CHAPTER II

LIFE HISTORY OF THE GRAYLING (Thymallus arcticus) IN BEAUFORT SEA

DRAINAGES IN THE YUKON TERRITORY

M. de BRUYN

P. McCART

a: w ~ Q. cC :I: 0

ERRATA- VOLUME FIFTEEN

TABLE OP CONTENTS

line 2: line 24:

Chapter I

p.l7, COMMENTS, line 3:

p.49, Conductivity: p.l41, COMMENTS: p.l52, Sample

locality: p.l54, Sample

locality:

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:

"LANDS" should read "LAKES" "SPRING TIED" should read "SPRING FED"

"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"

"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

INTRODUCTION

DESCRIPTION OF THE STUDY AREA

.1 Physiography

.2 Streams

.3 Lakes

MATERIALS AND METHODS

RESULTS AND DISCUSSION

.1 Distribution of Grayling in the Study Area

.11 Firth River

.12 Babbage River System

.13 Other Mountain Streams

.14 Tundra Streams

.15 Lakes

.2 Age & Growth ~~-

.21 First Year Growth

.22 Growth of Older Fish

.23 Comparison with Growth in Other Areas

.3 Age at Maturity

.4 Sex Ratios

.5 Egg Size, Fecundity and Frequency of Spawning

,6 Spawning Period

.7 Fry Emergence

.8 Spawning and Rearing Areas

.9 Movements in Streams and Overwintering Areas

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.10 Food Habits

.11 Parasites

LITERATURE CITED

PLATES

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[ Table 1.

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[ Figure 4.

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LIST OF FIGURES AND TABLES

Map of the study area showing the location of streams

and lakes. Unnamed waterbodies have been assigned a

number. Black triangle indicates location of sam­

pling site at the head of the Firth River Delta.

Location of spring-fed aufeis fields in the study

area.

Distribution of fish species in lakes examined during

fisheries investigations in Beaufort Sea drainages in

the Yukon Territory, 1972.

Fish sampling sites.

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

th~-year were taken.

Comparison of late summer growth of fry from Stream

1000 and Trail River. Temperature at the two study

sites also shown.

Comparison of age-length relationships determined

from both scales and otoliths for grayling from the

Lower Firth River.

Comparison of age-length relationships determined

from both scales and otoliths for grayling from

Trout Lake.

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Figure 8.

Figure 9.

Figure 10.

Figure 11.

Comparison of growth rates of grayling from the

Firth River, Trout Lake 100 with those of other

populations from Alaska and the Canadian Arctic.

Numbers of males and females in various size classes

in samples from three localities in the Yukon

Territory.

Seasonal development in egg size for mature grayling

from three locations on the Yukon North Slope.

Probable spawning areas for grayling along the

Yukon North Slope.

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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 Alaska­

Yukon border east to the Yukon-Northwest Territories border.

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

-1-

of the Walking River. The topography of the plain

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. The hills are

typically rounded. Drainage is good and there are a

number of small lakes scattered throughout the area.

3. 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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levels fluctuate considerably both during the spring and early

summer when snow melt occurs and later in the summ~r and early

fall as the result of rainstorms in the mountains. During freshets

the mountain streams become quite turbid. 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). 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.

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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. These are Tundra Lakes and Foothill Lakes (Plates 7 and

8). The former are situated on the Arctic Coastal Plain. They

are generally shallow and weedy: 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). Foothills Lakes are

generally deeper than Tundra Lakes. 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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Arctic grayling (ThymaZZus aratiaus)

Round whitefish (Prosopium ayZindraaeum)

Broad whitefish (Coregonus nasus)

Humpback whitefish (Coregonus pidsahian)

Least ciscoes (Coregonus sardineZZa)

Inconnu (Stenodus Zeuaiahthys meZma)

Pond smelts (Hypomesus olidus)

Arctic flounders (Liopsetta gZaaiaZis)

Nine spine stickleback (Pungitius pungitius)

Four horn sculpin (MyoxoaephaZus quadriaornis)

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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

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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

j was made to obtain as full a size range as possible. Therefore,

l 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

[ station at the head of the delta. This station was monitored

at intervals from June 13 to September 12, 1972. The sampling

r~ 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. Smaller

size classes were sampled using a fine mesh seine. Occasionally

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electrofishing and angling were used to obtain additional samples r--

downstream of the gillnet station.

L 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 l site.

[ 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 l in riffles in the vicinity of the sample sites.

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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

recorded. Sex and state of maturity were determined by examining

[ the gonads. Fish which would not spawn in the next spawning

period, judging by the appearance of their gonads and by general

[ body size, and which showed no evidence of previous spawning,

[ were classified as immature. The presence of retained eggs,

still attached to the ovarian wall or free within the abdominal

E 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

r features. In a few cases this assessment was corrected once

the fish had been aged. 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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r -- Gonads were removed from most fish over 150 mm in length. Total

L gonad weights were determined by weighing both gonads together.

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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 r-typical eggs aligned in a trough. 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. L For the purpose of aging, scales were taken from an area just [ 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. Therefore, both E

otoliths were also removed from each fish. These were placed [ 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, L etc.) without regard to the relative abundance of each group.

[ 4.0 RESULTS AND DISCUSSION [

.1 Distribution of Grayling in the Study Area

Localities at which sampling attempts were made are indicated L in Figure 3. Those at which grayling were obtained are indicated

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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 area (Figure 2) though larger

fish were abundant. 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

major aufeis area to the head of the Firth Delta but except

for a concentration of fry at Castle Rock, near the mouth of

Muskeg Creek, they were not abundant.

Adult and juvenile grayling were taken throughout the summer

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.

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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.

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.

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. This suggests

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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. It

seems likely that most of the adult fish and larger juveniles

do not spend the summer in the Babbage River. 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-of­

the-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).

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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. Two of these include populations

of grayling. Lake 109 contained grayling and broad whitefish

(Coregonus nasus). Lake 100 contains grayling, broad whitefish,

pond smelt (Hypomesus olidus) and ninespine sticklebacks (Pungitius

pungitius). One Arctic char juvenile was also captured in the

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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

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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.

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[ 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

in numbers of benthos available as food, or to water temperatures

[ since no distinct parallel pattern was found in these parameters

(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

those to the west, perhaps allowing spawning to occur sooner,

L affording a longer growing season.

[ 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

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 ~xtremely

large. 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-

[

[

[

[

[

[

[

c [

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

L '[

[

[

[ -f -

--~---------------~

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.

Location

Stream 1000 Trail #2 Crow Blow Deep Rq.pid Stream 1003 Trail 111 Walki11g

,....---

(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).

Mean No. Standard benthos Water

N Mean Deviation per ft2 Temp.

109 [25.5] 3.6 14 8.1°C 81 33.3 6.2 23 9.0 94 34.1 7.1 30 10.0 34 35.6 5.8 5 12.3 24 35.8 4.1 30 14.5 28 44.4 4.2 - 12.0 23 44.8 2.3 - 15.0

109 46.7 5.6 19 8.5 14 50.1 1.3 42* 17.0*

Shortest significant ranges (p < 0.01) for mean fork lengths.

p Rp

2 6.95

3 7.25

4 7.44

5 7.60

-15-

6 7.71

7 7.90

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

Trail River were able to spawn somewhat earlier than grayling

in Stream 1000.

From July 30 to September 12, 1972, temperatures in the Trail

River were consistently higher than those in Stream 1000 (Figure

5). This may be a further reason for the faster growth rate

of Trail River grayling fry.

Grayling fry from both the Trail River and Stream 1000 first

began to form scales at about 35 mm. 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 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-

[

[

[

fJ

D [

[

c c [

c [

[

[

[

[

[

[

r·

\, -(.) 0 -w 0::: :::::> 1-<l: 0::: w a.. ~ w 1-

-E E -

:r: 1-(!) z

14

10

6

2

60

w 40 _J

~ 0::: 0 LL

z <l: w 20 ::E

A.

T

B.

AUGUST

-- -o \ \ \ \ \ \

T

\ 0

\ \

\

T

\

0 Trail River

e Stream 1000

T

0 Trail River

e Stream 1000

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 ·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 annuli throughout the life of the

fish. For this reason, all growth rates are based on ages determined

by otoliths (Tables III, IV, V).

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 SIZE

Unsexed Fork Length (mm) Age Male % Female % Total Total Mean Range

0 6 6 44 34-49 1 5 28 9 50 4 18 82 55-96 2 11 48 9 39 3 23 121 88-151 3 1 100 1 137 4 9 75 3 25 12 225 182-281 5 2 67 1 33 3 232 183-303 6 1 100 1 294 7 1 .... 100 1 311

;o 8 9 1 50 1 50 2 338 331-345

10 4 50 4 50 8 348 319-370 11 2 100 2 355 352-357 12 1 20 4 80 5 351 304-394 13 6 46 7 54 13 357 328-399 14 7 47 8 53 15 351 318-395 15 6 50 6 50 12 350 319-376 16 4 50 4 50 8 358 326-401 17 3 75 1 25 4 380 368-392 18 4 67 2 33 6 393 349-430 19 20 1 100 1 350 21 22 1 100 1 388

Totals 65 50 64 50 13 142

------------ -----

,,i

I 1-' \.0 I

l J ,, ll' ll 1 ~ .Jl i-J J , I , .l L ,,.J

Table IV.

Age

0 1 2 3 4 5 6 7 8 9

10 11 12 13 14 15

Totals

Observed age-length relationship (based on otoliths) and age specific sex ratios of grayling from Trout Lake.

SAMPLE SIZE

Fork Length (mm) Male % Female % Unsexed Total Mean Range

2 67 1 33 3 99 89-108 8 42 11 58 19 144 120-185

6 40 9 60 15 212 191-258 2 100 2 293 292-293 6 60 4 40 10 284 228-284 4 33 8 67 12 307 265-340 3 30 7 70 10 331 283-361 6 50 6 50 12 343 315-354 5 50 5 50 10 359 332-379 6 46 7 54 13 364 311-399 3 50 3 50 6 379 358-3-86 4 100 4 382 375-392 1 100 1 381

1 100 1 367

56 47 62 53 118

Table V.

Age

0 1 2 3 4 5 6

I 7 tv 0 8 I

9 10 11 12 13 14 15 16

Totals

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 -SIZE

Fork Length (mm) Male % Female % Unsexed Total Mean Range

21 21 44 35-52 1 100 1 95

18 58 13 42 31 236 194-286 1 100 1 304 3 75 1 25 4 319 299-337

21 84 4 16 25 338 302-374 8 73 3 27 11 348 296-416 5 71 2 29 7 366 299-411 2 50 2 50 4 372 365-383 2 67 1 33 3 370 362-378 4 67 2 33 6 381 342-399 2 33 4 67 6 382 359-396

1 100 1 367 1 50 1 50 2 405 402-407 1 100 1 414

69 67 34 33 21 124

-i

·..11 ~~

-E E -:I:

300

.,_;. 200 (!)

z 1LI ...J

~ a:: 0 1L..

100

r-: j ~

2

[-­il r--J cr-:J rrr:J CJ ~ lJ ~] r-J r-l ~ ['I ' ' r-l r--J

0 · otoliths 0

0

....-------------0

6 10 AGE 14

Figure 6. Comparison of age-length relationships determined from both scales and otoliths for grayling from the lower Firth River.

0

18 22

:--)

-- ~·---- -----~-·-~-

I

[

[

l--

[ I

l

[

[

E E [

c r l_j

[

[

[

f'

400

........ E 300 E -

:J: I-(!)

z w 200 ....J

~ 0::: 0 LL..

100

0

0 io/ /

4

----~---~--~-------·- --·-

o" /

- -a- -o- -o- -, , ~., o otoliths o

...... 0

/

/'()

8 AGE

12

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

in Alaska and the Canadian Arctic. In comparison with these

c 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

Data describing the growth of grayling in other areas came from

the following sources: Great Slave Lake, Bishop (1967); Great

C 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.

[ -21-

r ,

--- . ~----------- -----------~---------- ·----- ---·--·---------------------------- ----------- ----~-- ----

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

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.

-22-

[

[

[ [~ "

[

[

[

c [

[

[

[

[

[

r ['

r· [ I) (

j ~ r-:1

400

-E .§. 300

:J: I­(!)

z IJ.J _J

~ a:: 200 0 LL

100

r-71 rJ c::7'"TI r-:1 r::-:1 m r-71 rJ ~1 rJ r-l r--"j r-l :-:-l :-l

Slave Lake

Lake - - Firth River

2

-=:..---- Happy Valley Creek --··-- .. --··-··-··-··-.......... -.. Kuparuk River

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

[

[

L [

[

L [

c [

[

E

t [

[

r L

[

l [ [ -

Table VI. Fecundity of mature, green female grayling from three

Firth River

Trout Lake

Lake 100

Total

locations in the Yukon Territory.

N

7

5

8

20

Fecundity

Mean

7328.6

11818.8

8620.2

8967.8

Standard Error

896.1

991.3

822.5

647.3

Range

4077-10891

8787-14429

5429-12976

4077-14429

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

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

of previous spawning (eg. retained eggs) and all of the older,

larger females contained maturing eggs (Table VII). Males

apparently also spawn every year after they have attained maturity

(Table VII) •

-23-

Table VII.

Age ,

1 2 3 4 5 6 7

I 8 N 9 ~ I 10

11 12 13 14 15 16 17 18 19 20 21 22

--~~ <' r:J ~ r--'j I ..

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.

FIRTH RIVER TROUT LAKE LAKE 100

Males Females Males Females Males Females N % Mature N % Mature N % Mature N % Mature N % Mature N % Mature

5 0 9 0 2 0 11 0 9 0 8 0

1 0 9 0 3 0 6 17 2 0 1 0 2 100

1 0 6 17 1 100 4 100

3 100 1 100 1 100 6 100 4 100 4 100 5 100

2 100 6 100 1 100 4 100 3 100 6 100 7 100 4 100 7 100 8 100 1 100 6 100 6 100 4 100 4 100 3 100 1 100 4 100 2 100

1 100

1 100

[""~ ~ r=J rr=J r-J Ll c-:J

1 0 1 11 0

9 0 18 1

4 75 3 8 100 21 7 100 8 6 100 5 5 100 2 7 100 2 3 100 4

2

1 100 1 1

u-:-J rJ r----"1 ~

0

22 100 100 100 100 100 100 100 100 100

100 100

r---J

13

1 4 3 2 2 1 2 4 1 1

,.-----..., !

15

100 100 100 100 100 100 100 100 100 100

:--J :--l

---, ,...-­l

en -N 1"1'1

n r l> en en

-3 3 -

r-1 ~:

I 25-49

50-741 ~ " 75-991 1"1'1

0 100-1241 0

125-1491

150-174

175-199

200-224

225-249

250-274

275-299

300-324

325-349

350 .. 374

375-399

400-424

425-4491

r--:-: r:J r-: r-J r-1 r-l ~I rr-:J r-: ...-----, r--"1 ~ ---: - r---"1

NUMBER OF FISH CAUGHT -01 01 01 01 0 01 01 01 0 9' 01 0 01 01 I I I I I I I I I

I I I I I I I I

..... ~

::0 ::0 0 ..... c :I: ..... r ::0 -l> < I~ 1"1'1

I ::0

.... 3 .... 3 ....

r 3 CD CD CD

3 e. 3 c. 3 c CD -Q fl) c CD c CD

CD - en iD fl) CD en en (II

Figure 9. Numbers of males and females in various size classes in samples from three localities in the Yukon Territory.

[

[ .6 Spawning Period

r~ In most Arctic regions, the spawning period of grayling coincides

with spring break-up, i.e., late May- early June. Weather

[ 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

r__, in the upper Firth River (i.e. above the aufeis). On that same

L 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. These data suggest that spawning in the upper

E Firth River occurs during the latter half of May and early

[J June.

E Grayling in the lower Firth River probably spawn about two weeks

later, during mid-June. A green female was taken on June 8,

E 1972. On June 13, 4 ripe males one ripe female and one spawned-

r out female were taken. Two days later, on June 15, a sample

~ consisting of 8 females and 3 males was taken; all the females

E and 2 of the males were spawned-out. Of a sample collected

June 19 (2 females and 8 males), all fish except two males were

L spawned-out.

L -25-

,-i

------------------ ---------------------------------------

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.

No ripe grayling were collected from any lakes. However, on

June 14, 1972, a ripe male and female were observed engaged

in courtship behaviour in Trout Lake outlet about 4 miles below

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

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.

.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. This was at least a month after

spawning occurred, and by this time the fry were already quite

-26-

I '" r-, L

r~

[

f '

r-L_ __

r--L r--,

l3

L r-1 L

[

c L [ r, L,

[

L L r~;

r

[

L L L [~

[

[ r·: L~

[

[

c ~

[

u [

[

L L r~

-e e -a: L&J ~ L&J 2 ct -Q

(!) (!) LLI

··~·---·-·- ·-··~~-~- -·------------·- -----

3.0

I • ... • • I

2.0 0 .& 0 t•

M :.~ •fA 0 •

.. oo ~ M

§ thfoo I.Ol ~~~ M

0

~ 0

<0.5-i da ali! a- • Firth River 0 Trout Lake

~ Lake 100

JUNE I

JULY I

AUGUST 1

SEPT. I

Figure 10. Seasonal development in egg size for mature grayling from three locations on the Yukon North Slope.

[

[ large (mean fork length 25.8 mm, range 17-33, N=l09).

[ Grayling fry usually hatch from the egg 14-21 days after spawning

[ (Nelson, 1954; Peterson, 1968; Schallock, 1965). Depending

[ upon water temperature. If the incubation period is similar

for grayling from the Yukon North Slope, the first fry would

L appear in late June.

[ .8 Spawning and Rearing Areas

r~ The distribution of grayling fry in our study area is sho~m

~j in Figure 4. 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

Rock (about 10 miles above Joe Creek), Stream 1000 at the pipeline

[ crossing, the Crow River at Peatbog Creek, at several locations

in the lower Trail River and the Blow River, and in the vicinity

l of the pipeline crossing in Deep Creek, Walking River, Rapid

Creek and Stream 1003. Ripe and spawned-out adult fish were

c found together in the Firth River above the aufeis field and

r, at the head of the delta, although fry were not abundant in

L these areas. In addition, two ripe grayling, a male and a

L female, were observed in courtship behaviour in Trout Lake

outlet on June 14, 1972. This stream is therefore also a probable

L spawning site for grayling.

L - 27 -

r-

-~-------------

[

In most streams found to support grayling, both fry and older r grayling were found together. In many areas, numbers were not

r sufficient to suggest spawning sites, and the fry may have moved

down from spawning sites further downstream or in tributaries. f

Grayling fry generally occupy shallow, calm waters found along l stream edges, in backwaters, and in side channels. During their

f I

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, r:

fry in Stream 1000 were commonly seen trapped in shallow pools b cut off from the main stream by lowered water levels or by L 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.

[ Where fry and older fish were found together, fry tended to c remain in very shallow waters while larger juveniles and mature

fish remained in deeper areas. 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 L spawn. Schallock (1965), however, found that grayling in the

L Chatanika River, Alaska, often spawn at the height of the spring

L -28-

r .

"'TI -· lO

c .., (1) - ""0 .., 0 r::r

!lJ r::r

- (1) Vl

"'0

!lJ

:::: :J

:J

lO

!lJ .., (1

) !l

J V

l

-to

0 .., lO .., !l

J -<

:J

lO

!lJ 0 :J

lO

,...,.

:::r

(1) -<

c 7'

0 :J

z 0 .., ,...,.

:::r

Vl - 0 "'

0

(1)

0

A 3

c.n

0 3

:

0 c.n

0

J J ] J J J j d ~ g 1 c:J J ~] J J J J J

L flood when waters are turbid and muddy. Observations on the

r 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

(Nelson, 1954; Schallock, 1965). Such substrates are very common

[ in most streams along the Yukon North Slope, and were found

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. Frequent high water levels and unfamiliarity with

the area made study of grayling movements very difficult. There

c 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. These sites are of special importance

c to fish of the Yukon North Slope, because during winter, most

r~ L

streams freeze completely. Ice depths of up to 2.3 meters were

encountered during late winter surveys in March, 1972 and April,

[ - 1973. The only areas on streams where there is any free water are

occasional deep pools and perennial groundwater springs. Most

L of these springs are found near the headwaters of a few major

l -29-

r-

-------~~~--------

[

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

I

fry from the spring areas, and the presence of large numbers b of fry in other areas, supports this speculation. A major exception L 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. c b

Grayling fry were found throughout the entire length of the Firth River

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, f'

L" or perhaps grayling spawn sporadically throughout the length

of the Firth River with few concentrated spawning areas. L L [

-30-f~

/

(

~~~~~--~~-~---~~·

[

[ 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. Several ripe and spawned-out grayling were caught

r, at this site on June 13-15, 1972. It is not known where these

L fish actually spawn, although small numbers of fry were caught

[ in the delta throughout the summer. It is not known where grayling

from the lower Firth River overwinter. The only possible overwintering

c site known in this area is a deep pool about 2 miles upstream

c of the pipeline crossing, which contained 0.5-0.7 meters of

free water on April 10, 1973. This water had a dissolved oxygen

c content of 9.4 ppm, sufficient to support overwintering fish.

Perhaps other similar pools exist, and these provide overwintering

l sites for grayling in the lower Firth River. It is also possible

E that grayling migrate down from the spring area on the upper

Firth in spring, and return in late fall to overwinter. However,

r of 170 grayling marked with a caudal fin clip in the upper L.-i

Firth, none was recovered in lower regions of the river. In

[ addition, it is most unlikely that fry and small juveniles from

[ the lower Firth migrate this distance.

L - 31 -r·

-------- ------------~~------

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. r On June 14, 1972, large numbers of mature grayling which may L have been moving up from the Babbage River to spawn, were observed [ in Philip Creek. 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 [

mature grayling rarely were taken in either river, suggesting c that after spawning, they return to other areas of the Babbage

drainage to summer. r~

From the above data, it appears that mature fish in the Babbage c system overwinter in a few specific sites, probably usually 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

L in the Babbage or in its tributaries such as the Crow River,

L -32-

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[ 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. No perennial

c ground water sources are known for the Blow River despite several

winter surveys, so it is not known where fish overwinter. It

c is possible that they utilize lakes. Spawning areas are generally

[ unknown, although the large numbers of fry suggest that several

major spawning areas exist.

C In most Foothill Streams examined, the arctic grayling was the

r L most abundant fish species. All such streams are associated

L with numerous tundra and foothill lakes, several of which are

known to support populations of grayling. Grayling populations

L in the tundra streams frequently may be associated with the

L - 33 -

( -

--------~-~~~--------

lake populations. Streams usually contained only juveniles

and fry; mature grayling were rarely encountered. On the other

hand, fry were 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

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

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. Fry and juveniles were very abundant in

Stream 1000. 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.

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,

-34-

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[ 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. The connection between

Lake 100 and Stream 1000 is very complex, flowing through at

[ least 4 small, shallow tundra ponds and several miles of meandering

stream. There is evidence, however, that grayling adults, juveniles

L and fry do, in fact, migrate upstream from Stream 1000 into

r"" Lake 100 to overwinter (Dirk de Graaf, Northern Engineering

L Services, personal communication).

[ .10 Food Habits

t Grayling are opportunistic in their feeding habits. Their diet

is extremely variable and includes bottom fauna, drift, terrestrial

E insects, fish, fish eggs, shrews and plant material. Items

c 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. Fish from all three areas relied heavily on surface

.__, insects for food. Firth River grayling also extensively utilized

L plecopteran nymphs, tipulid larvae and chironomid larvae. Grayling

from the two lakes fed extensively on trichopteran larvae,

[ amphipods and fish (Pungitius pungitius).

l -35-

------------------~ -·-- ~----------·--------

\

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).

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

Hymenoptera adults 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

Firth River N %

26 7

10 11 12 12 20 27 4

40 2 5 8

17 13

7 1 3

49 1

7 2 2

12 5

136

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

5.2 1.5 1.5

8.6 3.7

- 36 -

Trout Lake N %

59 51.0 - -1 0.9

14 12.2 1 0.9 1 0.9 - -2 1.7 1 0.9

11 9.6

- -. 26 22.6

2 1.7 7 6.1

- -24 20.9

2.3 2.4

5* 4.4

115

Lake 100 N %

16 -

7 3 4 -1'

2 -

28 1

20 5

. -10

1 1 5*

78

20.5 -

9.0 3.9 5.1 -1.3

2.7 -

35.9 1.3

25.6 6.4 -

12.8

0.9 1.3 6.4

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.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. The cysts are probably

caused by the larval stages of a tapeworm species (Dr. D. Mudry,

personal communication).

Lake 100 grayling (n=97) had an average of 40 cysts per stomach.

Those from Trout Lake 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.

- 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. Unpublished

[ report to Northern Engineering Services Limited. 183 p.

[~

Bishop, F.G. 1967. The biology of the Arctic grayling, ThymaZZus arcticus

[ (Pallas), in Great Slave Lake. M.Sc. Thesis, University of Alberta.

r L: Bryan, J.E., C.E. Walker, R.E. Kendal, M.S. Elson. 1973. The

n

L influence of pipeline development on fresh water aquatic ecology

in Northern Yukon Territory. Progress Report on Research Conducted

E in 1971.

~ Craig, P.C. 1973. Fall spawning and overwintering areas of fish populations

b along routes of proposed pipeline between Prudhoe Bay and the Mackenzie

Delta. Unpublished report to Northern Engineering Services Limited.

[ 36 p.

E McCart, P., P. Craig and H. Rain. 1972. Report on fisheries investigations

[ in the Sagavanirktok River and neighbouring drainages. Report to

Alyeska Pipeline Service Company. 87 p.

~ Miller, R.B. 1946. Notes on the Arctic Grayling,,ThymaZZus signifer, from

[ Great Bear Lake. Copeia 4: 230-234.

l -38-

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

(Thymallus signifer tricolor) in Montana. J. Wild. Management

18(3): 324-342.

Nordeng, H. 1961. On the biology of char (Salvelinus alpinus L.) in

Salanger, North Norway. Zoologi 10: 67-121.

Peterson, H.H. 1968. The grayling Thymallus thymallus (L.) of the Sundsvall

Bay area. Institute of Freshwater Fisheries 48: 36-56.

Roguski, E.A. and P.C. Winslow. 1969. Investigations on the Tanana River

and Tangle Lakes grayling fisheries: migratory and population

study. A Report of Progress 1968-1969. Federal Aid in Fish Restoration

Project F-9-1, Alaska Department of Fish and Game.

Schallock, E.W. 1965. Grayling life history related to hydroelectric development

on the Chatanika River in interior Alaska. M.Sc. Thesis,

University of Alaska.

-39-

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PLATE I . Male (background) and female (foreground) g rayling from Lake 100, Yukon Territory.

PLATE 3. Spring water source tributary to Upper Babbage River.

PLATE 2. Braided stream segment, Upper Firth River, Yukon Territory.

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 7. Firth Camp Lake illustrating shallow, weedy shoreline typical of Tundra Lakes.

PLATE 6. Beaded stream. Headwater tributary of Stream 1000.

PLATE 8. Lake 107, a typical Foothills Lake.

Arctic Gas BIOLOGICAL REPORT SERIES

VOLUME FIFTEEN

FISHERIES RESEARCH ASSOCIATED WITH PROPOSED GAS PIPELINE ROUTES IN ALASKA,

YUKON AND NORTHWEST TERRITORIES

Edited by

PETER J. McCART

Prepared by

AQUATIC ENVIRONMENTS LIMITED

ARLIS Resources~" lnfonnations..Jcel

Ubrury Buildmg, Suite 111 3211 Providence Drive

An<:horage.AK 99508-4614

FEBRUARY, 1974 ARLIS

Alaska Resources Librarv v Information Services

CANADIAN ARCTIC GAS STUDY LIMITED

ALASKAN ARCTIC GAS STUDY COMPANY

Ql-f 318 . . A7 f3S v.l :