SPATIAL DISTRIBUTION AND SPAWNING MIGRATION OF KOKANEE

(Qncorhynchus nerka) IN NICOLA LAKE, BRITISH COLUMBIA

by

HAROLD WILLIAM LORZ

B.Sc. University of British Columbia 1958

A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE

in the Department of Zoology

We accept this thesis as conforming to the required standard

THE UNIVERSITY OF BRITISH COLUMBIA

April 1962 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of

British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the Head of my Department or by his representatives.

It is understood that copying or publication of this thesis for financial gain shall not be allo\\red uithout ray written permission.

Department of Zoology

The University of British Columbia, Vancouver 3, Canada. ABSTRACT

Vertical distribution and onshore movement of maturing kokanee were studied by means of extensive gill net sets in Nicola Lake between 1958 and

1961. In late spring of 1959 maturing kokanee were found largely in the upper 30 feet of the lake but gradually dispersed to occupy all depths to

100 feet by mid-summer. A diel vertical migration occurred in which matur• ing kokanee moved surfaceward during the day and downward at night in 1959.

In 1961 the reverse condition was observed wherein kokanee avoided areas of bright illumination during the day but moved surfaceward at night. No effect on vertical distribution of kokanee by extensive and rapid fluctua• tions of the thermocline, initiated by wind induced seiches, was noted in

1959 or 1961. The 1961 vertical distribution appeared closely associated to light intensity.

Seasonal and diel changes in diet were observed in 1959. Chironomid pupae were the dominant food organisms eaten in late spring and summer.

Planktonic crustaceans were consumed in greatest numbers in late summer, autumn and spring. Kokanee captured in mid-summer in the surface water

(0-25 feet) generally had been feeding on planktonic crustaceans whereas those taken from below 25 feet contained largely chironomid pupae and

larvae.

Onshore movement of mature kokanee toward a spawning stream was initiated by falling light intensity and intensified by strong onshore winds. Possible mechanisms of location of the spawning stream were investigated.

Migration to an inlet spawning stream and movement within the stream iii

were recorded at two traps, one situated at the stream mouth, the other

1000 feet upstream. Movement into the spawning stream occurred only at night and was unaffected by changes in stream temperature and flow. A significant correlation was found between daily number of kokanee entering the stream and strength of onshore winds.

Differences in sex ratio of the spawning runs and length of mature kokanee were recorded and possible causal agents discussed. iv

TABLE OF CONTENTS

Page

TITLE PAGE i

ABSTRACT ii

TABLE OF CONTENTS iv

LIST OF FIGURES vi

LIST OF TABLES viii

ACKNOWLEDGEMENTS ix

INTRODUCTION 1

LIMNOLOGICAL CHARACTERISTICS OF NICOLA LAKE .' 3

Geography and Morphometry of the Lake 3

Physical and Chemical Characteristics 7

Biological Characteristics 7

PROCEDURE 11

Kokanee Movement in Nicola Lake 11

Kokanee Movement into Spawning Stream 14

Meteorological and Limnological Data 15

RELIABILITY OF GILL NET SAMPLES 16

RESULTS 20

Distribution of Maturing Kokanee 20

Vertical Distribution 20

Onshore Movement 30 V

Page

Entrance of Kokanee into Spawning Stream 32

Timing of Entrance 32

Stream Location 33

Daily Fluctuation in Number of Kokanee Entering

Moore Creek 37

Sex Ratio of Spawners Ascending Moore Creek 40

Size Distribution of the Spawning Run in Moore Creek ... 43

Age of Moore Creek Spawning Run 46

Stream Movement 49

DISCUSSION . 55

Vertical Distribution 55

Onshore Movement and Location of Spawning Stream 61

Stream Entry and Movement Within Stream 63

Sex Ratio, Size and Age at Sexual Maturity 66

SUMMARY 70

LITERATURE CITED ' 71 vi

LIST OF FIGURES

Page

Figure 1. Map of Nicola Lake showing depth contours in feet (1959 gill net stations plotted) 5

Figure 2. Diel movement of the thermocline in Nicola Lake during 33 hours of observation at Station I in 1959 8

Figure 3. Gill net stations at north end of Nicola Lake (depth contours in feet) . 12

Figure 4. Vertical distribution of all species of fish other than peamouth chub from August 20 .- 21, 1959 gill net sets . 19

Figure 5. Day and night vertical distribution of kokanee in Nicola Lake for three seasons of the year in 1959 ... 21

Figure 6. Vertical depth distribution of kokanee (July - September 1959) with temperature isopleths plotted 22

Figure 7. Vertical diel distribution of kokanee in mid August of 1959 and 1961 (numbers indicate kokanee catch in surface and bottom gill net sets) 24

Figure 8. Depth distribution of kokanee in August of 1959 and 1961 in relation to light. Isolumes are plotted in langlies x 10"^ per minute 26

Figure 9. Per cent composition of food eaten by kokanee captured in night gill net sets (surface and bottom) at Stations I and 2 in 1959; data for April 20 - 21, 1960 also included 27

Figure 10. Diel changes in food eaten by kokanee in 1959 (numbers indicate number of stomachs examined) 29

Figure 11. Diel periodicity in entrance of kokanee to Moore Creek in relation to surface light intensity in 1958 and 1959 34

Figure 12. Daily number of kokanee entering Moore Creek in 1958 and 1959 in relation to total miles of wind (1200 - 2400 hours) and maximum stream temperature.( indi• cates evenings of offshore (northerly) winds) 38

Figure 13. Length frequency distribution of the kokanee spawning run in Moore Creek 44

Figure 14. Length frequency distribution of mature kokanee captured from the spawning run to Moore Creek (1957 and 1961 represent gill net catches near creek mouth) 45 vii

Page

Figure 15. Length frequency distribution of kokanee taken in gill nets or with dynamite May 30, 1959 to August 30 1961. (August 30, 1960 distribution represents kokanee seined from Moore Creek) 47

Figure 16. Cumulative per cent length distribution of 486 kokanee captured by dynamite charged in Nicola Lake, August 4 - 6, 1959 48

Figure 17. Daily number of kokanee entering Traps I and II on Moore Creek during the 1959 spawning run 50

Figure 18. Number of kokanee entering Trap II on Moore Creek for three periods of the 1959 spawning run 51

Figure 19. Elapse of time between kokanee marked at Trap I and subsequent recovery at Trap II during the 1959 spawning run to Moore Creek. Abbreviations represent the following fin clips: OA - adipose; OA + UDC - adipose plus upper lobe of dorsal caudal; OA + LDC - adipose plus lower lobe of dorsal caudal; OA + UVC - adipose plus upper lobe of ventral caudal; UDC - upper lobe of dorsal caudal; UVC - upper lobe of ventral caudal 53 viii

LIST OF TABLES

Page

Table I Morphometry of Nicola Lake 6

Table II Species composition of Nicola Lake plankton .... 10

Table III Number of fish taken in simultaneous gill net sets (April 21 - 22, 1960) 17

Table IV Relationship of onshore movement of kokanee to light conditions at spawning time. (August 24 - 25, August 28, 1959) 31

Table V Movement of kokanee into Nicola River (inlet) in 1959 35

Table VI Comparison of the sex ratio of kokanee entering Moore Creek in 1958 and 1959 for three periods of the spawning run 41

Table VII Number of mature kokanee marked at Trap I and subsequently recaptured 1000 feet upstream at Trap II in 1959 54 ix

ACKNOWLEDGMENTS

The study was supported by the British Columbia Fish and Game Branch

of the Department of Recreation and Conservation.

The author wishes to express his gratitude to Dr. P. A. Larkin,

Dr. C. C. Lindsey and Dr. T. G. Northcote who suggested the study.

To Dr. T. G. Northcote the writer is greatly indebted for his

encouragement and guidance in the planning of the project, field assist• ance, and worthy comments and criticism in the writing of the paper.

Special thanks are due to Dr. W. A. Clemens, Dr. P. A. Dehnel,

Dr. K. Graham and Dr. C. C. Lindsey for their constructive criticism and assistance in preparation of the thesis.

Without the untiring efforts, often under much personal discomfort, of Mr. G. Eales, Mr. C. Gill, Mr. T. Miura, Mr. G. Halsey, Mr. D. Sinclair and Mr. M. Teraguchi in the summers of 1959 and 1961 the study would have been impossible. To Mr. G. F. Hartman, who gave liberally of his time and criticism both in the field and in valuable discussion of the results, the writer wishes to express his appreciation. INTRODUCTION

Kokanee, Oncorhynchus nerka, are the non-anadromous form of sockeye salmon that live and reproduce entirely in fresh water. They occur in many lakes over a wide area, from Oregon to northwestern Alaska, as well as in eastern Siberia and Kamchatka Peninsula.

Little information on spatial distribution of kokanee within a lake is available. Similarly, factors related to their spawning migration have not been investigated. To describe spatial distribution and related environ• mental factors such as temperature, light and food habits, a program of gill netting and collection of limnological data was carried out in the summers of 1958, 1959 and 1961 in Nicola Lake. Trapping, enumeration and marking of migrating adult kokanee into and within a major spawning stream (Moore

Creek) were conducted. This thesis reports on the observed spatial dis• tribution and spawning migration of mature kokanee as related to the environment. The study was begun in the summer of 1958 under the auspicies of the British Columbia Pish and Game Branch of the Department of

Recreation and Conservation.

In spite of the fairly common occurrence of kokanee the majority of biological investigations to date have dealt largely with the anadromous form, the sockeye. Vernon (1957) showed that in Kootenay Lake three separate races of kokanee exist in different parts of the lake, each

"homing" to a particular stream entering the lake. Ricker (1937, 1938,

1940, 1959) dealt with the food and food supply of young sockeye and kokanee in Cultus Lake and postulated the probable origin of the kokanee. Workers in Idaho (Allison, 1958; Stross, 1954; Whitt, 1958) studied the age, growth and ecology of kokanee in Lake Pend Oreille. Johnson (1958) 2

reported on some aspects of population density and distribution of young sockeye salmon found within Babine Lake. 3

LIMNOLOGICAL CHARACTERISTICS OF NICOLA LAKE

Geography and Morphometry of the Lake

Nicola Lake (Figure 1) lies approximately 45 miles southwest of

Kamloops, British Columbia, in 50°N latitude and 120°W longitude at an

altitude of 2,056 feet in the Southern Interior Plateau.

The lake, located in the area known as the Nicola Basin, is part of

the Princeton-Nicola-Kamloops Depression (Brink and Farstad, 1949). In

this and other basins described by Mathews (1944) series of lakes were

formed in late Pleistocene as melting ice successively dammed narrow basin

outlets. The present Nicola Lake is the remaining stage of three larger

lakes formerly occupying the same basin.

The whole Southern Interior Plateau, of which the Nicola Valley is

a part, has a low annual precipitation (15 - 20 inches) with a marked

December maximum and a July - August minimum (Chapman, 1952). The area is

also noted for its extreme temperature variation.

Four main inlets enter Nicola Lake which, except on very dry summers,

flow throughout the year. A number of small streams run intermittently in

the spring and early summer.

Moore Creek, entering the lake at the northeastern end, drains the

valley to the north arising in the Frogmore Lakes, which serve as agricul•

tural reservoirs. The discharge of Moore Creek fluctuates considerably,

over the year. During the summer large volumes of water are withdrawn from

Moore Creek for irrigation purposes. In the summer of 1958 a minimum flow

of less than 4 cfs (cubic feet per second) was recorded, whereas in the

spring of 1959 maximum discharge approached 150 cfs. 4

Stumplake Creek also enters the northeastern end of the lake about

two hundred yards east of Moore Creek. Its main sources of water are

springs, a few hundred yards from the lake, although in the spring and early summer it may receive sub-surface water from Stump Lake as well as runoff from Peterhope Lake. The flow for the majority of the year is about 1 cfs but in spring it may rise to 15 cfs.

Nicola River, entering the lake on the eastern shore, is the main tributary, draining Douglas Lake, Glimpse Lake and valleys to the east.

The average summer discharge is approximately 40 cfs with a spring maximum probably exceeding 400 cfs.

Quilchena Creek, entering on the southeastern shore of the lake, drains valleys to the south. This creek becomes dry in some summers but ran continuously in 1958 and 1959.

The Nicola River, outlet of Nicola Lake, has a six foot high irriga• tion control dam at its exit from the lake. The river flows southwesterly joining the Thompson River at Spences Bridge. Discharge of the outlet dur• ing spring freshet may reach 9000 cfs whereas by the end of August its flow has dropped to about 100 cfs.

Table I summarizes major morphometric features of Nicola Lake. The shores of the central basin are precipitous and rocky whereas those of the outlet and northeastern basins are more gradual. The eastern shore, with two large shallow bays, is not as precipitous as the west, as two large deltas have been built up by the inflowing streams. Figure 1. Map of Nicola Lake showing depth contours in feet. (1959 gill net stations plotted) Table I. Morphometry of Nicola Lake

Surface Maximum Mean Length of Shoreline Volume Area Depth Depth Volume Shoreline Development Development

6041 acres 181 ft. 77 ft. 45,900 27.8 mi. 2.5 1.27 acre ft.

2445 hectares 55.2 m. 23.5 m. 56.6 x 10^ 44.7 km. m 7

Physical and Chemical Characteristics

The lake shows thermal stratification but is never sharply stratified for long periods during the summer. The depth of the thermocline (area of rapid temperature change) may fluctuate extensively and rapidly under the influence of strong southeasterly winds. An example of such a fluctuation of the thermocline during a 33 hour period is given in Figure 2.

Oxygen concentration at 50 feet ranged from 8-10 ppm during the summer of 1959. At no time during the study was severe oxygen depletion noted in the lower strata.

Secchi disc readings of 5 - 7 feet were recorded throughout the summer of 1959, although in the spring of 1960 readings of 12 feet were obtained.

In the summer of 1961 readings of 11 - 13 feet were observed. The low summer readings were probably due to a heavy bloom of blue-green algae.

Total dissolved solids content of Nicola Lake ranged from 170 ppm in spring to 235 ppm in autumn.

Biological Characteristics

(a) Vegetation: Aquatic vegetation is generally sparse except in the

shallow southwest basin, the shores of the northeast basin and the

bays of the eastern edge of the lake. Ali (1959) reports the following:

Naias sp., Chara sp. and Callotrichi sp. in the shallow areas. Along

the east and southeastern shore, especially in the bays and back

waters, Scirpus sp. and Typha sp. are abundant. In the southwest basin

the dominant species are Potomageton sp., Zannichellia palustris,

Myriophy1lum sp., Scirpus sp. and Typha sp. 8

Figure 2. Diel movement of the thermocline in Nicola Lake during 33 hours of observation at Station I in 1959 9

(b) Plankton: Plankton samples were taken in total vertical and stage

hauls throughout the summer with a No. 10 silk Wisconsin type

plankton net. Table II shows the species composition.

(c) Bottom Fauna: Bottom fauna was not studied in the course of the

present investigation, but Rawson (1934) found a very scanty popula•

tion of bottom fauna in deep water composed of chironomid larvae,

Pisidium, Oligochaeta and Nematoda.

(d) Fish Fauna: Ali (1959) records fifteen species of fish from Nicola

Lake. As well as kokanee, two anadromous species of Oncorhynchus

(chinook and coho salmon) are known from the system. Other

salmonids include rainbow trout, both resident and anadromous forms,

and the Dolly Varden Salvelinus malma. The mountain whitefish

Prosopium williamsoni is the only coregonid inhabiting the lake.

Six species of cyprinids, two catostomids, the prickly sculpin Cottus

asper, and the burbot Lota lota are also present. 10

Table II. Species composition of Nicola Lake plankton

Blue-green Algae: Green Algae: Anabaena sp. Dictyosphaerium sp. * Aphanizomenon sp. Staurastrum sp. * Microcystis aeruginosa * Microcystis sp. * Coelosphaerium sp. *

Diatoms: Protozoa: Stephanodiscus sp. * Ceratium hirundinellia Fragillaria sp. Melosira sp.

Copepoda: Cladocera: Diaptomus sp. Daphnia longispina Cyclops sp. Bosmina longirostris Leptodora kindtii

Rotifera: Notholca longispina Anuraea cochlearis Triarthra longiseta * Branchionus sp. *

Species recorded by Rawson (1934) 11

PROCEDURE

Kokanee Movement in Nicola Lake

Gill nets were set at regular intervals throughout the summer and periodically in the autumn, winter and spring of 1958 and 1959. In August of 1959 dynamite charges were also employed to sample young not taken by gill nets. Stations I and II at 60 and 95 feet respectively were marked with permanent buoys for the majority of the sampling period (Figure 1).

Station III was located at 135 feet near the deepest portion of the lake.

Station IV (Figure 3), located 600 feet west of Moore Creek, was marked with three permanent buoys at depths of 8, 25 and 50 feet respectively. A number of other areas were also sampled during the study.

Monofilament nylon gill net of 1%, 2 and 2% inch stretched mesh

(19, 25 and 32 mm. knot to knot respectively) 40 feet in length and either

8 or 25 feet in depth were used. To establish the approximate depth in the net at which fish were caught, eight foot deep nets were marked off in two equal halves by a painted horizontal line two inches wide. Similarly the

25 foot deep nets were divided into 5 foot depth intervals.

In the summer of 1959 and 1961 intensive gill net sets were made in conjunction with limnological measurements. At each station the entire depth zone from surface to bottom was sampled. At the 50 foot station, one 25 foot deep net was floated on the surface while the second was set on

the bottom. Twenty-four and occasionally 48 hour gill net sets were made concurrently at the 8, 25, and 50 foot depths at Station IV. Each series consisted of: Figure 3. Gill net stations at north end of Nicola Lake. (Depth contours in feet) 13

1. Gill net sets utilizing 8 and 25 foot deep monofilament nylon nets of

1% and 2 inch stretched mesh. All nets were set simultaneously and

left in the water for a period of four hours.

2. Vertical temperature series using a thermistor.

3. Vertical stage hauls with a closing Wisconsin type No. 10 plankton net.

4. The above observations were performed four times at each station within

a 24 hour period.

(a) Day: 1000 - 1400 hours

(b) Evening: 1600 - 2000 hours

(c) Night: 2200 - 0200 hours

(d) Morning: 0400 - 0800 hours

All times referred to are Pacific Standard.

A net roller (Hartman, 1962) was employed for a number of sets in

August and early September which decreased the time required to lift and set gill nets. It was anchored at Station I for a few sets and then moved into a 42 foot station, off the mouth of Moore Creek, for the remaining sets.

Onshore and offshore movements of kokanee near the mouth of Moore

Creek were recorded by use of gill nets set perpendicular to the shore at

Station IV. Length and depth of 2 inch mesh nets were adjusted to sample the area from shore to a vertical depth of 8 feet and similarly the area at 25 feet (Table IV). Sets were lifted and replaced with duplicate nets every one to two hours for at least a 24 hour period.

All gill nets were brought to shore with the fish enmeshed and were spread out on a tarpaulin. The position of the kokanee was recorded as well as data on length, sex and condition. Scale samples and stomach 14

contents usually were taken immediately from all fish; in some instances the kokanee were preserved for later study.

Contents of the kokanee stomachs were measured by volume displacement.

The contents of that portion of the gut from the lower esophagus to the pyloric sphincter was observed under a binocular microscope and percentage composition of the various food items estimated. Following the observations of individual stomachs for a given depth distribution the contents were totalled and the mean volume and average per cent composition of food items contained were recorded. Empty stomachs were included in the averaging.

Kokanee Movement into the Spawning Stream

In the summer of 1958 traps designed to capture fish moving upstream and downstream (Shetter, 1938) were installed in Moore Creek. Trap I was located 50 feet from the lake's edge while Trap II was about 1000 feet farther upstream. A diagonal fence of 3/4 inch regalvanized wire screen acted as a lead for both the ascending and descending traps.

Kokanee that moved from the lake into Moore Creek on any particular evening either entered the ascender trap or remained in the pool immediately below the fence at Trap I. During the 1959 spawning run, kokanee not entering the trap were seined from the pool at the time of clearing the trap, and were passed upstream after being recorded. However, in 1958 kokanee were not seined from the pool until late in the spawning run.

Traps were checked and emptied of all fish four to five times during a 24 hour period in 1959. Generally traps were emptied at 1600, 2000, 2200

2400 and 0600 hours. All fish contained in the trap or seined from the 15

pool immediately below Trap I, between the hours of 1600 - 0600 (the following morning), were considered as one day's catch. In addition, the number of kokanee in Trap I. and II were recorded on an hourly basis at several times during the season.

In 1958 length, sex, condition and scale samples were taken from all fish entering Moore Creek (Trap I). However, in 1959 only periodic samples were taken, although the total run was enumerated.

Meteorological and Limnological Data

Daily tabulations of many limnological and meteorological conditions were recorded at Nicola Lake throughout the summers of 1958 and 1959 and periodically in 1959, 1960 and 1961. Water levels in Moore- Creek were taken once or twice daily in 1958 but less frequently in 1959. Moore

Creek temperature: was recorded on a Weksler continuous recorder at Trap II in the summers of 1958 and 1959. The velocity of Moore Creek was measured with a LeupoId-Stevens Midget Current Meter, No. 111. Daily weather records of estimated cloud cover, air temperature and rainfall were kept.

Wind velocity and direction were noted three to four times daily. Similarly the total day's wind was recorded on a totalizing anemometer. A Negretti-

Zambra - M-2127 - Jordan Photographic Sunshine Recorder recorded intensity and periodicity of sunlight.

Weekly vertical temperature series were taken with a thermistor at standard stations in the lake; additional temperature series also were taken during 24 hour gill net sets. Dissolved oxygen determinations utilizing standard Winkler technique were made weekly in conjunction with the temp• erature series. 16

RELIABILITY OF GILL NET SAMPLES

Information on movement of kokanee within Nicola Lake is based on the assumption that gill net catches indicate relative abundance of fish present in the sample area and' are not erratic movements of large schools. To test

this hypothesis, simultaneous gill nets were set in April, 1960 (Table III).

A.chi-square test of the number of kokanee captured in each series of net. sets indicated no significant departure from an expected 1:1 ratio

(p>0.5); similar results were obtained in a test for all fish (p>0.25).

Thus it is suggested that a positive correlation exists between the number of kokanee taken in a gill net and the concentration and activity of the fish within the area.

Fry (1937) points out that even though this evidence indicates a relationship between net catches and number of fish in a certain locality, it does not show that the fish were randomly distributed throughout a given stratum either individually or in small freely wandering schools.

However, it was noted that when nets were set for specific periods of time and checked every two to four hours a definite movement of kokanee in one locality could be shown in Nicola Lake. This suggests that the numbers captured are not representative of erratic movements of large schools.

A number of biases must be considered when discussing the distribution resulting from the catch. Gill net fishing requires the fish to come into contact with the net and so depends on the activity of the fish. This activity may vary because of a number of factors. For example, the analy• sis of stomach contents by Langford (1938) showed that when food was scarce the cisco apparently became more active in seeking it. This condition Table III. Number of fish taken in simultaneous gill net sets (April 21 - 22, 1960)

Total Number of Fish Total Number of Kokanee Time of Set Gill Net Set 1 Gill Net Set 2 Gill Net Set 1 Gill Net Set 2

1600 - 2000 2 1 2

2200 - 0200 16 12 13

0400 - 0800 7 5 4

1000 - 1400 6 17 0 18

would probably increase the number of fish taken relative to the number present. Dendy (1945, 1946) found a close relationship existed between temperature and the distribution of the middle fifty per cent of fish.

Fry (1937) noted that fish avoid gill nets under certain circumstances; i.e., daytime, however, this did not appear to be the case with fish in

Nicola Lake as shown in Figure 4 (which includes all species except chub which show a marked vertical distribution). The nets took rainbow trout, kokanee, squawfish, large-scale suckers and mountain whitefish equally as well during the day as they did at night. In nine gill net sets (from spring to late summer) 73 kokanee were captured in the surface water

(0-25 feet) during the day compared to 58 in these same waters at night.

The turbidity of the lake and use of translucent monofilament gill nets probably account for high efficiency during the day.

Size selectivity of gill nets is also known to effect the relative numbers of fish taken in each net of a standard graded series. In 1959 the maturing kokanee were most frequently captured in 2 inch nets and hence this was the dominant size of mesh set. However, gill nets from 3/4 inch to 3% inch mesh were also set. In 1961 the maturing kokanee were taken in the greatest number by using gill nets of 2% inch mesh. 0 i-

Ji 3 00 DAY EVENING NIGHT MORNING 1000 - 1400 1600 - 2000 2200 - 0200 0400-0800

= 5 FISH

Figure 4. Vertical distribution of all species of fish other than peamouth chub from August 20 - 21, 1959 gill net sets. 20

RESULTS

DISTRIBUTION OF MATURING KOKANEE

Vertical Distribution

Vertical distribution of kokanee during the day and night is summar• ized for three seasons of the year in Figure 5. During the late winter

(February - March) only a few kokanee were taken in the upper 10 feet of water during nocturnal net sets. In the spring (April - June) the kokanee occupied primarily the upper 30 feet during the day and night although a slight downward movement at night was noted. The summer distribution of kokanee (July - August) indicated a marked tendency for the fish to occupy deeper strata of the lake, especially at night. In September and October, however, kokanee were more concentrated in the upper 40 foot depth zone.

Since this study was primarily interested in the distribution and movement of maturing kokanee, the time period studied will be limited to the distribution observed immediately prior to spawning and during the spawning migration.

The diel vertical distribution of kokanee for four representative gill net sets in 1959 is shown in Figure 6. In nine gill net sets made between July and September 67 per cent of the kokanee (119 of 179) were obtained during the day from the upper 30 feet whereas only 44 per cent

(133 of 303) were found in these waters at night. During the spawning season, late August and early September, the kokanee showed a downward movement at night with a subsequent morning rise. During the day the mature fish were located predominantly in the surface to 30 foot depth zone. 21

SPRING SUMMER AUTUMN

DAY NIGHT DAY NIGHT DAY NIGHT

Figure 5. Day and night vertical distribution of kokanee in Nicola Lake for three seasons of the year in 1959 22

JULY 20-21

0 A Y EVENING NIGHT MORNING 1000-1400 1600 - ?r>00 2200 -0200 0400-OBOO

Figure 6. Vertical depth distribution of kokanee (July - September 1959) with temperature isopleths plotted 23

The vertical distribution of kokanee in August of 1961 illustrated a change from that recorded in 1959 (Figure 7). The distribution of kokanee in the mornings of both years was quite similar whereas the day and evening catches showed marked differences. It was noted that, in six gill net sets made in the latter portion of August, 24.6 per cent of the kokanee (15 of

61) were located above 30 feet at night in 1961 compared to 7 per cent in

1959; however, only 8.4 per cent were obtained during the day from the upper 30 feet in 1961 as compared to 66.7 per cent taken at this time in

1959.

Temperature isotherms and the distribution of kokanee are plotted against depth in Figure 6. The marked changes in the depth of the thermo- cline over 24 hours is probably the result of seiche activity. On some days the thermocline moved vertically 20 feet or more during a 24 hour period (Figure 2).

A distinct thermocline was absent on July 20 - 21, 1959, and on

August 31 - September 1. On August 3-4 the thermocline was located at a depth of 61 feet but moved upward to a depth of 41 feet in 11 hours. Fol• lowing this rise, it dropped to 47 feet in 8 hours but 12 hours later had risen to a depth of 16 feet. Similarly on August 17 and 18 vertical fluctuation of the thermocline from 42 feet up to 25 feet and back down to

33 feet was observed.

In 1961 vertical temperature series were recorded with all gill net sets. The temperature structure of Nicola Lake varied considerably from

August 18 to August 27. At the beginning of the netting series there was no indication of a thermocline; by August 25 a definite thermocline had developed and the position of it moved considerably during the next few days. -p-

DAY EVENING NIGHT MORNING 1000-1400 1600-2000 2200-0200 0400-0800

Figure 7. Vertical diel distribution•of kokanee in mid August of 1959 and 1961 (numbers indicate kokanee catch in surface and bottom gill net sets) 25

However, when the isotherms were plotted against the depth distribution of kokanee no obvious relationship existed. Thus, as was noted in 1959, the vertical distribution of kokanee in Nicola Lake is apparently not directly controlled by the temperature changes that occurred within the lake.

During the summers of 1959 and 1961 oxygen concentration at 50 feet ranged between 8-10 ppm and only once in 1959 fell to a level of 4 ppm.

This amount of available dissolved oxygen at the various depths was more than adequate (Vernon, 1956) and hence oxygen cannot be considered an important factor in explaining the observed kokanee distribution.

The association of kokanee and light intensity may be observed by referring to Figure 8. It is notable that no preferred optimum or minimum zone is inhabited by the kokanee in 1959. Though light intensity per se did not appear to inhibit the movement of kokanee in 1959 it may have been important for orientation and timing in the overall diel migration pattern.

In 1961, however, the kokanee did appear to be reacting to variation in light intensity and their vertical distribution in relation to underwater light intensity is plotted (Figure 8). Throughout the day the kokanee in -4

1961 did not move into areas of illumination greater than 100 x 10 langlies/minute. However, during the morning descent and evening rise a few kokanee were captured at depths having this light intensity.

Stomach analyses of preserved specimens indicated that kokanee were not specific in their choice of food, but often fed on the largest food organisms available even though plankton hauls suggested they were not necessarily the most abundant. Figure 9 shows the major food items contained within the stomachs of kokanee captured in night gill net sets at Stations I and II. I S 5 9 10,000 1000

UJ

100 X I- o. UJ O

ON

NIGHT MORNING DAY EVENING 2200-0200 0400 - 0800 1000- 1400 1600 - 2000

LIGHT INTENSITY = 5 FISH I N LANG LIES X IO"4/min

Figure 8. Depth distribution of kokanee in August of 1959 and 1961 in relation to light. Isolumes are plotted in langlies x 10 per minute.- T ION .1

JUNE 11-12 IB - 19 JULY 16-17 30- 31 AUG 13-14 SEPT 7-8 OCT 21-22 APRIL20-2I I960

Figure 9. Per cent composition of food eaten by kokanee captured in night gill net sets (surface and bottom) at Stations I and 2 in 1959; data for April 20 - 21, 1960 also included. 28

Marked seasonal changes in the diet were recorded. In winter and early spring kokanee fed extensively on crustacean plankton, whereas during the late spring, chironomid pupae composed the major portion of the diet. During the summer chironomid pupae with some larvae were the domin• ant food items, while in the autumn the major items of the diet were crustacean plankton.

Together with the seasonal changes observed in the kokanee's diet, diel changes in food organisms eaten occurred during the late spring and summer of 1959. Figure 10 shows the per cent composition of food eaten by kokanee captured in diel gill net sets immediately prior to and during their spawning migrations. To increase the sample size of stomachs examined, day and evening catches were combined and illustrated as food eaten during the day; similarly, night and morning catches were combined and illus• trated as food taken at night.

Kokanee taken from the surface water during the day fed to a large extent on crustacean plankton with some chironomid pupae in July and early

August whereas fish taken from these waters at night fed largely on chiro• nomid pupae with some crustacean plankton. Stomachs examined from kokanee taken in the bottom nets for both day and night sets contained chiefly chironomid pupae with small amounts of crustacean plankton.

Chironomid larvae were consumed in greatest abundance in late July and early August. They were found not only in fish captured in the bottom layers but also in fish taken from the surface water.

No marked differences in vertical distribution of the kokanee with regard to sex were apparent. In the gill net sets, though the ratio of males to females was greater (58.1 per cent males to 41.8 per cent females, DAY SET

Figure 10. Diel changes in food eaten by kokanee in 1959 (numbers indicate number of stomachs examined) 30

a significant departure from the 1:1 ratio p<0.05), there was no indica• tion of vertical stratification according to sex.

Onshore Movement

With the approach of spawning a noticeable increase occurred in the number of maturing kokanee captured in the northeastern basin. At Station

I gill net catches for equal periods of fishing time recorded 21 kokanee taken in early July, 52 in mid August and 90 in late August, the latter with less net than for previous sets. By the middle of September the maj• ority of mature kokanee had entered spawning streams and the gill net catches were then composed predominantly of immature fish.

The horizontal movement for a representative diel gill net set

(August 24 - 25) is illustrated in Table IV. The results are representa• tive of gill net catches made during the spawning season of 1959 in nets set perpendicular to the shore at Station IV for both calm and windy days.

Kokanee were taken only in offshore water (25 feet or more) prior to 1600 hours. Few kokanee were captured in the shallow nets before 1800 hours.

On calm days the kokanee moved gradually onshore appearing in the very shallow water at dusk (1800 - 2000 hours). On windy days the shoreward movement began somewhat earlier (1600 - 1700 hours,).

No onshore movement of kokanee was observed in sets made on

August 20 - 21 or August 25 - 26, 1961. At this time no fish were enter• ing the spawning stream (Moore Creek) which was extremely low (less than

3 cfs) thus providing little attractive flow. Furthermore, little wind was recorded in the area; in 1959 wind appeared to be an important factor in attracting fish into the spawning areas. Table IV. Relationship of onshore movement of kokanee to light conditions at spawning time. (August 24 - 25, August 28, 1959)

Distance Offshore (feet)

200 IOO 50 O 1 Time of Light Gill Net Set Condition

Number of Kokanee Captured

1000 - 1200 3 - - - 1200 - 1400 2 1 _ _ 1400 - 1600 Day 14 (4) - (-) - (-) - (-) 1600 - 1800 17 (5) 2 (4) - (3) - (-) 1800 - 2000 Dusk 8 (4) 24 "(19) 6 (18) 5 (11) 2000 - 2200 16 3 1 14 2200 - 0100 Night 9 3 6 6 0100 - 0300 5 I 4 8 0300 - 0500 Dawn 2 2 3 1

0500 - 0700 6 _ _ 0700 - 0900 Day 7 - - - 0900 - 1100 2 1 _ _

Figures in brackets are representative of catches made on a windy day (August 28) 32

Accompanying this onshore movement (Table IV), kokanee were observed to cruise parallel to the northeastern shore until they came into the influ• ence of the stream current and then moved abruptly into the spawning stream.

In 1958 parallel movements to the northeastern shore were observed on a number of nights in areas marked off on both sides of the spawning stream. Short bursts of light, from a flashlight, were used to note if kokanee were in the area, and to determine their direction of movement.

Similarly, schools of kokanee could be located without the use of the flashlight by the presence of ripples and rises on the lake's surface.

Numerous groups of kokanee were observed for a distance of 1000 feet on both sides of Moore Creek, with larger concentrations in the vicinity of the mouth. This parallel movement was not noted prior to 1900 hours and no kokanee were observed after 0400 hours in the inshore waters. Thus movement towards and along the shore appeared to be related to light intensity.

ENTRANCE OF KOKANEE INTO SPAWNING STREAM

Timing of Entrance

Comparison of visual counts of kokanee entering Moore Creek, from shore station situated at the mouth of the stream during 1958 and 1959, and the corresponding light intensity are illustrated in Figure 11.

Kokanee entering Trap I for the time interval observed are also plotted. 2

Once the light intensity dropped below 1 x 10 foot candles, active move• ment of mature kokanee into Moore Creek commenced. The movement began quickly, reached a peak within an hour of its origin and then gradually 33

declined. During the early portion of the spawning season no movement of kokanee into the stream occurred prior to 1930 hours, whereas in the later segments of the run, movement into the stream occurred at least one to two hours earlier. Very little movement of kokanee was noted after 0400 hours.

No movement of kokanee into the stream during the day was observed and, as was noted in Table IV, few kokanee were located in the inshore waters during the daylight hours that could move into the stream at this time.

As the light intensity diminished seasonally the kokanee were noted to enter the spawning stream earlier in the evening, however, the pattern of entry did not change.

Seine hauls showed a similar movement of kokanee into Nicola River

(inlet) which was related to the decreasing light intensity (Table V).

Stream Location

To determine the roles of olfactory and visual stimuli in aiding kokanee to locate the spawning stream, a number of experiments were con• ducted on fish that had entered the stream in 1958 and 1959.

In 1958, late in the spawning run (September 17), 100 kokanee (50 males, 50 females) were marked by removal of the posterior portion of the dorsal fin. Both nasal rosettes were cauterized (insertion of a heated probe) in half of these fish (25 males, 25 females); the other 50 were not treated. The entire group was released approximately 50 yards off

the mouth of Moore Creek the same day.

A total of 10 fish, all uncauterized controls, were recovered at

Trap I within six days of release. No fish with cauterized nasals were 34

103

10

19 AUGUST 1959 30 l

20

10 NO OBSERVATIONS 0 1

22-22 AUGUST 1959

2000 2200 2400 0200

STANDARD TIME - HOURS

•• KOKANEE COUNTED OVER STRIP

E:3 KOKANEE IN TRAP AND SEINED

— LIGHT NTENSITY (FOOT CANDLES)

Figure 11. Diel periodicity in entrance of kokanee to Moore Creek in relation to surface light intensity in 1958 and 1959. 35

Table V. Movement of kokanee into Nicola River (inlet) in 1959

Number Date Time Captured Weather

1130 1140 0 1845 1850 39 Calm and clear; September 2 1855 1925 12 no wind 1930 1955 31 2000 2030 30

1730 1735 0 1800 1805 0 4/10 overcast; September 3 1830 1835 0 15 mph wind from 1845 1850 158 southwest 1900 1905 33 36

taken during this period, after which the spawning was nearing completion.

On August 22, 1959, kokanee entering Moore Creek were fin clipped and treated in the following ways:

50 Controls

50 Both nasal passages filled with latex

50 One nasal passage filled with latex

50 Vision destroyed totally (injection of formaldehyde into pupil)

25 Both nasals cauterized

25 One nasal cauterized

The nasals were blocked by the following technique (modified from

Gunning, 1959). A Tuberculin syringe fitted with a No. 20 blunt needle filled with a weak acetic acid solution was injected into the nasal pit and the area douched with the solution. A similar syringe filled with

blue coloured biological latex was then inserted into the cavity and withdrawn when the cavity was filled.

Half of the adipose fin was clipped off all fish for later recogni• tion and following treatment they were released 50 yards directly off Moore

Creek mouth. All recoveries in Moore Creek were preserved. Of the 250 fish released, 30 were recovered in Trap I during its operation up to the

22nd of September. These consisted of (a) 26 controls, (b) 2 with one nasal cauterized, and (c) 2 with both nasals cauterized (when examined

subsequently, the nasal rosettes of these appeared to be only partially

cauterized). Twenty-two of the fish (20 controls, 1 with one nasal

cauterized and 1 with both nasals cauterized) were recovered within eight

days following release. None of the fish that were blinded or had the 37

nasal rosette occluded with latex were recovered although no mortality or apparent ill effects were observed in fish similarly treated and held in test cages for three days. Examination of the nasal regions of all recov• ered fish showed that none of the nasal plugs had become dislodged and hence fish recorded as controls at time of preservation were truly controls.

Daily Fluctuations in Number of Kokanee Entering Moore Creek

The numbers of kokanee entering the stream daily during the spawning period of 1958 and 1959 are shown in Figure 12. In 1959 marked "surges" of 300 or more kokanee entering the spawning stream were observed. These daily fluctuations continued until September 13 after which only a few fish entered the spawning stream. In 1958 daily fluctuations in number of kokanee entering Moore Creek were also observed although on a smaller scale. As previously noted all kokanee that entered Moore Creek on any evening in 1959 voluntarily entered Trap I or were seined from the stream and passed above the weir, whereas for the majority of 1958 only those fish that entered the trap voluntarily were placed above it. In 1958 from

September 15 onward, however, the kokanee within the trap were first counted and then together with the kokanee seined from below the weir were placed above the fence. Change in technique is shown by the cross- hatched portion of the histogram in Figure 12 for the year 1958.

Plots of wind, in miles per hour, from 1200 - 2400 hours (Figure 12), appeared to be closely related to the observed fluctuation in kokanee num• bers. The time period of 1200 - 2400 hours for recording total miles of wind was chosen because it was during this time interval that kokanee were

located immediately offshore and moved shoreward with falling light 38 5 i 1 i i i r i i r UJ 500 -j—T—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—r~i—i—i—i—i—i i—i r~i i i i r- tr r- 1958 400 o 300 or

r- 200 UJ 100 O Z 0

i/i UJ _)

2 1 00 z o z — 50 _J to- 0 jMJ

1336 1257 1 200

5 1000 -SEINE0 8 TRAPPED

0

200 (/I UJ _J

2 1 50 z

Q Z 1 00 5

_j •3 >- 50 O 1-

0

SEPTEMBER

irm WIND WATER TEMPERATURE

Figure 12. Daily number of kokanee entering Moore Creek in 1958 and 1959 in relation to total miles of wind (1200 - 2400 hours) and maximum stream temperature. ( indicates evenings of offshore (northerly) winds) 39

intensity. It was notable that the "surges" in kokanee numbers in 1959 appeared to be closely correlated to intensity of onshore wind.

Direction, as well as total miles of wind, appeared to be an import•

ant factor influencing the number of kokanee entering the stream.

Northerly or offshore winds resulted in lower daily catches than did

onshore or southerly winds. Offshore winds are indicated by small dots

under the histograms representing total miles of wind in Figure 12.

In 1958 daily fluctuations in kokanee numbers did not appear to be

closely related to wind for the majority of the spawning run. From

September 16 - 22, after which all kokanee entering the stream were placed

above the weir, there appears to be a closer relationship between the

amount of wind and number of kokanee entering the stream.

To determine the relationship between total miles of wind (1200 -

2400 hours), maximum stream temperature and daily fluctuation in number of

kokanee entering the spawning stream a multiple regression analysis was

used. The partial regression coefficients show that total miles of wind

is approximately 25 times as important in determining the number of kokanee

entering the stream as is the change in maximum stream temperature. The

total regression (Snedecor, 1948) is significant, (p<0.01) but only the

partial regression coefficient of total wind is significant (p<0.01)

whereas that for temperature is not significant. 40

SEX RATIO OF SPAWNERS ASCENDING MOORE CREEK

Data have been collected on the sex ratio of the kokanee spawning in

Moore Creek in the fall of 1958 and 1959. Of the 4,562 adults ascending

Moore Creek in 1958, 2,278 were males and 2,232 were females (a ratio of

50.5 males to 49.5 females). A chi-square test indicated that this differ• ence was not a significant departure (p>0.5) from a 1:1 ratio.

In 1959, because of inability to accurately determine sex of fish by external appearance, four lots of fish were preserved from Trap I through• out the spawning season. Analysis of the 177 preserved kokanee showed the

sex ratio to be 44 per cent males to 56 per cent females. However, when

the sex ratio of the individual collections were tabulated, they appeared

as follows: No. of Date of Kokanee No. of No. of Collection in Sample Males Females M/F

August 19, 1959 50 24 26 0.92 August 28, 1959 57 29 28 1.03 September 6, 1959 50 20 30 0.66 September 17, 1959 20 5 15 0.33

The sex ratio at the beginning of the spawning season does not

deviate significantly from 1:1 ratio, whereas, at the end of the spawning

run a preponderance of females occurred in the small sample examined.

Gill net sets made in the summer of 1959 captured approximately

1,300 maturing kokanee. The sex of 1,160 of these fish was recorded with

a ratio of 58.1 per cent males to 41.8 per cent females (675 males to 485

females). A chi-square test of the gill net catches indicated that these

differences in the sex ratio are a significant departure (p< 0.05) from a

1:1 ratio. Table VI. Comparison of the sex ratio of kokanee entering Moore Creek in 1958 and 1959 for three periods of the spawning run

Number of Number Time Period Kokanee Number of Males Number of Females Not Sexed

1958 Trap I

August 20 - 30 511 272 (53.2%) 235 (45.9%) 4 ( 0.8%) August 31 - September 9 2,104 1,097 (52.1%) 983 (46.7%) 22 ( 1.0%) September 10 - 21 1,947 907 (46.6%) 1,014 (52.1%) 26 ( 1.3%)

Total 4,562 2,278 (49.9%) 2,232 (48.9%) 52 ( 1.0%)

1959 Trap II

August 20 - 30 1,346 755 (56.1%) 364 (27.0%) 227 (16.9%) August 31 - September 9 2,397 1,267 (52.8%) 1,046 (43.6%) 84 ( 3.5%) September 10 - 20 1,538 854 (55.5%) 678 (44.1%) 6 ( 0.4%)

Total 5,281 2,876 (54.4%) 2,088 (39.5%) 317 ( 6.0%) 42

Kokanee observed at the Trap II site were easier to sex because of the marked sexual dimorphism that had developed since their first entry into the stream. Of the 5,365 fish observed at Trap II, 2,876 were males to 2,088 females; 401 of these kokanee did not have the sex recorded. This resulted in a ratio of 57.7 per cent males to 42.3 per cent females. A chi-square test indicated that this ratio was a significant departure from (p <0.001) the expected 1:1 ratio.

The spawning runs of 1958 and 1959 are broken into three component segments and are shown in Table VI. Unfortunately, the sex ratio of spawning individuals were kept at Trap I in 1958 and at Trap II in 1959.

Therefore, the data recorded are not completely comparable though observ• able changes in the sex ratio of the runs should appear if differences actually occur.

It is noteworthy that in both years the early portion of the spawning run was composed largely of males. In 1958 there is a shift in the sex ratio of the run with the number of females increasing and predominating at the end of the run.

In 1959, however, the ratio of males to females at Trap II would not shift to any extent especially if the non-sexed portion were included as part of the female count for the early part of the run. As non-ripe females were the most difficult on which to determine sex with any degree of accuracy, they probably make up the majority of the non-sexed portion.

In 1959 there is apparently a real difference in numbers of males within the spawning population. However, as will be shown shortly, only a small percentage of the late entering kokanee move upstream into Trap II.

Therefore, as the sex ratio of the spawnxng run is unequal (greater percent- 43

age of males) and the males move in first the sex ratio at Trap II site does not appear to change. But as the seine hauls at Trap I (four collec• tions of spawning run) during the later segment of the run, yielded a statistically significant number of females it appears that they are masked by the predominance of males already in the stream and the lack of upstream movement for late entering fish.

In 1960 only a small sample of kokanee were seined from Moore Creek on August 30. Of the 120 mature kokanee captured, 78 were females and 42 were males, a significant departure from the expected 1:1 ratio (p<.001).

In the 1961 gill net catches there was again a dominant number of males (309 males to 259 females). This gave a sex ratio of 54.7 per cent males to 45.3 per cent females. A chi-square test of these gill net catches showed that these differences in sex ratio are a significant departure from the expected 1:1 ratio (p<0.025). This divergence from an

equal sex ratio may be due to gill net selectivity. However, if all kokanee captured, less than 245 mm. in length, were subtracted from their

respective sex groups the population showed a 1:1 ratio.

SIZE DISTRIBUTION OF THE SPAWNING RUN IN MOORE CREEK

The size of mature kokanee taken from the spawning run in Moore Creek

in 1958 and 1959 ranged from 180 mm. to 275 mm. fork length (Figure 13).

In each year the mean length of males was greater than that of females.

In 1960 and 1961 the average size of mature kokanee was considerably

larger than in either of the two previous years. Figure 14 shows the size

range of the maturing kokanee taken in gill nets and also of fish in the 44 1 1 i i » i i i i i

1958

19 58

x = 229 6

nnn

959

x = 225.0

111 n 1111 MINIMI! i 195 205 2 I 5 225 23 5 245 258 265 FORK LENGTH M M

Figure 13. Length frequency distribution of the kokanee spawning run in Moore Creek 45 T "1 " r T i t iT I—T • -i—r 1 I JTT T "T ' r ! 1 1 I 1 1 1 1 1 1 I '

1957 - GILL N E T CATCHES.

I" • 1 1

1958 SPAWNING RUN Lni

100

80

60 - I 959 SPAWNING RUN 40T-

30

20

I 0

- - •M-L

I960 SPAW.NING RUN - Jr. F

FORK LENGTH - MM

Figure 14. Length frequency distribution of mature kokanee captured from the spawning run to Moore Creek (1957 and 1961 represent gill net catches near creek mouth) 46

spawning runs from 1957 to 1961. A striking increase in size is shown for the mature kokanee in 1960 and 1961.

AGE OF MOORE CREEK SPAWNING RUN

A number of difficulties were encountered in using scales to deter• mine age of kokanee in the spawning run (extremely small scales, presence of false annuli, annulus represented by only one broken circulus).

Consequently the length frequency method of aging was utilized (Figure 15).

Most fish captured from September, 1959 to August, 1960 are representative of the year class of kokanee spawning in the fall of 1960. Catches of kokanee (greater than 180 mm.) from May, 1959 to September, 1959 are rep• resentative of the 1959 spawning class.

Though there is some overlap in the size ranges of the various age groups there appears to be only three definite distributions of kokanee present in fish collected with dynamite in August of 1959. Thus kokanee spawning in Moore Creek are predominantly age III when they spawn though a few (mostly males) mature at age II.

Plots of length distribution of kokanee in 1960 and 1961 appear to indicate that these fish matured a year later than did the 1959 spawning class. However, analysis of a number of scale samples from these larger kokanee show that a striking amount of growth occurred in the final year of life in the 1960 spawning class and during the last two years in the 1961 spawning class. The number of annuli for the three spawning classes were considered to be identical and only the distance between circuli was changed. 47

20

10

0

30

20

I 0

0

30

20

10

0

30

20

10

O

50

40

30

20

10

0

10

0

30

20

10

0

10

0

10

0

50

40

30

20

10

0

Length frequency distribution of kokanee tak< in gill nets or with dynamite May 30, 1959 t< August 30, 1961. (August 30, 1960 distribut: represents kokanee seined from Moore Creek) CUMULATIVE FREQUENCY (%)

Figure 16. Cumulative per cent length distribution of 486 kokanee captured by dynamite charged in Nicola Lake, August 4 - 6, 1959 49

The length-frequency distributions for 1959 were further exploited by plotting the data on probability paper after Cassie (1954). This gives a linear transformation which allows the overlapping flanks to be more readily detected (Figure 16), as they appear as inflections on the graph.

Two points of inflection resulted from plotting the length-frequencies thus, again, emphasizing the presence of only three age classes.

STREAM MOVEMENT

Movement of kokanee both into and within Moore Creek for 1959 is o shown in Figure 17. Movement recorded as occurring within the stream is that of kokanee which ascended 1,000 feet above Trap I to enter Trap II.

All fish voluntarily entering the Trap II ascender were placed above the weir after information on sex, degree of maturity and marks on the fish were noted. Analysis of the spawning run ascending above Trap II showed that more males were present in the run than would be calculated from preserved specimens taken at Trap I. In 1958 the stream movement of kokanee was not recorded except for occasional counts made at the Trap II site.

Diel movements of kokanee within Moore Creek are recorded in

Figure 18 for 1959. Kokanee within the stream began to move in the late afternoon, with activity reaching a peak just before 2400 hours and then gradually declining in intensity. The movement observed within Moore

Creek is very similar to that recorded for kokanee entering the stream from the lake, except that its origin is earlier in the day. Similarly, the numerous "surges" noted at Trap I are not as evident in the upstream movement of the fish. However, the fluctuation in numbers of kokanee Figure 17. Daily number of kokanee entering Traps I and II on Moore Creek during the 1959 spawning run 51 -i—i—"—i—i r -i 1 ) i 1 1 1 r 100 AUG 22-23 I2C 75 • • • 50

25 Mi Ql 0 10° 14"

I 00 z AUG 26-27 13° o_ cc UJ 75 K 2 LU 50 12' UJ UJ 25 UJ 2

SEPT 9-10 I I' 200 o z I 50 I0C

I 00 - 9e 50

0 rTnV|,<'' 'i •1 • ••••••) '' i' i; tv 'vv(v V -r 1300 - 1800 1900 2000 2100 2200 2300 2400 0100 0200 0300 0400 0500 0600- 0800 STANDARD TIME

Figure 18. Number of kokanee entering Trap II on Moore Creek for three periods of the 1959 spawning run 52

moving within the stream appears related to the numbers entering as in• creased catches at Trap II occurred a few days after a large "surge" at

Trap I.

No apparent relationship exists between stream temperature, stream

level, sunlight duration or intensity and movement of fish within the

stream. There are indications that the movement is related to light

intensity for it was noted that as day length shortened seasonally, the movements of kokanee became earlier. However, light intensities were not measured at the Trap II site and readings obtained from Trap I would be much higher than corresponding readings at Trap II because of the less

extensive foliage and stream cover.

The elapsed time between kokanee being marked at Trap I and their movement upstream to Trap II is shown in Figure 19. Of the fish captured

and marked at Trap I at the beginning of the spawning run, approximately

50 per cent moved upstream 1,000 feet to enter Trap II and subsequently

spawned in the area above the trap site. Of the kokanee entering Moore

Creek towards the end of the spawning run only 10 per cent moved above the

Trap II site. The numbers of kokanee marked at Trap I and their subsequent

recovery at Trap II are given in Table VII.

During the early part of the spawning run four to five days were

required for the kokanee to move the 1,000 feet upstream and appear in

Trap II, whereas, in the middle of the run the fish were frequently cap•

tured at Trap II the day after being marked. In a number of cases kokanee

marked at Trap I were taken a few hours later at Trap II. Figure 19. Elapse of time between kokanee marked at Trap I and subsequent recovery at Trap II during the 1959 spawning run to Moore Creek. Abbreviations represent the following fin clips: OA - adipose; OA + UDC - adipose plus upper lobe of dorsal caudal; OA + LDC - adipose plus lower lobe of dorsal caudal; OA + UVC - adipose plus upper lobe of ventral caudal; UDC - upper lobe of dorsal caudal; UVC - upper lobe of ventral caudal 54

Table VTI. Number of mature kokanee marked at Trap I and subsequently recaptured 1000 feet upstream at Trap II in 1959

Number Number Per Cent Mark Dates Applied Marked Recovered Recaptured

OA August 15 - 18 338 153 45.3 OA + UDC August 19-21 670 251 37.5 OA + LDC August 22 - 24 324 117 36.1 OA + UVC August 25 - 27 68 20 29.4 UDC August 28 - 30 409 131 32.0 UVC September 5 100 10 10.0 55

DISCUSSION

Vertical Distribution

Several studies have suggested that temperature is a major factor governing spatial distribution of fishes (Odell, 1932; Fry, 1937;

Hile and Juday, 1941; Dendy, 1945, 1948; Ferguson, 1958 and Rawson,

1961). Clemens et al_. (1939) and Ferguson (1949) working on lakes in the

Okanagan Valley expressed the view that kokanee, an open water species, were found at intermediate depths during the summer because the thermo• cline presented a thermal barrier through which the kokanee would not pass. Similarly, Tokui (1959) studying kokanee in Lake Towada in northern

Honshu noted that the immature kokanee were found near upper levels in early June but descended into deeper water when the surface temperatures rose. However, he presented no data regarding the diel activity of fish during the summer.

In Nicola Lake, regardless of thermal structure, kokanee undertook diel vertical movements (Figure 5). During the summers of 1959 and 1961 thermal stratification was quite impermanent. Even when the lake was thermally stratified the position of the thermocline varied considerably over a 24 hour period because of wind-generated seiches.

Data collected in these years showed the vertical distribution of kokanee could not have been controlled directly by temperature. Black

(1953) noted that the upper lethal temperature of kokanee fry was 22°C.

Only on a few occasions in either of the study years did the surface water of Nicola Lake reach a temperature of 22°C. However, this tempera• ture was of short duration and did not appear to limit kokanee distribution. 56

Workers who have illustrated fish movement in relation to water ' temperatures have dealt with lakes having permanent stratification during the summer months, in which the fish were subjected to a more or less constant thermal condition. In most cases only the nocturnal distribution of the species was studied. In Nicola Lake, however, thermal conditions were in a state of flux, and changes of 6 or 8°C occurred at depths to 60 feet within a period of a few hours. Ferguson (1958) states (page 607)

temperature, if acting alone, can determine the distribution of fish in laboratory apparatus. Factors such as light, conditioned response related to feeding routines, and social behaviour can interfere with ex• pression of the response to temperature."

Dissolved oxygen available at the various depths is often quoted as an important factor in regulating the distribution pattern of fish or in modifying the response of fish to temperature. Pearse (1921) and Dendy

(1945) both noted that distribution of fish depended upon oxygen avail• ability at the various depths.

Vernon (1956) noted that 5 ppm of dissolved oxygen generally is considered necessary for survival of salmonids. Only once during the study did the concentration of oxygen in Nicola Lake fall below this value.

No apparent relationship between kokanee distribution and available dis• solved oxygen was observed. Under present field conditions the effect of available oxygen on vertical distribution of fish was not discernable particularly when conditions of decreased oxygen availability were only temporary.

The role of light as a determinant of fish distribution, particularly in the deeper water, is not clearly understood. Dendy (1945) observed 57

that the vertical distribution of game fish in Norris Reservoir showed no

tendency to be related to light intensity. However, Hart (1931); Bryon and Howell (1946); Carlander and Cleary (1949); Hasler and Wisby (1958) and McLeod (1960) all noted that vertical distribution of freshwater

fishes studied was regulated by light conditions. Similarly, in the marine environment, studies by Hickling (1927), Richardson (1952) and

Nomura (1958) have demonstrated diurnal vertical migration in hake, sar•

dine, herring, sprat and pilchards related to underwater light intensity.

The kokanee distribution in 1961 (Figure 8) suggested a negative

phototaxis with fish avoiding areas of bright illumination. The morning

and night distributions were similar for the two years (Figure 7) whereas

distribution during the day and evening were markedly different. In 1961, -4

kokanee did not move into areas of illumination greater than 100 x 10

langlies/minute whereas in 1959 their presence was noted through all

ranges of light intensity (Figure 8).

Under natural conditions pelagic species may keep within a given range

of light intensity by making a vertical migration from deep to shallow

water during the evening and returning to deep water the next day. Reverse migrations are also known. While the pattern of migration can be correl•

ated with changes in light intensity, the reactions of individuals cannot

be easily studied in the field. Furthermore, there is the question of how

the animals find their optimum range of light intensity and remain within

it as it moves up and down the water column. Cushing (1951) has reviewed

the problem for the planktonic Crustacea, but so far little work has been

done with fish. Jones (1956) using the minnow (Phoxinus phoxinus) made

observations on locomotory activity, shoaling and feeding behaviour in 58

relation to light intensity. He noted that the minnow appeared to keep below its upper limit of light intensity by a comparison of intensities, that is, by a taxis.

Hickling (1927) found hake to remain idle and inactive during day• light hours, whereas other workers asserted that some species of fish were active during daylight but became quiescent in the hours of twilight.

Hoar (1942), observing the feeding activity of young salmon and trout, noted a quiescence in the fish at night leading to a cessation of their feeding activity. Similarly, Spencer (1939) found that a number of species of fish showed either a fairly continuous pattern of activity over a 24 hour period or a monophasic pattern conditioned apparently by reaction to light. Spencer found differences in activity with the age of the indi• viduals and also over the seasons. Light intensity and time of feeding also affected the fishes* activity.

Hasler and Villemonte (1953) observed quiescence and sleep conditions in perch at night in Lake Mendota. In daylight, however, the perch moved in compact schools far above the bottom. In contrast to the above,

Hasler and Bardach (1949) found that various fish became active at night.

Light appeared to affect movement directly as well as indirectly through its influence on the behaviour of food organisms.

Hoar et al_.(1957) in a laboratory experiment, and Richardson (1952) in a field experiment, demonstrated that certain species of fish avoid bright light. In 1961 the maturing kokanee were found in the zone of low light intensity during the day, but during 1959 (Figure 8) the reverse situation was illustrated. In both years of study the kokanee exhibited 59 a continuous pattern of activity during a 24 hour period, whether the kokanee responded directly to light or whether the response was to some associated factor can be determined only by experiment.

Common food and food preferences are known to bring about the association of fish into different habitats. Fry (1937) and Godfrey

(1955) discuss the influence of feeding activity on the summer distribution of different fish species. In Lake Nipissing, Fry found that the cisco remained in the epilimnion in summer for some time to feed upon emerging

Mayflies, even if the temperature conditions became unfavourable. Simil• arly, Martin (1952) showed that lake trout (located in the upper hypo- limnion) came up through the thermocline to feed on perch concentrated in warmer water. Godfrey (1955) found inadequate bottom fauna was able to re-orient the feeding habits and distribution of the common whitefish in

Morrison Lake so it fed upon plankton crustacean, though normally they depend on bottom organisms.

The vertical distribution of kokanee in 1959 appeared to be related to diet in the spring and early summer. In May and June they were captured in the upper water levels throughout the day and night, and examination of their stomachs showed them to be feeding on chironomid pupae. Mundie (1959) found that chironomid pupae ascend mainly in the hours of darkness and emergence may be immediate or delayed for several hours. Chironomid larvae also occurred at the surface, thus showing that many benthic animals are less static in their distribution than is commonly accepted. During the evening and night sets chironomid pupae were the dominant items of food eaten from May to late August. In the morning and day catches it was evident that crustacean plankton was the major food 60

item, at this season for surface caught fish, though numbers of chironomid pupae were also eaten. However, fish captured in the bottom nets fed almost totally on chironomid pupae and larvae. During the autumn, winter and early spring the kokanee fed predominantly on crustacean plankton.

Ricker (1937), working at Cultus Lake, stated that the total amount of food found in the stomachs of fingerling sockeye varied throughout the year. It increased throughout the summer to late August, decreased greatly throughout the autumn and winter and increased again in the spring. The relative abundance of plankton in the lake was important but not the only factor determining the numerical proportions eaten. The size of the plankton was extremely important, and those plankton largest in size were more extensively exploited. Similarly, fish held in the upper ten meters captured more food than fish held in the twenty meter area.

Vertical migrations of fish have been attributed to various environ• mental factors. Most authors have been able to correlate temperature, light, oxygen, food preferences or a combination of these factors to the vertical migrations observed. In Nicola Lake the vertical migrations for kokanee during 1959 did not seem to be simply related to any of these factors, whereas in 1961 the kokanee reacted in a manner apparently directly influenced by the changing light intensity, or possible indirectly by following a food source; i.e., chironomids. The distribution during

1959 cannot be adequately explained, and indicates the need for controlled experiments if similar distributions are to be explained. 61

Onshore Movement and Location of Spawning Stream

Onshore movement of kokanee did not take place until the fish were almost sexually mature. When the movement did occur it consisted of shoreward movement under reduced light intensity and then parallel move• ment along the shore.

Shoreward movement (Table IV) commenced in the late afternoon with kokanee reaching inshore waters at dusk. Onshore movement was earlier on windy days than on calm days, particularly if the wind was blowing towards shore. Thus it appears that the shoreward movement is initiated by fall• ing light intensity and is intensified by the amount of onshore wind.

Mottley (1938) showed that in Paul Lake a direct relationship existed between the intensity of the rainbow trout spawning migration and the amount of wind. If the wind blew directly into the mouth of the stream and was of sufficient strength, large numbers of spawners entered the creek. According to Mottley, fluctuations in the spawning run of rainbow trout were not determined by chance though some fish may locate the creek by swimming at random near the mouth and thus encounter the stream current.

Mottley hypothesized that the movement of fish was related to the complicated interaction of wind-driven lake currents, the stream current and temperature.

This hypothesis may with modification apply to the onshore movement of kokanee in Nicola Lake. Because of the more or less constantly pre• vailing onshore winds, seiches and counteracting lake currents are in existence. The kokanee may possibly utilize wind-driven lake currents as 62

guides to movement, thus building up local concentrations of maturing fish in the two basins off the mouths of the main tributary streams.

As sexual maturity approaches the kokanee begin to make exploratory movements shoreward. Generally the water issuing from Moore Creek is approximately 3 to 4°C cooler than the lake surface. As the flow during the late summer is quite low it presents little attractive force and produces resultant currents of low magnitude. On calm days the flow from Moore Creek moves out as a narrow band across the sandy sill at the mouth and drops to its own density level. This restricted movement of the issuing water presents little opportunity for mature kokanee to come into contact with the influence of the stream unless they happen upon it by chance. However, if there is an onshore wind blowing this tends to hold the issuing water in close to shore and causes it to spread out laterally, presenting a greater area of attraction for the shoreward moving kokanee, particularly if the fish are "homing" to a characteristic odour.

Olfaction is known to play an important role in the orientation of fishes, since some find their food by smell. A number of workers have shown that the sense of smell is very acute, and several studies suggest that it may be involved in "homing". Brett and MacKinnon (1952) investi• gating the sense of smell in migrating adult coho (Oncorhynchus kisutch) and chinook salmon (0. tshawytscha) found that dilute rinses of mammalion skins had distinct repellant action. Hasler and Wisby (1951) postulated that river and creek waters contained some characteristic odour to which young salmon become conditioned while in the stream and to which they orient upon reaching the parent stream as mature migrants.

In a field experiment Wisby and Hasler (1954) filled the olfactory 63 pits of migrating coho salmon, thus preventing water from reaching the rosette of the olfactory tissue. The results they obtained were in accord with those which would be expected if the fish were relying on their sense of smell to choose the spawning "home" stream.

Though the returns from the experimentally marked kokanee in 1958 and 1959 were only 10 per cent and 12 per cent respectively, they suggest that olfaction played a part in the location of the "home" stream. The reason for the non-return of fish treated by filling only one nasal cavity with latex or fish blinded is unknown and further studies should be carried out.

Stream Entry and Movement Within Stream

Several theories have been formulated to provide a mechanistic explanation for the "homing" ability of salmonid fishes. Calderwood

(1903 in Briggs, 1953), Pritchard (1936), Davidson et al. (1943), and

Hayes (1953) all noted that a rise in water level or a continuous steady flow was responsible for movement of salmonids. Similarly, Calderwood

(1903), Mottley (1938) and Lindsey et al. (1959) noted that temperature was the factor that controlled intensity of migration whereas the authors cited previously found no relationship between temperature and migration. On the other hand, Neave (1943), working with coho and chinook salmon, found no correlation between migration numbers and either water temperatures or flows.

Gilhausen (1960) notes that sockeye maturation is largely a response to the pattern of changing length of day and the resulting migra• tion time is similarly related. 64

Collins (1952) states that it is an important consideration that not only are there many factors which have a directional influence upon the migrating fish but also they must all be considered together. It is quite possible that many apparently contradicting observations may be explained in this way.

Hayes (1953) and Huntsman (1939) both noted that onshore winds tended to increase the number of Atlantic salmon that entered the stream.

However, in the majority of their observations the increased wind was accompanied by rain which resulted in increased water flow. In two cases, however, Hayes was able to observe the effect of wind alone as it affected the salmon migration and noted large concentrations of fish moved into the stream at these times.

Decreasing light intensity (Table IV) appeared to govern the time of shoreward movement of kokanee while intensity of onshore wind appar• ently is related to the fluctuations in numbers of fish entering the stream (Figure 12). The following hypothesis is proposed to explain the relationship of onshore wind and fluctuations in numbers of spawners entering the stream. Onshore winds increase the turbulence of the surface waters thus reducing light penetration resulting in earlier shoreward movement of kokanee. Moreover, as discussed previously, onshore winds hold Moore Creek water close to shore causing it to spread laterally and increase its potential area of contact. Earlier shoreward movement in• creases the probability of kokanee contacting the stream's influence

(because they ascend only at night) thus increasing the number of kokanee that locate the stream in comparison to an evening with no wind when onshore movement is delayed for a couple of hours. 65

Cope (1956) studying cutthroat trout and Hayes (1953) working on

Atlantic salmon both recorded movement of their fish species at dusk with secondary migrations in the morning. Other authors note that salmanids move into the spawning streams during the day, generally in response to rising temperature or water levels. However, the kokanee movement in Nicola Lake took place only after dusk, and showed no rela• tionship to stream temperature or stream discharge.

Movement during the period of darkness certainly has increased survival value for kokanee populations in Nicola Lake. For if mature kokanee were to move shoreward and enter the stream during the daylight hours they would be subjected to a greater array of predators (ospreys, gulls, mergansers). At present only a few mammals (mink, bear, human beings) and piscivorous fish impede the nocturnal movement of the kokanee.

Movement of kokanee within the stream also inferred a probable relationship to light intensity (Figure 18). The movement originated in the late afternoon and declined at dawn with its peak at midnight.

Temperature and water level had no apparent effect on the movement of kokanee. The intensity of movement within the stream is apparently related to the number of kokanee that enter on any one evening (Figure 17). Once the run was in progress, competition for spawning space became acute and may have caused a number of fish to move upstream as spawning territories became established.

The rate of upstream movement apparently depended on the degree of sexual maturity. Approximately 50 per cent of the early portion of the spawning run moved upstream 1000 feet or more to spawn whereas only 10 per cent of the late run fish did so (Table VII). This phenomenon is very 66

similar to other salmon species in which the fish first entering a river system appear to move the farthest upstream whereas later migrating individuals tend to spawn in the lower reaches of the system.

Sex Ratio, Size and Age at Sexual Maturity

In both years of the study (1958 and 1959) as shown in Table VI there was a greater proportion of males in the early part of the spawning run than in the latter. Similarly, in anadromous salmonids the first part of most spawning runs is composed largely of males.

The sex ratio of the kokanee populations deviated from the 1:1 ratio in 1959, 1960 and 1961 whereas that of 1958 was 1:1. However, the excess of males in 1959 can be postulated as being due to the precocious "jacks" spawning a year prematurely. It would then follow that the excess number of females in 1960 is due to the loss of males spawning a year earlier.

In 1961 the gill net catches showed a preponderance of males. This divergence from a L:l ratio may be due to gill net selectivity. However, when fish of less than 245 mm. fork length were excluded from the cap• tures the resultant was a 1:1 sex ratio. Thus, in 1961 the majority of kokanee less than 245 mm. are probably "jacks".

Other workers present conflicting data as to the sex ratio of spawn• ing kokanee. Johnson (1958) reports that among Babine Lake kokanee there appears to be a consistent predominance of males in the spawning popula• tion (about 75 per cent). He states that most specimens examined were mating in their fourth year of life; however, a few three year olds and five year old spawners had been noted. 67

In Lake Pend Oreille, Whitt (1958) recorded the sex ratio of angler caught kokanee to be approximately 60 per cent males. The sex ratio of spawning fish in 1956 was almost equal; 51.3 per cent females to 48.7 per cent males as compared with 54.7 per cent and 45.3 per cent respectively in 1954.

Ricker (1959) noted that in Crawford Lake female land-locked sockeye salmon greatly outnumbered the males, whereas of the 13 kokanee captured in Cultus Lake in 1935 (only 10 preserved), Ricker (1938) noted that they consisted of equal numbers of males and females. In 1936 a single male and single female were taken. There is thus no suggestion of the unequal sex ratio characteristic of "residual" sockeye in Cultus Lake.

Tokui (1961) notes that of spawning kokanee caught at Lake Shikotsu for the years 1951 - 1960, males were abundant only in 1952 and 1955 and showed the ratio of females to males of 100:142. In most other years a predominance of females was found and the sex ratio varied yearly. During their spawning migration, the kokanee were rich in males in the early portion, in females at the peak and again in males at the last.

In Nicola Lake the proportion of males in the spawning run was greatest at the early portion of the run and then generally gave way to a greater percentage of females as the spawning run peaked and declined.

The size at sexual maturity may depend on the number of kokanee within the spawning population and the number in direct competition with the spawning population.

Svardson (1951) suggested that growth rates of fishes are related to age at sexual maturity. A rich food supply may cause accelerated physio• logical aging and an early sexual maturity. On the other hand, very poor 68

food supply may also produce forms maturing early in spite of retarded physiological aging. Selection under these extremely poor conditions may favour animals possessing hormonal mechanisms permitting early sexual maturity.

Kurohagi and Sasaki (1961) showed that fluctuation in mean body length of spawning adult females occurred between year classes and believed that insufficient plankton crustaceans was responsible for the diminutive size.

It was also observed that in years of large kokanee populations the length of the mature adults was quite small whereas if the population was small the mean length of individuals was greater.

Active competition for food by a dominant year class may decrease the mean length of fish at time of sexual maturity especially in mesotrophic or oligotrophic bodies of water. In Nicola Lake it appeared that the 1959 spawning year class was a dominant one which may account for lower mean size of kokanee compared with 1958, 1960 and 1961 spawning populations.

It is also proposed that this large year class reduced the ultimate size that could have been attained by the 1958 spawning population for in col• lections through dynamiting it was noted that fish in their second and final years of life were often in close association, whereas one year old and younger fish inhabited other areas. Similarly, the mean size of the

1960 spawning population probably was affected during its second year of life by the dominant year class. However, once the dominant year class was removed from the lake system, the 1960 spawning population being small in number illustrated considerable growth in the final year of life.

Though no weir was operated in 1960 (to enumerate the spawning run), observations of the Moore Creek spawning grounds resulted in only a few fish being seen two weeks after first entry of kokanee into the stream, 69

whereas in 1959 large numbers of kokanee were visible at this time.

Kokanee in Nicola Lake are sexually mature and spawn predominantly at three years of age although a few individuals (mostly males) may spawn at age two. Age at maturity was determined by the length frequency method even though scale samples were collected. Collections of mature and maturing kokanee taken during 1960 and 1961 were strikingly larger than

those captured in 1958 and 1959. It could be postulated that kokanee that matured in 1958 and 1959 were three years of age while the spawning class of 1960 and 1961 were four years old. This would appear to be a more

reasonable hypothesis than one postulating considerable growth for the

1960 and 1961 maturing year classes as little growth was evidenced in the

1959 year class. However, after viewing a number of scales it was

observed that circuli of the 1959 spawning class were more tightly grouped

than circuli observed for 1960 and 1961 spawning fish. The?greater width

between circuli of the kokanee that matured in 1960 and 1961 would lead one

to believe that considerable growth did occur in these years. Therefore,

from information gathered it is believed that regardless of size at matur•

ity the kokanee in Nicola Lake are predominantly three years of age.

Other authors also observed conflicting results in mean lengths and

age of kokanee at time of maturity. Vernon (1957) noted that in Kootenay

Lake the kokanee were of three distinct genetic stocks and depending on

the general lake area they matured at either two or three years of age.

Allison (1958) states that in Lake Pend Oreille kokanee matured at three

to six years of age. However, Allison's findings were based on scale

readings in which he was faced with a large number of inconsistencies. 70

SUMMARY

1. Vertical distribution shown by the 1959 maturing year class of kokanee

could not be related to temperature, oxygen or light conditions, or to

food preference whereas the 1961 vertical distribution appeared to be

more directly influenced by light.

2. Marked seasonal as well as diel changes in the diet were noted in 1959.

3. Daily onshore movement at time of sexual maturity was initiated by

falling light intensity and strengthened by onshore winds.

4. Movement into the spawning stream occurred when light intensity 2

dropped below 1 x 10 foot candles. Stream entry was intensified by

strong onshore winds but was apparently unaffected by changes in

stream temperature or flow.

5. Experiments suggested that olfaction may be involved in location of

the spawning stream.

6. Sex ratio of the spawning year class of kokanee was usually 1:1 unless

distorted by a preponderance of precocious males.

7. Size at sexual maturity varied considerably from 1957 to 1961 and may

be governed by food supply. 71

LITERATURE CITED

Ali, M. Y. 1959. Spatial distribution of fish in summer in Nicola Lake, British Columbia. M.Sc. Thesis, University of British Columbia, Dept. of Zoology, 132 pp.

Allison, D. 1958. Age and growth characteristics of Lake Pend Oreille kokanee, 1957. Idaho Fish and Game Department, Fisheries Division, 75 pp., 24 plates.

Black, E. C. 1953. Upper lethal temperatures of some British Columbia freshwater fishes. J. Fish. Res. Bd. Canada, 10 (4) : 196-210.

Brett, J. R. and D. MacKinnon 1952. Some observations on olfactory perception in migrating adult coho and spring salmon. Fish. Res. Bd. Canada, Pac. Prog. Rept., 90 : 21-23.

Briggs, J. C. 1953. The behavior and reproduction of salmonid fishes in a small coastal stream. Cal. Fish and Game, Fish. Bull., 94 : 62 pp.

Brink, V. C. and L. Farstad 1949. The physiolography of the agricult• ural areas of British Columbia. Sci. Agr., 29 : 273-301.

Bryan, P. and H. H. Howell 1946. Depth distribution of fish in Lower Wheeler Reservoir, Alabama. J. Tenn. Acad. Sci., 21 (1) : 4-9.

Calderwood, W. L. 1903. Water temperature in relation to the early annual migration of salmon from the sea to rivers in Scotland. Fishery Bd. Scotland, 21st Ann. Rept. for 1902, pt. 2, app. 5 p 71-76. (Briggs 1953).

Carlander, K. D. and R. E. Cleary 1949. The daily activity patterns of some freshwater fishes. Am. Midland Naturalist, 41 (2) : 447-452.

Cassie, R. M. 1954. Some uses of probability paper in the analysis of size frequency distributions. Aust. J. Mar. Fresh. Res., 5 (3) : 513-522.

Chapman, J. D. 1952. A preliminary study of the seasonal distribution of precipitation in British Columbia. Yearbook of the Association of Pacific Coast Geographers, 14 : 24-33.

Clemens, W. A., D. S. Rawson and J. L. McHugh 1939. A biological survey of Okanagan Lake, British Columbia. Fish. Res. Bd. Canada Bull., 56 : 70 pp. 72

Collins, Gerald B. 1952. Factors influencing the orientation of migrating anadromous fishes. U.S. Dept. Interior, Fish and Wildl. Serv., Fishery Bull. 73, 52 : 375-396.

Cope, 0. B. 1956. Some migration patterns in cutthroat trout. Utah Acad. Proc, 33 : 113-118.

Cushing, D. H. 1951. The vertical migration of planktonic crustacea. Biol. Rev., 26 : 158-192.

Davidson, F. A., E. Vaughan, S. J. Hutchinson and A. L. Pritchard 1943. Factors influencing the upstream migration of the pink salmon (Oncorhynchus gorbuscha). Ecol., 24 (2) : 149-168.

Dendy, J. S. 1945. Fish distribution, Norris Reservoir, Tennessee, 1943. II. Depth distribution of fish in relation to environmental factors, Norris Reservoir. J. Tenn. Acad. Sci., 20 (1) : 114 - 135.

1946. Further studies of depth distribution of fish, Norris Reservoir, Tennessee. J. Tenn. Acad. Sci., 21 (1) : 94 - 104.

1948. Predicting depth distribution of fish in three TVA storage-type reservoirs. Trans. Am. Fish. Soc, 75 : 65-71.

Ferguson, R. G. 1949. The interrelations among the fish populations of Skaha Lake, British Columbia and their significance in the production of Kamloops trout (Salmo gairdnerii kamloops Jordan), B-A Thesis, University of British Columbia, Dept. of Zoology, 84 pp.

1958. The preferred temperature of fish and their mid• summer distribution in temperate lakes and streams. J. Fish. Res. Bd. Canada, 15 (4) : 607-624.

Fry, F. E. J. 1937. The summer migration of the cisco, Leucichthys artedi (Le Sueur) in Lake Nipissing, Ontario. Univ. of Toronto Studies, Biol. Ser., 44 : 89 pp.

Gilhousen, P. 1960. Migratory behavior of adult Fraser River sockeye. Intern. Pac. Salmon Fish. Comm., Progress Report, 78 pp.

Godfrey, H. 1955. On the ecology of Skeena River whitefishes, Coregonus and Prosopium. J. Fish. Res. Bd. Canada., 12 (4) : 499-542.

Gunning, G. E. 1959. The sensory basis for homing in the longear sun- fish, Lepomis megalotis megalotis (Rafinesque). Invest. Indiana Lakes and Streams 5 : 103-130. Hart, J. L. 1931. On the daily movements of the Coregonine fishes. The Canadian Field Naturalist, 45 (1) : 8-9. 73

Hartman, G. F. 1962. Use of gill net rollers in fishery investigations. Trans. Am. Fish. Soc. 91 (2) : 224-225.

Hasler, A. D. and J. E. Bardach 1949. Daily migrations of Perch in Lake Mendota, Wisconsin. J. Wildl. Mgmt., 13 (1) : 40-51.

Hasler, A. D. and J. R. Villemonto 1953. Observations on the daily movements of fishes. Sci., 118 (Sept.) : 321-322.

Hasler, A. D. and W. J. Wisby 1951. Discrimination of stream odors by fishes and its relation to parent stream behavior. Am. Naturalist, 85 (823) : 223-238. 1958. Perch and lake research on Mendota. Wise. Cons. Bull., 23 (3) : 16-20.

Hayes, F. R. 1953. Artificial freshets and other factors controlling the ascent and population of Atlantic salmon in the LaHave River, Nova Scotia. Fish. Res. Bd. Canada Bull., 99 : 47 pp.

Hickling, C. F. 1927. The natural history of the hake. Parts I and II. Gt. Br. Min. Agr. and Fish., Fishery Invest., 10 (2) : 1-100.

Hile, R. and C. Juday 1941. Bathymetric distribution of fish in lakes of the northeastern highlands, Wisconsin. Trans. Wisconsin Acad. Sci., Arts and Letters, 33 : 147-187.

Hoar, W. S. 1942. Diurnal variations in feeding activity of young salmon and trout. J. Fish. Res. Bd. Canada, 6(1) : 90-101.

Hoar, W. S., M. H. A. Keenleyside and R. G. Goodall 1957. Reactions of juvenile Pacific Salmon to light. J. Fish. Res. Bd. Canada, 14 (6) : 815-830.

Huntsman, A. G. 1939. Salmon for angling in the Margaree River. Fish. Res. Bd. Canada Bull., 57 : 75 pp.

Johnson, W. E. 1958. Density and distribution of young sockeye salmon throughout a multi-basin lake system. J. Fish. Res. Bd. Canada, 15 (5) : 961-982.

Jones, F. R. Harden 1956. The behaviour of minnows in relation to light intensity. J. Exp. Biol., 33 (2) : 271-281.

Kurohagi, T. and S. Sasaki 1961. Some ecological studies on the kokanee salmon (0. nerka var adonis) in Lake Shikotsu, I. Frequent occurrence of adult salmon with abnormal ovaries in 1956. Sci. Rept. Hokkaido Salmon Hatchery 16 : 137-143 (English Summary).

Langford, R. R. 1938. Diurnal and seasonal changes in the distribution of the limnetic Crustacea of Lake Nipissing, Ontario. Univ. of Toronto Studies, Biol. Ser., 45 : 142 pp. 74

Lindsey, C. C, T. G. Northcote and G. F. Hartman. 1959. Homing of rainbow trout to inlet and outlet spawning streams at Loon Lake, British Columbia. J. Fish. Res. Bd. Canada, 16 (5) : 695-719.

MacLeod, J. C. 1960. The diurnal migration of peamouth chub Mylocheilus caurinus (Richardson) in Nicola Lake, British Columbia. M. Sc. Thesis, University of British Columbia, Department of Zoology, 54 pp.

Martin, N. V. 1952. A study of the Lake Trout, Salvelinus namaycush, in two Algonquin Park, Ontario, lakes. Trans. Am. Fish. Soc. 81 : 111-137.

Mathews, W. H. 1944. Glacial lakes and ice retreats in South Central British Columbia. Trans. Roy. Soc. Canada, Ser. Ill, 38 (4) : 39-57.

Mottley, C. McC. 1938. Fluctuations in the intensity of the spawning runs of rainbow trout at Paul Lake. J. Fish. Res. Bd. Canada, 4 (2) : 69-87.

Mundie, J. H. 1959. The diurnal activity of the larger invertebrates at the surface of Lac La Ronge, Saskatchewan. Can. J. Zool., 37 : 945-956.

Neave, F. 1943. Diurnal fluctuations in the upstream migration of coho and spring salmon. J. Fish. Res. Bd. Canada, 6 (2) : 158-163.

Nomura, M. 1958. Some knowledge on behaviour of fish schools. Symposium on fish behaviour, G. L. Kesteven ed. 8th Session Indo- Pacific Fisheries Council, Colombo, Ceylon.

Odell, T. T. 1932. The depth distribution of certain species of fish in some of the lakes of New York. Trans. Am. Fish. Soc, 62 : 331-335.

Pearse, A. S. 1921. The distribution and food of the fish in three Wisconsin lakes in summer. Univ. Wise Studies Sci., 3 : 1-61:

Pritchard, A. L. 1936. Factors influencing the upstream spawning migration of the pink salmon, Oncorhynchus gorbuscha (Walbaum) J. Fish. Res. Bd. Canada, 2 (4) : 383-389.

Rawson, D. S. 1934. Productivity studies in lakes of the Kamloops region, British Columbia. Fish. Res. Bd. Canada (formerly Biol. Bd. of Canada) Bull., 42 : 31 pp. 75

1961. The Lake Trout of Lac la Ronge, Saskatchewan. J. Fish. Res. Bd. Canada, 18 (3) : 423-462.

Richardson, I. D. 1952. Some reactions of pelagic fish to light as recorded by echo sounding. Gt. Br. Min. Agr. and Fish., Fishery Invest., Ser II, 18 (1) : 1-20.

Ricker, W. E. 1937. The food and the food supply of sockeye salmon (Oncorhynchus nerka Walbaum) in Cultus Lake, British Columbia. J. Fish. Res. Bd. Canada, 3 : 450-468.

1938. "Residual" and kokanee salmon in Cultus Lake. J. Fish. Res. Bd. Canada, 4 (3) : 192-218.

1940. On the origin of kokanee, a fresh-water type of sockeye salmon. Trans. Roy. Soc. Canada, Ser III, Sect. V, 34 : 121-135.

1959. Additional observations concerning residual sockeye and kokanee (Oncorhynchus nerka). J. Fish. Res. Bd. Canada, 16 (6) : 897-902.

Shetter, D. S. 1938. A two-way fish trap for use in studying stream- fish migration. Trans. 3rd N. Am. Wildl. Conf., 331-338.

Snedecor, G. W. 1948. Statistical Methods. The Iowa State College Press, Ames, Iowa. 534 pp.

Spencer, W. P. 1939. Diurnal activity rhythms in freshwater fishes. Ohio J. Sci., 39 (3) : 119-132.

Stross, Raymond G. 1954. A limnological study of Lake Pend Oreille, Idaho, with special consideration of the ecology of the kokanee. M.A. Thesis, University of Idaho.

Svardson, G. 1951. The Coregonid Problem. III. Whitefish from the Baltic successfully introduced into fresh waters in the north of Sweden. Insti. Freshw. Res. Drott. Rept. 32 : 79-126.

Tokui, T. 1959. Studies on the kokanee salmon in Lake Towada, Northern Honshu, Japan (II). Climatic and hydrologic factors. Sci. Rept. Hokkaido Salmon Hatchery, 14 : 169-192. (English abstract).

1961. Studies on the kokanee salmon (IV). Spawning migra• tion of the kokanee salmon in Lake Shikotsu, Hokkaido, Japan. Sci. Rept. Hokkaido Salmon Hatchery, 16 : 127-133. (English abstract). 76

Vernon, E. H. 1956. The effect on a stream of pollution by organic wastes. B. C. Game Comm. mimeo, 7 pp.

1957. Morphometric comparison of three races of kokanee (Oncorhynchus nerka) within a large British Columbia lake. J. Fish. Res. Bd. Canada, 14 (4) : 573-598.

Whitt, C. R. 1958. Age and growth characteristics of Lake Pend Oreille kokanee, 1956. Idaho Fish and Game Department, Fisheries Division, 34 pp.

Wisby, W. J. and A. D. Hasler 1954. Effect of olfactory occlusion on migrating silver salmon (0. kisutch). J. Fish. Res. Bd. Canada, 11 (4) : 472-478.

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