UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Spatial distribution of fish summer in Nicola Lake, British Columbia Ali, Mohammed Youssouf 1959

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
831-UBC_1959_A6_7 A5 S7.pdf [ 8.88MB ]
Metadata
JSON: 831-1.0106197.json
JSON-LD: 831-1.0106197-ld.json
RDF/XML (Pretty): 831-1.0106197-rdf.xml
RDF/JSON: 831-1.0106197-rdf.json
Turtle: 831-1.0106197-turtle.txt
N-Triples: 831-1.0106197-rdf-ntriples.txt
Original Record: 831-1.0106197-source.json
Full Text
831-1.0106197-fulltext.txt
Citation
831-1.0106197.ris

Full Text

SPATIAL DISTRIBUTION OF FISH IN SUMMER IN NICOLA. LAKE, BRITISH COLUMBIA by MDHAMMED YOUSSOUF ALI B.Sc. (Hons.), Un i v e r s i t y of Cal c u t t a , 1 9 4 5 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n the Department o f Zoology We accept t h i s t h e s i s as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA May, 1 9 5 9 ABSTRACT Diurnal and seasonal v a r i a t i o n i n s p a t i a l d i s t r i b u t i o n o f f i f t e e n species of f i s h were studied i n N i c o l a Lake during summer. Ifejdmum depth at which f i s h were taken was 110 f t . where only Kokanee were found. Peamouth Chub, Largescale Sucker and P r i c k l y Sculpin were found i n depths up to 80 f t . Chiselmouth were r e s t r i c t e d to the shallow southwest basin a l l throughout summer. Carp f i n g e r l i n g s were a l s o r e s t r i c t e d t o shallow weedy areas. A l l other species were a v a i l a b l e i n a l l major regions of the lake. Young-of-the-year of Peamouth Chub, Largescale Sucker, Squawfish, Red-side Shiner and P r i c k l y Sculpin stayed very close t o shore during d a y l i g h t . Fry of Kokanee, Rainbow Trout, Mountain Whitefish and Chinook Salmon appeared i n areas close to stream i n l e t s and o u t l e t s during day. Smaller s i z e groups of f i s h a v a i l a b l e on the shore i n daylight moved offshore at night, when l a r g e r f r y and adults appeared i n the shore. Young of Mountain Whitefish were dispersed i n d i f f e r e n t regions of the shore at night. V a r i a t i o n was observed between da y l i g h t and dark d i s t r i b u t i o n of d i f f e -rent species. Adult Peamouth Chub and Redside Shiners stayed on the bottom during daylight but they invaded surface and shallow shore areas at night. Squawfish also tended t o leave the bottom at night. Factors determining migration and summer d i s t r i b u t i o n o f f i s h e s were investigated. Thermal s t r a t i f i c a t i o n was unstable and had no apparent e f f e c t on v e r t i c a l migration of most species. Only Squawfish avoided the hypolimnion. Dissolved oxygen was p l e n t i f u l up t o a depth of 96 f t . and i t s e f f e c t , therefore, could not be assessed. Light apparently played an important r o l e i n determining movements of f i s h i n daylight and dark. Diurnal v a r i a t i o n i n d i s t r i b u t i o n i s a t t r i b u t e d to e f f e c t of l i g h t . 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 i t 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 allowed without my written permission. Department of 'T-OOLOGj The University of British Columbia, Vancouver 6% Canada. Date MA? ,«? , 1 ? ^ I TABLE OF CONTENTS PAGE I. INTRODUCTION 1 I I . MATERIALS AND METHODS 2 Description of the lake. 2 Morphometry of the lake • • 3 P h y s i c a l & chemical c h a r a c t e r i s t i c s 6 B i o l o g i c a l c h a r a c t e r i s t i c s 16 G i l l net stat i o n s 18 Sampling equipment & techniques. . . » 21 E f f i c i e n c y and R e l i a b i l i t y of g i l l net catches 26 Sampling by beach seine 34 Sampling by dip net 35 Treatment of Samples 35 I I I . RESULTS 38 Peamouth Chub 3& Redside Shiner 47 Squawfish 55 Carp 63 Longnose Dace • 65 Chiselmouth 66 E r i d g e l i p Sucker 66 Largescale Sucker. • . . . . . . . 67 Burbot 73 P r i c k l y Sculpin 75 Kokanee. . 75 Rainbow Trout 82 I I PAGE D o l l y Varden . &6 Chinook Salmon Mountain Whitefish 9^ Seine hauls i n north shore 95 Seine hauls i n other areas 99 Dip net sampling . . . . . . . . . . . . 101 17. FISH ASSOCIATIONS 102 V. FOOD AND FEEDING HABITS OF FISH AND RELATION THEREOF TO THEIR SPATIAL DISTRIBUTION. 106 VI. DISCUSSION H 2 VII. SUMMARY AND CONCLUSION 123 VIII. LITERATURE CITED 129 I l l TABLE . PAGE I* Proportion of t o t a l area of the lake under d i f f e r e n t depth contours . . . . . . 3 I I , P o s i t i o n of the thermocline i n the summer of 1958. . . . . 10 H I . (a) Dissolved oxygen determined from s t a t i o n IX. . . . . . . . 13, (b) Dissolved oxygen determined from s t a t i o n s VI and V I I I . . . 14" IV. Limits of v i s i b i l i t y determined by secchi d i s c 15> V. Time schedule f o r g i l l net sets i n stations IV, V and VI • 22 VI. Catch from g i l l nets set i n s t a t i o n I 24 V H . Catch from g i l l nets set i n s t a t i o n I I . 25 VIII. Catch from nets set i n st a t i o n s I I I and VII. . . . . . . . 27 IX. Catch from monofilament net set by species . . . . . . . . . 28 X. Catch from monofilament net set by mesh s i z e . . . . . . . 29 XI. Catch from nets set i n s t a t i o n V I I I • 3° X H . Analysis of catch i n d i f f e r e n t mesh siz e s of the 54 net-sets i n stati o n s IV-VI 31 XIII. Catch composition i n the surface, mid water and bottom nets set i n s t a t i o n VI on 16-17 August 32 XIV. Number of f i s h obtained i n g i l l net sets i n the day l i g h t , evening and at night 33 XV. (a-d) Number of Peamouth Chub obtained i n d i f f e r e n t g i n net sets 40-43 XVI. Number of Redside Shiners obtained i n d i f f e r e n t g in net (a-d) sets 49-52 XVLT. Number of Squawfish obtained i n d i f f e r e n t g i n net sets . . 58-61 (a-d) XVIII. Number of Carp obtained i n g i n net sets i n stations IV-VI. 64 XIX. Number of Largescale Sucker obtained i n g i n net sets i n (a-c) s tations IV-VI 69-71 XX. Number of Burbot obtained i n g i n net sets i n s t a t i o n s IV-VI 74 XXI. Number of P r i c k l y Sculpin obtained i n d i f f e r e n t g i n net sets i n stati o n s IV-VI. . . . . . . . . . . . . . 7° IV TABLE PAGE XXII. Number of Kokanee obtained i n d i f f e r e n t g i l l net sets i n (a-cf s tations IV-VI 79-81 XXIII. Number of Rainbow Trout obtained i n d i f f e r e n t g i l l net (a-c) sets i n s t a t i o n s IV-VI. 83-85 XXIV. Number of D o l l y Varden obtained i n d i f f e r e n t g i l l net sets i n stations IV-VI 87 XXV. Number of Chinook Salmon obtained i n d i f f e r e n t g i l l net sets i n stations IV-VI. 88 XXVI. Number of Mountain Whitefish obtained i n d i f f e r e n t g i l l net (a-c) sets i n st a t i o n s IV-VI 91-93 XXVII. Results of seine hauls i n the north shore . . . 96-98 (a-c) XXVUI. Results of seine hauls i n other regions of shore 100 ab XXIX. Food o f the f i s h species discussed 107 abc V FIGURE PAGE 1. Map of Nicola Lake showing the depth contours 2. Temperature curves from 80 f t . s t a t i o n ^ 3. Temperature curves from 60 f t . s t a t i o n & 4. Temperature curves from 40 f t . s t a t i o n 9 5. Dissolved 0£ p.p.m. i n Nicola Lake. 12 .2 6. Map of g i l l net st a t i o n s i n d i f f e r e n t parts of the lake . . . . 19 7. Ifep showing g i l l net st a t i o n s i n northwest end of lake 2 0 8. Map showing seine haul stations i n the la k e . . . . 36 9. Occurrence of Peamouth Chub i n the g i l l net sets i n northwest shore 39 10. Occurrence of Redside Shiner i n the g i l l net sets i n northwest shore 48 11. Occurrence of Squawfish i n the g i l l net sets i n northwest shore 57 12. Occurrence o f Largescale Sucker i n the g i l l net sets i n north-west shore 68 13. Occurrence of Kokanee i n the g i l l net sets i n northwest shore. . 78 14. Occurrence of Mountain Whitefish i n the g i l l net sets i n north-west shore 90 15. Occurrence of d i f f e r e n t species o f f i s h together i n the g i l l net sets i n northwest shore i n e a r l y summer 102 a 16. Occurrence of d i f f e r e n t species of f i s h together i n the g i l l net sets i n northwest shore i n mid summer. . . . . . . 102 b 17. Occurrence of d i f f e r e n t species of f i s h together i n the g i l l net sets i n northwest shore i n l a t e summer 102 c VI ACKNOWI£DGBSMBNTS The author wishes to express h i s gratitude to Dr. P. A. Larkin, Asso-c i a t e Professor and Dr. C. C. Lindsey, A s s i s t a n t Professor o f the Un i v e r s i t y of B r i t i s h Columbia. They have suggested the study, provided encouragement and guidance through the course of the study and given many h e l p f u l c r i t i c i s m s i n the preparation of the manuscript. S p e c i a l thanks are due to T. G. Northcote and G. F. Hartraan of the F i s h and Game Branch of the Department of Recreation and Conservation, and to K. Vermeer, f o r a i d i n c o l l e c t i o n of f i e l d data. Finance and equipment making the study p o s s i b l e were generously pro-vided by the Colombo Plan Administration, the F i s h and Game Branch of the Department of Recreation and Conservation and the I n s t i t u t e of F i s h e r i e s , U n i v e r s i t y of B r i t i s h Columbia. I. INTRODUCTION The s p a t i a l d i s t r i b u t i o n o f f i s h i n a lake i s a dynamic equilibrium between the biology of the f i s h species and the p h y s i c a l , chemical and b i o t i c environment. The d i s t r i b u t i o n i s constantly changing with time. The compre-hension of these movements, t h e i r causes and t h e i r e f f e t s would involve an understanding of the mechanics of the ecosystem of the lake i t s e l f . Various f a c t o r s are constantly at work, but to what extent each f a c t o r i s responsible i s rather d i f f i c u l t t o appreciate i n nature. Possibly, each causative f a c t o r might show i t s i n d i v i d u a l influence on f i s h d i s t r i b u t i o n . On the other hand, d i s t r i b u t i o n may be the resultant of the i n t e r a c t i o n s of two or more f a c t o r s . When one f a c t o r i n the environment i s constant, i t has been assumed that the other varying f a c t o r s determine the d i s t r i b u t i o n . S i m i l a r l y , 'modifier 1 f a c t o r s are known t o a l t e r the i n f l -uence of some dominant p h y s i c a l f a c t o r s . The purposes of the present study are ( l ) to observe the gross e f f e c t s of b i o t i c , chemical and p h y s i c a l environment on the d i s t r i b u t i o n of a f i s h i n a lake, and (2) to t r y to understand, where possible, the mechanisms which determine t h i s d i s t r i b u t i o n during the summer. Nicola Lake was chosen as the working s i t e because of two considera-t i o n s - (1) the lake provides a wide v a r i e t y of f i s h species and d i f f e r e n t habitats; and (2) f a c i l i t i e s f o r f i e l d study were a v a i l a b l e through the F i s h and Game Branch of the B r i t i s h Columbia Department of Recreation and Conservation. 2 I I . MATERIALS AND METHODS Descri p t i o n of the lake: Nicola Lake i s s i t u a t e d along the highway approximately 40 miles south o f Kamloops and 10 miles northeast of M e r r i t t , B. C. i n 50° 120° SW a t an a l t i t u d e of 2056 f t . above sea l e v e l , i n the southern i n t e r i o r plateau of the province of B r i t i s h Columbia. The area i n which the lake i s s i t u a t e d i s known as Nicola basin, a part i n the Princeton-Mcola-Kamloops depression formed and developed as a trough of some def i n i t e n e s s during the t e r t i a r y times (Brink and Farstad, 1949). In t h i s and two other basins, a se r i e s of lakes formed i n l a t e Pleistocene times - as the melting i c e dammed one or the other narrow basin o u t l e t s (Mathews, 1944). The area i s characterized by sedimentary and volcanic rocks extensive-l y g l a c i a t e d and with a mantle of l u c u s t r i n e s i l t s (Northcote and Larkin, 1956). C l i m a t i c a l l y , the region i s dry. The whole southern i n t e r i o r plateau, of which the Nicola v a l l e y i s a part, has a low annual p r e c i p i t a t i o n and extreme temperature conditions (Northcote and Larkin, 1956). During the summer of 1958, p r e c i p i t a t i o n i n and around the lake was extremely low. The maximum r a i n f a l l on any si n g l e day i n the whole season occurred on 2 September when i t was recorded as .095 inches. P r e c i p i t a t i o n i n the summer was very occasional and sparse. A i r temperature i n the middle of summer ranged between 90° and 100°F during the day while at night there was a rapid drop. The maximum daylight temperature of 100°F was recorded on 24 August, 1958. Northcote and Lark i n (1956) discussed the e f f e c t of c l i m a t i c f a c t o r s upon lake p r o d u c t i v i t y . According to them i n dry areas with low p r e c i p i t a t i o n and hot summer, the T.D.S. o f lakes should be r e l a t i v e l y high. The T.D.S. 3 o f Nicola Lake i s found to agree with the above observation. Morphometry of the lake Maximum length of Nicola Lake i s 12.7 miles, while i t s maximum width does not exceed 1.53 miles. In two places, about 1.3 miles southeast of and again about 493 yards southwest of Quilchena, width of the lake i s maximum. In the remaining parts, i t s width does not exceed one mile. The t o t a l length o f shore l i n e i s 27.8 miles while the shore development i s only 2.5. I t has a t o t a l surface area of 6041 acres with a maximum and mean depth of 181 f t . and 77 f t . r e s p e c t i v e l y . T o t a l volume, as ca l c u l a t e d , i s about 2,000,000,000 cubic f t . Depth contours of the lake are presented i n Figure 1. Proportion of the t o t a l area under d i f f e r e n t depth zones are summarized below. Table I. - Tot a l area i n d i f f e r e n t depth contours. Depth Zone % of t o t a l area 0' - 25' 27.3 25' - 50' 22.6 50' - 75' 20.1 75' - 100' 16.7 100' - 125' 8.4 125' - 1501 4.3 150' - 175 1 - 0.5 175' - Above 0.1 The lake basin can be divided i n t o two broad e c o l o g i c a l regions, the deeper and l a r g e r portion from point 'N' (shown i n F i g . 1) northwards up to the north end, and a shallow southwestern portion, from 'N' i n Figure 1 4 5 southwards down to Nicola River o u t l e t . Maximum depth i n the shallow basin does not exceed 10 f t . The shores are predominantly rocky and precipitous i n the deeper portion, while i n the shallow southwest portion, the shores are not as rocky and slope i n t o water very gradually. A steep chain of mountains r i s e from the water along the west shore of the deeper p o r t i o n of the lake, with the exception of some areas opposite Quilchena where sandy beaches occur. The eastern shore, though f o r the most part rocky, i s not as steep as the western shore. More sandy beaches are present along the eastern shore. A lagoon and some swam-py areas are found along the southeast shore between Nicola River i n l e t and Quilchena Greek. The eastern shore i s shallow f o r about 500 yards commenc-ing at the north t i p of the lake, and the slope of the bottom i s gradual. The north shore has a continuous sandy beach from one end to the other. As against the rocky and steep shore i n the deeper portion of the lake, shores of the shallow southwest part are composed of stone free t i l l . Here the shore has a very small d e c l i v i t y . Ih the main body o f the lake, the bottom i s mainly mud, and the mud bottom appears from below a depth of about 10 f t . In shallower zones along shore, the bottom i s e i t h e r gravel, sand or a mixture of sand, g r a v e l and mud. In the lagoon and swamps along the eastern and southeastern shore, the bottom i s mud. The shallow southwest portion of the lake has a l s o a th i c k deposit of mud mixed with decaying vegetation on the bottom. I n l e t a and Outlets: There are four i n l e t s that flow i n t o the lake, two i n the north shore and two on i t s southeast side. I n l e t s on the north shore are Moore Creek and Stump Lake Creek ( F i g . l ) . Both of the i n l e t s r e t a i n water during summer. 6 The l a t t e r (Stump Lake Creek) connects t h i s lake with Stump Lake s i t u a t e d at a distance of about 10 miles east. N i c o l a River enters the lake on i t s eastern side at a distance of about 4 miles from the northeast t i p and flows through the lake. The other i n l e t i n the southeast side i s Quilchena Creek which d r i e s up during summer. One very small i n l e t j o i n s the lake a t i t s northwest end ( F i g . l ) , but f o r most of the summer i t remains dry. The only o u t l e t of the lake i s Nicola R i v e r which i s wider than any of the i n l e t s and flows i n t o the Fraser River system through the Thompson River. P h y s i c a l and Chemical c h a r a c t e r i s t i c s : Temperature and other l i m n o l o g i c a l data were c o l l e c t e d c h i e f l y at s t a -t i o n s VI and IX ( F i g . 6 ) . Temperature and water samples were also c o l l e c t e d from s t a t i o n s I I and V U I ( F i g . 6) during e a r l y and mid summer r e s p e c t i v e l y . Temperatures were recorded with a maximum-Bdnimum thermometer, and a Thermistor. Figures 2, 3 and 4 summarize temperature recordings made i n d i f f e r e n t periods o f the summer. These f i g u r e s show that i n 1958 the lake became thermally s t r a t i f i e d during summer, but the s t r a t i f i c a t i o n tended to disappear from time to time (Table I I ) . Thermal s t r a t i f i c a t i o n , though not very sharp, commenced as earl y as June (10-11 June) when the thermocline was seen at a depth of 35-40 f t . With the progress o f the season, the sharpness of s t r a t i f i c a t i o n i n c r e a -sed, and the thermocline rose t o 15-17 f t . (22 J u l y ) . Three days l a t e r , on 25 July, the thermocline had descended t o 21 f t . , while on 28 Ju l y , no th e r -mal s t r a t i f i c a t i o n was notided. For the remaining period of the summer, f l u c t u a t i o n i n the p o s i t i o n of the thermocline can be seen, with complete disappearance once again on 25 August (Table I I and F i g . 3)» I t i s suspected 8 £ oo Q. x I I I I 1 : 1 40 50 60 70 80 TEMP. °F Figure 3» Temperature curves from 60 f t . s t a t i o n , N i c o l a Lake. 9 0 10 I x h-Q_ UJ Q 20 30 40 f TT • — — • 22 JULY X — X 25 JULY o — o 28 JULY © G 1 AUG o o 21 AUG • • —• 27 AUG 40 50 60 70 80 TEMP. °F Figure 4» Temperature curves from 40 f t . s t a t i o n , Nicola Lake. 10 TABLE I I . P o s i t i o n of thermocline i n Nicola Lake during summer, 1958. Date Depth of Upper l i m i t ( i n f t . ) ' thermocline Lower l i m i t ( i n f t . ) Remarks 12 June 35 40 Temperature recorded from s t a t i o n I I . 22 J u l y 15 17 Temperature recorded from s t a t i o n VI. 25 J u l y 21 23 Temperature recorded from s t a t i o n VI. 28 J u l y - - No thermocline. Tempera-ture recorded from s t a t i o n VI. 1 August 37 40 Temperature recorded from s t a t i o n VI. 4 August 21 26 Temperature recorded from s t a t i o n IX. 8 August 39 42 Temperature recorded from s t a t i o n IX. 15 August 45 50 Temperature recorded from s t a t i o n IX. 25 August - - No thermocline. Temperature recorded from s t a t i o n IX. 27 August 35 40 Temperature recorded from s t a t i o n IX. 11 that these a l t e r a t i o n s are the r e s u l t of strong and almost continuous wind a c t i o n t o which the lake was exposed throughout the summer. Wind blew from the west and southwest d i r e c t i o n and as a r e s u l t , p i l i n g up of the epilimn-i o t i c water occurred i n the north and northeast end of the Lake. Occurrence of temperature seiches i n Skaha Lake i s reported by Ferguson (1949). Complete disappearance of s t r a t i f i c a t i o n cannot perhaps be explained as the r e s u l t of wind a c t i o n . Occasional disappearance of the thermocline, however, i n d i c a t e s that thermal s t r a t i f i c a t i o n i s very unstable. Rawson (1934) found no thermal s t r a t i f i c a t i o n i n Nicola Lake when temperatures were recorded on 8 J u l y and 30 August i n 1931. For determining the dissolv e d oxygen content i n water, water samples were c o l l e c t e d with a "Keramerer" water sampler and analysed, by Winkler 1 s method. Results of the ana l y s i s are presented i n Figure 5 and Table I I I . In water up to the depth of 96 f t . , d i s s o l v e d oxygen content can be considered rather high (3.4 p.p.m.). The quantity of di s s o l v e d oxygen at a depth of 175 f t . was found t o be 1.8 p.p.m. This i n d i c a t e s that the lake i s o l i g o t r o p h i c i n nature and does not have much organic decomposition i n the hypolimnion during summer. The oxygen curves presented i n Figure 5 appear t o be rather of clinograde type, c h a r a c t e r i s t i c of the eutrophic type of lakes (Hutchinson, 1956). But since the oxygen depletion i n the deeper water i s more o r l e s s gradual, the s i t u a t i o n may be sai d to be somewhat intermediate between the orthograde and clinograde type of curves. Rawson (1934) found heavy deplet-i o n of oxygen (0.4 p.p.m.) i n the bottom regions when water samples were examined on 20 August, 1931, showing that marked di f f e r e n c e s may occur i n d i f f e r e n t years. Secchi d i s c readings taken are summarized i n Table 17. The readings i n d i c a t e that water remains f a i r l y c l e a r throughout the summer. Figure 5. A v a i l a b i l i t y of disso l v e d oxygen i n Nicola Lake during the summer of 1958. 13 TABLE I I I ( a ) . Dissolved oxygen i n p.p.m. recorded from s t a t i o n IX. 1 i Date Depth ( f t . ) Temperature i n OF Oxygen p.p.m. 4 August 1 70.0 8.4 10 69.7 8.4 20 68.1 8.0 30 51.8 4.8 40 50.3 5.0 50 49.1 5.0 58 48.6 5.0 11 August 1 67.0 11.6 10 67.0 9.4 20 66.5 8.6 30 66.0 8.2 40 60.0 6.8 50 55.0 5.4 58 50.8 4.6 25 August 1 69.8 9.5 10 69.3 9.0 20 67.3 9.2 30 66.0 6.2 40 60.3 5.6 50 58.5 5.8 58 - 3.6 TABLE 111(b). Dissolved Oxygen i n p. p.m. recorded from s t a t i o n s VI and VI I I . (a) S t a t i o n VI Date Depth Temperature Oxygen ( f t . ) op p.p.m. 19 August 1 9.2 10 8.2 20 7.6 39.5 3.8 27 August 1 68.5 9.2 10 68.4 9.2 20 68.1 9.2 30 66.8 9.1 37.5 66.8 6.6 (b) S t a t i o n VLTI. 22 August 96 - 3-4 107 45.8 2.4 175 — 1.8 1-5 TABLE 17. Secchi disc readings taken from station IX. Date Limit of visibility (ft.) Light condition and air temperature & August 4.5 Overcast 0/10 11 « 6 Overcast 10/10 15 " 5.5 Air temperature 70°F 20 » 6.5 Air temperature 68GF 25 » 6.9 Overcast 7/10 27 " 5 Overcast 9/10 air temperature 64 F 7 Septembez 5.4 Overcast O/lO air temperature 60°F 16 Total dissolved solid content of water was found to range between 151 and 200 p.p.m., which is high compared to the lakes in coastal regions of British Columbia. Biological characteristics? (a) Vegetation; Aquatic vegetation is sparse except in the shallow southwest portion of the lake. Najas sp., Chara sp., and Cal1otricha sp. grow in the shallow shore areas, specially in the north shore of the main body of lake up to a depth of about 6 f t . No vegetation grows in areas of the shore where the bottom is exclusively sandy. In the shallow shore areas of the east and southeast side, particularly in the swamps and lagoons, Scirpus sp. and Typha sp. grow abundantly. In the shallow southwest region, dominant species are Potamogeton richardsonii(?). P. panormitanus (?), Zannichellia palustris and Myriophyllum sp. Scirpus sp. and Typha sp. are also seen on either side of this shallow portion. (b) Plankton: Plankton samples were taken i n different periods of the season, and were found to be composed chiefly of Ceratium sp. (Dinoflagella-feSvv ta), Nothoca sp. (Rotifera), Diaptomus sp., Bosmina sp- and Daphhia.,sp. (Cladocera), Cyclops (Copepoda), Anabaena and Aphanizomenon (Blue green algae). Rawson (1934) mentions the same type of plankton organisms which were poor in quantity. (c) Bottom fauna: Bottom fauna was not studied in the course of the present investigation. Rawson (1934) found a very scanty population of bottom fauna composed of Chironomid larvae, Pisidium. Oligochaeta and Nema-toda. (d) Fish fauna: The lake contains several species of fish which are listed below. A l l but the carp are native species. 17 (1) Rainbow Trout, Salmo g a i r d n e r i i Jordan. (2) Chinook Salmon, Oncorhynchus tshawytscha (Walbaum). Both young and sexually mature adults are seen. (3) Kokanee, Oncorhynchus nerka (Walbaum). (4) D o l l y Varden, Salvelinus ma!ma (Walbaum). (5) Mountain Whitefish, Prosopium w i l l i a m s o n i i ( G i r a r d ) . (6) Largescale Sucker, Catostomus macrocheilus Girard. (7) B r i d g e l i p Sucker, Catostomus columbianus (Eigenmann and Eigenmann). This species i s recorded from t h i s lake f o r the f i r s t time. (8) Squawfish, Ptychocheilus oregonense Richardson. (9) Peamouth Chub, Mvlocheilus caurinum, (Richardson). (10) Redside Shiner, Richardsonius balteatus,(Richardson). (11) Chiselmouth, Acrocheilus alutaceus, Agassiz and P i c k e r i n g . This species i s a new record from the lake as w e l l as from the Thompson River drainage system to which the lake i s connected. (12) Carp, Cyprinus carpio, Linnaeus. An introduced species. (13) Longnose Dace, Rhinichthys cataractae (Cuvier and Valenciennes). Presence of t h i s species i s also recorded f o r the f i r s t time. (14) Burbot, Lota l o t a (Linnaeus). (15) P r i c k l y Sculpin, Cottus asper Richardson. 18 Sampling Stations:- To obtain a p i c t u r e of the a v a i l a b i l i t y of d i f f e r e n t spe-c i e s of f i s h i n d i f f e r e n t parts o f the lake, three sta t i o n s were selected i n di s t a n t areas. P a r t i c u l a r s of the l o c a t i o n of the stations are given below, and are also shown i n Figures 6 and 7. I - Stat i o n i n f r o n t of Moore Creek i n l e t along the 10 f t . contour l i n e of lake bottom. I I - Stat i o n i n 80 f t . o f water, approximately one mile from the north shore. I H - S t a t i o n i n the shallow southwest p o r t i o n of the lake i n 5-8 f t . contour. Three other s t a t i o n s were also set up along the northwest shore at a distance of about 800 yards from north shore i n d i f f e r e n t depths as d e t a i l e d below. These s t a t i o n s w i l l , henceforward, be r e f e r r e d t o as s t a t i o n s IV, V v and VI i n the folloxidng order ( F i g . 3 ) . IV. Station i n 10 f t . of water c l o s e s t to shore. V. Stat i o n i n 20 f t . of water next to but a l i t t l e south of s t a t i o n IV. VI. St a t i o n i n 40 f t . of water i n l i n e with but at a distance of about 100 f t . from the 10 f t . s t a t i o n ( IV). Owing to close proximity of 10 and 20 f t . contour l i n e , s t a t i o n V was f i x e d about 200 f t . south of s t a t i o n IV. These three s t a t i o n s were set up p r i m a r i l y to study inshore and offshore movement pattern of f i s h i n d i f f e r e n t periods of the day. In a d d i t i o n to the stations mentioned, g i l l net sets were also made i n fro n t of Nicola R i v e r o u t l e t once during the season and i n the deepest zone of the lake. These are shown i n Figure 3 as s t a t i o n V I I and s t a t i o n VIII. 19 N I C O L A L A K E 2 MILES I . NICOLA RIVER NICOLA RIVER QUILCHENA CREEK GILL-NET STATIONS I MOORE CREEK INLET I I 80 ' BOTTOM DT SOUTH-WEST END Y U S -W END IN FRONT OF NICOLA RIVER OUTLET VTTT DEEPEST PART OF LAKE f Figure 6. Map showing g i l l net stations i n d i f f e r e n t parts of the lake. r 20 O LIMNOLOGICAL STATION J X O GILL NET STATION TZ - 10 ' 3C - 20 ' 2 1 - 40 ' I - MOORE CREEK FRONT TJ — 80 ' Figure 7. Map showing g i l l net stati o n s i n northwest end of the lake. 21 Sampling equipments and technique Three gangs of nylon experimental g i l l net were used f o r obtaining samples from the stations r e f e r r e d to i n d i f f e r e n t periods of the season. Each gang o f net was composed of s i x pieces of d i f f e r e n t raesh s i z e , each piece being 25 f t . long and 12 f t . deep. T o t a l length of a gang of net was, there-f o r e , 150 f t . The s i z e s of mesh used were 1", 3", 2", 3.5", 1.5",and 2.5" (when stretched) and the pieces i n the gangs were joined together i n the same order. S e l e c t i v e f i s h i n g by any one p a r t i c u l a r mesh s i z e of net i s w e l l known but i n the present case p r o b a b i l i t y of s e l e c t i v e f i s h i n g was g r e a t l y reduced by the use of wide range o f mesh s i z e s i n each gang. Each gang of g i l l net was divided i n t o two equal halves, upper and lower by painting a l i n e across the middle of i t s e n t i r e length. F l o a t s i n each section of the gang were marked by l e t t e r s and the mesh s i z e was a l s o i n s c r i b -ed on each f l o a t . These marks were used to note the exact p o s i t i o n of a f i s h i n the net. In determining the p o s i t i o n of f i s h , each h o r i z o n t a l h a l f of net was again divided i n t o upper and lower halves. Thus a f i s h i n the net could be located i n r e l a t i o n to mesh s i z e , part of the net between two p a r t i c u l a r f l o a t s and the region i . e . , top, second, t h i r d or bottom quarter of net. In a d d i t i o n t o the three gangs of experimental nylon net, another gang of monofilament nylon net was used. This gang was composed of seven equal sections, each 40 f t . long. The gang was made up of 1", 4», 2.5", 3", 2", 1.5" and 3*5" i n c h mesh si z e s , joined together i n the order given. T o t a l length o f t h i s gang was 280 f t . This gang was used only once during the summer. Sampling methods For convenience, the whole period of summer was a r b i t r a r i l y d i vided i n t o three p a r t s . The ea r l y summer included the period from the middle of June to 22 the l a s t week of J u l y while the f i r s t two weeks of August were termed as mid summer. Late summer included the period between the t h i r d week of August and f i r s t week of September. As i t was intended to observe and study the v a r i a t i o n of movement and abundance of f i s h i n d i f f e r e n t periods of day, net sets i n stati o n s IV", V and VI were made on a six-hourly basis to cover the period of day l i g h t , evening and e a r l y night, and l a t e hours of night i n c l u d i n g e a r l y morning. Net sets f o r evening and night covered the period of t r a n s i t i o n from l i g h t to darkness i n the evening and darkness to l i g h t during e a r l y morning. The f i s h i n g hours followed are tabulated below and the d i f f e r e n t periods w i l l , henceforward, be r e f e r r e d to as day, evening and night. TABLE V. Fishi n g hours i n stations IV-?I. Period of day Time covered 1. Daylight 10.00 - 16.00 hours 2. Evening 18.30 - 00.30 " 3. Night 02.00 - 00.80 " During each period i n the summer, three gangs of nylon nets were set on the bottom at each of the stati o n s IV, V and VI simultaneously. Each net set was made p a r a l l e l t o the c l o s e s t shore i . e . , northwest shore. In each s t a t i o n , both ends of the gang of net covered the same depth of water. Ih every part of the season, bottom net sets at these s t a t i o n s were repeated f o r each period of the day, i . e . , daylight, evening and night. S i m i l a r l y , f o r each period of summer, another s e r i e s of net sets were made i n three d i f f e r e n t l a y e r s of water i n the v e r t i c a l plane at s t a t i o n VI. One gang of net was f l o a t e d on the surface with the help of f i v e l a rge buoys. The second set was suspended i n the midwater with the f l o a t s at the depth of 20 f t . The t h i r d gang was set on the bottom at s t a t i o n VI. These sets were 23 also made parallel to the northwest shore. This vertical series of net sets were repeated for every part of the day in each period of the summer. Thus i t can be seen that on the bottom at station VI, nets were set twice for every part of the day during each period of summer, once in relation to the bottom sets in different stations (TV to VI) and again in relation to the vertical series of net sets at station VI. In station I, nets were set in a manner to encircle the area in front of the Moore Creek inlet. Usually two gangs of nets were set together along the 10 ft contour line to block off the inlet mouth. These sets were made in the evening and taken out in the next morning. These sets too fished the same depth of lake a l l along its length except once in spring ( l May). Results of the sampling effort from the station are summarized in Table VI. These sets were always made parallel to the north shore and perpendicular to the north-west shore. In station II, two net sets were made during each period of summer. One gang of net was set on the lake bottom while the other gang was kept flo-ated in surface layer almost above the bottom set. Both the sets were made parallel to the northwest shore. Different mesh sizes in each gang fished the same depth and level of water for the given period of time. These two sets were made usually in the evening and taken out the next morning. Table VII summarizes sampling at this station. Sampling in station III in the southwest basin was repeated once for every period of the summer. One gang of net was set in this station perpen-dicular to southeast shore. These nets were set overnight. Net was put in water in the late afternoon and taken out the next morning. In this case, different mesh sizes fished different depths, the shore end and outer end being in depths of about 5 and 8 f t . respectively. Since the difference in depth is very small, i t can be ignored for a l l practical purposes. Besides TABLE VI. Particulars of g i l l net catches i n front of Moore Creek i n l e t , Nicola Lake during the summer, 1958. Net on the 10 f t . contour l i n e . Date Depth and position of net Relation to north shore KT KK DV SS Sp SQ ecies LSS caug BLS ht MW PM RSS BT SC total Remarks 30 A p r i l -1 May 10 f t . bottom parallel 6 - - - 8 7 - 1 24 9 - 1 56 Two nets self together 10-11 June u tt 5 — 1 — 35 14 4 13 21 60 1 • — 154 One net set 28-29 July 11 11 1 6 - 4 18 12 1 6 47 77 - - 172 Two nets set together 4- 5 August it 11 4 5 - - 24 7 - 17 51 110 1 4 223 Two nets set together 11-12 August ti it 6 10 - - 16 6 - 10 34 138 2 1 223 Two nets set together 18-19 August tt tt 4 14 ' - - 46 14 1 9 18 117 - 6 229 Two nets set together 25-26 August 11 it 6 50 — 3 6 13 3 3 29 141 1 5 260 Two nets set together Legend! KT - Rainbow Trout KK - Kokanee DV - Dolly Varden SS - Chinook Salmon SQ - Squawfish 1SS - Largescale Sucker BLS - Bridgelip Sucker MW - Mountain Whitefish RSS - Redside Shiner BT - Burbot SC - Prickly Sculpin PM - Peamouth Chub CP - Carp CM - Chisel Mouth TABLE 711. P a r t i c u l a r s of g i l l net catches at 80 f t . s t a t i o n , Nicola Lake during summer, 1958. Period of summer Date Depth and p o s i t i o n of net Relat i o n to shore KT S KK >peci DV es of LSS f i t SQ sh ob PM taine RSS d BT SC Tot a l i (Remarks E a r l y summer 11-12 June Bottom a t 80 f t . P a r a l l e l 2 1 3 1 1 8 Both ends of net i n 80 f t . of water Hid summer 29-30 J u l y II II - 6 - - - - - - - 6 ti Late summer 3-4 Sept. II II - 20 - - - 3 - - - 23 it E a r l y summer 11-12 June Surface at 80 f t . d e D t t . P a r a l l e l 1 1 - - 1 27 11 - - 41 Both ends of net i n surface Mid summer 29-30 J u l y it tt 2 - - - - 11 2 - - 15 tt Late summer 3-4 Sept. II ii 5 — — — - 10 15 — — 30 it 26 the sampling i n s t a t i o n I I I , sampling i n the southwest basin was done i n f r o n t of the Nicola River outlet ( s t a t i o n VII i n F i g . 6) once during mid summer. P a r t i c u l a r s of catch, time of net set and depth f i s h e s i n stations I I I and V H are presented i n Table VIII. The other sampling done i n the northwest shore was with the 280 f t . long gang of monofilament nylon net. This set was made perpendicular to shore across sta t i o n s IV and VI. The net set was made i n the evening and taken out on the next morning. This i s the only net set each component mesh-size of which f i s h e d at d i f f e r e n t depths a t the same time. The inshore end of t h i s gang was i n about 8 f t . of water, while i t s offshore end f i s h e d at a depth of about 50 f t . Table IX summarizes the catch of t h i s net set while p a r t i c u l a r s on species combinations t h a t appeared i n d i f f e r e n t mesh s i z e s of t h i s set are presented i n Table X. In the deepest region of the lake, three sets with experimental nylon net were made i n three d i f f e r e n t depth zones. The f i r s t was on the bottom at a depth of 173 f t . , but no f i s h appeared. The second e f f o r t f i s h e d a depth of 80-120 f t . Two gangs of nets joined together were set perpendicular to shore i n t h i s case. The t h i r d set, comprised of two gangs joindd together, and placed at r i g h t angle to shore, f i s h e d the bottom at depths from 110 to 140 f t . Results of the sampling are summarized i n Table XI. E f f i c i e n c y and r e l i a b i l i t y of g i l l net catches Table XII summarizes the catch each mesh s i z e had made i n 54 net sets made i n stati o n s IV, V and VI on the bottom as w e l l as i n d i f f e r e n t l e v e l s of water. I t can be seen from t h i s table that d i f f e r e n t s i z e groups of Peamouth Chub, Squavtfish, Rainbow Trout and Mountain Whitefish were f a i r l y sampled by the gangs of nets. Redside Shiners appeared c o n s i s t e n t l y i n the 1" mesh s i z e i n d i c a t i n g that any other mesh s i z e f o r t h i s small s i z e d f i s h i s i n e f f e c t i v e . TABLE VIII. P a r t i c u l a r s of g i l l net catches i n southwest end of Nicola Lake during summer, 1958. Date Depth and p o s i t i o n of net Relat i o n to shore Depth at O f I Inshore two ends et Offshore KT KK DV SS MW S] SQ 3eci< LSS 3S C augt PM it RSS CM CP BT SC T o t a l 10-11 June Bottom at 5-8 f t . Perpen-d i c u l a r 5' 8» 1 - 1 - 8 9 8 2 24 16 1 - - - 70 9-10 Aug. n II 4' 6' 1 - - 1 15 9 10 84 25 - 1 - 1 L47 9-10 Aug. Bottom at 3-7 f t . nearer t o Nic o l a River o u t l e t At 60° angle to west shore 3' 7' - - - - 12 28 6 1 16 13 2 2 - 1 81 5- 6 Sept. Bottom at 5-8 f t . as on 10-11 June '58 Perpen-d i c u l a r 2 2 - 2 28 19 17 3 49 63 18 3 - 10 216 TABLE T X Number of f i s h obtained i n the monofilament nylon experimental g i l l net set at r i g h t angle to shore across 10 and 40 fee t s t a t i o n . Date 9-10 Aug. 1958 Time 21.00-07.00 hours Species To t a l number of f i s h 'Number of f i s h moving to north shore Number of f i s h moving away from north shore Loose f i s h Peamouth Chub 99 53 39 7 Redside Shiner 23 L+ 8 1 Squawfish 39 26 8 5 Largescale Sucker 28 17 6 5 Burbot 5 0 4 1 Kokanee 2 1 1 0 Rainbow Trout 4 2 0 2 Mountain Whitefish 5 5 ' 0 0 TABLE X« Species combination and mean length of each species of fish caught in different mesh sizes of monofilament net set. Species ] No.of fish it .Mean length (in mm) 4 No. of fish Mean length (in mm) No. of fish M < Mean length (in mm) 3 s h 4 No. of fish S i z _Mean length (in mm) e s i No. of fish ?n .Mean length (in mm) 1 No. of fish Is" Mean length (in mm) No. of fish Mean length (in mm) Rainbow Trout 1 307 1 480 2 451.5 Mountain Whitefish 3 321.3 2 272.5 Kokanee 1 185 1 231 Largescale Sucker 2 444 1 332 1 370 5 212.5 8 292.6 11 149.9 Burbot 2 481 3 488.3 Squawfish 10 326.8 4 328 25 176.3 Peamouth Chub 24 2 217.5 34 231.8 39 187.5 Redside Shiner 23 TABLE XI. P a r t i c u l a r s of g i l l net catches a t depths beyond 80 f t . i n Nicola Lake during summer, 1958. ,Date Depth and p o s i t i o n of net Relation t o shore Depth o f lake of net ( Inshore end at two end i n f t . ) ^Sffshore end Species caught Kokanee Remarks 10-11 August Bottom at 173 f t . Perpen-d i c u l a r 173' 173' No f i s h caught 21-22 August Bottom a t 120 f t . it 80' 1201 5 F i s h obtained from the part of net l y i n g between 90-96 f t . bottom. Average length of f i s h : 234 mm. 22-23 August Bottom at 140 f t . tt 110' 140' 1 F i s h obtained from the part o f net l y i n g at approx. 110 f t . bottom. Length of - f i s h : 242 mm. TABLE XII. Species combination i n d i f f e r e n t mesh s i z e s i n 54 net sets i n stations IV, V and VI. Species of f i s h 1" mesh l | " mesh 2" mesh 2g» mesh 3" mesh 3ztt mesh Peamouth Chub 394 f i s h 386 212 9 1 -Redside Shiner 454 » Squawfish 7 " 34 16 27 27 9 Carp 1 Largescale Sucker 2 17 12 8 17 Kokanee 6 7 43 5 4 2 Rainbow Trout 2 13 6 2 6 4 D o l l y Varden 2 1 Spring Salmon 1 Mountain Whitefish 3 8 7 4 Burbot 2 1 8 Sculpin 8 32 Cartwright (1956) suggested that nets set perpendicular to shore catch more f i s h than nets set p a r a l l e l to shore. Results of the only set made per-pendicular to shore (Table IX) tend to agree with the above suggestion. Withler (1948) found that nets set on the bottom are more e f f e c t i v e and take l a r g e r numbers and more v a r i e t y of f i s h than sets made i n midwater or i n surface water. Results of the net sets made i n the present case do not agree with Withler's observation. Surface sets made i n s t a t i o n II always y i e l d e d a l a r g e r catch and more v a r i e t y of species than the sets made on the bottom i n the same s t a t i o n f o r i d e n t i c a l periods of time. This r e s u l t tends to show that effectiveness of net sets f o r capturing wider v a r i e t y and l a r g e r number of specimens depends on the abundance and movement of f i s h i n the v i c i n i t y of the net rather than on the p o s i t i o n of net sets. A comparison of the catches made i n surface, midwater and bottom net sets i n the evening of 16-17 August tend t o support t h i s view. Catches of these net sets are summarized below. TABLE XIII. Catch composition and the t o t a l number of f i s h captured i n the surface, midwater and bottom net sets i n s t a t i o n VI on 16-17 August. Species Number o f f i s h captured Surface set Midwater set Bottom set Peamouth Chub 27 23 22 Redside Shiner 29 • ' 14 6 Squawfish 2 - -Rainbow Trout 3 4 -Mountain Whitefish - 1 -Largescale Sucker - - 1 P r i c k l y Sculpin - - 1 Kokanee - - 1 To t a l 61 42 31 33 i Cartwright (1956) suggested that the hours o f darkness are the most e f f e c t i v e period f o r sampling by g i l l nets. In the present case, catches by the g i l l nets set on the bottom at 40 f t . depth were always greater i n the day-l i g h t than those at night. A summary of the t o t a l number of f i s h captured on the bottom at 40 f t . depth i s presented below. TABLE XIV. Number of f i s h caught by g i l l net i n daylight, evening and night on the bottom i n s t a t i o n VI. Season Daylight Evening Night E a r l y summer 34 23 4 Mid summer 74 31 54 Late summer 84 27 52 From the above i t can be i n f e r r e d that e f f i c a c y of g i l l net f o r captu-r i n g f i s h does not depend on the period of day i n so f a r as sampling i n deeper bottom regions i s concerned. In shallow waters, however, more f i s h may appear at night as at that time f i s h would not see the net and avoid i t . On the other hand, appearance of f i s h i n g i l l nets i s probably determined by the concentra-t i o n of f i s h i n and around the area where nets are set at a given period of time. A sample of one or more species of f i s h appearing i n a g i l l net can, therefore, be s a i d to represent the groups of f i s h t h a t remain d i s t r i b u t e d i n a given area f o r a given period of time. Much of the subsequent argument i s based on t h i s assumption that there i s a p o s i t i v e c o r r e l a t i o n between the number of f i s h taken by a g i l l net and the concentration of f i s h i n a given l o c a l i t y where the net was set. Fry (1937) suggests that there i s a strong p o s i t i v e c o r r e l a t i o n between the number of f i s h appearing i n a g i l l net and the concentration of f i s h i n a given l o c a l i t y . He f u r t h e r mentions of a consistency i n the number of f i s h taken from a given l o c a l i t y * " However, the surface catches, where a net l e f t out f o r long periods was 34 cleared dally, show that i n one l o c a l i t y there i s a definite trend i n the num-ber taken, which i s consistent with the belief that the numbers taken are not due to erratic movements of large schools". Sampling by beach seine net In the study of spatial distribution of fi s h , i t i s necessary to look into the habits and habitats of each species of f i s h i n different stages of i t s l i f e history. Habits and preferences of fry and young-of-the-year of fi s h species are known to d i f f e r from their adult stage. To complete the picture of distribution, an attempt was made to find out the habits of young-of-the-year and fry i n the lake. As the young f i s h are known to inhabit very shallow water along the shore, sampling was done along the shore with a beach seine net. The net used was of nylon material with £ inch mesh size. It was 30 f t . long and 8 f t . deep with proper lead l i n e and floats. Sampling by seine net f a l l under two categories,- (l) sampling at beaches i n different regions of the lake to observe v a r i a b i l i t y , i f any, i n the composition of the shore population and (2) sampling at the beaches on the north shore during different periods of the day to record variation i n the presence of different species of f i s h and their size composition i n the daylight and at night. Seine haul stations are shown i n Figure 8. Seine hauls i n different shores usually were taken from a depth of 3~4 f t . of water where bottom conditions permitted such an operation. Fish appearing i n these hauls were • chiefly composed of young-of-the year of various species. Depending on the bottom conditions, different species of f i s h appeared i n different regions of the lake. The second category of sampling was carried on i n the north shore i n the region lying west of Moore Greek in l e t , at a distance of about 100 f t . 35 from the i n l e t . The selected zone on the shore was divided i n t o nine equal sections, each section measuring 22 f t . i n length. The sections were marked o f f with wooden pegs. The substrate i n a l l these sections up t o the depth of 4 f t . was s i m i l a r . At the water edge the bottom was sandy but mud and gravel replaced sand with increasing distance from the shore. Seine hauls were taken from 1, 2, 3 and 4 f t . deep water during a singl e operation. The sections netted were selected i n a random manner but two adjoining sections were never used f o r taking hauls i n any si n g l e opera-t i o n . Seine hauls were made c h i e f l y i n daylight and a t night when l i g h t conditions were completely d i f f e r e n t . Some hauls were, however, made during the periods of t r a n s i t i o n e.g., dusk and dawn. For the purpose of the pre-sent analysis and discussion, samples obtained from 4 f t . of water have only been taken i n t o consideration. Species composition i n seine hauls i n 1, 2, and 3 f t . of water was s i m i l a r to that i n the hauls from 4 f t . of water but d i f f e r r e d only i n quantity. As such, these hauls were not taken i n t o account. Sampling by dip net Along the west shore, where seine n e t t i n g was not po s s i b l e , sampling was done sev e r a l times during the period between the t h i r d week of J u l y and second week of August with a dip net. The dip net was used i n c o l l e c t i n g f i s h t h a t were moving i n about 2 f t . deep water over the rocky bottom close to shore. Treatment of samples A l l g i l l net sets made between J u l y 17 and f i r s t week of September were brought to shore with f i s h t h e r e i n . On shore, each s t r i n g of net was spread on a piece of t a r p a u l i n and the p o s i t i o n of each f i s h was recorded i n r e l a t i o n to the depth of net, mesh s i z e and d i r e c t i o n i t was headed a t 36 Figure 8. Map showing seine haul s t a t i o n s . 37 the time of capture. The standard length of each f i s h was measured on a wooden board f i t t e d with a measuring scale i n m i l l i m e t e r . Thereafter, specimens from each net were preserved separately i n containers containing 10 % fromalin. In case of the seine hauls, each catch was preserved immediately a f t e r making the haul separately i n containers. Subsequently, catch i n each cont-a i n e r was sorted i n t o d i f f e r e n t species and length of each i n d i v i d u a l f i s h was measured and recorded. 38 III. RESULTS Peamouth Chub Movement of Peamouth Chub in both vertical and lateral planes during summer was studied and results thereon are presented in Table XV (a-d) and Figure 9 . Over the entire summer, Peamouth Chub, in general, tend to stay close to the bottom in deeper waters during the hours of daylight. An exception to this general trend is noticeable once in early summer (28 July) when five fish appeared in the surface set. This exception can be related to the fact that on this day intensity of light was very low which might have induced the fish to explore the surface region of water. Occurrence of fish in midwater during daylight i s indicated by the samples obtained in mid and late summer, but no generalization can be made as, on both occasions, number of fish sampled was small. Peamouth Chub sampled in the bottom net sets during daylight hours display a significant tendency of staying closer to the lake floor. This is seen to be a consistent feature a l l through the summer except once in mid summer ( l August) when a tendency of vertical spreading is indicated by the sample in the bottom net set at station ¥1. In early and mid summer, congregation of Peamouth Chub in and around the 20 f t . contour line is indicated, but in late summer more fish appear in the deeper bottom zone during daylight. In the evening during different periods of summer, Peamouth Chub, show a significant tendency to spread in a l l levels of water. During this part of the day, fish appear consistently in the surface and midwater net sets. More-over, from the position of fish in a l l bottom sets in the evening, the tenden-cy of remaining spread in the vertical plane is clearly visible. 39 PEAMOUTH CHUB EARLY SUMMER EVENING MID SUMMER DAY. LATE SUMMER F i g . 9. Occurrence of Peamouth Chub i n the g i l l net sets i n s t a t i o n s iv to VI m d i f f e r e n t periods of summer. Area of c i r c l e represents t o t a l number of f i s h . Arrow i n d i c a t e s d i r e c t i o n of f i s h . TABLE XV (a). Number of Peamouth Chub obtained i n net sets ( v e r t i c a l and l a t e r a l ) i n the stations along E a r l y Summer northwest shore, Nicola Lake. Date 1958 Depth and p o s i t i o n o f net set Period of day Total No. of f i s h No, o movd to shore f f i s h •ng o f f 'jshore Loose f i s h Conclusion (including X 2 value)) No. c i n top h a l f of net jf f i s h i n (bott-om h a l f of net Conclusion (inc l u d i n g X 2 value) 20 J u l y 10' Bottom Daylight 1 . 1 0 0 0 1 17-18 '» II . II Evening 31 6 22 3 moving offshore X2 = 9.14 11 19 23 J u l y II II Night 6 2 4 0 5 1 20 J u l y 20" Bottom Daylight 22 10 9 3 4 16 F i s h stay at bottom X 2 - 7.2 17-18 " II it Evening 26 10 16 0 13 13 23 J u l y it n Night 16 6 8 2 4 10 20 J u l v 40« Bottom Daylight 3 2 1 0 1 2 17-18 11 II it Evening 9 4 5 0 1 8 F i s h stay at bottom X2 - 7.0 23 J u l v it it Night 6 2 2 2 2 4 28 J u l y 24-25 " 26 J u l y Surface tt ti Daylight Evening Night 5 20 9 2 8 4 2 11 5 1 1 0 2 6 6 2 13 3 X 2 = 2.58 iitf J u l y 24-25 " 26 J u l y Suspended II tt Daylight Evening Night U 15 9 U 7 3 U 7 4 u 1 2 u 9 4 u 5 3 28 J u l y 24-25 " 26 J u l y 40' Bottom II it it II Daylight Evening Night 19 17 2 7 10 1 8 6 1 4 1 0 2 5 1 13 11 1 F i s h i n Bottom X 2 - 4.03 Note - Chi-aj«ar® is'not"calculated where sample size-is small and no- conclusion,is noted. TABLE XV (b). Mid Summer. Number of Peamouth Chub obtained i n net sets ( v e r t i c a l and l a t e r a l ) i n the stations along northwest shore, Nicola Lake. Depth and p o s i t i o n of net set Period of day-Tot a l No. of f i s h No. of f i s h moving to o f f shore Loose f i s h shore Conclusion ( i n c l u d i n g X 2 value) No,of f i s h i n top i n bott h a l f of net om h a l f of net Conclusion (including X^ value) 10' Bottom Daylight Evening Night 23 25 15 5 1 16 20 13 0 1 Moving offshore X 2 = 5.76 X 2 = 9.0 X 2 = 10.2 a 1 4 1 17 11 13 F i s h stay at bottom X 2 " 8.04 X2, = .36 X 2 = 10.2 ".-X 2 = x 2 = 4.66 3.56 2.25 2~6~ 20' Bottom 4 0 ' Bottom Daylight Evening Night 57 28 16 9 12 9 32 16 7 16" 0 0 X* = 12.9 X 2 = .56 .25 X 2 = 14 9 5 28 19 11 Daylight Evening Night "ICT 1 80 T " 0 22 0 12 T l 63 5 1 52 0 0 6 X 2 - 12.16 X2 = ,2 -Jf- = 34.6 Surface Daylight Evening Night 0 27 21 0 5 0 19 10 0 3 3 X 2 = 8.16 " 0 4 6 0 20 12 10.6 Suspended II Daylight Evening Night 5 23 39 2 9 13 2 13 26 1 1 0 X 2 = 4 . 3 2 " 1 14 21 1 18 Daylight Evening Night " T F 11 12 9 22 "8~ 3 8 18" 18 27 X 2 = 23.8 X 2 = 10.7 X 2 = 10.2 40« Bottom it it 22 37 0 2 3 X 2 = 4.16 " Note - Chi-square i s not calculated where sample siz e i s small and no conclusion i s noted. TABLE XV" ( c ) . Number of Peamouth Chub obtained i n net sets ( v e r t i c a l and l a t e r a l ) i n the stations along Late Summer*- northwest shore, Nicola Lake Depth and To t a l . No. of f i s h Conclusion No. of f i s h Conclusion Date p o s i t i o n Period of No.of moving Loose (including i n top i n bott- (including 1958 of net day- f i s h to o f f f i s h X 2 value) h a l f . om h a l f X 2 value) set shore shore of net of net 29 Aug. 10' Bottom Daylight 10 5 3 2 • 0 8 Stay at bottom 26-27" it ti Evening 9 3 5 1 3 5 28 Aug. II ti Night 14 5 8 1 4 10 29 Aug. 20' Bottom Daylight 6 1 5 0 0 6 Stay at bottom 26-27" tt ti Evening 17 7 5 5 8 4 28 Aug. ti tt Night 15 5 9 1 4 11 29 Aug. 4 0 ' Bottom Daylight 41 15 21 5 9 29 Stay at bottom; X 2 = 10.4 26-27" ti ti Evening 27 14 12 1 10 16 28 Aug. it II Night 33 13 lk 6 19 8 Do not stay at bot1 X 2 = 4 .48 31 Aug. Surface Daylight 0 0 0 0 0 0 2-3 Sept Evening 9 0 9 0 Moving offshore 4 5 2 Sept. it Night 5 1 4 0 2 3 31 Aug. Suspended Daylight 1 0 1 0 1 0 2-3 Sept Evening 15 5 9 1 6 8 2 Sept. ti Night 11 3 7 1 3 7 31 Aug. 40«.Bottom Daylight 59 26 25 $ 12 39 Stay at bottom; X 2 = 14.28 2-3 Sept Evening 14 6 7 1 •4 :.9 2 Sept. it II Night 32 9 21 2 Moving offshe re 4 26 Stay at bottom - X 2 - 6.12 X 2 = 16.. 5 Note - Chi-square i s not ca l c u l a t e d where sample siz e i s small and no conclusion noted TABLE XV (d). Number of Peamouth Chub caught i n the net sets i n fr o n t of Moore Creek i n l e t , (East end of lake) i n SO f t . s t a t i o n i n mid lake and i n fr o n t of Nicola River o u t l e t (west end of l a k e ) . Station Date 1958 Time (hours) Tot a l No. of f i s h Direct: to shore Lon of movemenl o f f shore b loose A, E a r l y Summer East end Moore C r . i n l e t 11 ti it it II n 30 Apr. 1 May 10-11 June 28-29 2 2 . 0 0 -10.15 19.30-1 2 . 2 5 3 1 . 3 0 -24 21 47 20 24 3 West end Nicola R.outl. 1 0 - 1 1 June 16.15-0 9 . 2 5 24 8 0 ' s t a t i o n at bottom 11-12 June 2 2 . 0 0 -09.00 3 _ 8 0 ' s t a t i o n at surface 11-12 June 21.30-1 0 . 0 0 27 B. Mid Summer East end Moore C r . i n l e t II it II West end Nicola R.outl. it ti tt 8 0 ' s t a t i o n at bottom 80' s t a t i o n at surface 4-5 Aug. 11-12 Aug. 9-10 Aug. 9-10 Aug. 29-30 J u l y 29-30 J u l y 2 1 . 0 0 -08.30 20.45-0 8 . 0 0 15.00-11.30 15.45-1 1 . 0 0 20.30-07.00 2 1 . 0 0 -07.30 51 34 84 16 0 11 18 11 57 11 0 3 31 21 20 2 0 8 2 2 7 3 0 0 C. Late Summer East end Ifoore C r . i n l e t ii II II West end Nicola R.outl. 8 0 ' s t a t i o n at bottom 8 0 ' s t a t i o n at surface 18-19 Aug. 25-26 Aug. 5-6 Sept. 3 - 4 Sept. 3 - 4 Sept. 2 0 . 0 0 -0 8 . 0 0 20.30-0 8 . 30 16.45-09.45 19.45-10.30 2 0 . 1 0 -10.40 18 29 49 3 10 5 6 28 1 2 10 21 20 2 8 3 2 1 0 0 44 Toward l a t e night and e a r l y morning, a trend of returning back from the upper l a y e r s toward bottom i s noticed i n mid and l a t e summer. At the same time, i n a l a t e r a l plane, f i s h tend to leave the shallower regions of the lake f o r the deeper bottom away from shore, during t h i s part of the day, i n both mid and l a t e summer. In ea r l y summer, on the other hand, samples do not i n d i -cate any movement back to deeper water from midwater, but f i s h from shallower bottom regions close to shore show the tendency of moving i n t o the deeper o f f -shore regions when l i g h t conditions change from night to day. The maximum depth at which Peamouth Chub are seen i n summer i s 80 f t . where the species was sampled on the bottom both i n e a r l y (10-11 June) and l a t e (3-4 September) summer. In mid summer (28-29 J u l y ) , no f i s h were, however, caught a t t h i s depth. Won appearance o f f i s h during the peak of sum-mer, and very small sample s i z e i n l a t e summer, may be in t e r p r e t e d to i n d i c a t e that 80 f t . bottom region i s not pre f e r r e d by t h i s species. Thermal s t r a t i f i c a t i o n does not seem to af f e d t the v e r t i c a l migration of Peamouth Chub. During d i f f e r e n t periods o f summer, Peamouth Chub are seen moving f r e e l y from epilimnion t o hypolimnion and v i c e versa i n d i f f e r e n t per-iods of the day. The f i s h was a v a i l a b l e i n a l l major regions of the lake. I t s abundance i n north and southwest ends was almost the same i n e a r l y summer, but with the progress of summer, p a r t i c u l a r l y i n the middle of August, sampling i n d i c a t e d more f i s h i n the southwest end. This pattern of r e l a t i v e abundance continued f o r the remaining peri o d of summer. This s h i f t i n r e l a t i v e abundance was probably due t o the f a c t that i n August (peak period of the summer), vegeta-t i o n grow more abundantly i n the shallow southwest basin than i n any other part of the lake. F i s h sampled i n net sets p a r a l l e l to the northwest shore do not d i s -play any s i g n i f i c a n t offshore or inshore d i r e c t i o n of movement i n every case. 45 In e a r l y summer, the evening sample i n 10 f t . bottom showed a s i g n i f i c a n t o f f -shore d i r e c t i o n of movement. In mid summer, the f o l l o w i n g samples showed a s i g n i f i c a n t d i r e c t i o n of movement, and i n every case, f i s h were headed offshore. (a) Sample i n 10 f t . bottom set i n the d a y l i g h t . (b) » '» 10 f t . " » » " evening. (c) » " 10 f t . » " at night. (d) » « 20 f t . « » i n the d a y l i g h t . (e) » " 40 f t . " « at night. ( f ) " " surface set i n the evening. (g) " " suspended set at night. (h) " 11 40 f t . bottom set at night. From the above i t appears that changes i n l i g h t conditions do not cause a change i n the d i r e c t i o n of movement of Peamouth Chub. In l a t e summer, the night sample from the bottom i n 40 f t . water shows a s i g n i f i c a n t offshore d i r e c t i o n of movement. Change i n season does not, therefore, appear to i n f l u -ence the d i r e c t i o n of movement. From the data, i t can be concluded that mid summer conditions produce offshore p a t t e r n of movement i n a pronounced manner, whereas i n e a r l y and l a t e summer, no such e f f e c t i s apparent and f i s h tend to show randomness i n movement. The above i n t e r p r e t a t i o n s would be made more c l e a r , i f information were av a i l a b l e on the l a t e r a l movement pattern of Peamouth Chub along shore. In the net set made perpendicular to shore across s t a t i o n s IV and VI, 99 Peamouth Chub appeared (Table IX)i Of these, 53 were headed towards the north shore and the balance i n the opposite d i r e c t i o n . This points to the f a c t that Peamouth Chub also move l a t e r a l l y along shore at night. Sizes of f i s h do not appear to influence t h e i r d i r e c t i o n of movement, but depth d i s t r i b u t i o n seems t o be influenced by s i z e . With the increase i n depth of water, the average size of f i s h was seen to increase. L i t e r a t u r e on Peamouth Chub 46 In Skaha Lake, Ferguson (1949) found that Peamouth Chub l i v e .'• i n s h a l l ^ ow water and he described t h i s f i s h as a shallow water species. Godfrey (1955) noted that the peak abundance of Peamouth Chub i n summer occurs i n the 0-5 meter (0-16 f t . ) zone. C a r l and Clemens (1953) describe Peamouth Chub as a species i n h a b i t i n g shallow weedy zones of a lake. Absence of Peamouth Chub i n 80 f t . deep water during the peak of sum-mer may be r e l a t e d to i t s preference f o r shallow waters as suggested by the authors quoted above. Appearance of more f i s h at night i n the weedy shallow southwest end i n the mid summer seems to be i n agreement with the f i n d i n g s o f C a r l and Clemens (1953)• There i s , however, no evidence that during the day-Light hours a s i m i l a r abundance of Peamouth Chub p e r s i s t s i n the weedy areas. Inferences drawn by both Godfrey (1955) and Ferguson (1949) seem to be based on sampling done at night. Samples from the night net sets of the present study agree with the above inferences. However, the s i t u a t i o n i n the daylight appears to be d i f f e r e n t when Peamouth Chub showed a preference f o r staying c l o s e r to the bottom i n deeper water. As f o r siz e s t r a t i f i c a t i o n i n the depth d i s t r i b u t i o n of Peamouth Chub, no reference i s seen i n e a r l i e r l i t e r a t u r e , but a s i m i l a r feature i s mentioned by Lindsey (1953) and Crossman (1957) i n the case of Redside Shiner. Schultz (1935) observed that schools o f Peamouth Chub gathering near shore i n very shallow waters i n the daylight f o r breeding purposes are scared away by the appearance of Squawfish. Consistent absence of Peamouth Chub i n shallow water and on the surface during daylight might probably be associated with some i n s t i n c t i v e response of the f i s h to avoid l i g h t e d areas and thereby avoid the a t t e n t i o n of the predators. The tendency of g e t t i n g spread.in a l l l e v e l s of water at night, on the other hand, was probably due t o increased 47 feeding a c t i v i t y of the species. Redside Shiner Results on the movement pattern are summarized i n Table XVI (a-d) and Figure 10. A l l through the summer, i n daylight, Redside Shiners tend to stay close to the lake bottom. This consistency i n behaviour during daylight hours i s not seen i n f i s h sampled at 40 f t . bottom during l a t e summer (29 and 31 August) when a tendency of spreading up v e r t i c a l l y i s not i c e a b l e . On both these days l i g h t i n t e n s i t y was extremely low which probably simulated a co n d i t i o n of night at deeper waters. Low l i g h t i n t e n s i t i e s may, therefore, be associated with the v e r t i c a l spreading of f i s h i n l a t e summer. In daylight during e a r l y summer, Redside Shiners appear t o remain u n i -formly d i s t r i b u t e d a l l over from shore t o the 40 f t . depth zone but i n mid summer a tendency of congregation around the 20 f t . contour l i n e i s not i c e d . In l a t e summer i n daylight, the mid summer feature i s l o s t again. A v a r i a t i o n i n the s i z e of sample i s seen i n 40 f t . s t a t i o n during mid as w e l l as l a t e summer. In mid summer, there was a time lapse o f 14 days between the two samplings (1 and 15 August) but i n l a t e summer, the samples were obtained within a day of each other. The v a r i a t i o n i n midsummer i s probably due to changes i n p h y s i c a l conditions that took place over a period o f two weeks. On 1 August, the thermocline i s seen i n 37-40 f t . of water when only 1 f i s h appeared i n the net set. On the other hand, on 15 August, when 16 f i s h appea-red i n the net set, there was no thermocline at t h i s depth. In the evening Redside Shiners d i s p l a y a trend o f spreading i n t o mid-water and i n t o the surface over both shallow and deep water. This tendency o f s c a t t e r i n g i s consistent i n a l l parts of the summer. F i s h sampled i n bottom sets i n the evening also show the spreading i n v e r t i c a l plane i n a l l 48 REDSIDE SHINER 0' 10. Occurrence of Redside Shiner i n g i l l net sets i n s t a t i o n s IV-VI i n d i f f e r e n t periods of summer. Area of c i r c l e represents t o t a l number of f i s h . Arrow i n d i c a t e s d i r e c t i o n of f i s h . TABLE XVI (a ) . Number of Shiners obtained i n net sets ( v e r t i c a l and l a t e r a l ) i n the stati o n s along northwest shore, Nicola Lake. A. E a r l y Summer Date Depth and Period of Total •No. of f i s h Conclusion No. of f i s h Conclusion ' 1958 p o s i t i o n day No. of .moving Loose (including. i n top i n b o t t -(including of net f i s h to o f f f i s h X 2 value) X 2 value) set shore shore h a l f om h a l f of net of net 20 J u l y 10 f t . daylight 2 1 0 1 1 0 17-18 » bottom evening 21 6 15 0 Moving.off- 5 16 Stay at bottom shore w = X 2 - 11 7.52 23 J u l y it night 11 5 6 0 u 7 20 J u l y 20 f t . daylight 1 0 1 0 0 1 17-18 '» bottom evening 7 1 6 0 3 4 23 J u l y II night 17 4 13 0 moving o f f 4 13 Back to bottom shore.X 2-4.26 20 J u l y 40 f t . daylight 1 0 1 0 0 1 17-18 " bottom evening 0 0 0 0 0 0 23 J u l y ti night 0 0 . 0 0 0 0 28 J u l y Surface daylight 0 0 0 0 0 0 24-25 " »' set evening 8 4 4 0 3 5 26 J u l y ti tt night 8 2 6 0 7 1 Not on bottom. X 2- 3.81 28 J u l y Suspend. daylight 0 0 0 0 0 0 24-25 " » set evening . 14 5 9 0 7 7 . 26 J u l y II it night 2 2 0 0 0 2 28 J u l y Bottom daylight 1 0 1 0 0 1 2A-25 " set 40 evening 2 1 1 0 2 0 26 J u l y f t . night 0 0 0 0 0 0 Note( 7 Chi-square i s not c a l c u l a t e d where sample-size i s small and no conclusion i s noted TABLE XVI (b)• Number os Shiners obtained in net sets (vertical and lateral) along northwest shore, Nicola Lake. B. Mid Summer Date 1958 Depth and position of net set Period of day-Total No .of fish No* of movin to snore i fish •g off shore Loose fish Conclusion (Including X 2 value) No. C in top half of net >f fish in bott-om half of net Conclusion (including X value) 1 Aug* 6-7 " 4 Aug. 10 f t . bottom n Day light Evening Night 2 26 47 1 1 6 10 1 20 37 0 0 0 Moving off shore X 2 * 7 .52 Moving off shore X 2 = 15.4 0 11 26 2 15 21 Fish not on bottom X2 » .614 Fish not on bottom X 2 a .52 1 Aug* 20 f t . bottom Daylight 18 4 13 0 Moving off shore X 2 ^ 4*5 Moving off shore X » 5 13 Fish on bottom X 2 = 3.54 6-7 " 4 Aug. tt it Evening Night 17 26 5 8 12 18 0 0 2 10 15 16 Fish on bottom X 2 - 9.8 Fish not' oh bottom X 2 » 1.38 3.3 1 Aug. 6-7 " 4 Aug. 40 f t . bottom n Daylight Evening Night 1 1 5 1 1 2 0 0 3 0 0 0 1 1 5 0 0 0 15 Aug. l$-17rt Surface set Daylight Evening 0 29 0 13 0 16 0 0 0 14 0 15 Fish not on bottom X 2 - .034 16 AUK. 1! Night 11 5 4 2 5 4 15 Aug. 16-17 » Suspend, set Daylight Evening 0 14 0 6 0 7 0 1 0 8 0 5 16 Aug* n Night 3 0 3 0 2 1 15 Aug. 16-17 n 40 f t . bottom Daylight Evening 16 6 9 3 6 3 1 0 2 3 13 3 Fish on bottom X-fn 8.06 16 Aug* n Night 9 3 6 0 6 3 Note 7 Chi-square i s not calculated where sample size i s small and no conclusion i s noted. TABLE XVI (c). Number of Shiners obtained in stations (vertical and lateral) along northwest shore, Nicola Lake, C» Late Summer Date 1958 Depth and position of net Period of ' day-Total No .of fish No. oi movi to .shore ' fish ng off shore Loose fish ponclusion (including X 2 value) No. o in top half of net f fish in bott-om half of net Conclusion (including X 2 value) 29 Aug. 26-27" 28 Aug. 10 f t . bottom M Daylight Evening Night 4 11 14 3 8 6 0 3 8 1 0 0 o 5 2 4 6 12 Fish back on bottom 29 Aug. 26-27" 28 Aug. 20 f t . bottom Daylight Evening Night 0 6 9 0 0 5 0 5 3 0 1 1 Moving offshore x 2 »4.l 0 3 3 0 2 5 29 Aug. 26-27" 28 Aug. 31 Aug. 2-3 Sept. 2 Sept. 40 f t . bottom ti Surface set II Daylight Evening Night Daylight Evening Night 3 10 7 sssasssa: 0 18 8 0 3 3 0 9 2 3 7 4 :asss=s: 0 6 5 0 0 0 0 3 1 sssssassssaasssa 2 5 5 0 9 4 1 5 2 ssssBaanaai 0 6 3 s atata^ j SH us —X Bfltai as sa&aa maas 31 Aug. 2-3 Sept. 2 Sept. Suspend. set if Daylight Evening Night 0 6 5 0 4 1 0 2 u 0 0 0 0 3 4 0 3 1 31 Aug. 2-3 Sept. 2 Sept. 40 f t . bottom n Daylight Evening Night 17 0 17 5 0 5 11 0 8 1 0 4 11 0 1 5 0 12 Fish back on bottom Note - Chi-square i s not calculated where sample size i s small and no conclusion i s noted. TABLE XVI ( d ) . Redside Shiner sampled i n net sets i n d i f f e r e n t parts of Ni c o l a Lake. Stations Pate 1958 Time (hours) T o t a l f i s h Direct move t o shore i o n of ment o f f shore 'Loose f i s h Remarks A. E a r l y Summej NE end ( i n f r o n t of Moore C r . i n l e t ) it n H f i 30 Apr. 1 May 22.00-10.15 9 Di r e c t i o n not noted. 2 net set c o n t i n -u a l l y across i n l e t mouth. 10-11 June 19.30-12.25 21 D i r e c t i o n not noted. 1 net set i n same po s i t i o n as above 28-29 Ju l y 21.30-08.30 77 26 48 3 2 net set c o n t i n u a l l y across i n l e t i n 10» contour. SW end (close to Ni c o l a R. outl e t ) 10-11 June 16.15-09.25 16 80 f t . s t a t i o n bottom set 11-12 June 22.00-09.00 0 No f i s h . 80 f t . s t a t i o n surface set 11-12 June 22.00-09.00 11 -D i r e c t i o n not noted. B. Mid Summe: NE end (Moore C r . i n l e t ) • it i i 4-5 Aug. 21.00-08.30 110 35 74 1 11-12 Aug. 20.45-08.00 138 66 69 3 SW end (close t o Nico l a R. outl e t ) 9-10 Aug. 15.00-11.30 25 18 6 1 SW end(in f r o n t of Ni c o l a R. outl e t ) 9-10 Aug. 15.45 11.00 13 9 4 0 80 f t . s t a t i o n bottom set 29-30 J u l y 20.30-07.00 0 No f i s h . 80 f t . s t a t i o n surface set 29-30 J u l y -21.00-07.30 1 D i r e c t i o n not noted. C. Late Summe] NE end (Moore C r . i n l e t ) tt tt 18-19 Aug. 20.00-08.00 117 50 56 11 25-26 Aug. 2O.3O-08.30 141 33 100 8 SW end(in f r o n t of Nic o l a R. o u t l e t ) 5-6 Sept. 16.45 09.45 63 31 32 0 80 f t . s t a t i o n on the bottom •3.*4 Sepfc • 19.45 10.30 0 No f i s h . 80 f t . s t a t i o n surface set 3V* Sept. 20.10-10.40 15 5 10 0 53 cases, except those from 20 f t . bottom set i n mid. summer. I t can thus be i n f e r r e d that changes i n l i g h t conditions a f t e r n i g h t f a l l induce Shiners to spread out i n shallow and surface water. During t h i s period, t h i s species goes i n t o open water along the surface l e v e l s as i s i n d i c a t e d by the sampling of surface net sets i n s t a t i o n I I during d i f f e r e n t periods of summer. In e a r l y summer, more f i s h appear to stay i n midwater i n the evening but i n mid and l a t e summer, they appear to congregate i n the surface region. A large v a r i a t i o n i n the number of f i s h sampled i n s t a t i o n VI on the bottom i s seen i n mid as w e l l as l a t e summer. These v a r i a t i o n s i n the number of f i s h sampled i n mid summer i s a t t r i b u t a b l e to causes mentioned i n case of daylight sets. In l a t e summer, the net set made on 26-27 August y i e l d e d 10 f i s h , but the other set made on 2-3 September y i e l d e d none, i n s p i t e of the f a c t that a thermocline was i n 40 f t . of water on the former occasion but on 2-3 Sept-ember, the thermocline had disappeared. This v a r i a t i o n was probably caused by some other f a c t o r . Towards l a t e night and dawn i n early summer Redside Shiners do not exhibit any tendency of returning to deeper regions (towards the bottom i n 40 f t . depth) but seem to congregate around the 20 f t . contour l i n e . In mid summer, some f i s h show the tendency to return to the bottom region i n 40 f t . though most f i s h seem to hold on to t h e i r p o s i t i o n i n surface and midwater. In l a t e summer, during the same period of the day, more f i s h show the tend-ency to return to deeper water. The o v e r a l l tendency of Shiners appear to be to head back into the lake bottom from surface and midwater towards l a t e night and dawn, but instead :.of making a s t r a i g h t v e r t i c a l descent, they probably move i n an oblique manner from the surface region i n open water to the shallower bottom zone. In l a t e summer, more f i s h appear i n the bottom around 40 f t . depth zone. Like Peamouth Chub, some of the samples of Redside Shiner show a s i g n i -54 f i c a n t d i r e c t i o n of movement and i n a l l such cases most f i s h were headed o f f -shore (Table XVI a-c). In case of t h i s species, neither d i f f e r e n t periods o f day, nor the changes i n condition i n d i f f e r e n t periods of summer, seem to have any influence i n determining the d i r e c t i o n of movement. The sample of Redside Shiners obtained i n net sets perpendicular to shore i n the northwest end i n d i -cate that the f i s h move p a r a l l e l to shore at night. In the bottom net set i n s t a t i o n I I , Redside Shiners never appear i n any part of the summer. Moreover, sample s i z e obtained i n bottom net sets i n s t a t i o n VI are c o n s i s t e n t l y small. E v i d e n t l y Redside Shiners p r e f e r to l i v e i n shallow areas close to shore during summer. The species i s a v a i l a b l e i n a l l regions of the lake, but the sampl-in g r e s u l t s i n d i c a t e that i t i s more abundant i n the northeast end. E f f e c t of thermal s t r a t i f i c a t i o n on t h i s f i s h does not appear to be very c l e a r . During d i f f e r e n t periods of summer, i t was seen within the thermocline, though not i n s i g n i f i c a n t numbers. I t i s known, however, to prefe r to l i v e i n the epilimnion and the appearance of large number of f i s h i n the epilimnion i n the evening and at night tend to agree to the above b e l -i e f . Occurrence of the f i s h i n the hypolimnion during the daylight i s pro-bably induced by i t s tendency to avoid l i g h t . L i t e r a t u r e on Redside Shiner Crossman (1957), Ferguson (1949) and Lindsey (1953) mentioned that Redside Shiners prefer to stay i n shallow waters close to shore. The present findings also agree with t h i s observation of the above authors. Crossman (1957) and Lindsey (1953) also observed that at n i g h t Redside Shiners become sc a t t e -red i n d i s t r i b u t i o n . Crossman suggested that f i s h e i t h e r come up from deeper water at the centre or move i n t o open water from shore during the hours of darkness. Lindsey (1950) considered that Redside Shiners come to surface at 55 night as a r e s u l t of t h e i r increased a c t i v i t y . The present information tend to be i n agreement with the above f i n d i n g s . Lindsey (1950) and Crossman (1957) f u r t h e r observed a h o r i z o n t a l s i z e s t r a t i f i c a t i o n of Redside Shiner i n e a r l y J u l y immediately a f t e r the newly hatched out f r y become abundant i n shore regions. Crossman also mentioned that i n mid July, Redside Shiner f r y move offshore making the species l e s s abundant i n the shore region but they return to shore i n schools by the end of the f i r s t week of August. Seine hauls i n the present case showed a s i m i l a r i t y i n the movement of newly hatched f r y of Redside Shiner. A v e r t i c a l s t r a t i f i c a t i o n i n s i z e groups of the Redside Shiners was observed by Lindsey (1953). He mentioned that d i f f e r e n t s i z e groups of f i s h i n h a b i t d i f f e r e n t depth zones, smaller f i s h occupying shallower water. In the present study, no such phenomena are detectable from the daylight samples i n any period of summer. But the samples obtained a f t e r n i g h t f a l l i n a l l depths i n e a r l y summer and those from surface and midwater i n mid and l a t e summer show si z e s t r a t i f i c a t i o n . No general conclusion can, however, be drawn from the present study, because of the v a r i a b l e and small sample s i z e obtained. L a r k i n and Smith (1953) pointed out that Redside Shiner f r y show a tendency of staying i n the inshore areas during daylight while the adults remain i n the l i t t o r a l zone i n mid summer. Results of seine hauls and g i l l nettings agree i n general with the above observation. Ferguson (1949) observed that Redside Shiners p r e f e r t o Live i n the epilimnion. This observation was apparently based on the catches made at night with g i l l nets. S i t u a t i o n at night i n the present case was found s i m i l a r but during daylight, f i s h appeared to keep away from the epilimnion. Northern Squawfish Results are presented i n Table XVII (a-d) and Figure L l . In e a r l y summer, 56 during d i f f e r e n t periods of day, Squawfish d i s p l a y a preference to remain on the bottom i n the l i t t o r a l zone, but with the progress of summer, they appear i n deeper water. During the daylight hours, i n early summer the tendency t o stay close t o shore i s pronounced. In mid and l a t e summer, a l l the daylight samplings i n d i -cate a spreading i n the depth d i s t r i b u t i o n when f i s h appeared i n a l l the samples of 40 f t . depth zone. During evening, i n early summer, f i s h tend to invade very shallow shore areas as w e l l as the surface and mid water. In mid summer, the trend of e a r l y summer i s maintained, but i n l a t e summer i n the evening, more f i s h appear i n the bottom around the 20 and 40 f t . contour l i n e s . In l a t e summer, no f i s h seem to invade the surface or midwater i n the evening. At night, f i s h tend to leave d i f f e r e n t l e v e l s of water (surface and mid-water) invaded i n the evening and return t o the bottom i n the l i t t o r a l zone. In mid summer at night, though more f i s h appear on the l i t t o r a l zone, some of them appear to stay on i n the surface and midwater. In l a t e summer, f i s h tend to return to deeper bottom waters rather than to the l i t t o r a l zone. The tendency of remaining spread i n surface and midwater, detected i n mid summer, i s also maintained. A l l through the summer, a general trend of staying close t o the bottom i s noticeable,during the daylight hours. In the evening, f i s h tend t o get spread v e r t i c a l l y . At night again, they appear to come back close to the bottom. The f i s h sampled do not show any s i g n i f i c a n t d i r e c t i o n o f movement away from or toward the shore i n any period of summer. But the sample from the net set made perpendicular to the northwest shore i n d i c a t e s that the species moves p a r a l l e l t o shore at night. In t h i s set, 39 Squawfish appeared of which 29 are found headed north. 57 SQUAWFISH F i g . 11. Occurrence of Northern Squawfish i n g i l l net sets i n stations IV-VI i n d i f f e r e n t periods of summer. Area of c i r c l e represents t o t a l number of f i s h . TABLE XVII (a). Number of Squawfish obtained i n net sets ( V e r t i c a l and Lateral) i n the stations along E a r l y Summer - Northwest shore, Nicola Lake Date 1958 Depth and p o s i t i o n t o f net set Period of day Tot a l No. of f i s h No. of movin " to shore f i s h g o f f shore Loose f i s h v Conclusion (Including X 2 value) No. of i n top ha l f o f net, f i s h i n bott- , om h a l f o f net Conclusion (inc l u d i n g X 2 value) 20 J u l y 17-18" 23 J u l y 10» Bottom ti II II II Daylight Evening Night 2 3 13 1 2 5 1 0 8 0 1 0 X 2 - .68 1 2 3 1 1 10 X 2 = 3.76 20 J u l y 17-18 " 23 J u l y 20 1 Bottom ii II n n Daylight Evening Night 6 1 5 1 1 1 5 0 4 0 0 0 X 2 = 2.66 X 2 - 1.8 1 0 0 5 1 5 X^ =2.66 20 J u l y 17-18 " 23 J u l y 40' Bottom II it II II Daylight) Evening ) Night ) 0 0 0 • 0 0 0 20 J u l y 24-25 " 26 J u l y Surface it II Daylight Evening Night 0 5 0 0 3 0 0 2 0 0 0 0 0 2 0 0 3 0 28 J u l y 24-25 " 26 J u l y Suspended II it Daylight Evening Night 0 3 0 0 1 0 0 2 0 0 0 0 0 2 0 0 1 0 28 J u l y 24-25 " 26 J u l y 40' Bottom tt it it tt Daylight) Evening ) Night ) 0 0 0 0 0 0 Note - (1) Chi-square i s not cal c u l a t e d where sample s i z e i s small and no conclusion i s noted. TABLE XVII (b)« Number of Squawfish -: obtained i n net sets ( v e r t i c a l and l a t e r a l ) i n the stations along Mid Summer Northwest shore, Nicola Lake Depth and Total No. of f i s h Conclusions No. of f i s h Conclusions Date p o s i t i o n Period of No. o f moving Loose (Including i n top i n b o t t - (Including 1958 of net day- f i s h to o f f f i s h X 2 value) h a l f om h a l f X 2 value) set shore shore of net of net 1 Aug. 10' Bottom Daylight 2 1 1 0 0 2 6-7 " tt it Evening 8 1 7 0 3 5 4 Aug. ti u Night 12 4 8 0 X 2 " = 2. 3 9 X 2 " 3.0 1 Aug. 20« Bottom Daylight 1 0 1 0 0 1 6-7 » II II Evening 2 1 1 0 2 0 4 Aug. tt II Night 4 2 2 0 3 1 1 Aug. 40' Bottom Daylight 1 0 1 0 1 0 6-7 " II II Evening 1 1 0 0 1 0 4 Aug. II II Night 0 0 0 0 0 0 15 Aug. Surface Daylight 0 0 0 0 0 0 16-17" it Evening 2 1 1 0 2 0 16 Aug. it Night 7 4 3 0 2 5 15-Aug. Suspended Daylight 0 0 0 0 0 0 16-17" ti Evening 0 0 0 0 0 0 16 Aug. it Night 1 1 0 0 1 0 15 Aug. 40« Bottom Daylight 0 0 0 0 0 0 16-17" ti II Evening 0 0 0 0 0 0 16 Aug. it II Night 1 0 1 0 1 0 Note - v } Chi-square i s not cal c u l a t e d where sample i s small and no conclusion i s noted. TABLE XVII ( c ) . Number of Squawfish .. •: obtained i n net sets ( v e r t i c a l and l a t e r a l ) i n the stati o n s along Late Summer Northwest shore, N i c o l a Lake. Depth and Tot a l No. of f i s h Conclusions No. of f i s h Conclusions Date p o s i t i o n Period of No. of moving Loose (Including i n top i n b o t t - (Including of net day- f i s h to o f f f i s h h a l f ' om h a l f X 2 value set shore shore X 2 value) of net o f net 29 Aug. 10» Bottom Daylight 1 0 0 1 6 26-27" 11 11 Evening 7 3 4 0 1 X^ * 3 . 4 28 Aug. 11 11 Night 1 1 0 0 0 1 2 9 Aug. 2 0 1 Bottom Daylight 1 1 0 0 0 1 2 6 - 2 7 * 11 11 Evening 1 0 5 3 2 4 4 28 Aug. 11 11 Night 1 0 1 0 0 1 29 Aug. 40« Bottom Daylight 1 1 0 0 0 1 2 6 - 2 7 " 11 11 Evening 1 0 5 4 1 1 8 2 8 Aug. 11 ti Night 3 1 2 0 2 1 3 1 Aug. Surface Daylight 0 0 0 0 0 0 2 - 3 Sept Evening 0 0 0 0 0 0 2 Sept. it Night 2 0 2 0 2 0 3 1 Aug. Suspended Daylight 0 0 0 0 0 0 2 - 3 Sept » Evening 0 0 0 0 0 0 2 Sept. tt Night 4 2 2 0 1 3 3 1 Aug. 4 0 ' Bottom Daylight 1 0 0 1 1 0 2 - 3 Sept Evening 1 1 0 0 1 0 2 Sept. it it Night 0 0 0 0 0 0 Note: Chi-square i s not ca l c u l a t e d where sample s i z e i s small and no conclusion i s noted. TABLE XVII (d). Number of Squawfish obtained i n net sets made i n d i f f e r e n t parts of Nicola Lake i n 1958. Stations Date Time (hours) t T o t a l f i s h D irect move to shore i o n of ment o f f shore Loose f i s h Remarks Early-Summer \NE End ( i n front of Moore C r . i n l e t ) ti II it n 30 Apr 1 May 22.00-10.15 8 Di r e c t i o n not noted. Two nets set together. 10-11 June 19.30-12.25 35 D i r e c t i o n not noted. One net set. 28-29 J u l y 21 .30-08.30 18 8 8 2 Two nets set together. SW End (close to Nicola R. out l e t ) 10-11 June 16 .15-09.25 9 Di r e c t i o n not noted. 80 f t . Sta t i o n Bottom set 11-12 June 22.00-09.00 0 No f i s h . 80 f t . Station Surface set 11-12 June 22.00-09.00 1 D i r e c t i o n not noted. B. Mid Summer NE End ( i n front of Moore C r . i n l e t ) II II 4-5 Aug. 21.00-08.30 24 10 11 3 Two nets set together 11-12 Aug. 20.45-08.00 16 10 5 1 Two nets set together SW End (close to Nicola R. out l e t ) 9-10 Aug. 15.00-11.30 9 7 1 1 SW End(in front of Nicola R. ou t l e t ) 9-10 Aug. 15.45-11.00 28 15 8 5 -80 f t . Station Bottom set 29-30 J u l y 20 .30-07.00 0 80 f t . Station Surface set 29-30 J u l y 21.00-07.30 0 C. Late Summer NE End(in f r o n t of Moore Cr. i n l e t ) II it 18-19 Aug. 20.00-08.00 46 15 24 7 25-26 Aug. 20 .30-08.30 6 1 5 0 SW End (close to Nicola R. outlet) 5-6 Sept. 16.45-09.45 19 13 5 1 80 f t . Station Bottom set 3-4 Sept. 19.45-10 .30 0 80 f t . Station 3-4 Sept. 20.10-10.40 0 62 Vertical distribution of Squawfish i n summer appears to be influenced by the position of the thermocline. They did not appear below the thermocline during any period of the summer. Some f i s h appeared within the thermocline once i n early and again i n late summer. Literature on Squawfish Cartwright (1956) mentioned that i n summer months Squawfish inhabit the l i t t o r a l zone. In his sampling effort, Cartwright captured more than 90% of Squawfish from above the 30. f t . contour line of the lake. In Cultus Lake, during the months of Ap r i l to early July, Squaxtffish appear i n larger numbers i n net sets made close to shore where 90% of the total catch come from sets made within the 3° f t . contour line (Ricker, 1941] Foerster and Ricker, 1941). This greater abundance of Squawfish i n shallow water i n Cultus Lake continues u n t i l mid September. Results of the present study are i n agreement with the findings both i n Shumway and Cultus Lake, except for the tendency of spreading into the deeper water i n late August. This exception may be induced by feeding as i s seen for f i s h i n Skaha Lake (Ferguson, 1949). In Okanagan Lake, smaller f i s h of the size range of 6-3" were consist-ently found i n the shore region, while larger f i s h appeared to dominate the region of the "drop off"(Cartwright, 1956). No such size s t r a t i f i c a t i o n of Squawfish i s detectable i n the present case. In early summer, the average size of f i s h near shore was larger than those offshore, particularly during daylight and evening. In mid summer, at night only, size s t r a t i f i c a t i o n similar to that i n Okanagan Lake was seen. Variation i n the size composition of f i s h i n different periods of the day i s , however, noticeable i n mid summer. In the daylight hours, average size of the f i s h seemed to be less than that of evening and night. In late summer, during the daylight hours smaller f i s h appeared i n areas close to shore while i n offshore waters, only larger f i s h 63 were seen. But with n i g h t f a l l , l a r g e r sized, f i s h invade the shore region r e -pl a c i n g the smaller f i s h seen i n t h i s zone during day. Average s i z e of f i s h sampled i n surface as w e l l as midwater was c o n s i s t -e n t l y found greater than those on the bottom. According to Ricker (1941), Squaw-f i s h p r e f e r to feed upon Redside Shiners i n summer and the appearance of l a r g e r Squawfish i n surface and midwater may be ascribed to t h e i r feeding a c t i v i t y . Carp Tables VIII, XVIII and XXVIII summarize the catch of Garp. Fry and f i n g e r l i n g s remained confined to the south and southwest region . of the lake near shore. The area extends from the Lagoon near Quilchena up to the southwest shallow basin. Carps appear to p r e f e r areas with mud bottom covered with vegetation. F i n g e r l i n g s were taken i n g i l l nets i n the southwest basin only a f t e r the appearance of vegetation i n that region. Only one adult Carp appeared i n the g i l l net sets i n the deeper main body of the l a k e . From t h i s sampling, no general conclusion on the movement and d i s t r i b u t i o n of Carp i s p o s s i b l e . L i t e r a t u r e on Carp Richardson (1913) observed that Carp f i n g e r l i n g s p r e f e r areas with mud bottom with vegetation. Richardson suggested that f i n g e r l i n g s abound i n weed covered areas, not only t o feed upon the vegetation but a l s o to take smaller organisms that inhabit the weedy zone. He observed that i n the Ceratophyllum zone i n the west shore of I l l i n o i s River, f i n g e r l i n g s feed upon H y a l e l l a  Knickerbocker! l i v i n g on the vegetation. According to Cahn (1929), Carp feed upon aquatic vegetation so i n t e n s i -v e l y that they change the ecology of t h e i r habitat by completely e r a d i c a t i n g p l a n t s . TABLE 2VIII. Number of Carp obtained from the net sets i n the stati o n s along the northwest shore of Nicpla Lake during the summer, 1958. Date Depth and p o s i t i o n of net Period of day T o t a l No. o f f i s h .No. mov to shore of f i s h i n g o f f shore Loose f i s h Conclusion on d i r e c t -i o n of mo-vement of f i s h No. o i top h a l f of net f f i s h n bottom h a l f of net Conclusions on p o s i t i o n held by f i s h Remarks 28 Aug. 20 f t . bottom night 1 1 0 0 0 1 Late summer Note: No Carp was caught i n any other net sets i n these stat i o n s during the whole period of summer. 65 Cady (1943) observed that Garp have a wide range of depth d i s t r i b u t i o n . In N o r r i s r e s e r v o i r , Carp were taken from the upper 60 f t . of water but occas-i o n a l l y they were netted from depths of 85 and 95 f t . as w e l l . Cady (1943) concluded that t h i s species tends to remain d i s t r i b u t e d evenly from surface to a depth of 50 f t . during the period from the middle of March t o l a t e October. Haslbauer (1945) suggested that Carp remain associated with the bottom but o c c a s i o n a l l y 'jump1 over deep water f a r from shore. According to Pearse (1921), Carp do not go below the 5 meter (18 f t . ) depth zone. From the above f i n d i n g s , i t appears that Carp probably have d i f f e r e n t ranges o f depth d i s t r i b u t i o n i n d i f f e r e n t water systems. In the case of Perch, Birge and Juday (1941) reported s i m i l a r d i f f e r e n c e i n depth d i s t r i b u t i o n . The experimental work of P i t t , et a l (1950) showed that Carp have a f i n a l temperature preferendum of 32°C (89.6°F). Richardson (1913) reported a temperature tolerance of 92°F by Carp finger-lings. In the context of the above f i n d i n g s , i t can be assumed that i n lakes, d i s t r i b u t i o n of the species would remain confined to the epilimnion. Longnose Dace Longnose Dace have not been p r e v i o u s l y recorded from N i c o l a Lake. Seine hauls made i n shores close t o Quilchena Creek show that t h i s f i s h l i v e i n shallow water along shore. In a d d i t i o n , i t also was seen i n the trap i n the Moore Creek i n l e t several times during the summer. Seine hauls i n Nicola River o u t l e t at a distance of about eight miles from the lake show an abund-ance of t h i s species i n the r i v e r . L i t e r a t u r e on Longnose Dace This species i s known to l i v e i n shallow shore areas of lakes and i n 66 c o o l streams ( C a r l and Clemens, 1953). I t i s known to have a preference f o r i n s e c t larvae as food. In addi-t i o n , i t a l s o feeds upon Copepods, Nematodes, Algae and fragments of higher plants (Johannes, 1957). Since mud bottoms along shore support more i n s e c t larvae and plants (Pearse,192l), the presence of Longnose Dace can be asso-c i a t e d with i t s food and feeding habits. Chiselmouth Data on Chiselmouth are presented i n Table VIII. This i s also a new record from Nicola Lake and the Thompson River drainage system to which the lake i s connected. I t was found i n the shallow southwest basin of the lake only i n a l l parts of summer. In e a r l y summer, only one f i s h appeared i n the net set i n s t a t i o n I I I but i n mid and l a t e summer, more f i s h were sampled. Analysis of stomach contents of the f i s h sampled re v e a l that i t feeds c h i e f l y on fragments of Potamogeton and Ifyripphyllum sp. But these plants are a v a i l a b l e i n abundance i n the southwest basin during the summer. D i s t r i b u t i o n of Chiselmouth may be ascribed to t h e i r food and feeding habits. Seine hauls i n the Nicola River o u t l e t at distances of about 1 mile, 8 miles and 12 miles away from the lake revealed the presence of young C h i -selmouth i n good numbers i n the r i v e r . No young Chiselmouth were taken i n seine hauls made i n the lake. B r i d g e l i p Sucker P a r t i c u l a r s of the sampling of B r i d g e l i p Suckers appear i n Tables VI and VIII. This i s a new record from t h i s l o c a l i t y . This species was sampled i n d i f f e r e n t regions of the lake i n shallow water. In e a r l y summer, l a r g e r sized specimens were found but i n mid and l a t e 6_7 summer, only small si z e d specimen were found i n the net sets* Young-of-the-year of t h i s f i s h were seen i n large numbers i n N i c o l a • Rive r o u t l e t . The sample s i z e s are too small t o make any conclusion on the d i s t r i -b ution and movement of t h i s f i s h . According t o Lindsey (personal communication) B r i d g e l i p Suckers are pr i m a r i l y stream dwelling f i s h with the habit of scraping rocks f o r c o l l e c t i o n of food. Largescale Sucker Results are summarized i n Table XIX (a-c) and Figure 12. During the daylight hours, t h i s f i s h apparently stays close to the ground i n d i f f e r e n t periods of summer. In e a r l y summer i t tends t o avoid areas close to shore i n daylight, but with the progress of summer, spreading on the bottom occurs. No f i s h on the bottom around 20 f t . depth zone were, however seen i n l a t e summer. I t does not d i s p l a y any tendency of spreading i n t o the mid or surface water at n i g h t f a l l during any part of the summer. This i s contrary t o what i s observed i n Peamouth Chub, Redside Shiner and Squawfish. In e a r l y summer during evening, f i s h are seen on the bottom i n 10 f t . depth zone but i n mid summer, f o r the same period of day, these are found i n the bottom away from shore ( F i g . 12). In l a t e summer again, the d i s t r i b u t i o n on the bottom appears somewhat d i f f e r e n t , when samples of the f i s h appear i n the net sets on the bottom at 10 and 40 f t . At night, f i s h are seen on the bottom i n a l l depths i n e a r l y summer. During mid summer, f i s h appear t o remain congregated on the bottom close t o shore at night though the tendency of remaining spread i n depths of 40 f t . s t i l l p e r s i s t s . In l a t e summer, at night, they tend to avoid the shallow water near shore. 68 L A R G E S C A L E S U C K E R F i g . 12. Occurrence of Largescale Sucker i n g i l l net sets i n sta t i o n s IV-VI i n d i f f e r e n t periods of summer. Area of c i r c l e represents t o t a l number of f i s h . TABLE XIX (a). Number of Largescale Sucker obtained in net sets (vertical and lateral) in the stations along Early Summer Northwest shore, Nicola Lake. Depth and Total No. of fish Conclusion sNo. of fish Conclusion Date position Period of No. of moving Loose (including in top in bott- (including 1958 of net day fish to off fish X 2 value) half om half set shore shore of net of net X^ value) 20 July 10* Bottom Daylight 6 0 0 0 0 0 17-18 " ti I I Evening 3 2 1 0 2 1 23 July a • " Night 1 0 0 1 0 0 20 July 20' Bottom Daylight 1 . 1 0 0 0 1 17-18 " it I I Evening 0 0 0 0 0 0 23 July it I I Night 2 1 1 0 0 2 20 July 40' Bottom Daylight 0 0 0 0 0 0 17|l8 « I I . " Evening 0 0 0 0 0 0 23 July I I it Night 1 0 1 0 1 0 28 July Surface Daylight 0 0 0 0 0 0 24-25 " I I Evening 0 0 0 0 0 0 26 July it Night 0 0 0 0 0 0 28 July Suspended Daylight) 0 0 0 0 0 24-25 r ' ti Evening ) 0 26 July I I Night ) 28 July 40« Bottom Daylight 2 1 1 0 2 0 24-25 " I I it Evening 0 0 0 0 0 0 26 July ii I I Night 0. 0 0 0 0 0 Note - Chi-square is not calculated where sample size is small and no conclusion i s noted. TABLE X I X (b). Number of Largescale Sucker obtained i n net sets (vertical and lateral) i n the stations along Mid. Slimmer northwest shore, Nicola Lake. Date 1958 Depth and position of net set Period of day-Total No.of fi s h No. of movi to shore f i s h off shore Loose f i s h .Conclusion (including X 2 value) No. c i n top half of net f f i s h i n bott-om half of net Conclusion (including X 2 value) 1 Aug. 6-7 " 4 Aug. 10» Bottom it it it tt Daylight Evening Night 3 0 7 0 0 2 2 0 3 1 0 2 ' 0 0 1 3 0 5 1 Aug. 6-7 " 4 Aug. 20' Bottoa it tt it it Daylight Evening Night 1 5 0 1 3 0 0 2 0 0 0 0 0 1 0 1 4 0 Ur* 2 Aug. 40' Bottom n II it II Daylight Evening Night 0 1 3 0 0 1 0 1 2 0 0 0 0 0 0 0 1 3 15 Aug. 16-17 " 16 Aug. Surface II it Daylight) Evening ) Night ) 0 0 0 0 0 0 15 Aug. 16-ir" 16 Aug. Suspended it Daylight) Evening ) Night ) 0 0 0 0 0 0 15 Aug. 16-17" 16 Aug. 40' Botton it II II it Daylight -Evening Night 2 1 0 1 1 0 1 0 0 0 0 0 0 1 0 2 0. 0 Note - Chi-square i s not calculated where sample size i s small and no conclusion i s noted. TABLE XIX ( c ) . Number of Largescale Sucker obtained i n net sets ( v e r t i c a l and l a t e r a l ) i n the stations along Late Summer - northwest shore, Nicola Lake. - Depth and Tota l «No. of f i s h (Conclusion •No. of f i s h Conclusion Date p o s i t i o n Period of No. of moving Loose (incl u d i n g i n top i n bott- ( i n c l u d i n g 1958 of net day- f i s h to o f f f i s h h a l f om h a l f set shore shore If- value) of net of net X 2 value) 29 Aug. 10" Bottom Daylight 1 0 1 0 0 1 26-27 " ti II Evening 3 1 2 0 1 2 28 Aug. II II Night 0 0 0 0 0 0 29 Aug. 20« Bottom Daylight 0 0 0 0 0 0 26-27 " II . II Evening 0 0 0 0 0 0 28 Aug. II II Night 2 1 0 1 0 2 29 Aug. 40« Bottom Daylight 1 1 0 0 0 1 26-27 11 it II Evening 2 0 2 0 1 1 28 Aug. II II Night 1 1 0 0 1 0 31 Aug. Surface Daylight) 0 0 2-3 Sept. it Evening ) 0 0 0 0 2 Sept. II Night ) 31 Aug. Suspended Baylight) 0 0 0 0 2-3 Sept, II Evening ) 0 0 2 Sept. it Night ) 31 Aug. 40' Bottom Daylight 3 1 2 0 2 1 2-3 Sept. it II Evening 0 0 0 0 0 0 2 Sept. II it Night 2 1 1 0 1 1 Note - Chi-square i s not cal c u l a t e d where sample s i z e i s small and no conclusion i s noted. 72 Sampling on the bottom at s t a t i o n I I i n d i c a t e s that the Largescale Sucker has a depth d i s t r i b u t i o n up to 80 f t . i n e a r l y summer only (June). Movement of t h i s f i s h i n the v e r t i c a l plane does not seem to be i n h i -b i t e d by thermal s t r a t i f i c a t i o n . In e a r l y summer, i t was found on e i t h e r side of the thermocline. S i m i l a r l y i n mid summer (4 August) i t was sampled i n both the epilimnion and hypolimnion. Largescale Suckers remain d i s t r i b u t e d i n a l l the major regions of the lake during the summer, but more of them appear to stay i n the deeper p o r t i o n . The samples from stations IV-VI do not show any s i g n i f i c a n t d i r e c t i o n of movement offshore or inshore. On the other hand, sample i n the net set perpendicular to northwest shore i n d i c a t e d that Largescale Sucker move p a r a l l e l to shore at night and remain on the bottom up to a depth of about 50 f t . from shore. In contrast to adult f i s h , young ones seemed to be influenced by l i g h t i n t h e i r movement towards or away from the shore. Seine hauls i n d i c a t e d that during the daylight hours, f r y of Largescale Suckers remain very c l o s e to the shore, but at night they move away and i n t h e i r place bigger young f i s h come to the shore. L i t e r a t u r e on Largescale Sucker Ferguson (1949) mentioned Largescale Suckers as bottom dwelling f i s h . Clemens (1939) also noted them as bottom dwellers i n Okanagan Lake. Spoor and Schloemer (1938) observed that the White Sucker, Catostomus  commersoni i n Muskellunge Lake move inshore at night and offshore i n the morning. In the case of Largescale Sucker, a s i m i l a r trend can be c l e a r l y detected i f only the seine haul c o l l e c t i o n s are analysed. Burbot Burbot 73 Summary of sampling r e s u l t s i s presented i n Tables VI, VII, IX, and XX from which i t would be apparent that t h i s f i s h do not show any consistency i n t h e i r appearance i n areas sampled. In daylight, i t was seen on the bottom i n 10 f t . during e a r l y summer but i n mid and l a t e summer, no f i s h were seen i n t h i s region. In Late summer, f i s h were found on the bottom i n 40 f t . depth during the daylight hours. In the evening, f i s h appeared on the bottom i n 20 f t . depth zone i n ear l y summer while i n mid summer, f i s h were seen on the bottom at s t a t i o n VI. In l a t e summer only, the samples i n d i c a t e a complete spreading of Burbot on the bottom from shore to deeper water up to 40 f t . At night, none of the sampling e f f o r t s i n e a r l y and l a t e summer caught any f i s h . In mid summer only, f i s h were seen on the bottom i n 40 f t . depth zone. Thermal s t r a t i f i c a t i o n does not appear to l i m i t the v e r t i c a l migration of t h i s species. They were found moving i n t o shallow water very close to shore while following schools of Kokanee. In mid summer when the thermocline was at a depth of 20 f t . Burbot were seen i n 10 as we l l as 40 f t . depth zone. Burbot appeared i n the trap set i n the mouth of Moore Creek i n l e t quite f r e -quently during the summer. They were found i n increased number i n front of Moore Creek i n l e t i n l a t e summer, when spawning run of Kokanee had commenced. L i t e r a t u r e on Burbot According to Ferguson (1949) and Godfrey (1955), Burbots i n h a b i t the deeper bottom zones of lake. Absence of Burbot i n any net set i n the shallow southwest basin and t h e i r appearance i n the net set i n 80 f t . bottom i n ea r l y summer are i n agreement with the above obsrvation* TABLE XX. Number of Burbot obtained i n net sets i n the s t a t i o n slong northwest shore of Nicola Lake During summer, 1958. Date 1958 jDepth and p o s i t i o n of net set Period of day T o t a l No. of f i s h No. c mov to shore >f f i s h ring o f f shore Loose f i s h Conclusion (inc l u d i n g X 2 value) No. o i n top h a l f o f net f f i s h i n bott-om h a l f of net Conclusion (including X 2 value) Remarks 28 J u l y 40' Bottom Daylight 1 1 0 0 0 1 E a r l y summer. f i s h i n other sets 17-18 20' Bottom Evening 1 0 1 0 0 1 n II 6-7 Aug. 4 Aug. 16 " 40' Bottom 10' " 40' » Evening Night Night 2 1 1 1 1 1 1 0 0 0 0 0 0 0 1 2 1 0 Mid Summer it tt tt it No.fish i n any other sets. 31 Aug. 26-27" 26-27" 2-3 Sept 40' Bottom 10' " 20' .40'- » Daylight Evening Evening Evening 1 1 1 2 1 0 1 1 0 1 0 1 0 0 0 0 0 0 1 0 1 1 0 2 Late Summer it it it II ti tt No f i s h i n any other sets. 75 Clemens (1950) suggested that l a r g e r Burbot p r e f e r to eat large s i z e d food. Ferguson (1949) commented that Burbot have a preference f o r feeding upon Kokanee. Godfrey (1955) pointed out that Burbots appear i n very shallow water i n the Skeena R i v e r system when the spring migration of Salmon smolts commences. He associated t h i s with the preference of Burbot f o r Salmon smolts as food. P r i c k l y Sculpin Results are presented i n Tables VI, VII, VIII, IX and XXI. According to Ricker (1941), P r i c k l y Sculpin i s a bottom dwelling species and i n h a b i t s p r i n c i p a l l y the regions close t o shore. Results i n the present study agree i n general with Ricker. Appearance of stray Sculpins on the bottom at 80 f t . and 40 f t . i n d i f f e r e n t periods of the summer i s probably an i n d i c a -t i o n that adult and l a r g e P r i c k l y Sculpins tend to explore deeper p a r t s of the lake. But since the samples are extremely poor, t h i s phenomenon cannot be considered as s i g n i f i c a n t . During the daylight hours, young f i s h are seen to move i n small schools a l l along the shore i n c l u d i n g the rocky west shore. In north shore, seine haul samplings showed that with n i g h t f a l l , young and small f i s h seen i n the daylight move offshore and i n t h e i r place, l a r g e r f i s h appear i n 2-3 f t . water on the shore. P r i c k l y Sculpins are known to l i v e i n the epilimnion only (Ferguson, 1949) but the appearance of s i n g l e i n d i v i d u a l s on e i t h e r side of the thermocline i n the present study shows that thermal s t r a t i f i c a t i o n does not act as a strong b a r r i e r f o r the species. Kokanee Data on Kokanee are presented i n Table XXII (a-c) and Figure 13. Only •TABLE X X I . Number of Sculpins obtained i n net sets i n the stations along the northwest shore of Nicola Lake during the summer, 1958. Date 1958 Depth and p o s i t i o n of net set Period of day Total No. of f i s h No. o mov to shore f f i s h ing o f f shore Loose f i s h Conclusion (including X 2 value) No. of i n top h a l f of net f i s h i n bott-om h a l f of net Conclusioii (including X 2 value) It ; Remarks 17-18 J u l y II ii 10 1 Bottom 20' Bottom Evening 1! 1 1 1 0 0 1 0 0 0 1 1 0 E a r l y Summer No ; f i s h i n any other sets* 16-17 Aug. 40' Bottom Evening 1 0 0 1 0 1 Mid Summer no f i s h i n any other set. 26-27 Aug. 31 Aug. 10' Bottom 20'. « 40' '» Evening Evening Daylight 1 3 1 0 2 0 1 1 0 0 0 1 0 0 0 1 3 1 Late Summer tt II II ti No f i s h i n any other set. 77 large Kokanee were taken by g i l l n e t t i n g and the discu s s i o n r e l a t e s to only f i s h i n t h e i r ultimate year. A l l through the summer, Kokanee tend to stay on the bottom i n deeper regions of the lake during the hours of daylight. In the evening, movement of f i s h towards the shore and upward in t o mid-water was noticeable i n ea r l y summer. In mid summer, movement towards shallow-er water was i n d i c a t e d by the appearance of f i s h i n net sets on 10 f t . bottom zone i n the evening. In l a t e summer, Kokanee tended to get d i s t r i b u t e d i n surface, midwater and i n the bottom regions along shore. This departure from t h e i r normal tendency o f staying i n deeper water was probably spurred by the sexual maturity of the f i s h . At night i n e a r l y summer, f i s h stayed i n the deeper bottom zone, and the same trend p e r s i s t e d i n mid summer. But i n l a t e summer f i s h were seen i n the surface l e v e l as w e l l as i n midwater at night. This i s evide n t l y the r e s u l t of sexual ripening of f i s h . During t h i s period, schools of Kokanee were found near the Moore Creek i n l e t mouth even a f t e r dawn. L i t e r a t u r e on Kokanee Kokanee are known to l i v e i n deeper water i n the hypolimnion during summer. With the r i s e of temperature i n summer they go i n t o deeper water (C u r t i s and Fraser 1948). According to Ferguson (1949), i n Skaha Lake Koka-nee were sampled i n greatest numbers from 60 f t . of water, but they a l s o appeared i n depths up to 131 f t . In the present study, Kokanee i s the only species that was found to l i v e i n depths of 110 f t . i n the summer (Table XI). Further, i t was sampled from a depth of 80 f t . a l l through the season. Thus i t may be concluded that i t i s a deep water species. Clemens, et a l (1939) noted that Kokanee l i v e i n intermediate depths i n Okanagan Lake. 73 KOKANEE F i g . 13. Occurrence of Kokanee i n g i l l net sets i n stations IV-VI i n d i f f e r e n t periods of summer. Area of c i r c l e represents t o t a l number of f i s h . TABLE. XXII ( a ) . Number of Kokanee obtained, i n net sets i n the stations along northwest shore of Nicola Lake during E a r l y Summer. Depth and To t a l No. of f i s h Conclusion No. of f i s h Conclusion Date p o s i t i o n Period of No. of moving Loose (including i n top i n bott- ( i n c l u d i n g 1 9 5 8 of net day f i s h to o f f f i s h h a l f om h a l f set shore shore X 2 value) o f net of net X 2 value) 2 0 J u l y 1 0 ' Bottom Daylight 0 0 0 0 0 0 1 7-18 " ii ti Evening 0 0 0 0 0 0 2 3 J u l y ti it Night 0 0 0 0 0 0 2 0 J u l y 2 0» Bottom Daylight 0 0 0 0 0 0 1 7-18 » n it Evaning 1 1 0 0 1 0 2 3 J u l y it it Night 0 0 0 0 0 0 2 0 J u l y 4 0 ' Bottom Daylight 7 5 2 0 0 7 1 7-18 » tt II Evening 0 0 0 0 0 0 2 3 J u l y n it Night 4 3 1 0 2 2 28 J u l y Surface Daylight) 2 4 - 2 5 " it Evening ) 0 0 0 0 0 0 2 6 J u l y it Night ) 28 Ju l y Suspended Daylight 0 0 0 0 0 0 2 4 - 2 5 " it Evening 1 0 1 0 0 1 2 6 J u l y tt Night 0 0 0 0 0 0 28 J u l y 4 0« Bottom Daylight 4 1 2 1 2 2 2 4 - 2 5 " II it Evening 3 0 3 0 1 2 2 6 J u l y n it Night 2 0 1 1 0 2 Note - Chi-square i s not calculated where sample s i z e i s small and no conclusion i s noted. TABLE XXII(b). Number of Kokanee obtained i n net sets i n the statio n s along northwest shore of Nicola Lake . - during Mid Summer. Depth and To t a l No. of f i s h tConclusion No. of f i s h Conclusion' Date p o s i t i o n Period of No.of moving Loose (including i n top i n bott- (including 1958 of net day- f i s h to o f f f i s h X 2 value) h a l f om h a l f X 2 value) set shore shore of net of net 1 Aug. 10 ' Bottom Daylight 0 0 0 0 0 0 6-7 " II . ti Evening 1 1 0 0 0 1 4 Aug. II ii Night 0 0 0 0 0 0 1 Aug. 20' Bottom Daylight) 0 0 6-7 " II it Evening ) 0 0 0 0 4 Aug. it II Night ) 1 Aug. 40' Bottom Daylight 6 3 3 0 2 4 6-7 " ii ti Evening 4 2 2 0 2 2 4 Aug. II it Night 2 1 1 0 1 1 15 Aug. Surface Daylight) 0 0 0 0 1 6 - 1 7 " it Evening ) 0 0 16 Aug. n Night ) 1 5 Aug. Suspended Daylight) 16-17" ti Evening ) 0 0 0 0 0 0 16 Aug. it Night ) 1 5 Aug. 4 0 '-Bottom Daylight 1 1 0 0 0 1 16-17" n it Evening 1 1 0 0 1 0 16 Aug. II it Night 1 0 1 0 0 1 Note - Chi-square i s not cal c u l a t e d where sample s i z e i s small and no conclusion noted. TABLE XXII(c). Number of Kokanee obtained i n net sets i n the stations along northwest shore of Nicola Lake during Late Summer. Depth and To t a l No. of f i s h Conclusion No. of f i s h Conclusion Date p o s i t i o n Period of No. of moving Loose f l n c l u d i n g i n top i n bott- ( i n c l u d i n g 1958 of net day- f i s h to o f f f i s h X 2 value) h a l f om h a l f set shore shore of net of net ST value) 29 Aug. 10' Bottom Daylight 0 0 0 0 0 0 26-27" II n Evening 1 0 1 0 1 0 28 Aug. II ti . Night .0 0 0 0 0 0 29 Aug. 20' Bottom Daylight) 2 6 - 2 7 " tt it Evening ) 0 0 0 0 0 0 28 Aug. II it Might ) 29 Aug. 4 0 ' Bottom Daylight 4 3 1 0 2 2 26-27* tt it Evening 0 0 0 0 0 0 28 Aug. II it Night 7 6 1 o • 1 6 31 Aug. Surface Daylight 0 0 0 0 0 0 2-3 Sept « Evening 2 0 2 0 1 1 2 Sept. II Night 2 0 2 0 2 0 31 Aug. Suspended Daylight 0 0 0 0 0 0 2-3 Sept " Evening 1 1 0 0 1 0 2 Sept. II Night 1 0 1 0 1 0 31 Aug. 40' Bottom Daylight 0 0 0 0 0 0 2-3 Sept . I I it Evening 10 2 8 0 3 7 2 Sept. II ii Night 1 1 0 0 l 0 ! Note - Chi-square i s not cal c u l a t e d where sample'size i s small and no conclusion i s noted. 82' Rainbow Trout Results are summarized i n Table XXIII (a-c). No Raibow Trout were seen i n the day l i g h t and evening i n 10 or 20 f t . depth zone i n any period of the season. At night, however, i t appeared i n 10 and 20 f t . depths on the bottom but t h i s was not consistent i n d i f f e r e n t periods of the summer. On the bottom i n the 40 f t . depth zone, i t was found i n a l l periods of day i n mid as we l l as l a t e summer. In the v e r t i c a l plane, no f i s h were seen i n the surface waters during the daylight hours a l l through the summer. In l a t e summer only, f i s h were seen i n the surface l e v e l at night. In midwater, f i s h appeared i n the daylight, evening and at night during the mid summer. In e a r l y summer, f i s h were seen i n midwater at night. The i r r e g u l a r appearance of Rainbow Trout i n d i f f e r e n t l e v e l s and depths of water shows that i t i s an open water species and remains d i s t r i b u t e d i n d i f f e r e n t depths. No f i s h were, however, sampled from depths of 80 f t . or more during any part of the summer. Observations i n the present case i n d i c a t e that thermal s t r a t i f i c a t i o n does not act as a b a r r i e r i n the v e r t i c a l movement of t h i s f i s h . The samples obtained also do not i n d i c a t e the existence of any o f f -shore or inshore d i r e c t i o n of movement i n Rainbow Trout during d i f f e r e n t periods of the day,-L i t e r a t u r e on Rainbow Trout Clemens (1939) described Rainbow Trout as an open water species. Findings of Ferguson (1949) i n Skaha Lake showed that Rainbow Trout l i v e i n d i f f e r e n t depths i n the open water during summer. TABLE X X I I I (a). Number of Rainbow Trout obtained i n net sets i n the stations along the northwest shore of Nicola Lake during E a r l y Summer. Date 1958 Depth and p o s i t i o n o f net set Period of day \Total No. of f i s h No. c mo\ to shore >f f i s h ring o f f shore Loose f i s h Conclusion (including X 2 value) No. c i n top half of net >f f i s h i n b o t t -om h a l f of net Conclusion (including X 2 value) 20 July 17-18" 23 July 10 ' Bottom II tt II 1! Daylight Evening Night 0 0 1 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 20 July 17-18 ?' 23 July 2 0 ' Bottom it II II it Daylight) Evening ) Night ) 0 0 0 0 0 0 20 July 17-18 Ti 23 July 4 0 ' Bottom it it it ti Daylight) Evening ) Night ) 0 0 0 0 0 0 28 July 24-25 " 26 July Surface ii II Daylight) Evening ) Night ) 0 0 0 0 0 0 28 July 24-25 " 26 J u l y Suspended n ti Daylight Evening Night 0 0 2 0 0 0 0 0 2 0 0 0 0 0 2 0 0 0 28 J u l y 24-25 " 26 July 4 0 ' Bottom it ti II it Daylight) Evening ) Night ) 0 0 0 0 0 0 XXIII (b). Number of Rainbow Trout obtained i n net sets i n the stati o n s along the northwest shore of N i c o l a Lake during Mid Summer. - Depth and T o t a l No. of f i s h Conclusion •No. of f i s h Conclusion Date p o s i t i o n Period of No. of moving Loose (i n c l u d i n g i n top i n b o t t - ( i n c l u d i n g 1958 of net day- F i s h to o f f f i s h X 2 value) h a l f om h a l f set shore shore of net of net X 2 value) 1 Aug. 10' Bottom Daylight 0 0 0 0 0 0 6-7 " it it Evening 0 0 0 0 0 0 4 Aug. II ti Night 3 2 1 0 2 1 1 Aug. 20' Bottom Daylight 0 0 0 0 0 0 6-7 11 II II Evening 0 0 0 0 0 0 4 Aug. II ti Night 2 2 0 0 1 1 1 Aug. 40' Bottom Daylight 0 0 0 0 0 0 6-7 " it it Evening 1 0 1 0 1 0 4 Aug. ii it Night 1 0 1 0 0 1 15 Aug. Surface Daylight 0 0 0 0 0 0 16-17" tt Evening 3 2 1 0 1 2 16 Aug. it Night 2 0 2 0 0 2 15 Aug. Suspended Daylight 1 1 0 0 1 0 16-17" II Evening 4 1 3 0 3 1 16 Aug. it Night 4 3 0 1 2 1 15 Aug. 40' Bottom Daylight 1 0 0 1 16-17" tt it Evening 0 0 0 0 0 0 16 Aug. it it Night 4 3 0 1 3 0 TABLE XXIII ( c ) . Number of Rainbow Trout obtained i n net sets i n the stations along the northwest shore of N icola Lake during Late Summer. Date 1958 (Depth and p o s i t i o n of net set Period of day T o t a l No. of f i s h No. of movin to shore f i s h o f f shore Loose f i s h Conclusion ( i n c l u d i n g X 2 value) •No. 0 .in top h a l f of net f f i s h i n b o t t -om h a l f o f net •Conclusion" ( i n c l u d i n g X 2 value) 29 Aug. 26-27" 2 8 Aug. 10' Bottom II 1! tt tt Daylight) Evening ) Night ) 0 0 0 0 0 0 2 9 Aug. 26-27" 2 8 Aug. 20' Bottom tt tt tt tt Daylight) Evening ) Night u 0 1 u 0 0 u 0 1 u 0 0 U 0 1 u 0 0 2 9 Aug. 26-27" 2 8 Aug. 40' Bottom tt 11 11 tt Daylight Evening Night 0 1 0 0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 31 Aug. 2-3 Sepi 2 Sept. Surface " ti Daylight Evening Night 0 0 2 0 0 2 0 0 0 0 0 0 0 0 1 0 0 1 31 Aug. 2-3 Sepi 2 Sept. Suspended 11 it Daylight) Evening ) Night ) 0 0 0 0 0 0 31 Aug. 2-3 Sepi 2 Sept. 40' Bottom , 1 1 11 it 11 Daylight Evening Night 2 0 0 2 0 0 0 0 0 0 0 0 0 0 0 2 0 0 86 D o l l y Varden Data on D o l l y Varden are presented i n Table XXIV. Information obtained are not adequate to give a c l e a r p i c t u r e of the d i s t r i b u t i o n of the species. In the whole summer, i t was sampled once, i n the daylight i n e a r l y summ-er and twice during l a t e summer - i n the daylight and at night. Every time, i t was found i n the nets set on the 40 f t . bottom. Ricker (1941) states that D o l l y Varden l i v e on the bottom. In Cultus Lake, t h i s species was captured i n g i l l nets set i n deeper waters only (Foerster and Ricker, 1941)* The present data appear s i m i l a r to the f i n d i n g s r e f e r r e d to above. Though a bottom dwelling species, i t never appeared i n net sets made on the bottom at 80 f t . or at 100 f t . This i n d i c a t e s that D o l l y Vardens do not probably frequent deep water i n the summer. In early summer, one D o l l y Varden was sampled i n the southwest basin. From t h i s s t r a y f i s h , i t i s d i f f i c u l t to i n f e r that i n summer D o l l y Vardens come i n t o shallow shore areas. Chinook Salmon P a r t i c u l a r s of Chinook -Salmon are presented i n Tables VI, V I I I and XXV. The adult Chinook Salmon appeared i n the nets set at night only. In net sets i n fr o n t of Moore Creek i n l e t , Chinook Salmon appeared i n e a r l y as well as l a t e summer. From the southwest end net set, i t was obtained i n mid and l a t e summer, while i n l a t e summer, only one f i s h was found on the northwest shore. A l l f i s h sampled were found sexually mature and the movements at night p a r t i c u l a r l y near the streams may be r e l a t e d to t h e i r reproductive a c t i v i t y . TABLE XXIV. Number of D o l l y Varden obtained i n net sets i n the stations along northwest shore of Nicola Lake during summer. Depth and Total , No. of f i s h Conclusion No. of f i s h Conclusion Bate p o s i t i o n 1 Period of No. of moving Loose (incl u d i n g i n top i n bott- (including Remarks 1958 of net day f i s h to o f f f i s h h a l f om h a l f X2 value) set shore shore X^ value) of net of net 28 July 4 0 ' Bottom Daylight 1 0 1 0 0 1 E a r l y Summer 29 Aug. 4 0 ' Bottom Daylight 1 1 0 0 0 1 Late Summer 28 " II ti Night 1 0 0 1 1 0 it ti Note: No other net sets i n these stations y i e l d e d any more D o l l y Varden, during the whole summer. TABLE XXV. Number of Chinook Salmon obtained i n the net sets i n the stations along northwest shore of Nicola Lake during Summer, 1958. Date 1958 'Depth and p o s i t i o n of net set Period of day-T o t a l No. of f i s h No. 0] mov: to shore f f i s h -ng o f f shore Loose f i s h Conclusion ( i n c l u d i n g X 2 value) No. oJ i n top h a l f of net f f i s h i n b o t t -om h a l f of net ^Conclusion (including X 2 value) 'Remarks 26-27 Aug. 10» Bottom Evening 1 1 0 0 0 1 Note: NoChiji'ook Salmon was caught i n any other net sets made i n these s t a t i o n s during the whole summer. 39 Young of Chinook Salmon also were found i n seine hauls made close t o the Moore Creek i n l e t and i n the Nicola River o u t l e t . Once during the whole perio d of summer, one small young Chinook Salmon was taken i n the net set i n s t a t i o n I I I . Presence of large number of young f i s h i n Nicola R i v e r o u t l e t seemed to ind i c a t e that the young f i s h commence t h e i r seaward journey during summer months. From Shuswap Lake, commencement of seaward journey of young Chinook Salmon i n J u l y was recorded by Clemens (1934). Mountain Whitefish Results are presented i n Table XXVI (a-c) and Figure 14. In the daylight hours of ea r l y summer, f i s h were found on the bottom i n deeper waters but i n mid summer, f i s h tended to remain spread a l l over the bottom from shore to the depth of 40 f t . In l a t e summer, on the other hand, no f i s h were seen on the bottom during d a y l i g h t hours. In the evening, f i s h were seen on the bottom at 40 f t . i n e a r l y summer but i n mid summer, f i s h appeared on the bottom near shore as w e l l as i n mid-water. In l a t e summer, f i s h appeared only on the bottom i n s t a t i o n .'IVf. (10 f t . ) . In the nets set at night, f i s h were seen i n 40 f t . bottom i n e a r l y summer but i n mid summer, f i s h appeared on the bottom both i n stati o n s IV and VI. In l a t e summer, no f i s h were seen i n the northwest region of the lake. The general disappearance of f i s h i n the northwest shore i n l a t e summer coincided with a r e l a t i v e l y l a r g e catch of the species i n s t a t i o n I I I . Exami-nation of gonads of these f i s h from s t a t i o n I I I revealed that they were sexu-a l l y r i p e . Their disappearance from the main body of the lake and congrega-t i o n i n front of Nicola River o u t l e t can be r e l a t e d to the spawning a c t i v i t y of the species i n the l a t e r part of summer. 90 MOUNTAIN WHITEFISH F i g . 14. Occurrence of Mountain Whitefish i n g i l l net sets i n stations IV-VI i n d i f f e r e n t periods of summer. Area of c i r c l e represents t o t a l number of f i s h . TABLE XXVI (a). Number of Mountain Whitefish obtained i n net sets ( v e r t i c a l and l a t e r a l ) i n stations along northwest shore of Nicola Lake during E a r l y Summer. Date 1958 Depth and p o s i t i o n of net set Period of day Total No.of f i s h No. of movii t o shore f i s h o f f shore 'Loose f i s h Conclusion ( i n c l u d i n d X 2 value) • No. i n top h a l f o f net of F i s h i n bott-om h a l f o f net Conclusion (including X 2 value) 20 J u l y 17-18 ti 23 J u l y 10' Bottom II . II II ti Daylight) Evening ) Night ) 0 0 0 0 0 0 20 J u l y 17-18 » 23 J u l y 20' Bottom it II II II Daylight) Evening ) Night ) 0 0 0 0 0 0 20 J u l y 17-18 " 23 J u l y 40' Bottom II , II II II Daylight Evening Night 2 0 2 0 0 0 2 0 1 0 0 1 0 0 1 2 0 1 28 Ju l y 24-25 11 26 J u l y Surface ti II Daylight) Evening ) Night ) 0 0 0 0 0 0 28 J u l y 24-25 " 26 J u l y Suspended it it Daylight) Evening ) Night ) 0 0 0 0 0 0 28 J u l y 24-25 " 26 July 40' Bottom II ti it II Daylight Evening Night 5 1 0 2 0 0 3 1 0 0 0 0 0 0 0 5 1 0 Note - Chi-square i s not calculated where sample s i z e i s small and no conclusion i s noted. TABLE XX.Y/I (b). Number of Mountain Whitefish obtained, i n net sets ( v e r t i c a l and l a t e r a l ) i n stations along northwest shore of Nicola Lake during Mid Summer. Date 1958 Depth and p o s i t i o n of net set Period of day-T o t a l No. of f i s h No. of moving to shore f i s h y ' O f f shore Loose f i s h Conclusion (i n c l u d i n g X 2 value) Jfo. i n top h a l f o f net of f i s h i n b o t t -om h a l f o f net ponclusion' (inc l u d i n g X 2 value) 1 Aug. 6-7 " 4 Aug. 10' Bottom II . it n II Daylight Evening Night 2 1 3 1 0 1 1 0 1 0 1 1 0 0 .0 2 1 3 1 Aug. 6-7 " 4 Aug. 20' Bottom it . I I II it Daylight Evening Night 2 0 0 0 0 0 2 0 0 0 0 0 1 0 0 1-0 0 1 Aug. 6-7 " ^ Aug. 40« Bottom II it it II Daylight) Evening ) Night ) 0 0 0 0 0 0 15 Aug. 16-17" 16 Aug. Surface II it Daylight) Evening ) Night ) 0 0 0 0 0 0 15 Aug. 16-17" 16'Aug. Suspended tt ti Daylight Evening Night 0 1 0 0 1 0 0 0 0 0 0 0 0 0 0 0 1 0 15 Aug. 16-17" 16 Aug. 40' Bottom II it II it Daylight Evening Night 0 0 1 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 Note - Chi-square i s not calculated where sample s i z e i s small and no conclusion i s noted. TABLE XXII ( c ) . Number o f Mountain Whitefish obtained i n net sets ( v e r t i c a l and l a t e r a l ) i n stations along northwest shore of Nicola Lake during Late Summer. Date 1 9 5 8 Depth and p o s i t i o n of net set Period of day-Tot a l No.of f i s h No. of movii to shore f i s h o f f shore Loose f i s h Conclusion (including X 2 value) No. i n top h a l f of net of f i s h i n b o t t -om h a l f o f net Conclusion (including X 2 value) 29 Aug. 2 6 - 2 7 " 28 Aug. 1 0 " Bottom it II II it Daylight Evening Night 0 2 0 0 0 0 0 2 0 0 0 0 0 2 0 0 0 0 29 Aug. 2 6 - 2 7 " 28 Aug. 2 0 ' Bottom tt II II II Daylight) Evening ) Night ) 0 0 0 0 0 0 29 Aug. 2 6 - 2 7 f f 2 8 Aug. 4 0 ' Bottom it II ti II Daylight) Evening j Night ) 0 0 0 0 0 0 31 Aug. 2 - 3 Sepi 2 Sept. Surface " II Daylight) Evening ) Night ) 0 0 0 0 0 0 31 Aug. 2 - 3 Sepi 2 Sept. Suspended " it Daylight) Evening ) Night ) 0 0 0 0 0 0 31 Aug. 2 - 3 Sep. 2 Sept. 4 0 ' Bottom u II • it II Daylight) Evening ) Night ) 0 0 0 0 0 0 Note - Chi-square i s not calculated where sample s i z e i s small and no conclusion i s noted. 94 Literature on Mountain Whiterish In his study of the ecology of Skeena River System Whitefish, Godfrey (1955) reported that Mountain Whitefish are more abundant on the bottom in 16-321 depth zone. Present data are in agreement. According to Ferguson (1949). position of Mountain Whitefish is intermediate between shallow water and deep water fishes in Skaha Lake where i t was seen to come to shore zone for feeding on the bottom. Appearance of the species in shallow shore areas in the present case appears to be similar to the situation in Skaha Lake. Non-availability of Mountain Whitefish in net sets made on the bottom in 80 f t . and deeper waters a l l through the summer agrees completely with the results of Godfrey (1955) in Babine and Lakelse lakes. McHugh (1940) mentioned that with the increase in their size, Mountain Whitefish modify their feeding habits to include larger plankton and other bigger organisms including fish. Ferguson (1949) observed that in areas with sparse bottom fauna, this fish moves into different areas to look for food. Appearance of the species in midwater during mid summer may be related to i t s feeding activity as suggested above. Influence of thermal stratification on this species is not clear. In early summer i t is never found above the thermocline but in late summer, i t was never seen in the hypolimnion. In Skaha Lake, i t is found to occupy a position intermediate between epilimnion and hypolimnion (Ferguson 1949)* 95 Seine hauls in north shore Results of seine hauls made in the north shore in different periods of the day are presented in Table XXVII (a-c). In the early summer, young-of-the-year of Largescale Sucker, Squawfish, Peamouth Chub and Prickly Sculpin of sizes ranging from 16 to 33 mm. inhabited the sandy beaches along north shore during the daylight hours• At dusk, larger size groups of Peamouth Chub, Largescale Sucker, Squawfish invaded the shore. Redside Shiners of the size range of 43-91 mm* also appeared on the shore at this time. In the case of Prickly Sculpins, the same size group of fry as seen in the daylight were found to continue to live on the shore. The young-of-the year class of fry of a l l species except Prickly Sculpin appeared to move off-shore with change in light condition. At night, this off shore movement of smaller fry and inshore movement of bigger specimens appeared to become complete. In addition, fry of Mountain Whitefish also were observed to come into the beach. Proportion of different species in the shore population also appeared to undergo changes with variation in light conditions. In mid summer, the same phenomena of the variation in the size group and species composition in daylight and at night were found to continue. During this period, larger size groups of Prickly Sculpin came into shore at night• In late summer, the same pattern in the inshore and offshore movement; of the different size groups of young fish as seen in the preceding periods of summer continued* During this period, a seine haul made in the predawn period showed that very few fish stay near the beach at this part of the day. Towards the middle of August, young-of-the-year of Redside Shiner, Peamouth Chub and Largescale Sucker were found to move about in 2-3 f t . deep TABLE XXVIT (a). P a r t i c u l a r s of seine hauls i n the north shore, Nicola Lake i n E a r l y Summer, 1958. Date Time Period of Weather Bottom Species (hrs.) day conditions conditions Range of size (mm.) Total of each s i z e group and each species Percent t o t a l catch 17 Ju l y 16.30 Daylight Bright and c l e a r day, l i t t l e •wind Sandy and muddy ( i ) Largescale Sucker 16^28 ( t t ) Squawfish I6r23 (III) PM Chub 21-33 (IV) Sculpin 16-29 Tota l (I) Largescale (a) 68-251 Sucker (b) 21-25 (II) Squawfish 16-27 (III) PM Chub (a) 66-225 (b) 17-33 (17) Redside Shiner 52-7IOO (V) Sculpin 16-31 (VI) Mount.Whitef. 57-71 435 322 392 43 1192 ^ O j 85) 27 11) 4) 125 52 36.5 27,0 32.9 100 17 J u l y 23.30 Night Clear sky; l i t t l e wind Sandy and muddy Total (I) LargescSucker (II) Squawfish (a) (III) PM Chub [a] (b) (IV) Reds.Shiner (y) Sculpin  (a) 17-26 (b) 63-200 .16-25 133-215 15-29 62-185 43-91 18-33 338 •"816T 4) 64) 8) 9 60 34.0 8.0 4.4 37.0 15.4 11.2 100 17 J u l y 21.00 Dusk Clear sky wind-nil Sandy and muddy To t a l 1065 77.0 6.38 10.14 0.85 5.63 100 TABLE XXVII (b ) . P a r t i c u l a r s of seine hauls i n the north shore, Nicola Lake, i n Mid Summer, 1958. Date Time Period of Weather Bottom Species (hrs.) day conditions conditions 6 Aug. 12.20 Daylight (I) Largescale(a) Sucker (b) (II) Squawfish(a) (III) PM Chub [a] (b) (IV) Redside (a) Shiner (b) (V) Sculpin (VI) M. Whitefish sRange of size (mm.) Tot a l of each size group and each species Percent t o t a l catch Complete overcast wind 15-18 M.P.H. s.s-w Sandy and muddy 21-43 65-131 18-38 86 17-51 114 17-51 57-102 15-31 JL T o t a l 153) 2) 225) 1) 70) 1) 344) 47) a 1 885 17.5 25.5 8.1 44.2 4.6 0.1 1UU.U 6 Aug. 23.00 Night Complete Sandy and (I) Large.seale(a) 21-45 88) 10.8 overcast muddy Sucker (b) 73-215 20#31 21) wind 3-4 (II) Squawfish(a) 11) 1.2 M.P.H. (b) 100 1) (III) PM Chub (a) 16-38 67) 7.1 (b) 117-240 4) (IV) Redside (a) 18-31 119) 32.1 Shiner (b) 52-116 203) (V) Sculpin 16-76 486 48.4 (VI) M.Whitefish 81-217 4 0.4 T o t a l 1004 100.0 TABLE XXVII ( c ) . P a r t i c u l a r s of seine hauls i n north shore, Nicola Lake, i n Late Summer, 1958. Date 26 Aug. Time (hrs.) 04.15 Period of Weather Bottom day Conditions Conditions Cloudy. Species Range of Tot a l of each Sandy and muddy (I) L a r g e s c a l e f a ) Sucker (b; (II) Squawfish (III) PM Chub (a) size (mm.) 31-62 254 23-45 21-43 215-253 17-40 60-114 16-68 s i z e group and each species Percent t o t a l catch If 18 8) 2) 6) 30) Pre-dawn Overcast 5/10 Wind 12-16 M.P.H. S.-SW. (iV)Redside Shiner (V) Sculpin (b) (a) (b) Total 26 Aug. 14.30 Daylight (I) Largesoale(a) 22-67 . Sucker (b) 95-108 (II) Squawfish(a) 25-49 (b) 50-130 ( I I I ) PM Chub (a) 22-57 (b) 90-135 (IV) Redside Shin. 22-106 (V) Sculpin (a) 17-33 (b) 57 Total 110 "I83T 2) 1153) 20) 266) 6) I63O 5) 1) 3266 7.3 16.4 9.1 32.7 100.0 Overcast Sandy and S/]0 almost muddy complete Wind 12,14 M.P.H. SW, 5.7 35.9 8.3 49.9 0.2 100.0 26 Aug. 22.30 Night Overcast complete Wind-very l i g h t to n i l . Sandy and muddy (I) Large.sca^e(a) Sucker (b) (II) SquawfishUU (I I I ) Redside (a) Shiner (b) (IV) M. Whitefish 40-57 78-400 28-45 129-105 21-42 57-116 88-260 55) 63 2J 19; 92) - J L 26.0 26.7 45.7 1.6 Total 243 100.0 99 . water i n moderate s i z e d schools. In l a t e summer, the schooling appeared to become pronounced with more i n d i v i d u a l s i n each school. Predominance of d i f f e r e n t species i n the shore population a l s o tended to vary i n d i f f e r e n t periods of summer and also over day and night i n the same period of the season. In e a r l y summer, during the daylight hours, Largescale Sucker f r y vrere seen as the dominant group but at night, P r i c k l y Sculpins became the major species. But from mid summer on, Redside Shiner f r y became the dominant group i n the daylight hours. At night, dominance of P r i c k l y Sculpin continued. In l a t e summer, a reversed p i c t u r e of the mid summer s i t u -a t i o n was found to develop with P r i c k l y Sculpin dominating during the day, but y i e l d i n g t h e i r p o s i t i o n to Redside Shiner at night. Presence of newly hatched Redside Shiner f r y along the shore i n d i f f e -rent periods of the season show a s i m i l a r i t y to conditions i n Paul Lake where Shiner f r y were not found i n the middle of J u l y but reappeared i n e a r l y August (Crossman 1957). Seine hauls i n other regions of shore Results are summarized i n Table XXVTH. Peamouth Chub were found on a l l shores i r r e s p e c t i v e of the nature of bottom. But one seine haul made i n f r o n t of Moore Creek i n l e t d i d not y i e l d any Peamouth Chub. Largescale Suckers also appeared i n a l l p arts except i n Nicola River i n l e t . In the lagoon on the southeast shore, Carp appeared i n seine hauls together with Peamouth Chub, Largescale Sucker, Redside Shiner and P r i c k l y Sculpin. I n l e t and outlet streams seemed to infl u e n c e the composition of shore populations of young f i s h . Seine hauls made i n fr o n t of Moore Creek i n l e t and Nicola River i n l e t tended to bear out the above observation. The haul TABLE XXVIII. P a r t i c u l a r s of seine hauls i n d i f f e r e n t parts of Nicola lake, taken i n the daylight hours. Date 1958 ' Location 1 Bottom of 'condi-haul I t i o n s <PM mm Tot-a l RSS mm Tot-a l •SQ mm Tot-a l •LND mm - S i Tot-a l b e *CP mm c i < Tot-a l 3 S KT mm C c Tot-a l 1 u SS mm g h 1 Tot-a l t KK mm Tot-a l MW mm Tot-a l SC mm Tot-a l LSS mm Tot-a l 18 J u l y SE shore south o f Quilchena Cr. i n l e t Sandy beach 16-32 122 14-49 4 20-24 • 2 20-31 43 17- 483 ti LagOon i n SE shore Middy bottom Smurky 21-60 24 44-48 76 4 61-66 6 51-70 25 22-77- 87 23-61 13 II ii II 18-67 32 53-78 2 63 1 20-j 107 85 21-95 23 ri SE shore south of Quilchena Cr. Sandy 30-75 11 4 1 -78 6 51-73 10 30-33 2 27-104 25 1 1 Aug. N. shore 1 f r o n t of Moore Cr. i n l e t I » 12C 1 61-115 38 14C 1 62-22i 19 24-36 18 230 8 Aug. Magi Moore's bay SE shore Sandy with gravel upto4' 16-32 318 19-37 246 17-26 17 12-35 L40 15-27 155 ti Nicola R. i n l e t SE shore 20 1 15-50 261 it NE Q u i l -chena Poi Rocky it 15-40 33 16-33 39 1& 26 29 1 22-39 31 tt E. of Quilchena SE side of lake Stagn. murky stinky Ooze bottom 20-35 12 I 8 -60 65 21 85 44 56-96 8 30-32 2 23-36 62 Cont TABLE XXVIII - Cont'd. Date 1958 Location of haul Bottom condi-t i o n s PM mm Tot-a l RSS mm Tot-a l SQ mm Tot-a l LND mm S p < Tot-a l 3 C CP mm i e E Tot-a l KT mm c a i Tot-a l SS mm h t Tot-a l KK mm Tot-a l W mm Tot-a l SC mm Tot-a l LSS mm Tot-a l _ 8 Aug. SW End 1 mile from N i -cola R, o u t l e t Muddy-wit h deca-yed veget. 30-48 305 30-32 5 20-36 39 38-65 6 27-50 497 8 Aug. Nicola R.outlet Rocky, s i l t , weed beds; slow c u r r t . 43-12; 8 31-105 124 25-92 11 81-98 4 90-1 28-13C 79 30-95 40 o Note: LND m Longnose Dace. For other abbreviations, Table VI may be seen. 101 i n front of Moore Creek i n l e t showed young Kokanee, Chinook Salmon, and Rainbow Trout as the dominant group of f i s h . The haul i n fr o n t of Nicola River i n l e t showed only Peamouth Chub and P r i c k l y Sculpins. Sampling i n the Nicola River o u t l e t about a mile down from the lake produced Redside Shiner, Peamouth Chub, Carp f i n g e r l i n g s and young of Chinook Salmon. Seine hauls along the southeast shore a l i t t l e south of Quilchena Creek, showed Longnose Dace i n the beach i n a d d i t i o n to other usual species whereas the haul made i n the lagoon i n e a r l y summer revealed the presence of Carp f i n g e r l i n g s i n that l o c a l i t y . Fry of d i f f e r e n t species seen to i n h a b i t the shores are believed to have a common food habit (Larkin 1956). Occurrence of these species together i n the lake can, therefore, be r e l a t e d t o t h e i r food and feeding habits. Dip net sampling In the steep rocky shore, along the western side, f r y of Peamouth Chub, P r i c k l y Sculpin, Redside Shiner and Squawfish were found moving i n schools i n 2-3 f t . of depth during the period from the t h i r d week of J u l y to middle of August. Largescale Sucker f r y was conspicuous by t h e i r absence along the rocky shore regions and t h i s i s probably due t o the d i f f e r e n t substrate over which they could not feed e f f e c t i v e l y . 102 17. FISH ASSOCIATIONS Assemblage of d i f f e r e n t species i n c e r t a i n habitat zones i s the outcome of t h e i r response t o seasonal or d a i l y changes i n the p h y s i c a l , chemical or b i o l o g i c a l conditions. Assemblage may a l s o be induced by the urge of reproduc-t i v e a c t i v i t y or by s o c i a l a t t r a c t i o n s as i n the higher animals (Odum, 1954). In the case of f i s h , i n t r a s p e c i f i c s o c i a l a t t r a c t i o n s may e x i s t , but i n t e r -s p e c i f i c a s s o c i a t i o n can be considered as the r e s u l t of t h e i r i d e n t i c a l res-ponse to c e r t a i n p h y s i c a l or chemical changes i n the environment or the r e -s u l t of t h e i r tendency to share a common source of food supply. Factors o f food and feeding may brings about the a s s o c i a t i o n of predator and prey species. Associations of f i s h i n d i f f e r e n t habitats are, therefore, the outcome of the i n t e r a c t i o n s of various f a c t o r s - p h y s i c a l , chemical and b i o l o g i c a l . The season, e.g. summer, during which the present study was made, i s known to b r i n g about c e r t a i n p h y s i o l o g i c a l b a r r i e r s f o r f i s h over which l i t t l e migration takes place (Ferguson, 1949). Ferguson defines Peamouth Chub, Redside Shiner, P r i c k l y Sculpin, Squawfish, Carp and Largescale Sucker as shore species l i v i n g above the epilimnion. The present study also showed a s i m i l a r a s s o c i a t i o n of shore dwelling species. A l l throughout the season, Peamouth Chub, Redside Shiner, Largescale Sucker and Squawfish are seen to occupy the bottom of the lake i n the shore regions, during daylight hours. During night, t h i s bottom a s s o c i a t i o n of f i s h i s strengthened by P r i c k l y Sculpins. In the shallow southwest end, Chiselmouth, Longnose Dace, Carp and B r i d g e l i p Sucker come i n t o t h i s a s s o c i a t i o n of f i s h occupying shallow shore regions of the lake. Figures 1% 16 and 17 summarize the a s s o c i a t i o n of f i s h as seen i n the net sets on the northwest shore during the summer. This basic a s s o c i a t i o n of shore zone f i s h e s can be f u r t h e r subdivided i n t o two groups according to t h e i r food habits. Carp, P r i c k l y Sculpin, EARLY SUMMER N O . O F F I S H N I G H T 15 30 45 DAY-PEAMOUTH CHUB LARGESCALE SUCKER MOUNTAIN WHITEFISH F i g . 15. Occurrence of f i s h i n g i l l net sets i n northwest shore i n e a r l y summer. MID SUMMER NIGHT -y'X X X ~X~At ^T"x X * X * r i / x * * x to5-0' >oo\ - , - J O O O O o \ - / o o o o o o o o o \ 70000000000) E V E N I N G Vxxxxxx X Nf VXxxx.* xx XK/ ^<X*xXj£/ 0 f x X X X X A X J I x x x x * x / U x x x x K x X X J / 20 40 120 40' j s r r t * x x x xxx i ^**xxxxx££--iXxxj^C fx x\ x x x \ SQUAWFISH oo o o OO o o oo o oo o o o o o o o o o o PEAMOUTH CHUB REDSIDE SHINER y x x x x X x x x x RAINBOW TROUT LARGESCALE SUCKER MOUNTAIN WHITEFISH DOLLY VARDEN ro 16. Occurrence of f i s h i n g i l l net sets i n northwest shore i n mid summer. LATE SUMMER NO. O F F I S H NIGHT o ro F i g . 17. Occurrence of f i s h i n g i l l net sets i n northwest shore i n l a t e summer. 103 Largescale Sucker, and Ghiselmouth can be s a i d t o represent the bottom dwell-i n g a s s o c i a t i o n while the a s s o c i a t i o n of Peamouth Chub and Redside Shiner which c o n s i s t e n t l y show the tendency to form an a s s o c i a t i o n i n surface and midwater at n i g h t f a l l , may be termed as the intermediate group. But t h i s a s s o c i a t i o n of Peamouth Chub and Redside Shiner as seen i n upper l a y e r s of water during night i s transient as they b a s i c a l l y r e l y on bottom food (Ferguson 1949). The appearance of Squawfish i n the shore zone i s probably due to the f a c t that i t preys upon a l l the shore zone f i s h e s , p a r t i c u l a r l y Redside Shiner, young of Peamouth Chub and P r i c k l y Sculpin (Ferguson 1949). I t s occasional presence at night i n the a s s o c i a t i o n of Peamouth Chub and Redside Shiners i s probably due to i t s tendency to a c t i v e l y hunt f o r the prey f i s h , p a r t i c u l a r l y Redside Shiners. The other major a s s o c i a t i o n can be termed as the open water a s s o c i a t i o n which includes Rainbow Trout, D o l l y Varden, Mountain Whitefish, Kokanee and Burbot. D o l l y Varden, Mountain Whitefish, Kokanee and Burbot are known t o l i v e i n deeper waters below the thermocline and therefore, t h i s a s s o c i a t i o n i n c l u -ding Rainbow Trout can also be defined as deep water a s s o c i a t i o n . In the deep water, the a s s o c i a t i o n i s however not as intense as i n the case of shore zone association. Larger Rainbow Trout and Burbot are p r i m a r i l y f i s h eaters, main-l y feeding upon Kokanee (Ferguson, 1949)# while Kokanee and Mountain Whitefish share the plankton food a v a i l a b l e . Data obtained i n the present study tend to agree, i n general, to t h i s pattern of f i s h associations which was also observed i n Okanagan Lake (Clemens, 1939) and Skaha Lake (Ferguson, 1949). In d i f f e r e n t periods of summer, c e r t a i n exceptions to the general habitat pattern are noticeable. One or more species belonging t o one p a r t i c u l a r a s s o c i a t i o n are seen t o invade the other zone f o r some period of time. Such exceptions to the general r u l e are displayed by Mountain White-f i s h , Rainbow Trout, Kokanee and Burbot on the one hand and Peamouth Chub, 1 0 4 Largescale Sucker and Prickly Sculpin on the other. Mountain Whitefish were seen i n the shore zone twice during the summer i n the northwest end of lake while i n the southwest basin, these were present consistently a l l throughout the summer. This i s however, i n agreement with the findings of Godfrey (1955) and Ferguson (1949). Ferguson considers the position of Mountain Whitefish as intermediate between shore zone association and deep water association, but Clemens (1953) describes this species as belonging to offshore population. Though primarily a bottom feeding species,, larger Mountain Whitefish invade other habitats to obtain additional food (Ferguson, 1949). Nicola Lake i s poor i n bottom fauna, particularly i n the deeper regions, and as such the appe-arance of Mountain Whitefish i n shore zones seems logical i n the light of the findings i n Skaha Lake (Ferguson, 1949) and Babine Lake (Godfrey, 1955). In Skaha Lake, Burbot and Rainbow Trout were observed to venture into shallow zones of water for short periods of time. These two species i n the present case show similarity i n behaviour with that of Skaha Lake f i s h generally. Burbot, apparently, come inshore i n search of prey fi s h which are available i n the shore association, or for Kokanee moving into the shallow water during different periods of the season. Numbers of Peamouth Chub, Largescale Sucker, and Prickly Sculpin seen i n 80 f t . depth zone are not significant and these can be termed as 1 stragglers'(Allee, et al.(1950)), which move into zones other than their own as a result of some secondary influence. The third association of f i s h that i s of importance i n Nicola Lake i s that of the fry and young-of-the-year of different species. In the case of young-of-the-year, the association i s seen to be composed of Redside Shiner, Peamouth Chub, Squawfish, Largescale Sucker, Prickly Sculpins. During day-light} this composition of the association of young i s noticeable i n shores with sandy beach conditions. In shores with muddy substrates, Carp finger-lings become a part of the association. In rocky shores along the western 105 side of the lake, the young-of-the-year of Largescale Sucker drop out of t h i s a s s o c i a t i o n of Peamouth Chub, Squawfish and P r i c k l y Sculpin seen on other parts of the shore. Fi n g e r l i n g s and f r y of Chinook Salmon, Kokanee, Rainbow Trout and Mountain Whitefish appear i n the general a s s o c i a t i o n of the young f i s h only i n areas where stream water mingle with lake water and i n the out-l e t stream. This preference shown by the SaLnonid and Coregonid young f o r areas close t o stream mouths cannot be a t t r i b u t e d to food preferences as can be done i n the case of other species. This a s s o c i a t i o n of f r y and young-of-the-year shows a s l i g h t modifica-t i o n i n so f a r as t h e i r s i z e i s concerned. Smaller f r y seem to move away from the shore at night g i v i n g place to comparatively l a r g e r specimen of t h e i r own kind. In a d d i t i o n , f i n g e r l i n g s of Mountain Whitefish also appear i n the a s s o c i a t i o n at night. 106 V. FOOD AND FEEDING HABITS OF FISH AND RELATION THEREOF TO THEIR SPATIAL DISTRIBUTION In order of importance, feeding a c t i v i t y i s next to breeding a c t i v i t y i n modifying habits and habitats of f i s h . Breeding a c t i v i t y , although domi-nant, i s temporary i n nature, but feeding governs the a c t i v i t y a l l the year round. From t h i s point of view, a n a l y s i s of the food and feeding habits may throw more l i g h t on the problem and c l e a r the p i c t u r e of the summer d i s t r i b u -t i o n of f i s h . Food and feeding habits of almost a l l the species of f i s h found i n Nicola Lake have been dealt with adequately i n the l i t e r a t u r e , a summary of which i s presented i n Table XXIX. Fry (1937) and Godfrey (1955) discuss the i n f l u e n c e of feeding a c t i v i -t y on the summer d i s t r i b u t i o n of d i f f e r e n t f i s h species. In Lake N i p i s s i n g , Fry found that Ciscoes remain i n the epilimnion i n summer f o r some time to feed upon emerging Mayfly even i f the temperature conditions become unfavour-able t o the f i s h . Poor bottom fauna can force a bottom feeding f i s h t o r e -or i e n t i t s feeding habits and d i s t r i b u t i o n . Common Whitefish i n Morrison Lake are found to feed upon plankton crustaceans though normally they depend on bottom organisms i n other lakes (Godfrey, 1955)* Increase i n body s i z e some-times forces a f i s h to look f o r a d d i t i o n a l d i e t i n areas other than i t s former feeding zone. In the case of Mountain Whitefish, both McHugh (1940) and Ferguson (1949) note the existence of such a phenomenon. In Nicola Lake al s o , appearance of the Mountain Whitefish i n midwater i s probably induced by the f i s h e s ' requirements of l a r g e r food organisms and plankton. The opposite of what i s discussed above i s sometimes found to occur. The influence of p h y s i c a l environment becomes so great at times that f i s h are forced to modify or r e s t r i c t t h e i r feeding a c t i v i t y under such conditions. .TABLE XXIX. Food of the species of f i s h e s discussed. A s t e r i s k i n d i c a t e s major item of food. Species F i s h Bottom fauna F o o Surface i n s e c t s d Plankton Miscellaneous A u t h o r i t y Remarks Peamouth Chub Chironomidae, Mayfly Nymph Mollusc, Caddis larvae Moths,Beetle, F l i e s , Hyme-noptera jfiCopepods, aCladocera Algae Plant material Clemens et al(1939 Ferguson (1949) (Godfrey (1955) Redside Shiner Chironomid, larvae,Mayfly nymphs and aquat.insects wCopepods, Cladocera Plant material Clemens et al(1939 Ferguson (1949) Squawfish Kokanee, Mountain WhitefisJ xChub, jdShiner and Sculpin Snail,clams, Insect larvae, , Mayfly nymph, Caddis larvae, water-mite and jfiCrayfish Water boat-man Algae and other plankton i n small quantity Other plant materials Cartwright (1956) Clemens (1939 Clemens and Monro (1937) Ferguson (1949) Godfrey (1955) Ricker (1941) Carp Oligochaeta, Ostracoda, Mayfly nymphs, Caddis larvae, Chironomid larvae, Hyalela, Hydracarina. Copepods, R o t i f e r s , Cladocera, Algae and shrimp Fragments of higher p l a n t s . Clemens e t a l (193^  Ferguson (1949 Haslbauer (1945) Richardson (1913) Longnose Dace xln s e c t larvae and Nematodes Copepods, xAlgae Fragm. of h i -gher p l a n t s . Breder and Crawford (1922) Johannes (1957) Hubbs and Cooper (1936) Chiselmouth i Algae and frag-ments of Myrio-phyllum and Potamogeton Result of stomach a n a l y s i s . TABLE XXIX. Cont'd. Spesies F i s h Bottom fauna F o Surface. i n s e c t s o d Plankton Miscellaneous Authority Remarks Mountain Whitefish Sculpin, Kokanee, Mountain Whitefish Chironomid larvae,Caddis, larvae & pupae, other ins e c t larvae and mollusc Cladocera and other plankton Ferguson (1949) Godfrey (1955) McHugh (1940) Kokanee Toung of Kokanee Cladocera Clemens (1939) Ferguson (1949) Ricker (1941) Chinook Salmon ( f r y only) Chironomid larvae & pupae, Hydracarina, Chaoborus ^Diptera, '^Hymenoptera, Homoptera, Heteroptera Aphid •^aphnia, •^Bosmina, Eurycerus & Copepods Clemens (1934) Rainbow Trout *Shiner, Chub,Squ-awfish, Kokanee, Whitefish Chironomid larvae, Mayfly larvae Sc. nymph, Snails,Amphi-pods,Crayfish, Watermite •^richoptera, Coleoptera Cladocera Spiders Clarence (1942) Crossman (1957) Larkin & Smith (195 Leonard & Leonard ( 4) 1949) D o l l y V Varden Shiners, S t i c k l e -back, Squawfish, Sucker, Sculpin, Sockeye f r y Bottom insect materials of the orders of Odonata,Coleo-ptera, Tricho-ptera,Leeches and S n a i l s . Salmon eggs Delacy & Morton (1942) Godfrey (1955) Ricker (1941) Largescale Sucker Mayfly nymph, $Caddis larvae, ^"Chironomid larvae,Molluscs, Amphipods. Cladocera, Copepods, Ostracods, '-•Diatom Det r i t u s & algae other than Diatom C a r l (1936) Clemens (1939) Ferguson (1949) Cont'd TABLE XXIX. Cont'd. Species Fi s h Bottom fauna F o Surface i n s e c t s o d Plankton Miscellaneous Authority Remarks Burbot Rainbow Trout, Dace,Cotti ds,Corego-nids, *Kbkanees, ^Shiners, Perches Amphipods, Mayfly nymph, - Diptera larvae Mollusca, Caddis larvae C r a y f i s h Copepods Cladocera Beeton (1956) Bjorn (1937) Clemens (1950) Ferguson (1949) Van Oosten (1937) P r i c k l y Sculpin Sculpin Chironomid larvae, '"•Gastropods, ^Amphipods, C a d d i s larvae Copepods, Cladocera Clemens (1939) Ferguson (1949) Koster (1937) 108 Ferguson (1949) points out the existence of such influence i n the case of Rainbow Trout, Kokanee and Mountain Whitefish i n Skaha Lake. He ascribes the erratic growth of these species to poor feeding caused by high temperature. Light condition probably modifies the feeding activity of f i s h directly by restricting their movement and indirectly by regulating distribution of organ-isms upon which f i s h feed. Spreading of Peamouth Chub and Redside Shiner i n different levels of water after nightfall i s probably a reflection of their increased feeding activity under the cover of darkness. Redside Shiners appearing i n the seine hauls at night were almost always* found to have their stomachs gorged with food. This feeding tends to support the speculation made above. Common food and food preferences are known to bring about the associa-tion of fishes i n different habitats. Ferguson (1949) c l a s s i f i e s different f i s h associations on the basis of their common food preferences. Prickly Sculpin, Largescale Sucker and Burbot are shown as members of the shore asso-ciation of f i s h i n Skaha Lake. A l l the three species share insect larvae, Copepods, Ostracods, Algae and Diatoms, although emphasis for one or the other item of food d i f f e r for different f i s h . Godfrey (1955) describes Peamouth Chub as the most important competitor of Mountain Whitefish i n Lakelse Lake. Both species consume mostly bottom organisms and show similarity in. their depth distribution. Table XXIX shows the common food habits of Largescale Sucker, Peamouth Chub, Prickly Sculpin, and Redside Shiner and these four species are found to be i n association a l l through the summer i h Nicola Lake. Similarly, young-of-the-year of the freshwater f i s h often share a common diet of plankton food (Larkin, 1956). These appear together i n a compact association i n the shore areas during different periods of summer. Larkin (1956) mentions that various species of f i s h though showing a preference for some common food, collect the same from different regions of the 109 lake and thus remain d i s t r i b u t e d d i f f e r e n t i a l l y . Non-appearance of smaller s i z e group of Burbot i n the shore region of Nicola Lake can probably be ex-plained i n terms of the observation mentioned above. In Okanagan Lake, f i s h remain d i s t r i b u t e d i n space i n two d i s t i n c t groups - one i n shallow shoreward a s s o c i a t i o n and the other i n open water as s o c i a t i o n (Clemens, 1939). The two associations are fundamentally based on t h e i r d i s t i n c t i v e food habits. The shore a s s o c i a t i o n included Largescale Sucker, Carp, Redside Shiner, Squawfish, Peamouth Chub, Longnose Dace, Leopard Dace and P r i c k l y Sculpin. The open water a s s o c i a t i o n , on the other hand, i s composed of Kokanee, Rainbow Trout, Mountain Whitefish, Eastern Whitefish, Burbot and Longnose Sucker. In Nicola Lake, d i s t r i b u t i o n of the a v a i l a b l e species appears to be s i m i l a r to that of Okanagan Lake. Redside Shiner, Peamouth Chub, Squawfish, P r i c k l y Sculpin, Largescale Sucker, B r i d g e l i p Sucker, Carp, Longnose Dace and Chiselmouth appear i n the shoreward shallow region although a l l the species do not occur together a l l around the lake. Chiselmouth, Carp ( f i n g e r l i n g s ) and B r i d g e l i p Sucker occur together i n the shallow weedy south west basin and food habits of these species agree with the type of t h e i r habitat. Peamouth Chub and Redside Shiner show a s t r i k i n g s i m i l a r i t y i n t h e i r s e l e c t i o n of food and feeding habit i n summer (Ferguson, 1949). Occurence of these two species i n surface or midwater can e a s i l y be ascribed to t h e i r common food habits. Ferguson suggests t h a t the open water a s s o c i a t i o n of Kokanee, D o l l y Varden, Rainbow Trout and Mountain Whitefish i s the r e s u l t of t h e i r common feeding on plankton. D o l l y Varden take i n s e c t larvae on the bottom and thus compete f o r the food of Mountain Whitefish (Godfrey, 1955). The d i e t o f Mountain Whitefish again overlaps that of the Carp-Sucker combination (Ferguson, 1949). Feeding habits of Mountain Whitefish are also known to overlap those of Peamouth Chub, Squawfish and Suckers and competition between these species 110 f o r food i s suggested by Godfrey (1955). Overlap i n food habits of Mountain Whitefish helps i n i n t e r p r e t i n g i t s presence i n shallow shore areas and i n the midwater. Any discussion of food and feeding habits of f i s h remains incomplete i f the r e l a t i o n s h i p and d i s t r i b u t i o n of predator and prey species of f i s h are not analysed. The p r i n c i p a l predators i n Nicola Lake are Rainbow Trout, D o l l y Varden, Kokanee, Burbot and Squawfish. Squawfish are known t o confine t h e i r predatory a c t i v i t y i n the shallow and surface regions of lake during summer, but o c c a s i o n a l l y go i n t o the thermo-c l i n e i n search f o r prey f i s h (Ferguson, 1949)• Appearance of Squawfish i n surface and midwater i n the evening, as w e l l as i n the thermocline, may be ascribed to i t s predation on d i f f e r e n t prey species that are a v a i l a b l e i n those zones. I t s food f o r summer i s tabulated i n Table XXIX. Burbot, a deepwater species, have a tendency to take Kokanee and Redside Shiners i n summer (Ferguson, 1949)• Appearance of Burbot i n the shallow region i n e a r l y and mid summer i s probably associated with the presence of Redside Shiners. In l a t e summer, i t shows a d i s t i n c t tendency to prey upon Kokanee. Twice i n the summer, l a r g e Burbot with Kokanee stuck i n t h e i r g u l l e t were seen f l o a t i n g on the lake surface. ' D o l l y Varden feed upon Redside Shiners, Sticklebacks, Squawfish and P r i c k l y Sculpins (Ricker, 1941)• D o l l y Varden appear i n shallow water i n the summer probably t o prey upon these species, p a r t i c u l a r l y because of poor bottom fauna i n Nicola Lake. Rainbow Trout are reported to depend on chance contact with the prey species f o r feeding upon them (Crossman, 1957). Conditions i n summer o f f e r t h i s contact by br i n g i n g them together i n surface and midwater. Lack of Rainbow Trout i n large numbers with the prey species i n the shore regions tend I l l to support the conclusion of Crossman. Kokanee i s known to be c a n n i b a l i s t i c i n habit and feed upon young Koka-nees (Ricker, 1941). Findings of Ferguson i n Skaha Lake appear to support the views of Ricker. Though food and feeding habits are considered one of the major f a c t o r s i n f i s h d i s t r i b u t i o n , t h e i r e f f e c t s become complicated due to the overlap i n food habits displayed by d i f f e r e n t species. Larkin (1956) concludes that f i s h are not t y p i c a l l y confined to a p a r t i c u l a r zone as a whole at any time or as sub-groups d i s t r i b u t e d i n the same way at d i f f e r e n t time. This conclusion seems to be very much appl i c a b l e to the f i s h a s s o c i a t i o n of Nicola Lake. 112 VI. DISCUSSION Temperature The r o l e of temperature i n shaping and regulating the summer d i s t r i b u -t i o n of f i s h has been discussed i n a comprehensive manner by Fry (1937). F r y observed that Ciscoes i n Lake N i p i s s i n g leave the shallow waters and head f o r the bottom i n l a t e spring and ea r l y summer when temperature i n the upper s t r a t a of water s t a r t s to r i s e . He also observed that the commencement of downward migration was co r r e l a t e d with the temperature i n upper 30 f t . of water a t t a i n -i n g a c e r t a i n threshold. A temperature of 20°C was found to t r i g g e r o f f the downward movement. In e a r l y as w e l l as i n mid summer, Ciscoes tended to keep within the hypolimnion by moving downward with the descending thermocline. In l a t e summer, oxygen depletion and excess of carbon dioxide forced Ciscoes to leave the bottom, and during t h i s period, f i s h were seen to l i v e i n the region j u s t below the thermocline. The concentration of f i s h immediately below the thermocline was considered to be the r e s u l t of the ascending populations' avoidance of the warm water of the epilimnion when suddenly subjected to i t a f t e r experiencing the c o o l and even temperature! waters of the hypolimnion. The f i n a l evacuation of the hypollnmion by Ciscoes was ascribed to the destruc-t i o n of the balance between the opposing e f f e c t s of the warm water above and the unfavourable concentrations of dissol v e d gases below. The downward movement was found to be order l y with the l a r g e s t males moving down f i r s t , followed by la r g e males and l a r g e s t females. The youngest age groups of the two sexes were the l a s t to move down. This a s s o c i a t i o n i n the downward move-ment was re l a t e d to the lowest upper temperature threshold of the d i f f e r e n t s i z e groups of the Ciscoes. Odell (1932) believes that the p r i n c i p a l f a c t o r that regulates the d i s t r i b u t i o n of deepwater f i s h i s t h e i r requirement f o r low temperature, while 113 the shallow water species are obliged to stay i n t h e i r habitat because of the requirements of warm water and abundant food supply. According t o O d e l l , Smelt, Cisco, Whitefish, Lake Trout, Finescaled Sucker and Burbot are deep-water forms. Dendy (1945, 1946, 1948) has also studied the r e l a t i o n s h i p between tem-perature and d i s t r i b u t i o n of f i s h i n the Tennessee V a l l e y r e s e r v o i r s . Accord-i n g to t h i s author, a very close c o r r e l a t i o n between temperature and f i s h d i s t r i b u t i o n cannot be expected, as some i n d i v i d u a l s of a p a r t i c u l a r species are always found above and below the preferred temperature zone. In the case of Sauger, Walleye, Largemouth Bass, Spotted Bass, Drum and Shad, a d e f i n i t e c o r r e l a t i o n was found to ex i s t between the temperature and d i s t r i b u t i o n of the middle f i f t y percent of each of the species. Sauger showed a preference to l i v e i n the temperature range of 60°-70°F, but Walleye displayed preference f o r temperature ranging between 70° and 80°F. Largemouth Bass showed preferen-ce to l i v e i n the warm epilimnion iirhile Drum tended to l i v e i n the cooler water only. Drum occupied the thermocline but when stagnant water moved in t o that l a y e r , they moved downwards i n cooler water instead of coming up i n t o w e l l aerated but warm water above. Spotted Bass and Shad showed the same tempera-ture preference as Walleye. The wide spread of Carp and Redhorse was, accord-ing to Dendy, an i n d i c a t i o n of the wide temperature tolerance of these species. Another instance of temperature a f f e c t i n g the d i s t r i b u t i o n of f i s h can be seen i n the work of Martin and Baldwin (1958: i n Ferguson, 1958). In two lakes of Algonquin Park, Ontario,, the hybrid of S a l v e l i n u s (fontinalisxnamaycush) was found to occupy three d i f f e r e n t depth zones i n three d i f f e r e n t years and t h i s apparently r e s u l t e d from the change i n depth and p o s i t i o n of the thermo-c l i n e over the years. H i l e and Juday (1941) also mentioned the importance of temperature as a f a c t o r regulating the s p a t i a l d i s t r i b u t i o n of f i s h but they believed that - 1 1 4 temperature does not work alone. They f u r t h e r mentioned that the same species of f i s h might d i s p l a y preference f o r d i f f e r e n t temperature zones i n d i f f e r e n t lakes. Perch were found to inhabit the shallow and warm water i n 3-5 meter zone i n Nebish, Trout and S i l v e r lakes, but the same f i s h displayed a marked p r e f e r -ence f o r the deeper and cooler areas i n Muskellunge Lake. A s i m i l a r v a r i a b i l i t y i n temperature preference of a s i n g l e species i n d i f f e r e n t lakes was recorded by Pearse ( 1 9 2 1 ) i n the case of Rock Bass. Bryan and Howell (1946) suggested that i n uniform temperature, depth d i s t r i b u t i o n of f i s h i s regulated by other f a c t o r s . In two interconnected lakes i n Algonquin Park, Ontario, Whitefish (genus Coregonus), Lake Trout and Burbot were found to exhibit a d e f i n i t e migration from the warmer lake to the cooler one when temperature i n the warmer lake reach 1 2 ° C i n summer (Kennedy, 1 9 4 1 ) . E f f e c t of a thermocline on f i s h d i s t r i b u t i o n has been discussed by various authors. The thermocline i s looked upon as a n a t u r a l boundary w i t h i n the lake that l i m i t s the d i s t r i b u t i o n of f i s h . Fry (1939: i n Ferguson, 1958) pointed out that the sharpness of the thermocline i n e a r l y summer i n Lake Opeongo determines the a v a i l a b i l i t y of Perch to Lake Trout. Bardach (1955« i n Ferguson, 1958) r e l a t e d oxygen conditions to Perch d i s t r i b u t i o n when he considered the e f f e c t s of shallow and deep thermoclines i n lake West Okobogi. From the work of Dendy i n Norris r e s e r v o i r , i t appears that f i s h can overcome f the b a r r i e r of the thermocline f o r at l e a s t a temporary period when confronted with other unfavourable environmental f a c t o r s . In Lake N i p i s s i n g , Ciscoes were found to p i e r c e the thermocline i n l a t e summer and e a r l y f a l l when conditions of dissolved gases i n the hypolimnion became i n t o l e r a b l e . Ferguson (1958) i n d i c a t e d that the evidence at hand i s not s u f f i c i e n t to reach a f i r m conclu-sion on the thermocline as a b a r r i e r t o f i s h d i s t r i b u t i o n . 115 Temperature influence i n Nicola Lake The fin d i n g s discussed above r e l a t e d to f i s h species that are not a v a i l -able i n Nicola Lake, and an exact comparison of the conditions i s , therefore, not p o s s i b l e . Temperature preferences of the various species i n Nicola Lake are not very c l e a r . The p i c t u r e becomes a l l the more complicated by the appearance of the same species i n d i f f e r e n t thermal zones i n the d a y l i g h t and at night. A v a i l a b i l i t y of Peamouth Chub i n a l l temperature zones probably i n d i c a t e s that the species can t o l e r a t e a wide range of temperature conditions i n case of necessity. Redside Shiners are known to have a preference f o r the e p l i l i m n i o n but here they showed a tolerance f o r the environment i n the hypo-limnion during d a y l i g h t hours. A general conclusion cannot be drawn as the samples obtained are not of s i g n i f i c a n t s i z e . Squawfish tend to remain above the thermocline with occasional exceptions when they were taken within a short distance below the upper l i m i t of the thermocline. This occasional penetration of the thermocline was probably induced by some other f a c t o r s . Burbot, knowm as deep and coo l water dwelling species, appeared i n the shallow water zones, p a r t i c u l a r l y at night. Kokanee, a col d water species, were also found i n shallow warm water i n summer. This migration of Kokanee was apparently s t i -mulated by t h e i r spawning a c t i v i t y . Thus i t may be i n f e r r e d that to meet other n e c e s s i t i e s of l i f e , f i s h can temporarily l i v e i n zones with temperature conditions that are not i n the preferred l i m i t but are w i t h i n the l i m i t of t h e i r tolerance. The thermocline i n Nicola Lake appeared very unstable. Twice during the summer of 1958, once on 28 J u l y and again on 25 August, no thermocline was seen. In other periods of summer, the thermocline was found to s h i f t p o s i t i o n frequently. How f a r t h i s s h i f t i n the thermocline a f f e c t e d f i s h d i s t r i b u t i o n i s d i f f i c u l t to estimate from the a v a i l a b l e data. Observations 116 of Fry (1937) i n the case of Cisco and movement pattern of Peamouth Chub, Redside Shiners, Burbot and Rainbow Trout tend to show that f o r these species, the thermocline does not act as a strong b a r r i e r . Ferguson (1958) points out that temperature, a c t i n g alone, can determine the d i s t r i b u t i o n of f i s h i n laboratory conditions. In nature, however, t h i s i s not po s s i b l e as other f a c t o r s such as l i g h t , oxygen a v a i l a b i l i t y , c o n d i t i o -ned response r e l a t e d to feeding routines and s o c i a l behaviour can i n t e r f e r e with the expression of response to temperature. Oxygen The second important f a c t o r that regulates the d i s t r i b u t i o n pattern of f i s h or modifies the response of f i s h to temperature i s the amount of d i s s o l v e d oxygen a v a i l a b l e i n d i f f e r e n t depths. According to Pearse (1921), maximum depth d i s t r i b u t i o n of Perch depen-ded upon the oxygen a v a i l a b i l i t y i n d i f f e r e n t l e v e l s of water. In Norris r e s e r v o i r , during the peri o d from mid-April to mid-July, when oxygen was abundant up to a depth of 100 f t . , many f i s h showed a wide range of d i s t r i b u -t i o n extending both above and below the thermocline (Dendy, 1945). But i n the presence of a stagnant density l a y e r i n the thermocline, Sauger moved up i n t o l a y e r s with s u f f i c i e n t oxygen. Black Crappie also tended t o move upwards when oxygen content i n the o r i g i n a l habitat dropped to l e s s than 1.5 p.p.m. Most of the f i s h i n Norris r e s e r v o i r stayed below the stagnant l a y e r as long as oxygen condition permitted and then passed through the stagnant l a y e r t o the w e l l aerated water above, but remained within the coldest p o s s i b l e part of the upper l a y e r s . Dendy f u r t h e r suggests that i n an environment having adequate dissolved oxygen, depth d i s t r i b u t i o n of f i s h i s determined by thermal s t r a t i f i c a t i o n . Instances are also on record where f i s h were seen to surmount the d i f f i -117 c u l t i e s of oxygen supply f o r short periods of time i n order t o meet c e r t a i n other needs. Pearse and Achtenburg (1920) found that Perch i n lake Mentoda •would go i n t o oxygen d e f i c i e n t water, stay there f o r about two hours f o r feeding and come back to the o r i g i n a l h abitat. That f i s h cannot stay i n oxygenless water f o r a longer period of time was also demonstrated by the above authors. F i s h were kept i n l a y e r s of water with .07 p.p.m. of oxygen and at the end of three hours, none of the f i s h were found a l i v e . H i l e and Juday (1941) consider that d i s t r i b u t i o n i s influenced not only by the abundance of oxygen but also by the concentration of f r e e carbon dioxide i n water. Fry (1937) suggests that upward movement of Ciscoe i n l a t e summer occurs due to depletion of oxygen i n the hypolimnion coupled with a r i s e i n ca r -bon dioxide concentration i n that l a y e r . According to Powers (1938), f i s h can l i v e i n water having a higher quantity of f r e e carbon dioxide provided the r i s e i n carbon dioxide content i s gradual. Oxygen influence i n Nicola Lake In Nicola Lake, during the summer oxygen was a v a i l a b l e i n abundance even i n deeper regions. Dissolved oxygen at a depth of 96 f t . was 3*4 p.p.m. during the peak of summer. Accordingly, d i s t r i b u t i o n of f i s h i n water of that depth and above was probably not determined by oxygen. Absence of any f i s h i n depths beyond 110 f t . might be due to low temperature and low di s s o l v e d oxygen i n that region. Dissolved oxygen at a depth of 175 f t . was found to be 1.8 p.p.m. Presence of Kokanee i n depths of 100-110 f t . might be in t e r p r e t e d as an i n d i c a -t i o n that t h i s species can t o l e r a t e both low temperature and low oxygen a v a i l a -b i l i t y i n water. Bottom conditions Condition of the bottom and configuration of the slope of the basin are l i s known to exert some influence i n determining f i s h d i s t r i b u t i o n ( H i l e and Juday, 1941). Bryan and Howell (1946) compared the a v a i l a b i l i t y of f i s h on the bottom i n Norris r e s e r v o i r and Wheeler r e s e r v o i r . In the former, c e r t a i n species of f i s h were always found on the bottom but i n the l a t t e r r e s e r v o i r , the same f i s h e s were found to keep away from the bottom. This d i f f e r e n c e was suggested to be due to the f a c t that i n Wheeler re s e r v o i r , no such accumulation occurs (Dendy, 1948). Haslbauer (1945) discussed the r e l a t i o n s h i p of f i s h d i s t r i b u t i o n to bottom conditions with reference to the feeding habits of f i s h . He r e l a t e d the r e l a t i v e l y higher abundance of Sauger, Walleye, Drum, Shad and Carp near the bottom to the feeding behaviour of these species. Fry (1937) believed that presence of f i s h i n any p a r t i c u l a r stratum of water depends on the r e l a t i o n of that stratum to the bottom. Jji Nicola Lake, the d i s t r i b u t i o n of f i s h can be r e l a t e d to the bottom only as f a r as feeding was concerned. Chiselmouth were found i n an area with bottom conditions that favour growth of the food f o r the species. Appearance of Mountain Whitefish i n midwater may be ascribed to the poor bottom conditions of the lake. Light. Role of l i g h t as a determinant of f i s h d i s t r i b u t i o n , p a r t i c u l a r l y i n deeper water, i s not c l e a r l y understood. Dendy (1945) pointed out that game f i s h i n Norris r e s e r v o i r showed no tendency to be r e l a t e d t o l i g h t i n t e n s i t i e s . Discussion by Dendy does not contain any information on the changes of d i s t r i -bution that might occur i n daylight and a t night. The statement of Dendy, therefore, i s d i f f i c u l t to accept so f a r as v a r i a t i o n i n the movement of f i s h over 24-hour period i s concerned. References t o 24-hour v a r i a t i o n i n f i s h movement are not numerous. Russel (1926 and 1928) reported v a r i a t i o n i n v e r t i c a l d i s t r i b u t i o n of the |19 pelagic young of various Teleostean f i s h i n Plymouth area during d i f f e r e n t periods of a day. In Lake Nipigon, Coregonid f i s h were taken i n greater num-bers i n nets set at night (Hart, 1931)• Yellow Perch were found to migrate upwards at night (Pearse and Achtenburg, 1920). H i c k l i n g (1927) i n d i c a t e d that Hake migrate upwards at night. Bryan and Howell (1946) considered that d i s t r i -bution of f i s h i n Wheeler resejrvoir i s regulated by l i g h t conditions when tem-perature i s uniform. Carlander and Cleary (1949) observed that Gatostomus  commersonii show a s t r i k i n g degree of change i n habitat i n d i f f e r e n t periods of the day. In daylight, t h i s f i s h was taken i n nets set i n deeper water, but at night, f i s h appeared only i n nets set i n shallow water. Light i s believed to exert influence on movement by regulating the a c t i v i t y pattern of f i s h . Some f i s h are found to remain i n a c t i v e i n higher l i g h t i n t e n s i t i e s as i n the day. According to H i c k l i n g (1927), Hake remain i d l e and i n a c t i v e during the hours of daylight. Some f i s h , on the other hand, remain a c t i v e during daylight but become quiescent i n the hours of darkness. In an experimental study on 24-hour change i n the feeding a c t i v i t y of young Salmon and Trout, Hoar (1942) observed that at night a quiescence overcame the f i s h l eading to a complete cessation of t h e i r feeding a c t i v i t y . This phenomenon was i n t e r p r e t e d by the author as a sleep condition i n the hours of darkness when food i s l e s s l i k e l y to be a v a i l a b l e . Hasler and Villemonte (1952) observed quiescence and sleep c o n d i t i o n at night i n Perch i n Lake Mendota. In daylight, Perch were found moving i n compact schools i n water l e v e l s f a r above the bottom. In the presundown period, these schools were found to move inshore on t o a s h e l f but kept above the bottom. The maximum concentration of Perch i n the inshore region occurred j u s t before evening. When l i g h t i n t e n s i t y drops o f f sharply during the t w i l i g h t hours, f i s h s e t t l e d down on the bottom as i s o l a t e d i n d i v i d u a l s . I t was postu-l a t e d by the authors that with approaching t w i l i g h t the Perch, accustomed to 120 seeing one another, l o s e t h e i r tendency to school, s e t t l e t o the bottom and maintain contact with sand. I t was also considered possible that t h i s noctur-n a l quiescentobehaviour could have s u r v i v a l value i n escaping n a t u r a l enemies l i k e Northern Pike which hunt f o r food at night and can perceive the prey p r i n c i p a l l y by v i b r a t i o n s r e s u l t i n g from the l a t t e r ' s swimming movement. In contrast to the above, various f i s h are known to become a c t i v e at night. The reasons why some f i s h become more a c t i v e i s not c l e a r . Probably l i g h t a f f e c t s movement d i r e c t l y as w e l l as i n d i r e c t l y through i t s i n f l u e n c e on the behaviour of food organisms (Hasler and Bardach, 1949). The s c a t t e r i n g of Redside Shiners at night was suggested to be i n response to increased a c t i v i t y (Lindsey, 1953). Light i n f l u e n c e i n N i c o l a Lake In the present study, Redside Shiners and Peamouth Chub were found to move i n t o the surface and midwater at night a l l throughout the summer. Besides, they were also found to come i n t o very shallow regions close to shore. During the hours of daylight, they seldom appeared i n the areas mentioned above. The spawning movement of Kokanee also was found t o commence a f t e r n i g h t f a l l , reaching i t s peak i n the hours of maximum darkness. S i m i l a r l y , Burbot vrere found i n the shallower waters at night only. Mountain Whitefish and Largescale Suckers also showed a tendency of coming close to shore at night. Squawfish a l s o appeared i n areas other than on the bottom at night. This changed pattern i n d i s t r i b u t i o n may be associated with the increased feeding a c t i v i t y of Redside Shiners and Peamouth Chub. Redside Shiners obtained i n seine hauls at night were found to have t h e i r stomachs gorged with food. In the case of Rainbow Trout, more specimens were taken at night, suggesting that t h i s f i s h does not become quiescent at night under n a t u r a l conditions. 121 Offshore and inshore movement Evermann and Clark (1920) observed that i n Lake Masancucke, Suckers and Rock Bass move inshore on s t i l l nights. Spoor and Schloemer (1938) poin-ted out that Suckers i n Muskellunge Lake move inshore i n the evening and off-shore i n the morning. The findings of Carlander and Cleary (1949) mentioned earlier can also be treated as another evidence of the existence of inshore movement of f i s h at night. In the present study, an attempt was made to detect the existence of inshore and offshore movement of different species of f i s h . Results obtained were not clear i n the case of most species, as the number i n each sample was very small. In the case of Peamouth Chub and Redside Shiners only, a s i g n i -ficant pattern of movement away from shore was detected. No variation i n the offshore direction of movement i n different periods of day or i n different periods of the summer could be detected from the samples. This, however, does not appear reasonable. If f i s h had moved offshore, they should come back to the shore region sometime to show up i n the net sets i n offshore direction the next time. The net sets from which samples were analysed for detecting movement pattern (net sets i n stations 17, 7 and VI) were within about 150 f t . from shore. Within this short distance from shore, f i s h probably move about i n a rather circular fashion instead of making a movement perpendicular to shore, and i n the process of their oblique movement, some schools of f i s h hit the nets from one side only. Existence of a la t e r a l movement along shore could be detected from the net that was set perpendicular to shore across stations IV and VI. Cn the other hand, i f only the seine haul results are viewed, the existence of an inshore movement i n the evening and offshore movement i n the morning can be noticed i n the case of Redside Shiners, Peamouth Chub, Mountain Whitefish and Largescale Suckers. 122 The factors believed to induce movement and regulate spatial distribut-ion of fish seem to act independently. Although the principal factors tend to dominate, some local factors may act as modifiers. Thus fish are obliged to reorient their distribution, to a certain extent keeping within the general framework set up by the major factors of temperature and oxygen. 123 VII. SUMMARY AND CONCLUSION The spatial distribution of f i s h species i n Nicola Lake, their move-ment i n day and at night and variation thereof i n different periods of the summer have been studied. The pattern as observed i n each f i s h species are summarized below. 1. Peamouth Chub - This f i s h generally stays on the bottom i n the daylight a l l through the summer. In the evening, a spreading of the f i s h occurs from bottom towards the surface. Intensity of this spreading varies i n different periods of summer. In early and mid summer, they remain almost uniformly dis-tributed i n a l l levels from surface to the bottom but i n late summer more f i s h are seen on the bottom and i n midwater than on the surface. Towards late night and early morning, they leave the surface and midwater for the bottom. This trend i s noticeable only i n mid and late summer whereas i n early summer, no such trend i s detectable from the f i s h sampled. Existence of a significant offshore direction of movement i s revealed by some of the samples. But no variation i n the direction of movement with change of light conditions or with changes i n the season i s revealed by the samples. During the hours of darkness, they appear to move about parallel to shore. The f i s h l i v e i n water up to 80 f t . deep during summer. Thermal str a t i f i c a t i o n does not appear to hinder the vertical movement of the fi s h . Young-of-the-year of Peamouth Chub l i v e i n schools i n very shallow areas along shore a l l around the lake i n the daylight i n association with the young of other Cyprinid f i s h and Suckers. At night, these young f i s h move offshore when young and adult of bigger size come to l i v e on the shore. 2. Redside Shiner - Redside Shiners li v e i n the bottom i n the daylight i n different periods of summer. This i s a shallow water species and i s never seen on the bottom i n deeper waters. It i s never found i n depths beyond 40 1 2 4 f t . In the evening, they spread into surface, midwater and shallower bottom zone near shore. Fish in surface water move into the open water far away from shore. During this period, more fish come to live in the surface water and on the bottom close to shore. This pattern of distribution in the evening is consistent a l l through the summer. Except in late summer, no tendency of returning to the deeper bottom from the surface level is displayed by Redside Shiners towards late night and early morning. Existence of a significant off-shore direction of movement is revealed by some of the samples of fish. This direction of movement does not appear to change with changes in the periods of day or with changes in conditions of the season. At night, Redside Shiner, like Peamouth Chub, appear to move about parallel to shore. Newly hatched fry of Redside Shiner live in the shallow shore regions in the daylight in association with the young of other species. At night, these young fry move offshore and in their place, larger Redside Shiner appear on the shore. Movement of this species does not appear to be affected by thermal st r a t i f i -cation. 3. Squawfish - In the daylight, Squawfish remain on the bottom. In early summer they appear to remain in depths up to 20 f t . but in mid and late summer, the range extends out to the bottom at about 40 f t . In the evening, Squawfish also show a tendency to become spread up in surface and midwater during early summer. Laterally they become spread on the bottom in deeper waters. In mid summer, they appear in the surface water in addition to becoming spread along the bottom. In late summer, spreading along the bottom is maintained but the tendency of going up into surface and mid-water i s not detectable from the sampling. Towards late night and early morning, they remain spread in different water levels from surface to the bottom in mid and late summer. In early summer, they are seen on the bottom close to shore only during l a t e night p e r i o d . Samples obtained do not show any s i g n i f i c a n t offshore or inshore d i r e c t i o n of movement. At night, they also appear to move about p a r a l l e l to shore. Young-of-the-year remain i n a s s o c i a t i o n with Peamouth-Chub and Redside Shiner f r y i n the shore areas i n the d a y l i g h t . With n i g h t f a l l , an offshore movement of smaller f r y and inshore movement of l a r g e r f r y and young occur i n the same manner as seen i n the case of Peamouth Chub and Redside Shiner* V e r t i c a l d i s t r i b u t i o n of. Squawfish i s inf l u e n c e d by thermal s t r a t i f i c a t i o n . They are never seen i n the hypolimnion. 4« Carp - F i n g e r l i n g s l i v e i n southeast shore regions and the southwest basin where the bottom i s muddy and contains weed beds. 5» Chiselmouth - This species i s a new record from N i c o l a Lake and the Thomp-son River drainage system. They l i v e e x c l u s i v e l y i n the warm and shallow south-west basin which, as a habitat, i s d i f f e r e n t from the deep portion of the l a k e . Young of the f i s h are a v a i l a b l e i n the N i c o l a River o u t l e t i n numbers. 6. Longnose Dace - Dace l i v e a l l around the lake i n shallow waters close t o shore. Specimens are seen t o ascend Moore Creek i n l e t i n summer. In N i c o l a River o u t l e t , they are a l s o a v a i l a b l e . 7« Largescale Sucker - Largescale Sucker l i v e on the bottom i n t h e daylight during the e n t i r e period of summer. In the e a r l y summer, no Sucker are seen > on the bottom i n 10 f t . depth zone while i n l a t e summer, none are found around 20 f t . depth zone. In the evening, they remain i n the bottom but get spread i n a l l depths from shore t o 40 f t . depth zone and congregation i n d i f f e r e n t depths changes s l i g h t l y . Towards l a t e night and e a r l y morning, d i s t r i b u t i o n remains more or l e s s the same as seen i n the evening. I t s d i s t r i b u t i o n i n d i c a t e s that i t i s a bottom dwelling species and prefers to l i v e i n areas close to shore. 126 Vertically, i t remains distributed up to 80 f t . bottom i n early summer only but, subsequently, moves into the shore zone. Young-of-the-year l i v e i n the daytime very close to shore a l l around the lake except i n the rocky margins. In the shores of southwest basin, young are seen i n larger schools. At night, young f i s h move offshore while larger size group of f i s h come inshore. Ther-mal str a t i f i c a t i o n does not act as a complete barrier i n i t s movement. 8. Bridgelip Sucker - This species i s available i n a l l major regions of the lake but i s not as abundant as the Largescale Sucker. Relatively more of this f i s h are available i n the southwest basin. Seine hauls i n the Nicola River outlet show that young of this f i s h frequent the stream i n large numbers. 9. Kokanee - This i s the only species of f i s h that lives i n depths up to 110 f t . during summer. In daylight, they l i v e on the bottom of the lake i n deeper regions during the whole summer. In the evening they tend to come near shore and into the upper levels of water during early summer. In mid summer, they also are seen on the bottom i n shallow zones i n the evening. In late summer, sprea-ding i n a l l levels of water i s marked. This phenomenon i s related to the spawning activity of the f i s h . They ascend the Moore Creek inlet for spawning during late summer. Towards late night and morning, f i s h go back into deeper regions i n early and mid summer but i n late summer, they are found to remain spread even after dawn. No significant offshore or inshore direction of movement i s detectable i n this case. Thermal str a t i f i c a t i o n does not appear to stand as a barrier for this f i s h i n i t s vertical migration. 10. Chinook Salmon - Adults of this species move into the shallow waters i n the evening. The adults sampled are found to be almost ripe sexually. Young 127 of the species are found to move into the inlet stream at night and stay close to the streams. Seine hauls in the Nicola River outlet show large numbers of young descending the stream. 11. Rainbow Trout - Rainbow Trout live in open water during the summer. They never live close to the bottom. A l l through the season, they are mostly found in areas away from the shore. At night, they show a tendency to come closer to shore, as indicated by their appearance in 10 and 20 f t . bottom zones sev-eral times during the season. In mid summen they remain distributed from mid-water and downwards in the daylight but in the evening and night, get spread into the surface levels of water. Ih late summer, they appear in the surface water at night only. They live in intermediate depths during summer and are never found in depths of 80 f t . or more. Sample sizes are too small for the purpose of studying direction of movement. Thermal stratification does not appear to hinder the movement of this fish in the vertical plane. 12. Dolly Varden - This is also a bottom dwelling form and is found to live on the bottom away from shore. In this lake, they are never found in 80 f t . or deeper water. They also come into shallow waters at night presumably for the purpose of feeding. Invasion of shallow water appears to occur in early summer only. This fish seems to have a preference for living in the hypolim-nion. 13. Mountain Whitefish - This i s a bottom dwelling species and lives in the open water area. In early summer, they remain on the bottom in deeper waters during the periods of daylight, evening and night. In mid summer, they come to live in the shallow shoreward region and are seen on the 10 f t . bottom in the daylight, evening and at night. In the evening in mid summer,spreading occurs into midwater from where they come back to the bottom in the morning. Disappearance of the fish from the deep portion of the lake in late summer is associated with their sexual maturity. During this period, they appear in 123 large numbers i n the southwest basin i n front of the Nicola River outlet. Young Whitefish come into different regions of shore during night only. 14. Burbot - It i s also a bottom dwelling f i s h and occupies the bottom areas i n depths /ranging from 20 to 80 f t . i n early summer. In mid and late summer no f i s h are seen i n 80 f t . of water. At night only, they come into the shallow areas close to shore presumably to feed upon other fishes. While following the school of Kokanee, they come into Moore Creek i n l e t mouth. They are never found i n the southwest basin during the whole period of summer. 1$. Prickly Sculpin - This f i s h usually remains on the bottom up to a depth of 20 f t . during the daylight and at night. Once i n early summer, one f i s h was found on the bottom i n 80 f t . Young Sculpins are found to move about along the shore a l l around the lake i n the daylight i n association *d.th the young of Cyprinid and Catostomid fishes. At night, bigger individuals come into the shore region. 16. Fish Association: Two broad associations of f i s h are noticeable during summer. One association can be defined as the shore zone association which includes Peamouth Chub, Redside Shiner, Squawfish, Chiselmouth, Longnose Dace, Carp, Bridgelip Sucker, Largescale Sucker and Prickly Sculpin. The other, open water association, includes Rainbow Trout, Kokanee, Mountain Whitefish and Burbot. In the shore zone association, the constituent fishes vary i n different region of the lake. In the deeper portion of the lake, i t consists chiefly of a l l the f i s h described above except Chiselmouth and Bridgelip Sucker. In the southwest basin, Chiselmouth and Bridgelip Sucker come into the shore zone association. Several times during the summer, fishes belong-ing to one association are found to frequent the habitat zone of the other. 129 VIII. LITERATURE CITED Allee, W. C , A. E. Emerson, 0. Park and K. P. Schmidt. 1950. Principles of Animal Ecology. ¥. B. Saunders and Co. Philadelphia. 837 PP. Beeton, A. M. 1956. Pood habits of the burbots i n the White river, a Michi-gan trout stream. Copeia ( l ) : 58. Bjorn, E. E. 1939. Preliminary observation and expreimental study of the lin g , Lota maculosa i n Wyomin. Trans. Am. Fish. Soc, 69s 192-196. Breder, C. M., Jr. and D. R. Crawford. 1922. The food of certain minnows. A study of the seasonal dietary cycle of six Cyprinoids with special refe-rence to f i s h culture. Zoologica, Sci. Contrib. New York Zool. Soc, 2: 287-327. Brink, V. C. and L. Farstad. 1949. The physiography of the agricultural areas of Bri t i s h Columbia. Sci. Abri., 29: 273-301. Bryan, P. and H. H. Howell. 1946. Depth distribution of f i s h i n Lower Whee-le r Reservoir, Alabama. Jour. Tenn. Acad. Sci., 21 ( l ) : 4-9. Cady, E. R. 1945. Fish distribution, Norris Reservoir, Tennessee, 1943* I. Depth distribution of f i s h i n Norris Reservoir. Rep. Reelfoot Lake Biol. Stn. (Reprinted i n Jour. Tenn. Acad. Sci., 20(1): 103-114. Cahn, A. R. 1929. The effect of carp on a small lake: the carp as a dominant. Ecology, 10(3): 271-274. Carl, G. C. 1936. Food of the coarsescaled sucker, (Catostomus macrocheilus). Jour. Biol. Bd. Canada, 3 : 20-25. Carlander, K. D. and R. A. Cleary. 1949. The daily activity pattern of some freshwater fishes. Am. Midi. Nat., 41: 447-452. Cartwright, J. W. 1956. Contributions to the l i f e history of the northern squawfish Ptychocheilus oregonense (Richardson). B.A. thesis, Universi-ty of British Columbia. Clemens, H. P. 1950. The food of the burbot, Lota lota maculosa (Le Sueur) i n Lake Erie.. Trans. Am. Fish. Soc, 80: 56-66^ Clemens, W. A. 1934* The food of young spring salmon i n Shuswap lake, British Columbia. Can. Field Nat., 48: 142. 1939. The fishes of Okanagan Lake and nearby water. Bull. Fish. Res. Bd. Canada, 56: 27-38. Clemens, W. A. and J. A. Munro. 1934. The food of the squawfish. Pr. Reprt., Pac. Biol. Stn., 19: 3-4. Clemens, W. A., D. S. Rawson and J. L. McHugh. 1939. A biological survey of Okanagan Lake, Bri t i s h Columbia. Fish. Res. Bd. Can., Bull. 56: 1-70. 130 Grossman, E; J. 1957. Factors involved in the predator-prey relationship of Rainbow trout (Salmo gairdneri Richardson) and Redside shiners Richardso-nius balteatus (Richardson) in Paul Lake, British Columbia. Ph.D. thesis, University of British Columbia Curtis, B. and J. C. Fraser. 1948. Kokanee in California. Calif. Fish and Game, 34: 111-114. Delacy, A. C. and W. M. Morton. 1942. Taxonomy and habits of the Chars, Sal-velinus malma and alpinus of Karluk drainage system. Trans. Am. Fish. Soc, 72: 79-91. Dendy, J. S. 1945. Fish distribution, Norris Reservoir, Tennessee, 1943* II. Depth distribution of fish in relation to environmetal factors, Norris Reservoir. Rep. Reelfoot Lake Biol. Stn., (Reprinted in Jour, Tenn. Acad. Sci., 20(1): 114-135. 1946. Further studies of depth distribution of fish in Norris Reser-voir Tennessee. Jour. Tenn. Acad. Sci., 2 l(l): 94-104. 1948. Predicting depth distribution of fish in three T.V.A. storage type reservoirs. Trans. Am. Fish. Soc, 75: 65-71. Evermann, B. W. and H. W. Clark. 1920. Lake : Maxincucke—A physical and biological survey. Indiana Dept. Cons. Publ., 7(1): 286-287. Ferguson, R. G. 1949. The interrelation 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, Univ. of B. C. 1958. The preferred temperature of fish and their midsummer distri-bution in temperate lakes and streams. Jour. Fish. Res. Bd. Can., 15(4): 607-624. Foerster, R. E. and W. E. Ricker. 1941. The effect of reduction of predac-ious fish on survival of young sockeye salmon at Cultus Lake. Jour. Fish. Res. Bd. Canada, 5(4): 315-336. Fry, F. E. J. 1937. The summer migration of the Cisco, Leucichtys artedi (Le Sueur), in Lake Nipissing, Ontario. Univ. Toronto, Studies Biol. Ser.44, (Pub. Ont. Fish. Res. Lab., No. 65): 1-91. Godfrey, H. 1955. On the ecology of Skeena River whitefish, Coregonus and Prosopium. Jour. Fish. Res. Bd. Canada, 12(4): 499-542. Hart, J. S. 1931. On the daily movements of the Coregonine fish. Can. Field Nat., 45: 8-9. Haslbauer, 0. F. 1945. Fish distribution, Norris Reservoir, Tennessee, 1943. III. Relation of the bottom to fish distribution, Norris Reservoir. Rep. Reelfoot Lake Biol. Stn. (Reprinted in Jour. Tenn. Acad. Sci., 20(l):135-38. Hasler, A. D. and J. E. Bardach. 1949* Daily migration of Perch in Lake Mendota, Wise Jour. Wild. Mgt., 13: 40-41. 131 Hasler, A. D. and J. R. Villemonte. 1953* Observations on the daily move-ments of Fishes. Sci., 118 (3O64): 321-322. Hickling, C. F. 1927. The natural history of hake, Part I and II. Min. Agri. and Fish., Fish. Investig., 10(2): 1-100. Hile, R. and C. Juday. 1941. Bathymetric distribution of f i s h i n lakes of the northeastern highlands, Wisconsin. Trans. Wise. Acad. Sci., Arts and Lett., 33* 147-187. Hoar, W. S. 1942. Diurnal variation i n the feeding activity of young salmon and trout. Jour. Fish. Res. Bd. Canada, 6(1): 90-101. Hubbs, C. L. and G. P. Cooper. 1936. Minnows of Michigan. Cranbrook Inst. Sci. Bull., 8: 1-84. Hutchinson, G. E. 1957. A treatise on Limnology. Vol. I—Geography, Physics and Chemistry. John Wiley and Sons, New York. Idyll, Clarence. 1942. Food of the Rainbow, Cutthroat and Brown Trout i n the Cowichan River System, Bri t i s h Columbia. Jour. Fish. Res. Bd. Can., 5(5): 448-458. Johannes, R. E. 1957. The feeding relationship of Rhinichthys cataractae and Rhinichthys falcatus i n British Columbia. B.A. thesis, University of British Columbia. Kennedy, W. A. 1941. The migration of f i s h from a shallow to a deep lake i n spring and early summer. Trans. Am. Fish. Soc, 70(1940): 391-396. Koster, W. J. 1937. The food of Sculpins (Cottidae) i n Central New York. Trans. Am. Fish. Soc, 66: 374-382. Larkin, P. A. 1956. Interspecific competition and population control i n Freshwater Fish. Jour. Fish. Res* Bd. Canada, 13(3): 327-342. Larkin, P. A. and S. B. Smith. 1954. Some effects of introduction of the Redside Shiner on the Kamloops trout i n Paul Lake, British Columbia. Trans. Am. Fish. Soc, 83(1953): 161-175. Lindsey, C. C. 1950. Structural variation as related to the ecology of the Redside shiner, Richardsonius balteatus (Richardson). M.A. thesis, University of British Columbia. 1953. Variation i n anal f i n ray count of the Redside shiner Richard-sonius balteatus (Richardson). Can. Jour. Zool., 31: 211-225. Mathews, W. H. 1944» Glacial Lakes and ice retreat i n South-Central British Columbia. Trans. Roy. Soc. Canada, 38(4): 39-57. McHugh, J. L. 1940. Food of Rocky Mountain Whitefish, Prosopium williamso-n i i (Girard). Jour. Fish. Res. Bd. Canada, 5(2): 131-137. Northcote, T. G. and P. A. Larkin. 1956. Indices of productivity i n British Columbia lakes. Jour. Fish. Res. Bd. Canada, 13(4): 515-540. 132 Odell, T. T. 1932. The depth distribution of certain species of f i s h i n some of the lakes of New York. Trans. Am. Fish. Soc, 62: 331-335. Odum, E. P. 1954. Fundamentals of Ecology. W. B. Saunders Co., Philadelphia: 1-384. Pearse, A. S. 1921. The distribution and food of the f i s h i n 3 Wisconsin lakes i n summer. Univ. Wise Studies Sci., 3 : 1-61. 1921. Distribution and food of the fishes of Green Lake, Wisconsin i n summer. Bull. Bur. Fish., 37: 254-272. Pearse, A. S. and H. Achtenburg. 1920. Habits of yellow perch i n Wisconsin Lakes. Bull. U.S. Bur. Fish., 36: 294-366. P i t t , T. K., E. T. Garside and R. L. Hepburn. 1956. Temperature selection of the carp (Cyprinus carpio, Linn.). Can. Jour. Zool., 34: 555-557. Powers, E. B. 1938. Factors involved i n the sudden mortality of fishes. Trans. Am. Fish. Soc, 67 : 271-281. Rawson, D. S. 1934. Productivity studies i n lakes of the Kamloops region, British Columbia. Biol. Bd. Canada, Bull. No. 42: 1-31. Richardson, R. E. 1913* Observations on the breeding of the European Carp i n the v i c i n i t y of Havana, I l l i n o i s . Bull. 111. St. Lab. Nat. Hist., 9: 387-404. Ricker, W. E. 1941. The consumption of sockeye salmon by predaceous f i s h . Jour. Fish. Res. Bd. Canada, 5: 293-313. Russel, F. S. 1926. The ve r t i c a l distribution of marine macroplankton. III. Diurnal observation on the pelagic young of teleost fishes i n the Plymouth area. Jour. Mar. Biol. Assocn., 14(2): 387-414. 1928. The vertical distribution of marine macroplankton. VIII. Furt-her observation on the diurnal behaviour of the Pelagic young of teleost-ean fishes i n the Plymouth area. Jour. Mar. Biol. Assocn., 15(3):829-50. Schultz, P. 1935. The spawning habits of the Chub, Mylocheilus caurinus. A forage f i s h of some value. Trans. Am. Fish. Soc, 65: 143-147. Spoor, W. A. and C. L. Schloemer. 1938. Diurnal activity of the common suck-er (Catostomus commersoni Lac) and the Rock bass (Ambloplitis rupestris Rafinesque) i n Muskellunge Lake. Trans. Am. Fish. Soc, 668 : 211-220. Withler, F. C. 1948. Fish predation on the young sockeye i n certain lakes of the Skeena River drainage as evaluated by the study of catches and sto-mach contents of the predators obtained by g i l l netting. M.A. Thesis, University of British Columbia. Van Oosten, J. and H. J. Deason. 1937- The food of the lake trout (Salveli-nus namaycush) and of the Lawyer (Lota maculosa) of Lake Michigan. Trans. Am. Fish. Soc, 67: 155-157. 

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
http://iiif.library.ubc.ca/presentation/dsp.831.1-0106197/manifest

Comment

Related Items