Spatial Distribution and Spawning Migration of Kokanee
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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.