified
-"
on a foothills stream, this a minor seep on the Spring River
(Aquatic Environments Limited, Winter Data Report).
For this
reason, tundra streams, almost without exception, are frozen
to the bottom throughout the winter.
-3-
Summer flows in the foothills streams tend to fluctuate less
than those in mountain streams.
Banks are generally stable
supporting a thick growth of dwarf willow and birch with a heavy
mat of mosses beneath (Plate 5).
In many places, particularly
on the Arctic Coastal Plain, the foothills streams are "beaded"
(Brown, 1971).
Large pools (the beads) have formed where massive
ground ice has melted out.
These pools, the bottoms of which
are covered with organic debris, alternate with straight stretches
of stream (Plate 6).
Where velocities are sufficient, the latter
are characterized by gravelly riffles.
Water temperatures in
the tundra streams are generally higher than those in mountain
streams, sometimes exceeding 60°F •
•3
Lakes
There are two types of lakes important to grayling in our study
area.
8).
These are Tundra Lakes and Foothill Lakes (Plates 7 and
The former are situated on the Arctic Coastal Plain.
are generally shallow and weedy:
They
Firth Camp Lake has a maximum
depth of approximately 2.5 m and Lake 100 a maximum depth of
approximately 3.0 m.
Many are even shallower and have insufficient
free water under winter ice, which averages approximately 2
m, to support fish populations (Table I).
generally deeper than Tundra Lakes.
Foothills Lakes are
Maximum recorded depths
are 10 m for Trout Lake, 12.5 m for Lake 105 and 13.4 m for Lake
107.
Their bottoms are generally stony without an extensive
development of the rooted aquatic vegetation which is a characteristic
feature of the shallower tundra lakes.
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3. 0
MATERIALS AND METHODS
Samples were obtained from most of the major lakes and streams
[
[
throughout the study area to determine the general distribution
of grayling.
These samples were obtained by a variety of methods
including monofilament gillnets, seine, back-pack electrofishing
[
units, fyke nets and angling.
[
In addition to this general sampling effort, more detailed life
history samples were obtained from three major and two minor
[
study sites.
The three major sites were:
the lower Firth River,
from the head of the delta (Figure 1) to its mouth; Lake 100, a
~
typical tundra lake located about 3 miles north of the pipeline
route and four miles south of Roland Bay; and Trout Lake, a
foothills lake situated about 40 miles south of the pipeline
[
route west of the Babbage River.
At each locality an effort
was made to obtain as full a size range as possible.
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Therefore,
the samples taken do not reflect the relative abundance of the
[
various age groups.
[
Grayling in the lower Firth River were sampled at a gillnet
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station at the head of the delta.
This station was monitored
at intervals from June 13 to September 12, 1972.
The sampling
gear consisted of a gang of variable mesh monofilament gillnets
(1, 1 1/2, 2, 2 1/2, 3, 3 1/2 and 4 inch stretch mesh) set within
a deep, backwater pool, usually for a 12 hour period.
size classes were sampled using a fine mesh seine.
--"
-5-
Smaller
Occasionally
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electrofishing and angling were used to obtain additional samples
downstream of the gillnet station.
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Lake 100 and Trout Lake were sampled by means of gangs of variable
[
mesh gillnets similar to those described above and with a five
foot diameter nylon mesh fyke net, and a fine mesh seine.
Sampling
was carried out on Lake 100 periodically from July 2 to August
25, and on Trout Lake from July 9 to September 12, 1972.
[
[
[
Since regular samples of young-of-the-year fry were not easily
obtainable from any of the three major study areas, fry only
were taken from two other areas, Stream 1000 and the Trail River.
Fry in Stream 1000 near the pipeline crossing were sampled weekly
between July 30 and September 12, 1972.
Samples were collected
[
[
[
by means of a fine mesh seine from small back pools and along
the stream edges.
In the Trail River, fry samples were collected
by electrofishing at a point about 10 miles above the pipeline
crossing.
The first samples were taken on August 2 along the
edges of a large deep pool below a 100 foot cliff.
Subsequent
[
[
[
samples were collected weekly until September 12 in a riffle
and shallow pool about 200 yards upstream from the first sampling
site.
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[
Between July 30 and August 5, 1972, samples of grayling fry were
obtained from 8 streams within the study area.
[
Water temperatures
and surber samples of benthic invertebrates were taken simultaneously
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in riffles in the vicinity of the sample sites.
-6-
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---------·-------·-·-----------------------·----
[
[
[
Grayling captured were retained for detailed examination, usually
performed on the day of capture.
Where this was not possible
the fish were frozen for later analysis.
[
[
During detailed examination, fork length and total weight were
[
the gonads.
recorded.
Sex and state of maturity were determined by examining
Fish which would not spawn in the next spawning
period, judging by the appearance of their gonads and by general
[
[
E
[
[
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body size, and which showed no evidence of previous spawning,
were classified as immature.
still attached to the ovarian wall or free within the abdominal
cavity, was regarded as positive evidence of previous spawning
in females.
In early summer immediately after the spawning
period, the distinction between small mature and immature fish
was not always clear.
[
[
In these cases a subjective assessment
of maturity was made on the basis of body size and external
features.
In a few cases this assessment was corrected once
the fish had been aged.
[
The presence of retained eggs,
Fish which would spawn in the next
spawning period were classified as mature but green.
Fish were classified as mature and ripe if sex products (sperm or eggs)
could be expressed by gentle pressure on the abdomen.
Females
which had recently spawned, and males that had exhausted their
milt supply, were classified as spawned-out.
,---'
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Gonads were removed from most fish over 150 mm in length.
Total
gonad weights were determined by weighing both gonads together.
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-7-
·-··-··-----------·--·---
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The width of the gonads at their widest point was also recorded.
Mean egg diameter was determined from the total length of ten
typical eggs aligned in a trough.
[
r-
For fecundity counts, subsamples
(approximately 10-15% of the total ovary weight) were weighted
and preserved in 10% formalin for later enumeration.
Total egg
counts were then determined by the simple ratio of number of
eggs in the subsample to the total number of eggs.
For the purpose of aging, scales were taken from an area just
[
[
L
[
above the lateral line and below the posterior portion of the
dorsal fin.
Scales were placed between two microscope slides
and read at a later date.
McCart et al (1972) have shown that
scales may give unreliable ages for grayling.
otoliths were also removed from each fish.
Therefore, both
These were placed
[
E
[
in a small vial containing a drop of glycerine, and read at a
[
later date under a binocular microscope.
An examination was made of the stomach contents of most fish
subject to detailed analysis.
First a rough estimate was made
of the percent of fullness of each stomach.
[
Then the contents
were listed according to major groups (ChiPonomidae, TPichoptePa,
4.0
[
L
etc.) without regard to the relative abundance of each group.
[
RESULTS AND DISCUSSION
[
.1
Distribution of Grayling in the Study Area
Localities at which sampling attempts were made are indicated
in Figure 3.
Those at which grayling were obtained are indicated
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-8-
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---·------- __,_____.,__
_________
-------------------~---------------
·---~··--------···--···-··-·--···
-----
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[
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in
Fig~re
4.
As the data indicate, grayling are widely distributed
in the study area.
In the following, the distribution of grayling
is discussed in more detail.
[
.11
[
[
[
Firth River - Grayling fry were rarely taken in the upper
Firth River, above the major aufeis
fish were abundant.
area (Figure 2) though larger
Of 191 grayling captured in the area September
25, 1972, only one (48 mm in length) was a young-of-the-year.
The smallest of the other 190 fish was 275 mm.
It would appear
that though grayling utilize this as a summer feeding and, possibly,
[
overwintering area, it is not an important spawning area for
this species.
__;
It is however, a major spring area utilized by
a large population of spawning and overwintering Arctic char.
Juvenile, young-of-the-year and adult grayling were distributed
[
throughout the middle course of the Firth River from below the
r
major aufeis
area to the head of the Firth Delta but except
for a concentration of fry at Castle Rock, near the mouth of
r
Muskeg Creek, they were not abundant.
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Adult and juvenile grayling were taken throughout the summer
[
[
L
L
at the gillnet station at the head of the Firth Delta and fry,
though difficult to sample, were found in the braided channels
within the delta.
- 9 -
[
Within the study area, grayling appear to make little use of
tributary streams.
Except for Joe Creek, a major spring-fed
[
[
tributary important to anadromous Arctic char, grayling were
absent from mountain streams entering the Firth River sampled
during the course of surveys.
In Joe Creek, a few adults were
taken but no juveniles or fry were located despite extensive
electrofishing.
r
[
[
Occasionally during the summer, adult grayling were taken from
[
Okpioyuak Creek, a tundra stream tributary to the lower Firth.
However, the presence of fish in this stream was sporadic because
of its extremely unstable nature.
Several times it dried up
almost entirely, only to flood overnight with the next rainstorm.
Kuparyuk Creek, another tundra stream with its mouth on the Firth
[
[
[
River about 1/2 mile from the ocean, also yielded only an occasional
grayling.
Reasons for this remain obscure, since the stream
flowed all summer.
.12
[
[
Babbage River System - The Babbage River is a
[
major mountain stream supporting a large population of grayling. There is
a major waterfall located about 50 miles south (upstream) of
[
the pipeline crossing, which presents an impassable barrier to
fish movements.
Above the falls is a series of perennial ground water
springs which support a large population of resident Arctic char.
L
[
Neither juvenile nor mature grayling have yet been captured above
these falls, but three grayling fry were taken on August 28,
1972, about one mile downstream of the springs.
- 10 -
This suggests
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.,
<.0
J
J
J
J
J
J
J
J
J
0
J
J
J
J
J
J
J
[
[
[
[
[
[
that a spawning population of grayling does exist somewhere
above the falls.
~elow
the falls, few mature grayling were taken in the Babbage
River itself.
Of the 95 grayling sampled, only 3 were mature.
All others were fry and juveniles up to 172 mm in length.
seems likely that most of the adult fish and larger juveniles
do not spend the summer in the Babbage River.
[
[
c
c
c
c
[
It
Large numbers
of adults and older juveniles were, however, present in the
spring waters of Canoe (Fish Hole) Creek, a major tributary and
overwintering site for anadromous Arctic char.
Of the 26 fish
sampled from this area, the smallest had a fork length of 226
mm.
The Trail and Crow Rivers, two mountain streams tributary
to the lower Babbage River, contain large numbers of young-ofthe-year grayling, plus some mature and juvenile fish, though
only in their lower halves.
No fish were found in the upper
courses of either of these rivers.
.13
Other Mountain Streams - Other mountain streams
which were found to support populations of grayling are the
[
[
Blow River and its major tributary, Rapid Creek to the east and
Craig Creek to the west.
These streams were sampled only qualitatively
to determine species present in the vicinity of the pipeline.
[
.14
[
[
Tundra Streams - Tundra streams which were found to
contain grayling are Stream 1000, Peatbog Creek, Deep Creek,
Walking River, Tundra Creek and Stream 1003 (Figures 1 and 4).
- 11-
--------··------
[
With the exception of Stream 1000, these were sampled only qualitatively
in the vicinity of the pipeline.
Stream 1000 was extensively
[
[
surveyed from the air on July 30, 1972 and only twelve adult
grayling were seen in its entire length.
-,
However, fry were very
abundant at that time, particularly near the pipeline crossing,
and remained so at least until September 12 when the stream was
[-~
[
beginning to freeze over.
['
Bryan et al (1973) captured one grayling from the Spring River,
[
but we found no grayling in this system. · It seems doubtful
[
that a large population utilizes this river.
[
.15
Lakes- Although 11 tundra lakes were sampled (Table I),
only six are known to contain fish.
of grayling.
Two of these include populations
Lake 109 contained grayling and broad whitefish
(Coregonus nasus).
Lake 100 contains grayling, broad whitefish,
pond smelt (Hypomesus olidus) and ninespine sticklebacks (Pungitius
pungitius).
[
c
[
One Arctic char juvenile was also captured in the
latter lake.
~
Of the eight foothills lakes sampled, five were found to support
[
populations of fish, and three of these contained grayling.
[
Lake 107 has a large population of grayling which appears to
be isolated for much of the summer as its outlet dries up.
Lake
105 contains grayling, least cisco (Coregonus sardinella), lake
trout (Salvelinus namayaush) and ninespine sticklebacks.
Trout
Lake supports populations of grayling, least cisco, humpback
-12-
[
[
L
r
c--J~rJrJ~r--1r:-J~r:le71r-:Jrlr-lr-Jr.-1rJr-1r--l
0
I
0
I
kilometr11
I
I
I
miles
50
I
50
FJgure 4. Distribution of grayling in samples. Closed circles are sites
at which adult and juvenile grayling were captured. Open circles are those
at which young-of-the-year were taken.
[
[
whitefish (Coregonus pidschian) and ninespine sticklebacks.
[
.2
[
Age and Growth
.21
First Year Growth - Grayling fry from streams across
the Yukon North Slope exhibit considerable variation in their
[
[
[
growth rates:
a comparison of the mean fork lengths of fry
from nine different sampling sites, collected during a 6-day
period (July 30 to August 5, 1972) shows that fry fall into
three different size groups (Table II).
It appears that fry
from streams situated close to the Mackenzie River Delta are
[
significantly larger (p.<O.Ol) than fry from more westerly streams.
r=L
This phenomenon does not appear related either to differences
[
since no distinct parallel pattern was found in these parameters
in numbers of benthos available as food, or to water temperatures
(Table II).
[
However, the time of break-up may be an important
factor in the apparent growth rates of fry; more easterly streams
[
were observed to break up considerably earlier in spring than
L
affording a longer growing season.
[
[
[
those to the west, perhaps allowing spawning to occur sooner,
Data presented in Table II suggest that fry taken from Stream
1000 are somewhat atypical in their growth.
Fish taken from
this stream were significantly (p ;c:;:O. 01) smaller than fry from
any other area sampled, and constitute a size group by themselves.
This unusually slow growth rate is not demonstrably related
L
to numbers of benthos or to temperature, since neither of these
[
-
13 -
[
parameters for Stream 1000 was exceptionally low in comparison
[
to other streams.
[
There is evidence of considerable variation in size between locations
[
within a single stream.
On the Trail River, one sampling site
(Trail #1) was along the edges of a large deep pool about 10
miles upstream of the pipeline crossing.
Table II shows that
fry taken from this locale on August 2, 1972 were significantly
[
[
(p.<:O.Ol) larger (fork length 46.7 mm, N=l09) than fry taken
[
on the same date just below the pipeline crossing in shallow
c
waters along the edges of the stream (Trail #2, 33.3 mm, N=81).
Subsequent weekly samples from the Trail River were taken about
200 yards above Trail #1, and these fry continued to be
large.
~xtremely
This difference in growth for fry from two areas of the
[
[
same stream again does not appear related to either benthos density
or to temperature, since both were lower at Trail #1.
[
A comparison was made of the late-summer, seasonal growth of
[
grayling fry from the Trail River and Stream 1000 (Figure 5).
[
Fry from the former were significantly larger than those from
Stream 1000.
The mean fork length of fry from the Trail River
was 46.7 mm (N=l09) on August 2, while on July 30 fry from Stream
1000 had a mean fork length of only 25.8 mm (N=l09).
The more
rapid growth apparent in the early weeks of life for Trail River
[
[
[
fry is probably at least partly a result of the early break-up
occurring there.
On May 24, 1972, Stream 1000 was still frozen
[
[
-14-
--~---------------~
[
[
Table II.
[
[
[
Comparison of the mean fork lengths of fry collected from the
Yukon North Slope on July 30 -August 5, 1972, using the
Multiple Range Test (Duncan 1955). Any two means encompassed
by the same bracket do not differ significantly. Temperatures
and densities of benthic invertebrates are indicated.
(Data marked by an asterisk (*) were collected on July
18, 1972). N is the number of fry in a sample. Mean
is the mean fork length (in mm) of the sample. Mean no.
of benthos is the mean number of benthic invertebrates,
calculated from 6 Surber samples taken at the sampling
site. P is the ranking number of 2 or more streams being
compared using the Multiple Range Test. Rp is the shortest
significant range (p < 0.01).
[
[
[
[
[
Location
Stream 1000
Trail #2
Crow
Blow
Deep
Rq.pid
Stream 1003
Trail 111
Walki11g
[
Mean
109
81
94
34
24
28
23
109
14
[25.5]
33.3
34.1
35.6
35.8
44.4
44.8
46.7
50.1
3.6
6.2
7.1
5.8
4.1
4.2
2.3
5.6
1.3
14
23
30
5
30
p
Rp
2
3
4
6.95
7.25
7.44
5
6
7.60
'[
[
[
[
-15-
7.71
-
19
42*
7
7.90
Water
Temp.
8.1°C
9.0
10.0
12.3
14.5
12.0
15.0
8.5
17.0*
Shortest significant ranges (p < 0.01) for mean fork lengths.
L
-f -
Mean No.
benthos
per ft2
,....---
[
[
N
Standard
Deviation
8
7.96
---~----·-----
----------~----
[
solid, while the Trail River had some water beginning to flow
underneath rotting ice.
On June 2, the upper Trail River was
[
[
completely open (water temperature= 0.5°C), whereas Stream 1000
was just beginning to break up.
It may be that grayling in
fJ
Trail River were able to spawn somewhat earlier than grayling
D
[
in Stream 1000.
From July 30 to September 12, 1972, temperatures in the Trail
River were consistently higher than those in Stream 1000 (Figure
[
of Trail River grayling fry.
c
Grayling fry from both the Trail River and Stream 1000 first
c
began to form scales at about 35 mm.
[
5).
This may be a further reason for the faster growth rate
This observation is similar
to that made by McCart et al (1972) for Alaskan North Slope grayling.
However, unlike fry from the upper Atigun River in Alaska, it
is likely that almost all fry from both locations studied formed
scales by the end of their first summer.
[
Fry collected from
Stream 1000 (N=48) and Trail River (N=35) on September 12, 1972
all were greater than 35 mm in length.
.22
c
Growth of Older Fish - In order to establish the
[
[
[
reliability of growth rates determined from scale-based agings,
both scales and otoliths were read for fish from the lower Firth
River and Trout Lake.
In both cases discrepancies between the
two methods were found similar to those described by McCart et
al (1972).
[
Figure 6 shows that for Firth River grayling both
-16-
[
[
r·
\,
-( .)
-- -o
14
\
10
\
\
\
0:::
1-
0
6
\
\
\
2
\
A.
T
T
-
Stream 1000
\
1<l:
w
a..
~
w
e
\
w
:::::>
Trail River
\
0
0:::
0
T
T
60
E
E
:r:
1-
(!)
z
w 40
_J
~
0:::
0
LL
z
<l:
w 20
::E
0
Trail River
e
Stream 1000
B.
AUGUST
SEPTEMBER
Figure 5. Comparison of late summer growth of fry from
Stream 1000 and Trail River. Temperature at the two
study sites also shown.
I
I
I
I
I
I
I
I
·I
I
I
:I
methods gave similar mean fork lengths for ages one through 7,
by which time most fish have matured and growth slows abruptly.
However, mean fork lengths determined from scales exceed those
determined from otoliths in 6 out of 7 age groups beyond age
7.
For the Trout Lake sample, mean lengths determined by the
two methods were similar through age 6, but in 4 of 5 ages beyond
age 6, scale-based mean lengths exceeded those determined from
otoliths (Figure 7).
Furthermore, the maximum ages determined
from otoliths (Firth River, age 22; Trout Lake, age 15) far exceed
those from scales (Firth River, age 14; Trout Lake, age 11).
These discrepancies between readings based on otoliths and scales
are probably caused by the "dense edge" (Nordeng, 1961) developed
by scales in later life, which tends to obscure annuli on the
scales of aged fish.
Otoliths, on the other hand, usually continue
developing reasonably clear
fish.
annuli throughout the life of the
For this reason, all growth rates are based on ages determined
by otoliths (Tables III, IV, V).
·I
Comparative growth curves for grayling from the three study
areas are illustrated in Figure 8.
Fish from the lake systems
grow more rapidly than those from the Firth River.
The population
in Lake 100 has the fastest growth rate.
The growth of fish from the Firth River and Trout Lake slows
markedly by age 10 (at lengths of 348 mm and 359 mm respectively).
Grayling from Lake 100, however, continue to grow to about age
- 17 -
[
SAMPLE
Age
Male
%
5
11
1
9
2
28
48
100
75
67
SIZE
%
Unsexed
Total
9
9
50
39
6
4
3
3
1
25
33
100
100
Female
0
1
....
;o
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
Totals
1
1
1
4
50
50
1
6
7
6
4
3
4
20
46
47
50
50
75
67
1
100
65
50
Total
6
18
23
1
12
3
1
Fork Length
Mean
1
44
82
121
137
225
232
294
311
4
2
4
7
8
6
4
1
2
50
50
100
80
54
53
50
50
25
33
2
8
2
5
13
15
12
8
4
6
338
348
355
351
357
351
350
358
380
393
1
100
1
350
1
388
1
64
50
13
142
(mm)
Range
34-49
55-96
88-151
182-281
183-303
331-345
319-370
352-357
304-394
328-399
318-395
319-376
326-401
368-392
349-430
l
,,i
Table IV.
J
,,
ll'
ll
1
0
1
2
.Jl
i-J
J
,
L
I , .l
,,.J
Observed age-length relationship (based on otoliths) and age specific sex ratios of grayling
from Trout Lake.
SAMPLE
Age
~
Male
SIZE
%
Female
%
2
8
67
42
1
11
33
58
6
2
6
40
100
60
33
30
50
50
46
50
100
100
9
60
4
8
7
6
5
7
3
40
67
70
50
50
54
50
1
62
Unsexed
Total
Fork Length
Mean
(mm)
Range
19
99
144
89-108
120-185
212
293
284
307
331
343
359
364
379
382
381
367
191-258
292-293
228-284
265-340
283-361
315-354
332-379
311-399
358-3-86
375-392
100
15
2
10
12
10
12
10
13
6
4
1
1
53
118
3
3
I
1-'
\.0
I
4
5
6
7
8
9
10
11
12
13
14
15
Totals
4
3
6
5
6
3
4
1
56
47
-i
Table V.
Observed age-length relationships (based on otoliths) and age specific sex ratios of grayling
from Lake 100. Percentages are calculated only from fish for which sexes are available.
SAMPLE
Age
I
tv
0
I
0
1
2
3
4
5
6
7
8
9
10
Male
%
100
13
18
1
3
21
8
5
2
2
4
2
58
100
75
84
73
71
50
67
67
33
14
15
16
1
1
50
100
69
67
11
Totals
Female
%
Unsexed
21
1
12
-SIZE
13
42
1
4
3
2
2
1
2
4
1
1
25
16
27
29
50
33
33
67
100
50
34
33
Total
(mm)
Range
21
1
44
95
35-52
31
1
4
25
236
304
319
338
348
366
372
370
381
382
367
405
414
194-286
11
7
4
3
6
6
1
2
1
21
Fork Length
Mean
124
299-337
302-374
296-416
299-411
365-383
362-378
342-399
359-396
402-407
·..11
~~
r-:
j
~
--
[
il
r--J
cr-:J
rrr:J
CJ
~
lJ
~]
r-J
r-l
~
[ ' 'I'
0
0
r-l
· otoliths
r--J
0
....------------0
0
300
-
E
E
:I:
.,_;. 200
(!)
z
1LI
...J
~
a::
0
1L..
100
2
6
10
AGE
14
Figure 6. Comparison of age-length relationships determined from both
scales and otoliths for grayling from the lower Firth River.
18
22
:--)
--
----~---~--~-------·-
~·---- -----~-·-~-
--·-
I
[
400
[
,,
l--
/
I
l
[
[
E
E
[
... 0
/
........
[
o"
~.,
- -a- -o- -o- o otoliths
o
E 300
E
-
0
io/
/'()
/
:J:
I(!)
z
w 200
....J
~
0:::
0
LL..
100
c
r
l_j
[
[
[
f'
0
4
8
12
AGE
Figure 7. Comparison of age-length relationships
determined from both scales and otoliths for grayling
from Trout Lake.
16
[
[
12 (length 381 mm).
[
Grayling sampled in the Firth River had a greater maximum age
[
than those in the lakes.
One Firth River fish was aged at 22
years, while the oldest fish from Trout Lake was 15 and from
[
Lake 100, 16.
[
.23
Comparison with Growth in Other Areas - Figure 8 compares
[
growth of grayling from the Firth River with that of other areas
c
in Alaska and the Canadian Arctic.
In comparison with these
populations, ours are intermediate in their growth, but fish
from the Firth River attain greater ages than those of any other
[
area.
[
As pointed out by McCart et al (1972) for Alaskan grayling, this
may be an artifact of the method of aging (scale reading) used
by other researchers.
E
E
C
Data describing the growth of grayling in other areas came from
the following sources:
Great Slave Lake, Bishop (1967); Great
Bear Lake, Miller (1946); Tangle Lakes, Roguski and Winslow (1969);
Happy Valley Creek and Kuparuk River, McCart et al (1972).
[
r
.3
Age at Maturity
L
Table 7 gives data describing the age at maturity for grayling
[
from the three major study areas.
Though data are scarce for
several age groups, it seems likely that fish from the two lakes
[
first mature at an earlier age than fish from the Firth River.
[
-21r
,
---
.
~-----------
-----------~----------
·-----
---·--·----------------------------
- - - - - - - - - - - ----~--
----
[
[
Males from Trout Lake, and both males and females from Lake
100, first mature at age 4.
[
By age 7 all fish in Trout Lake
are mature, and those from Lake 100 are all mature by age 6.
[~
Data for the Firth River are few, but no mature fish younger
than age 7 was taken.
By age 9 all fish, male and female were
"
[
mature.
[
.4
Sex Ratios
[
The total sample of grayling from the Firth River consisted
of almost exactly 50% males and 50% females (Table III).
Trout
c
Lake grayling showed a slight predominance of females (53%),
but this is not a significant departure from the expected 1:1
ration (Table IV).
[
the sex ratio of Lake 100 grayling was 2.0
males to 1 female (Table V) and males were more abundant than
[
females throughout the Age (Table V) and size (Figure 9) ranges
sampled.
~
In the Firth River and Trout Lake populations males
tended to dominate among older, larger fish (Tables III, IV and
Figure 9).
[
[
[
.5
Egg Size, Fecundity and Frequency of Spawning - The eggs of mature
females increase in diameter during the course of the summer
(Figure 10).
In mid-June, immediately after spawning, eggs are
usually less than 0.5 mm in diameter.
By mid-September eggs
have increased in diameter to approximately 1.7 mm.
Eggs continue
to grow during the winter, and just prior to spawning in spring,
they attain a diameter of 2.0-2.5 mm.
[
r
['
r·
[
-22I)
(
j
~
r-:1
r-71
rJ
c::7'"TI
r-:1
r::-:1
m
r-71
rJ
~1
r-l
rJ
r--"j
r-l
:-:-l
:-l
Slave Lake
400
Lake
-=:..----
- -
-
.......... - . .
E
Firth River
--··-- --··-··-··-··..
Happy Valley Creek
Kuparuk River
.§. 300
:J:
I(!)
z
IJ.J
_J
~
a:: 200
0
LL
100
2
6
10
AGE
14
Figure 8. Comparison of growth rates of grayling from the Firth River,
Trout Lake and Lake 100 with those of other populations from Alaska and
the Canadian Arctic.
18
22
r-l
[
[
Table VI.
L
Fecundity of mature, green female grayling from three
locations in the Yukon Territory.
[
Fecundity
N
Mean
Firth River
7
Trout Lake
Lake 100
[
L
[
Standard Error
Range
7328.6
896.1
4077-10891
5
11818.8
991.3
8787-14429
8
8620.2
822.5
5429-12976
20
8967.8
647.3
4077-14429
c
Total
[
The mean fecundity of samples of mature green females taken in August and
September, 1972 was 8,967.8 eggs with a range of 4077 to 14,429
[
eggs (Table VI).
Regression analysis revealed that, for the
combined sample from the three localities, there was no significant
E
t
[
correlation between
LlO fecudnity and LlO fork length (r=O.l5,
N=20).
It appears that once mature, female grayling spawn every year.
[
None of the female grayling classified as immature showed evidence
r
L
of previous spawning (eg. retained eggs) and all of the older,
larger females contained maturing eggs (Table VII).
apparently also spawn every year after they have attained maturity
[
(Table VII) •
l
[
[
Males
-23-
Table VII.
Percent by age of male and female grayling from three locations on the Yukon North Slope whose
gonads indicated that they had just spawned or would spawn the following spring. Ages were
determined from otoliths.
Age
,
1
2
3
4
5
6
7
8
9
10
I
N
~
I
N
Males
% Mature
5
11
1
9
2
0
0
0
0
0
1
4
100
100
1
6
7
6
4
3
4
100
100
100
100
100
100
100
11
12
13
14
15
16
17
18
19
20
21
22
--~~
<'
r:J
~
1
r--'j
I. .
N
LAKE 100
TROUT LAKE
FIRTH RIVER
Females
% Mature
N
Males
% Mature
N
Females
% Mature
N
Males
% Mature
9
9
0
0
2
8
0
0
1
11
0
0
1
0
3
1
1
1
0
0
0
100
0
100
100
100
100
100
100
100
100
100
100
17
100
17
100
100
100
100
100
100
100
100
9
1
4
2
4
7
8
6
4
1
2
6
2
6
4
3
6
5
6
3
4
1
4
8
7
6
5
7
3
75
100
100
100
100
100
100
18
1
3
21
8
5
2
2
4
2
22
100
100
100
100
100
100
100
100
100
1
100
1
1
100
100
1
100
u-:-J
rJ
~
r---J
N
Females
% Mature
13
15
1
4
3
2
2
1
2
4
1
1
100
100
100
100
100
100
100
100
100
100
100
[""~
~
r=J
rr=J
r-J
Ll
c-:J
r----"1
,.-----...,
!
:--J
:--l
---,
,...-l
r1
r--:-:
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NUMBER OF FISH CAUGHT
01
25-49
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150-174
175-199
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en 225-249
en
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275-299
300-324
325-349
350 .. 374
375-399
400-424
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Figure 9. Numbers of males and females in various size classes in samples
from three localities in the Yukon Territory.
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[
.6
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In most Arctic regions, the spawning period of grayling coincides
Spawning Period
with spring break-up, i.e., late May- early June.
[
[
[
[
r__,
L
[
[
and water conditions during this period restricted survey crews
in our area, and consequently data on times and sites of spawning
are incomplete.
Available data do show that spawning times
vary from one locale to another.
The first ripe grayling (a female) was taken on May 13, 1972
in the upper Firth River (i.e. above the aufeis).
On that same
date a spawned-out female was taken in Joe Creek.
Additional
samples were taken from the upper Firth on May 17 (one female)
and May 28 (a male and a female), all of which were ripe.
On June 17, 1972, three spawned out females were caught at the
same location.
E
Weather
These data suggest that spawning in the upper
Firth River occurs during the latter half of May and early
[J
June.
E
E
Grayling in the lower Firth River probably spawn about two weeks
later, during mid-June.
1972.
A green female was taken on June 8,
On June 13, 4 ripe males one ripe female and one spawned-
r
out female were taken.
E
L
L
and 2 of the males were spawned-out.
~
,-
i
Two days later, on June 15, a sample
consisting of 8 females and 3 males was taken; all the females
Of a sample collected
June 19 (2 females and 8 males), all fish except two males were
spawned-out.
-25-
------------------
---------------------------------------
I
'r-,"
On May 21, 1972 a sample of 4 green males and 4 green females
was taken in Canoe Creek, a major tributary and overwintering
site on the Babbage River about 10 miles below the falls.
The
next sample collected there, a spawned-out male, was taken on
July 9, well after the spawning period.
Judging from these
data, grayling in this stream probably spawn during the middle
of June.
L
r~
[
f'
r-
L_ __
r--
No ripe grayling were collected from any lakes.
However, on
L
June 14, 1972, a ripe male and female were observed engaged
r--,
in courtship behaviour in Trout Lake outlet about 4 miles below
l3
the lake.
These fish may have moved out of the lake to spawn.
A collection of 7 fish (3 males and 4 females) was taken from
L
r-
Lake 100 on July 2, all of which were spawned out.
From these data it is clear that spawning of grayling on the
Yukon North Slope begins around the middle of May, and may continue
until the latter part of June in some areas.
1
L
[
c
L
.7
Fry Emergence
Considerable difficulty was experienced in locating fry in
any of the streams in our study area.
Consequently no data
are available on time of emergence from the onset of spawning.
The first fry were encountered on July 30, 1972 in Stream 1000
at the pipeline crossing site.
[
r,
L,
[
This was at least a month after
spawning occurred, and by this time the fry were already quite
-26-
L
L
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-·------------·-
·-··~~-~-
-----
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3.0
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ct
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da ali! a-
• Firth River
0 Trout Lake
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thfoo
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(!)
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JUNE
I
JULY
I
AUGUST
1
Lake 100
SEPT.
Figure 10. Seasonal development in egg size for mature
grayling from three locations on the Yukon North Slope.
I
[
[
large (mean fork length 25.8 mm, range 17-33, N=l09).
[
Grayling fry usually hatch from the egg 14-21 days after spawning
[
[
L
[
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[
(Nelson, 1954; Peterson, 1968; Schallock, 1965).
upon water temperature.
Depending
If the incubation period is similar
for grayling from the Yukon North Slope, the first fry would
appear in late June.
.8
Spawning and Rearing Areas
The distribution of grayling fry in our study area is
in Figure 4.
sho~m
Probably spawning areas, shown in Figure 11,
were determined on the basis of the presence of large numbers
of fry, the occurance of ripe and spawned-out fish.
[
c
Large numbers of fry were found in the Firth River at Castle
[
crossing, the Crow River at Peatbog Creek, at several locations
Rock (about 10 miles above Joe Creek), Stream 1000 at the pipeline
in the lower Trail River and the Blow River, and in the vicinity
l
of the pipeline crossing in Deep Creek, Walking River, Rapid
c
Creek and Stream 1003.
r,
L
L
L
L
r-
Ripe and spawned-out adult fish were
found together in the Firth River above the aufeis field and
at the head of the delta, although fry were not abundant in
these areas.
In addition, two ripe grayling, a male and a
female, were observed in courtship behaviour in Trout Lake
outlet on June 14, 1972.
This stream is therefore also a probable
spawning site for grayling.
- 27 -
-~-------------
[
In most streams found to support grayling, both fry and older
grayling were found together.
In many areas, numbers were not
r
r
sufficient to suggest spawning sites, and the fry may have moved
down from spawning sites further downstream or in tributaries.
Grayling fry generally occupy shallow, calm waters found along
stream edges, in backwaters, and in side channels.
During their
f
l
fI
first several weeks of life they tend to congregate in small,
dense schools.
Later they become more solitary and hide between
rocks in the stream bed.
During late summer and early fall,
fry in Stream 1000 were commonly seen trapped in shallow pools
cut off from the main stream by lowered water levels or by
ice.
This appears to be a common plight of grayling fry as
noted by Peterson (1968) and McCart et al (1972), and many fry
must perish in this manner.
[
r:
b
L
[
[
remain in very shallow waters while larger juveniles and mature
c
fish remained in deeper areas.
[~
Where fry and older fish were found together, fry tended to
This is presumably a behavioural
adapatation allowing all size classes of grayling to inhabit
a particular stream without older fish cannibalizing smaller
[
ones.
r-,
L~.
It has long been thought that grayling require clear water to
spawn.
Schallock (1965), however, found that grayling in the
Chatanika River, Alaska, often spawn at the height of the spring
-28-
L
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r.
(1)
"'0
0
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..,0
,...,.
z
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flood when waters are turbid and muddy.
Observations on the
Yukon North Slope suggest that in most areas grayling also spawn
during the spring flood in turbid waters.
Only those fish in
the upper Firth River, where the main source of flow is ground
water, have relatively clear water during the spawning period.
[
[
A coarse sand or gravel substrate is required by spawning grayling
[
in most streams along the Yukon North Slope, and were found
(Nelson, 1954; Schallock, 1965).
Such substrates are very common
in all probable spawning sites shown in Figure 11.
r
L
.9
[
Movements in Streams and Overwintering Areas
Migratory patterns of grayling in our area remain almost totally
[
u~known.
c
Frequent high water levels and unfamiliarity with
the area made study of grayling movements very difficult.
is little doubt, however, that extensive and complex movements
do occur in several of the drainages examined.
[
[
Grayling movements are of necessity closely related to their
overwintering sites.
c
r~
These sites are of special importance
to fish of the Yukon North Slope, because during winter, most
streams freeze completely.
Ice depths of up to 2.3 meters were
encountered during late winter surveys in March, 1972 and April,
L
[
There
1973.
The only areas on streams where there is any free water are
-
occasional deep pools and perennial groundwater springs.
L
l
r-
Most
of these springs are found near the headwaters of a few major
-29-
-------~~~--------
[
Mountain Streams (see Figure 2), and all of them are known to
be important overwintering sites for Arctic char (Craig, 1973).
[
[
In the upper Firth River, Joe Creek and Canoe Creek, these open
water sites are also used by arctic grayling.
In fall these
two species have been observed together in these areas, particularly
Canoe Creek.
In spring, anadromous char vacate these overwintering
sites and do not return until late summer.
However, juvenile
grayling and char remain all summer long.
It appears that in
spring, mature grayling leave the overwintering sites in the
Mountain Streams to spawn.
The almost total absence of grayling
fry from the spring areas, and the presence of large numbers
of fry in other areas, supports this speculation.
A major exception
is the upper Firth River, where ripe and spawned-out fish occurred
together in early spring, and where one grayling fry was found
on September 25.
This suggests that grayling do spawn in the
upper Firth, although the exact location remains unknown.
[
[
[
[
I
b
L
[
c
Grayling fry were found throughout the entire length of the Firth River
b
below the aufeis field but usually in small numbers.
[
Only
at "Castle Rock" (Figure 1) were numbers abundant enough to
suggest a major spawning area.
Fry in the rest of the river
may have been washed down from this and other spawning sites,
or perhaps grayling spawn sporadically throughout the length
of the Firth River with few concentrated spawning areas.
[
f'
L"
L
L
[
-30f/
~
(
~~~~~--~~-~---~~·
[
[
[
Unlike grayling in the Sagavanirktok Drainage in Alaska (McCart
et al, 1972), Firth River fish do not appear to utilize tributaries,
either to spawn or to spend the summer.
[
Only Joe Creek is
known to be inhabited by grayling, and again, no fry were taken
[
at this location.
L
Mature grayling were taken all summer long (June 13 to September
9, 1972) at the gillnet station maintained at the head of the
[
Firth Delta.
r,
at this site on June 13-15, 1972.
L
fish actually spawn, although small numbers of fry were caught
Several ripe and spawned-out grayling were caught
It is not known where these
[
in the delta throughout the summer.
c
c
from the lower Firth River overwinter.
c
l
E
r
It is not known where grayling
The only possible overwintering
site known in this area is a deep pool about 2 miles upstream
of the pipeline crossing,
which contained 0.5-0.7 meters of
free water on April 10, 1973.
This water had a dissolved oxygen
content of 9.4 ppm, sufficient to support overwintering fish.
Perhaps other similar pools exist, and these provide overwintering
sites for grayling in the lower Firth River.
It is also possible
that grayling migrate down from the spring area on the upper
Firth in spring, and return in late fall to overwinter.
However,
of 170 grayling marked with a caudal fin clip in the upper
L.-i
[
[
Firth, none was recovered in lower regions of the river.
addition, it is most unlikely that fry and small juveniles from
the lower Firth migrate this distance.
L
r·
In
- 31 -
--------
------------~~------
r=
In the Babbage River system, only the perennial ground water
areas of the Canoe Creek-Wood Creek area contain mature grayling
consistently throughout the summer and early fall.
[
Very few
mature fish were taken in the Babbage itself, although smaller
juveniles and fry are very abundant.
[__
Even below the Babbage
Falls, where a large, deep pool exists suitable as an overwintering
[
[
area, only juvenile grayling were caught.
[-
Some evidence exists to suggest that grayling in the Babbage
[
drainage utilize some of the tributaries to the main river.
On June 14, 1972, large numbers of mature grayling which may
have been moving up from the Babbage River to spawn, were observed
in Philip Creek.
r
L
[
Three of four fish caught on this date (mean
fork length 307 mm, range 295-317) were ripe.
The Trail and
Crow Rivers, both tributaries of the Babbage in its lower reaches,
contained large numbers of grayling fry.
Throughout the summer
[
[
that after spawning, they return to other areas of the Babbage
c
drainage to summer.
r~
mature grayling rarely were taken in either river, suggesting
From the above data, it appears that mature fish in the Babbage
system overwinter in a few specific sites, probably usually
c
r-
L_c
associated with perennial ground water sources.
The only such
site known to date is the Canoe Creek-Wood Creek area.
These
[
fish apparently leave the overwintering area and spawn either
in the Babbage or in its tributaries such as the Crow River,
-32-
L
L
f
/
-~
!
[
[
Trail River and Philip Creek.
[~
They then leave the spawning
areas and return to the vicinity of their overwintering sites
to spend the summer.
[
It is not known where juvenile grayling and fry in the Babbage
L
system overwinter.
In the Crow and Trail Rivers several deep
holes are known to exist, which may provide overwintering sites
[
for large numbers of small fish.
Some also may move into the
Babbage River itself, which is large enough that it may have
[
areas of free water beneath the ice in winter.
r-~
L
The Blow River and its major tributary, Rapid Creek, are known
l
to contain numerous grayling fry and juveniles, as well as some
mature fish.
[
The latter, however, did not appear nearly so
abundant as in the Firth and Babbage drainages.
c
No perennial
ground water sources are known for the Blow River despite several
c
winter surveys, so it is not known where fish overwinter.
[
unknown, although the large numbers of fry suggest that several
Spawning areas are generally
major spawning areas exist.
C
r
L
L
L
L
(
is possible that they utilize lakes.
It
-
In most Foothill Streams examined, the arctic grayling was the
most abundant fish species.
All such streams are associated
with numerous tundra and foothill lakes, several of which are
known to support populations of grayling.
Grayling populations
in the tundra streams frequently may be associated with the
- 33 -
--------~-~~~--------
[
r-lake populations.
Streams usually contained only juveniles
and fry; mature grayling were rarely encountered.
hand, fry were
On the other
l
l-
found in only one lake examined (Lake 100),
and even in this lake they were sparse.
It appears that grayling
[
dwelling in the lakes may move into streams associated with
such lakes to spawn.
Fry and juveniles remain in the streams
during the summer, but mature fish return to the lakes.
In
fall, fry and juveniles must also return to the lakes to overwinter,
[
[~
since none of the tundra streams (with the exception of the
[
Spring River, and no grayling were found there) have perennial
c
ground water sources of flow, and all are believed too shallow
to contain free water during the winter.
[
One such foothill stream associated with lakes is Stream 1000.
[
This stream is loosely connected to Lake 100, Lake 105 and
c
Lake 107, all of which contain large populations of mature grayling.
Fry were found only in Lake 100 and small juveniles were rare
in all three lakes.
Stream 1000.
Fry and juveniles were very abundant in
Perhaps mature fish from these three lakes enter
the stream to spawn.
[
[
Juveniles and one spawned-out female
were found on July 17, 1972 in the upper portions of the outlet
[
of Lake 105, which enters Stream 1000.
r-,
L~
If the lake populations depend upon associated streams for their
[
spawning and nursery areas, survival rates of fry and juveniles
may vary considerably.
Outlets to these lakes are unstable,
L
[
-34-
r,
r'
[
[
[
the outlet to Lake 107 was never observed to be active, and
grayling in this lake may be isolated for long periods.
Similarly,
the lower portions of the Lake 105 outlet were very unstable
[
[
[
qnd it is questionable whether fry and small juveniles could
migrate back into the lake to overwinter.
Lake 100 and Stream 1000 is very complex, flowing through at
least 4 small, shallow tundra ponds and several miles of meandering
stream.
L
r""
L
The connection between
There is evidence, however, that grayling adults, juveniles
and fry do, in fact, migrate upstream from Stream 1000 into
Lake 100 to overwinter (Dirk de Graaf, Northern Engineering
Services, personal communication).
[
.10 Food Habits
t
E
c
Grayling are opportunistic in their feeding habits.
Their diet
is extremely variable and includes bottom fauna, drift, terrestrial
insects, fish, fish eggs, shrews and plant material.
Items
of no nutritional value, such as stones, feathers and caribou
hair, are also commonly found in their stomachs.
[
The stomach contents of grayling from the lower Firth River
G
(n=l36), Trout Lake (n=llS), and Lake 100 (n=78) are given in
r
Table VIII.
L
plecopteran nymphs, tipulid larvae and chironomid larvae.
.__,
[
l
Fish from all three areas relied heavily on surface
insects for food.
Firth River grayling also extensively utilized
from the two lakes fed extensively on trichopteran larvae,
amphipods and fish (Pungitius pungitius).
-35-
Grayling
------------------~
-·--
~----------·--------
[
\
Table VIII.
Stomach contents of grayling from a Tundra Lake, a Foothills
Lake and a Mountain Stream along the Yukon North Slope. N=
number of times a particular food item occurred; these values
do not add up to the total number of fish in each sample since
stomachs generally contained more than one food item. %= percent
of fish analyzed which had eaten a particular item. The category
"surface insects" indicates occasions when specific components
were not recorded. (* These empty stomachs are probably the
result of holding the fish for 3-4 days before killing and
analyzing them).
Firth River
N
Stomach Contents
Plecoptera
Trichoptera
Ephemeroptera
Coleoptera
Tipulidae
Simulidae
Chironomidae
Other diptera
nymphs
adults
larvae
adults
nymphs
aquatic
terrestrial
larvae
larvae
larvae
pupae
adults
larvae
adults
adults
Hymenoptera
Hemiptera (corixidae)
Arachnida (spiders, mites)
Grasshoppers
Surface insects
Mollusca (snails)
Amp hi pods
Plant material
Shrews
Fish
Fish eggs
Miscellaneous (caribou hair,
feathers, sticks, plastic
ribbon, exuviae, rocks)
Parasitic nematodes
Empty
Total fish sampled
26
%
49
1
19.1
5.2
7.4
8.1
8.8
8.8
14.7
19.8
2,9
29.4
1.5
3.7
5.9
12.5
9.6
5.2
0.7
2.2
36.0
0.7
7
2
2
5.2
1.5
1.5
12
8.6
3.7
7
10
11
12
12
20
27
4
40
2
5
8
17
13
7
1
3
5
136
Trout Lake
N
%
Lake 100
59
-
51.0
0.9
12.2
0.9
0.9
2
1
1.7
0.9
-
l["
[
%
[
16
20.5
[
7
3
4
9.0
3.9
5.1
1'
1.3
N
-
-
1
14
1
1
~-
-
~-~
-
-
-
b
[
[
11
9.6
2
2.7
[
-
-.
-
-
26
2
7
22.6
1.7
6.1
28
1
20
5
35.9
1.3
25.6
li
-
6.4
-
r~
10
12.8
-
-
24
20.9
.
~
[
2.3
2.4
5*
4.4
115
1
1
5*
78
0.9
1.3
6.4
[
[
[
- 36 -
L
r
-
-----~--------------------------------------------
[
[
r-
.11 Parasites
From the onset pf the fish sampling program, it was clear that
grayling taken from lake habitats frequently had large numbers
[
of cysts in the body cavity on their stomachs, while those found
[
in streams were relatively cyst-free.
L
L
personal communication).
r
Those from Trout Lake
L
[
The cysts are probably
caused by the larval stages of a tapeworm species (Dr. D. Mudry,
Lake 100 grayling (n=97) had an average of 40 cysts per stomach.
gr~yling
(n=67) had about 3 cysts and
only two stomachs from the Firth River (n=50) had one cyst each.
This distribution probably reflects the availability, as food
items, of intermediate hosts, common in lakes but rarely found
[
in streams.
c
[
[
[
r
[
L
[
-
37 -
---~-----
[
[
[
[
LITERATURE CITED
Aquatic Environments Limited.
1973.
Late winter surveys of lakes and
streams in Canada and Alaska along the gas pipeline
routes under consideration by Canadian Arctic Gas Study Limited.
[
report to Northern Engineering Services Limited.
Unpublished
183 p.
[~
1967.
Bishop, F.G.
[
r
L:
n
L
E
~
b
[
E
[
~
[
l
The biology of the Arctic grayling, ThymaZZus arcticus
(Pallas), in Great Slave Lake.
M.Sc. Thesis, University of Alberta.
Bryan, J.E., C.E. Walker, R.E. Kendal, M.S. Elson.
1973.
The
influence of pipeline development on fresh water aquatic ecology
in Northern Yukon Territory.
Progress Report on Research Conducted
in 1971.
Craig, P.C.
1973.
Fall spawning and overwintering areas of fish populations
along routes of proposed pipeline between Prudhoe Bay and the Mackenzie
Delta.
Unpublished report to Northern Engineering Services Limited.
36 p.
McCart, P., P. Craig and H. Rain.
1972.
Report on fisheries investigations
in the Sagavanirktok River and neighbouring drainages.
Alyeska Pipeline Service Company.
Miller, R.B.
1946.
Report to
87 p.
Notes on the Arctic Grayling,,ThymaZZus signifer, from
Great Bear Lake.
Copeia 4:
230-234.
-38-
[
Nelson, P.R. 1954.
Life history and management of the American grayling
[
,~
(Thymallus signifer tricolor) in Montana.
18(3):
J. Wild. Management
324-342.
l
l.
Nordeng, H.
1961.
On
the biology of char (Salvelinus alpinus L.) in
Salanger, North Norway.
Zoologi 10:
67-121.
[
r'
Peterson, H.H.
1968.
Bay area.
The grayling Thymallus thymallus (L.) of the Sundsvall
Institute of Freshwater Fisheries 48:
36-56.
[
I
Roguski, E.A. and P.C. Winslow.
1969.
Investigations on the Tanana River
and Tangle Lakes grayling fisheries:
study.
migratory and population
A Report of Progress 1968-1969.
1965.
[
Federal Aid in Fish Restoration
[
Project F-9-1, Alaska Department of Fish and Game.
Schallock, E.W.
b.~
Grayling life history related to hydroelectric development
on the Chatanika River in interior Alaska.
M.Sc.
Thesis,
[
[J
University of Alaska.
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PLATE I . Male (background) and female (foreground)
g rayling from Lake 100, Y uk on Territory.
PLATE 2. Braided stream segment, Upper Firth River,
Yukon Territory.
PLATE 3. Spring water source tributary to Upper
Babbage River.
PLATE 4. Looking downstream to large aufeis area on
Upper Firth River.
PLATE 5. Tundra Stream, Kugaryuk Creek, during
nood stage. Note stability of banks.
PLATE 6. Beaded stream.
Stream 1000.
Headwater tributary of
PLATE 7. Firth Camp Lake illustrating shallow, weedy
shoreline typical of Tundra Lakes.
PLATE 8. Lake 107, a typical Foothills Lake.
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Arctic Gas
BIOLOGICAL REPORT SERIES
VOLUME FIFTEEN
FISHERIES RESEARCH ASSOCIATED WITH
PROPOSED GAS PIPELINE ROUTES IN ALASKA,
YUKON AND NORTHWEST TERRITORIES
Edi ted by
PETER J. McCART
Prepared by
AQUATIC ENVIRONMENTS LIMITED
ARLIS
Resources ~" lnfonnations..Jcel
Ubrury Buildmg, Suite 111
32 11Providence Drive
An<:horage.AK 99508-4614
ARLIS
FEBRUARY, 1974
Alaska Resources
Librarv v Information Services
CANADIAN ARCTIC GAS STUDY LIMITED
ALASKAN ARCTIC GAS STUDY COMPANY