REPRODUCTION OF THREE SPECIES OF SUCKERS (CATOSTOMIDAE)
IN BRITISH COLUMBIA.
by GLEN HOWARD GEEN
B. A., University of British Columbia, 1955.
A Thesis Submitted in Partial Fulfilment of the
Requirements for the Degree of
Master of Arts
in the Department
of
Zoology.
We accept this thesis as confirming to the required standard.
THE UNIVERSITY OF BRITISH COLUMBIA
April, 1958. ABSTRACT
Reproduction of three species of suckers, Catostomus catostomus, the longnose sucker, Catostomus commersoni, the white sucker, and Catostomus macrocheilus, the largescale sucker, has been studied in British Columbia during the summers of 1956 and
1957. These species spawned in the spring months depending on locality and annual differences in climate. 'White and longnose suckers spawned primarily in inlet streams although moderate runs of the former to outlet streams have been noted. Largescale suckers usually spawned in outlets. No lake spawning was observed. Over• lap of breeding seasons and co-habitation of the same spawning stream by white and largescale suckers may explain occasional hybridization between these species. Spawning females matured a year later, were larger and lived longer than the males of all three species. Detailed work at Baker Lake, near Quesnel, indi• cated males entered the spawning stream before the females and generally remained till the females had returned to the lake. In
1956 the sex ratio of white suckers was 1:1. In 1957? 2 males to
1 female were present in the spawning stream. Low water levels may have prevented larger females, which were predominantly marked, from moving upstream. As a result of these conditions fish may have spawned in other streams thus masking any tendency to return to the same stream in successive years. The longnose suckers sex ratio of 2 marked females : 1 marked male suggests that a differen• tial mortality acting either from hatching or after first spawning is in effect. Numbers of unmarked fish were not significantly different. , Factors associated, with migrations at Baker Lake were studied. Adult migration was primarily at night. Numbers-, of white suckers migrating into the inlet stream were dependent on temperature change from one day to the next. A similar situation prevailed during the main portion of the longnose sucker run but no such relationship existed at the beginning of the run. Limno- logical conditions in the lake may have influenced migration to the creek. Fry in the inlet streams moved downstream at night.
The migration was halted by placing a gas lantern over the creek.
Juveniles remained in the outlet- stream up to four years before entering the lake. Their migration into the lake was related to rising temperature. In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the Head of my Department or by his representative. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission.
Department of ^-^n^ The University of British'Columbia, Vancouver 8, Canada.
Date Jl IfSt TABLE OF CONTENTS
PAGE
I. INTRODUCTION 1
II. ACKNOWLEDGMENTS 3
III. PROCEDURES k
Study Sites. k
Collection of Data 7
Fish Traps 7
Other Methods of Sampling Fish 9
Marking "..... 12
Meteorological and Limnological Data
Collected ih
Age Determination 15
Preservation of Specimens 15
Nomenclature 15
IV. THE LONGNOSE SUCKER 17
Spawning Locality 17
Timing and Duration of Spawning Runs 20
Characteristics of Areas Used for Spawning. 2k
Size Distribution of Baker Lake Inlet
Spawners ••• 2if
Age of Spawning Fish in the Baker Lake
Inlet Run 26
Sex Ratio of Spawners Ascending Baker Lake
Inlet 27
Length of Time Spent in the Inlet at
Baker Lake. . 31 PAGE
Sex Ratio of Eish Descending to Baker Lake.
After Spawning 3^-
Sexual Condition of Fish Migrating Upstream 36
Distribution of Spawners in Baker Inlet
Creek 36
Survival in Baker Lake Inlet hO
Extent of Utilization of Same Spawning
Stream by Longnose Suckers in Successive
Years
Incubation Period .' *+2
The Early Life of the Fry and Fingerlings.. h2
V. THE "WHITE SUCKER Mf
Spawning Localities . *+5
Timing and Duration of the Spawning Run.... k6
Characteristics of Spawning Grounds k-8
Age at Spawning 1 ^9
Size Distribution of Spawners 50
The Sex Ratio of White Suckers Ascending
the Baker Lake Inlet 51
Length of Time Spent in the Spawning Stream %
Survival of Spawning Adult White Suckers in
Baker Lake Inlet Stream 59
Distribution of Spawners in the Inlet
Stream 60
Extent of Utilization of the Same Spawning
Stream by White Suckers in Two Successive
Years 60 PAGE
Incubation Period of Eggs <. 6l
Early Life of "White Sucker Fry and
Fingerlings 62
VI. THE LARGESCALE SUCKER 6k
Spawning Locations 65
Comparative Dates and Duration of Spawning
. Runs 66
Hybridization of Largescale "White Suckers... 67
Size Distribution of Spawners 70
Age of Spawning Largescale Suckers 71
Survival of Adults 71
Characteristics of Areas Utilized for
Spawning 72
Incubation Period of the Eggs 72
Early Life 72
VII. FACTORS INFLUENCING MIGRATIONS 7 4
Literature Review 7*+
White Suckers 76
Longnose Suckers 81
Diurnal Movement of Longnose and Hhite
Suckers 88
Factors Associated' with the Return of
Juvenile Longnose Suckers to the Lake 91
VIII. CONCLUSIONS AND SUMMARY 98
Spawning Localities of Suckers 98
Timing and Duration of Spawning Runs 99 PAGE
Size and Sex Ratio of Spawning Fish 100
Age of Spawning Suckers... 102
Sexual Differences in the Movement into and
out of the Stream 103
Survival of Spawning Fish 103
Distribution on Spawning Grounds 10*+
Nature of Spawning Grounds 10h
Streams Used for Successive Spawnings 105
Factors Influencing Spawning Migration'of
Suckers 106
Factors Associated with Lakeward Migration
of Fry and Fingerlings 109
IX. LITERATURE CITED 113 LIST OF FIGURES
FIGURE PAGE
1. Baker Lake near Quesnel, B. C, indicating
streams, trap sites and lake depth contours... 6
2. Baker Lake outlet trap viewed from downstream.
Wire screening acts as lead to ascending
section of trap which is on the right side of
the photograph 10
3. Baker Lake outlet trap viewed from right bank.
Descender trap on the left side of the photo•
graph 10
h. View from downstream of Baker Lake inlet trap
at low water. Screen acts as lead to ascender
trap (right side) and descender trap 11
5. Sketch of hypothetical sucker to show location
of marking sites 16
6. Length-frequency distributions of male and
female longnose suckers in Baker Lake inlet. • 1956 25
7. Length-frequency distributions of marked and
unmarked spawning longnose suckers in Baker
Lake inlet. 1957. Marked fish returning as
multiple spawners 28
8. Daily number of male and female longnose
suckers moving upstream in Baker Lake inlet
during 1956 spawning run. Male catch super•
imposed on female catch 32 FIGURE PAGE
9. Length of time spent by portions of longnose;,
sucker run in the inlet spawning stream at
Baker Lake as determined from date of marking
and dates of return through descender trap. 1956 33
10. Movement of male and female longnose suckers
through Baker Lake inlet descending trap as
measured by daily catches. 1956. Male catch
superimposed on female catch ... 35
11. Daily numbers of green and ripe female long•
nose suckers in Baker Lake inlet trap. May
1956. Ripe fish superimposed on green fish.. 37
12. Length frequency of spawning male and female
white suckers in Baker Lake inlet. 1956 52
13. Daily numbers of male and female spawning
white suckers ascending Baker Lake inlet
trap. 1956 53
lk-. Length-frequency of marked and unmarked
spawning white suckers passing through
ascender trap in Baker Lake inlet. May 1957*
Marked fish returning as multiple spawners... 55
15« Time spent by portions of the white sucker
run in the inlet spawning stream at Baker
Lake as determined from the date of marking
and dates of return through descender trap. 1956 57 FIGURE PAGE
16. Daily number of spent male and female white ^
suckers in Baker Lake inlet descending trap. 1956 58
17. Number of white suckers migrating up Baker
Lake in relation to the change in daily max•
imum temperature from previous day. 1956.... 77
18. Relationship of daily maximum temperature
change, water levels and number of white
suckers moving into Baker Lake inlet. May 1957 78 19. Probit analysis of arrival frequencies of
longnose suckers in Baker Lake inlet com•
pared with daily maximum temperature. May 1956 86
20. Probit analysis of arrival frequencies of
longnose suckers in Baker Lake inlet compared
with daily maximum temperature. May 1957•••• 87
21. Diurnal movement of longnose and white
suckers in Baker Lake inlet compared with
stream temperature and periods of daylight.
and darkness. May 1^-16, 1957 90
22.. Relationship of temperature change from
previous day to the numbers of longnose
sucker fingerlings moving up the Baker Lake
outlet. 1956 95. LIST OF TABLES-
TABLE PAGE
I. Latex injection marks used on Baker Lake long•
nose and white suckers. Spring 1956. Each
] mark used for two days during main portion of
run 16
II. Timing and duration of spawning runs of long•
nose suckers. 1956. Lakes in increasing order
of latitude. Dates approximate 20
III. Numbers of marked and unmarked longnose suckers
in Baker Lake spawning streams in 1957. Inlet
A (main inlet in Fig. 1) was site of 1956
marking hi
IV. The incubation period of longnose sucker eggs
at three temperatures h2
V. Timing and duration of 1956 white sucker runs
in Four Lakes in the Quesnel-Prince George area
Dates approximate. Temperature approximately
daily maximum... h6
VI. Survival of marked white suckers in Baker Lake
during the 1956 spawning run. The two day
periods were indicated by distinctive marks.... , 59
VII. Numbers of marked and unmarked white suckers in
Baker Lake spawning streams. 1957. Inlet "A"
was site of 1956 marking 6l
VIII. Counts of white largescale and hybrid suckers
from Summit Lake indicating the intermediacy of
the taxonomic characteristics. Counts by
CC. Lindsey. 68 I. INTRODUCTION
The suckers of the genus Catostomus are among the most widely distributed fish in North America. Several species, such as the white sucker, Catostomus commersoni (Lacepede) and the longnose sucker, Catostomus catostomus (Forster) are found in the waters of the western portions of Canada and the United States, extending across these two countries and the Northwest Territories to the east coast of North America and southward to the Gulf of
Mexico. Rostlund (1952) illustrates the range of the genus in
North America.
In spite of their common occurrence and wide distribution, little of the general biology of the genus Catostomus is known.
A few-detailed studies have been carried out but the majority of the literature which is published on members of this genus deals with a taxonomic description of the fish or discusses them in a very superficial manner.
This thesis presents some of the information which has been collected on three of the species of suckers in British Columbia.
Some insight into the more general features of the biology of the members of the genus Catostomus has been obtained by comparing the results of this study and those of other investigators. The results may also have some value in the management of sport fish• eries, as these species often occur in lakes and streams from which non-sport fish are to be removed by lake poisoning.
Five species of suckers are present in British Columbia. . The stream life of three species, Catostomus catostomus, Catostomus commersoni and the largescale sucker, Catostomus macrocheilus Girard, has been studied in some detail and the results are presented in - 2 - this thesis,. Two other species of suckers which occur in the province are primarily river dwelling forms. They are Catostomus columbianus (Eigenmann and Eigenmann), the bridgelip sucker, and and Pantosteus Jordan! Evermann. the northern mountain-sucker.
Insufficient information has been collected on these two species to merit their inclusion in this thesis. - 3 - II. ACKNOWLEDGMENTS
The author would like to express his appreciation to the
many people who have assisted in one way or another in the col•
lection of the data which have been used. G. Atkinson,
E. Crichlow, A. Hanslip, G. Hartman, H. Lorz, W. McLaren,
D. McPhail, K. Ricker and G. Sparrow all spent time at Baker Lake
assisting with the.work.
T.G. Northcote spent a great deal of time and effort on this
work during the summer of 1957 and%criticized the manuscript. His
valuable assistance is gratefully acknowledged.
The author is grateful to the British Columbia Game Commission
for the opportunity of using the data collected by the Fisheries
Research Division during the summers of 1956 and 1957.
P.A. Larkin and G.F. Hartman read the thesis and offered many helpful suggestions and criticisms.
The author would like to express his appreciation to his wife,
Olga, who typed the thesis.
The co-operation and tolerance of Mr. and Mrs. Peter Thomas
and family of Baker Lake is gratefully acknowledged.
And finally, the author wishes to express his sincere appre-
ciation to Dr. CC. Lindsey who devoted much time and effort to
guiding the work and assisting with all phases of the programme. III. PROCEDURES
Study Sites.
Data for this study have been collected throughout the province of British Columbia. However, the major portion of the detailed work was in the Quesnel-Prince George area in a group of seven lakes.
A field crew stationed at Baker Lake, some fifteen miles east of Quesnel on the Wells-Barkerville road, was responsible for the collection of data on the fishes in lakes and streams of this area during the summers of 1956 and 1957> concentrating primarily on
Baker Lake.
Baker Lake, as shown in Fig. 1, is a relatively small lake of eighty acres. The maximum depth of this brown-stained lake is
2k feet and the mean depth 12 feet.
Three creeks flow into this lake; one on the south-eastern side and two smaller streams on the east and south-western side.
The main inlet stream which enters the south-eastern side of the lake flows from 15-Mile Lake, a similar small lake one mile south• east of Baker Lake. The eastern stream rises in the hills to the south of Baker Lake and enters the lake through a willow swamp.
The third stream is a small one and enters through the large bog area on the southwest corner of the lake.
The outlet stream, as can be seen from Fig. 1, flows out the north-east corner of the lake and drains from there into the
Cottonwood River some five miles away.
The main inlet and outlet are small streams. The inlet stream, which has an average width of 10 feet, has a good flow of water in - 5 - the spring and early summer months but this gradually decreases as the summer progresses and in mid-summer the stream may dry up completely.
The outlet stream maintains its flow throughout the summer.
This is due primarily to seepage through a beaver dam at the out• let of the lake. The width of this stream varies between 10 and
15 feet.
Two species of suckers, Catostomus catostomus. the longnose sucker, and Catostomus commersoni. the white sucker, are present in the lake along with rainbow trout, Salmo gairdneri (Richardson), squawfish, Ptychocheilus oregonense Richardson*and the red-side shiner, Richardsoneus balteatus (Richardson).
Since most of the time in the summers of 1956 and 1957 was spent at Baker Lake, more extensive data have been obtained on the two species of suckers occuring there than on any of the other
British Columbia catostomids.
Other data relevant to a study on the life history of suckers in B. C. have been collected by members of the Fisheries Research
Division of the B. C. Game Commission from 1953 to 1957. Much of the data were gathered as a result of collections made for the
Institute of Fisheries, University of British Columbia, in various lakes and streams of the province.
Data on the catostomids were collected specifically in the summers of 1956 - 57 when several lakes in the Quesnel-Prince George area were visited regularly. Among these were Dragon Lake, Bouchie
Lake, and the Shelley Slough in the Prince George area. Information was also collected at 108 - Mile Lake, ten miles south of Lac La Hache. Fig. 1. Baker Lake near Quesnel, B.C., indicating streams, trap sites and lake depth contours. - 7 -
Collection of Data.
The method of gathering information of the life history of
these fish varied. Often casual observations were all that were
available. Periodic observations were used to determine in a i general way the life history of the fish in the previously men•
tioned lakes and streams in the Quesnel-Prince George area.
Detailed work, supplemented by marking fish and passing them
through the traps, provided precise information at Baker Lake.
Data, when available from other sources, were compared with those
obtained in Baker Lake.
Fish Traps.
In the late summer of 1955 two-way traps, i.e. those designed
to capture fish moving upstream and downstream, were installed on
the inlet and outlet streams of Baker Lake. The trap on the out• let stream is a modification of the trap described by Wolf (1950) and is shown in Fig. 2 and 3« The trap described by Wolf was
designed only for sampling fish which were moving downstream. For
purposes of this study, however, a two-way trap was imperative.
The trap was so constructed that water flowing out of the lake
passed over a sill constructed on top of a beaver dam which was
present at the lake outlet. It then dropped onto screen panels
which were slightly inclined. The majority of the water passed
through the screens but because of the incline some of the water ran
down into a flume at the bottom of the screens. Fish which landed
on the screen after passing over the sill found their way down the
inclined screens into the flume and, thence with very little dif•
ficulty into the descending trap. - 8 -
Some of the water which passed through the inclined screens flowed into the ascender trap through screen sides, and then out the lead at the downstream end of the trap. In this way an attracting flow was present. To assist fish moving upstream in locating the appropriate trap, and to prevent them from congre• gating under the screen panels, a lead of fine mesh screen was installed from the upstream corner of the descender box to the downstream corner of the ascender box (Fig. 2 and 3). Eight mesh to the linear inch regalvanized wire screen was used on screen panels below the sill, on sides of traps and on the ascending lead fence. The lead fence and screen panels were backed with 3/V' regalvanized screen which prevented any sagging and could be used alone in times of high and dirty water.
The inlet trap was built in a manner similar to that des• cribed by Shetter (1938). Since there was no appreciable drop in the creek comparable to that in the outlet stream, a trap of other than the Wolf type was necessary. Fig. h illustrates the trap which was installed. Simply, an ascending and descending trap were placed on opposite banks of the stream with the former somewhat further upstream. The lead ends of both traps were joined by a fence of eight-mesh per linear inch screen which acted as a lead for both the ascending and descending traps.
Ascender and descender boxes of the inlet trap and the ascender box of the outlet trap were provided with leads which provided a means of entrance to and retention in the traps.
During 1956 tarred seine was used for leads. The material was attached to the open end of the trap and was tapered down to - 9 - a four inch diameter ring which constituted the actual opening to the trap. The leads were held taut by securing the ring to the sides of the trap with wire hooks. Use of this material pro• vided flexibility at various water levels. However, it rotted after extended periods in the water necessitating replacement.
This problem was alleviated in 1957 by using lA" mesh nylon material.
All boxes were provided in the centre with vertical slot "V" leads. - The width of the opening was adjusted so that it permit• ted only small fish to enter this area of the trap. In this way possible predation in the trap was reduced. Traps on inlet and outlet streams proved effective at normal water levels. Only at extremely low water did the fish in the inlet stream experience any difficulty in moving upstream into the trap.
Other Methods of Sampling Fish.
The traps which were used to capture adults were ineffective in retaining fry of the year. As the result plankton nets and
Surber type stream samplers were anchored in the stream. The latter worked especially well in capturing fry of the year that moved down the inlet creek during the night. Stream samplers were also valuable aids in collecting eggs and fry from the gravel.
In this way a good measure of the number of eggs and fry in a par• ticular area of stream bed was obtained.
Dip nets, seines, and liquid rotenone were used to collect samples of fish in the streams which were visited only periodically. - 10 -
Fig. 2. Baker Lake outlet trap viewed from downstream. Wire screening acts as lead to ascending section of trap which is on the right side of the photograph.
Fig. 3» Baker Lake outlet trap viewed from right bank. Descender trap on the left side of the photograph. - 11 -
Fig. 4. View from downstream of Baker Lake inlet trap at low water. Screen acts as lead to ascender trap (right side) and descender trap. - 12 -
Marking.
To assist in gathering precise information on the longnose and white suckers, a system of marking was necessary. Various methods for marking adults were considered but a relatively new technique described by Davis (1955) was finally decided upon. Fish were marked in the inlet and outlet stream at Baker Lake.
Adult suckers were marked in the following manner. A small drop of colored liquid latex was injected under the scales of the fish. The latex used in this work was either blue or pink. A yellow latex based paint was also used with some degree of success in the summer of 1957. Best success in marking was obtained by using a one cubic centimeter B-D tuberculin syringe and a li" #20 hypodermic needle. A hypodermic syringe proved unsatisfactory as latex tended to coagulate between the barrel and shaft of the syringe.
Adults were marked in this manner throughout the spawning run.
In order to separate the different segments of the spawning pop• ulation, a specific mark was used for each day. The position, of the marks was changed every second day. -Fig. 5 illustrates the plan of marking used in this study. Fish in the inlet stream were marked on their right side and fish in the outlet on their left side. The marking site of a specific day was designated according to the side of the fish marked, the color of the latex and the hypothetical horizontal and vertical position on the fish. Fig. 5 represents a hypothetical sucker. Four horizontal lines, des• ignated A, B, G, & D, and four vertical lines 1, 2, 3, & if were identified. Injections were made only at the intersection of a - 13 - hypothetical vertical and horizontal lines.
For the purposes of recording data collected in the field an abbreviated system was set up to identify each particular mark.
A fish was marked on either the left or right side and was des• ignated "L" or "R" respectively. The position of the mark was recorded according to the horizontal and vertical position. The color of the latex was designated as "P" for pink and "B" for blue.
Therefore R1AB meant that the fish was marked with blue latex on the right side where horizontal line "A" and vertical line "1" crossed.
Table 1 lists the marks utilized throughout the spawning run in Baker Lake inlet. Very few fish were marked in the outlet stream. The mark was changed every other day during the main por• tion of the run but less often during the last portion of the run when very few fish were moving upstream.'
Juvenile suckers were marked'by removing either the left or right ventral fin. The former was removed in the inlet and the latter in the outlet stream. No fish under 100 mm. fork length were marked or injected.
Scale samples were taken from the majority of fish over 100 mm. fork length. Several scales were removed from the left side of the fish in the region below the dorsal fin. Records on the sex and sexual condition of the adults were kept for all fish.
Marking was carried out at least once a day when the traps on the inlet and outlet streams were emptied. During periods of peak runs, the fish were marked and put into the stream at least two times a day. On several occasions the traps were emptied every - Ik - one or two hours for a period of three to four days to obtain data on the diurnal movement of the fish.
Meteorological and Limnological Data Collected.
Daily records of many physical and limnological conditions were taken at Baker Lake during the summers of 1956 and 1957.
Water levels in the streams were recorded once or twice daily.
Temperatures of the creeks were recorded at least once daily if no continuous temperature recording device was present. A
Negretti-Zambra continuous temperature recorder was used at the outlet stream and a Taylor maximum-minimum recording thermometer was used in the inlet stream. The latter was replaced by a
Weksler continuous recorder in 1957*
Daily weather records, including wind, cloud cover, air temperatures and rainfall were kept.
Data on lake temperatures in the form of periodic vertical temperature series were recorded. Water currents in the lake were measured by vanes at the surface and 15 feet. The vanes were made of two pieces of sheet aluminum two feet square set at right angles to each other to form a symetrical cross. These were suspended at the desired depth from a wooden float with a piece of wire, placed in the lake at the central buoy and the rate of movement from this point estimated.
Oxygen samples were taken with a Kemmerer oxygen bottle and analysed by the standard Winkler method. - 15 -
Age Determination.
The age of suckers was obtained from reading scales which
were taken from fish in the traps during spawning runs. The
scales were mounted on a celluloid slide which in turn was passed
through a jeweller's press. This left the impression of the
scale on the slide which was examined under the 38X magnification
of a Bausch and Lomb microprojector.
Preservation of Specimens.
All fish specimens kept for later study were preserved in a
10$ solution of formalin. The specimens collected are in the
Fish Museum at the University of British Columbia.
Nomenclature.
Nomenclature follows Lindsey (1956a) who has revised the com•
mon and scientific names of the freshwater fish in British Columbia
in accordance with a list of common and scientific names of the
better known fishes of the American Fisheries Society (TAFS list). - 16 -
TABLE I. Latex Injection marks used on Baker Lake longnose and white suckers. Spring 1956. Each mark used for two days during main portion of run.
10 May R1AP 12 May R1AB lk- May R1BP 16 May < R1BB 18 May R2AP 20 May R2AB 22 May R2BP 2k May R2BB 26 May R3AP 28 May R3AB 30 May R3BP 1 June R3BB 3 June J R^fAP 5 June RlfAB 7 June R1CP 9 June R1CB 11 June R1DP 13 June R1DB 15 June — R2CP 17 June R2CB 19 June R2DP 21 June R2DB 25 June R3CP - 17 - IV. THE LONGNOSE SUCKER
Catostomus catostomus. the longnose sucker, is probably the most widely distributed species of this genus. It occurs all across the northern half of the United States, across Canada and the Northwest Territories. A subspecies C. catostomus rostratus is found in Siberia (Walters-1955). As such it repre• sents the only member of the genus Catostomus found outside North America.
It is the most abundant and most widely distributed of the suckers in British Columbia. It occurs in most of the important river systems of the province including the Columbia, Fraser, Skeena, and Peace. Lindsey (1956b) states that it is abundant in the Peace and Liard systems and extends northward to the delta of the Mackenzie River. The longnose sucker is an important member of the fish fauna of many rivers and lakes, as it may compete with sport fish. These suckers, In some cases at least, spawn at the same time as rainbow trout, and possibly utilize the same spawning grounds the trout, disturb the redds of the trout, and compete for food with the fry and adults of the sport species. Stenton (1951) reports that Eastern brook trout eggs are consumed by longnose suckers. Since this species plays such an important role in the economy of lakes and streams, more detailed knowledge of its biology is desirable. Spawning Locality.
Observations were carried out in some detail oh four lakes in the Quesnel area in the summer of 1956 to determine where long- - 18 - nose suckers spawn.
Large runs of spawning fish were observed in the inlet streams of Baker, Bouchie, Ten-Mile and Dragon Lakes. Only a few longnose suckers were seen in the outlet streams of these lakes over the period of the summer, hut some very limited
spawning did occur in the outlet of each lake.
Lake spawning was not observed nor were any congregations of fish noted which might be indicative of it. Lake spawning must occur in certain cases however, as populations of this species persist in lakes which have no inlet or outlet streams.
A survey of the literature indicated a considerable diversity
in the spawning sites of Catostomus catostomus. Rawson and Elsey (19^8) noted that spawning occurred in the streams and certain shallow rocky parts of Pyramid Lake in Alberta. Scott (195*+)
stated that spawning of this species takes place over gravelly
bottoms of lakes and streams. The results of other workers would
seem to substantiate the view that Catostomus catostomus spawns primarily in inlet streams. Weisel (1957) mentioned the fact that short spawning migrations upstream generally occurs in May. Carl and Clemens (1953) and Brown and Graham (1953) also mention spawning runs to tributary streams.
Mention has also been made by Weisel (1957) concerning the outlet spawning of a dwarf form C. c. pocatello. Observations
by the writer in the East Kootenay region of British Columbia at
Edwards Lake also revealed a small form of the longnose sucker
spawning in the outlet stream on June 19, 1955. This was appar• ently some time after the spawning of the larger, frequently - 19 - observed longnose suckers. Larger dead Individuals were seen along the banks of the inlet stream. The possibility of pre• cocity is discussed in a later section.
Usually longnose suckers spawned in inlet streams although some spawning did occur in the outlet streams. Lake spawning, while not observed, must take place to perpetuate the species in lakes which have no streams.
Timing and Duration of Spawning Runs.
Data have been obtained on the timing and duration the annual spawning migrations of the longnose sucker. Observations on lakes in the Quesnel-Prince George area have supplied the bulk of the information but observations from other parts of the province have been useful.
The results of observations, primarily those from 1956 are presented in Table II. - 19 - observed longnose suckers. Larger dead individuals were seen along the banks of the inlet stream. The possibility of pre• cocity is discussed in a later section.
Usually longnose suckers spawned in inlet streams although some spawning did occur in the outlet streams. Lake spawning, while not observed, must take place to perpetuate the species in lakes which have no streams. - 20 -
Timing and Duration of Spawning Runs.
Data have been obtained on the timing and duration the annual spawning migrations of the longnose sucker. Observations on lakes in the Quesnel-Prince George area have supplied the bulk of the information but observations from other parts of the Province have been useful.
The results of observations, primarily those from 1956 are presented in Table II. Temperatures were recorded in the after• noon and probably approach the daily maximum. Although there was some variability in the time and weather when they were recorded, an indication of the temperature of peak spawning is obtained.
TABLE II. Timing and duration of spawning runs of long• nose suckers. 1956. Lakes in increasing order of latitude. Dates approximate.
Lake & Locality Stream Beginning Peak of End of Temp. of Run Run Run Peak-1 108-Mile Lake Lac La Hache Inlet May 1 May 10-15 May 21 55 Dragon Lake Quesnel Inlet May 12 May 21 May 31 52 Baker Lake Quesnel Inlet May 10 May 17 May 31 56 Bouchie Lake Inlet May 11 May 21 June 8 53 Quesnel Outlet Late April Early May May 15 52 10-Mile Lake Quesnel Inlet May 10 May 17 May 25 55 Shelley Slough Prince George Inlet May 9 May 23 June 1 56 Cluculz Lake Prince George Inlet May 15 May 23 June 1 53 Summit Lake Prince George Inlet May 15 May 23 June 1 55 - 21 -
The results, although approximate in some eases, indicate
that spawning dates are somewhat later in the more northerly
areas.
Although very few fish spawned in outlet streams, it appeared
that they entered these streams before the runs moved into the
inlet spawning streams. Observations from Bouchie, Dragon and
Ten-Mile Lakes in the Quesnel area supported this conclusion.
The earliest record of a mature longnose sucker in B. C, as far as can be determined, is April 2, 1956 when a mature male longnose sucker with well developed tubercles was taken in "Wolfe
Creek in the Princeton area. Mature individuals in the outlet
of Edwards Lake in the east Kootenays have been noted as late as
June 19.
All information on the timing of spawning runs gathered in
B. C. concurs in a general way with results reported from other parts of America. Wynne-Edwards (1952), Eddy and Surber (195*0>
Dymond (1926), Brown and Graham (1953) and Carl and Clemens (1953)
all report spawning runs of fairly short duration during the
spring months - generally April to June depending on the location.
An exception to the general picture of the timing of the
spawning run was recorded at Edwards Lake near Crahbrook on
June 19, 1955* At this time some small mature male and female longnose suckers were collected in the outlet of this lake.
These fish, though six inches long, were mature. The length of these fish was several inches smaller than the size at maturity of the more frequently observed longnose suckers. Inspection revealed no differences between these small specimens and larger - 22 - mature longnose suckers.
Both sexes of these smaller fish were mature. The fins of the males were well tuberculated and the eggs of the females were well developed. The Edwards Lake outlet creek collection of fish were predominantly males. If the sample was represen•
tative of the population of these fish, it might be concluded that these fish were precocious individuals which spawned some• what later in the season than the more frequent larger forms.
These fish appeared similar in many respects to the dwarf white sucker, Catostomus commersoni utawana. which has been stud• ied extensively by Dence (19^8). This subspecies of fish spawned later than its larger counterpart C. c. commersoni. As a large dead spawned-out longnose sucker was seen in the inlet of Edwards
Lake, it seems reasonable to suggest that the time of spawning of these small longnose suckers was somewhat later than that of the larger forms. The dwarf white sucker was recognized as a sep• arate subspecies because of late spawning habits and small size.
Dence's work suggested that it was not merely a precocious fish
as might be suspected from its size and the sexual composition of
the runs. The age of the dwarf suckers was similar to that of
the predominant large white sucker which occurred in the lake and
on that basis they may merit some special taxonomic description.
Scales from the small forms taken at Edwards Lake were read.
The results suggested that these fish were probably precocious.
The mature males were three or four years old and the two females
taken in the collection were four and five years old. The spawn•
ing age of longnose suckers at Baker Lake was between five and - 23 - eight years. Runs of precocious fish are usually predominantly males. Clutter and Whitesel (1956) have tabulated the results of exam• inations of jack sockeye, i.e. those precocious sockeye which for some reason mature a year before the majority of the sockeye, and found that only 0.6$ to 7.0% of these fish were females.
This lends further support to the idea that the small Edwards
Lake fish are not a distinct "race" of longnose sucker, but merely a run of precocious fish.
For the most part longnose suckers move into spawning
streams in British Columbia lakes in late April and May. There
is some indication of latitudinal variation in the time of spawn•
ing. Fish migrate into the streams earlier in the more southerly parts of the province than they do in the northern areas. Annual variations in spawning time also occur. In 1956 the first long• nose suckers moved into the spawning stream at Baker Lake on
May 10, while they first appeared in 1957 on May h. Migrations
appeared to begin a few days after the ice left the lake. This
in turn was an expression of the severity of the winter and the
time of warming of the spring.
Climatic differences, which are a function of the altitude
and latitude and several other factors appear to influence the
time of migration. Spawning migrations were somewhat later in
the Prince George area than in either the Clinton or Vancouver
regions. Prince George is on the 5^-th latitude and Vancouver, the ^th. Chapman (1952) has discussed the importance of latitude - 2k - and altitude in determining the climate.
Characteristics of Areas Used for Spawning.
As mentioned previously, longnose sucker spawning takes place primarily in inlet streams. Sampling with a Surber stream sampler has indicated the nature of the areas in the stream used for spawning by members of this species. It was apparent that longnose suckers were quite selective in the areas utilized for
spawning. Eggs and alevins were found, for the most part, only in riffle areas of the stream. Gravel size in these areas varied from pea gravel to stones roughly four inches in diameter. The depth of water over such areas was generally less than a foot.
Little evidence of spawning was noted in the slow moving or silty areas of the creek. Eggs found in such areas were generally dead.
Spawning did not appear to be related in any way to cover. How• ever, the streams were small. A different situation may exist in larger rivers although no information is available. No mention of the areas utilized for spawning by longnose suckers has been found in the literature. Observations at Baker Lake and other nearby lakes indicated a close agreement of the spawning ground requirements of longnose suckers with those found for other species of suckers studied.
Size Distribution of Baker Lake Inlet Spawners.
The size of mature individuals in the spawning run varied from 175 to 350 mm. fork length. The average length of the females was 287 mm. and of males 256 mm. Fig. 6 indicates that the mode of the size distribution of the females is somewhat higher than that of the males. - 25 -
120
100
80
60
1 40
50 300 Length ( |0 mm. group)
Fig. 6. Length-frequency distributions of male and female longnose suckers in Baker Lake inlet. 1956. - 26 -
A "t" test indicated that the difference was significant at
the p <0.01 level.
Brown and Graham (1953) noted that spawning male longnose
suckers in Yellowstone Lake averaged lk" 355 mm. and the
females 17" V30 mm. While the size of fish under consideration
is somewhat different than those encountered in this study, the
range of the difference is much the same.
Age of Spawning Fish in the Baker Lake Inlet Run.
A study of the age of spawning fish was carried out by means
of scale reading. Scale samples were examined from twenty-five
fish, covering the range of sizes of adults found in the spawning
run.
Scales of Catostomus catostomus were difficult to read. The
central portion of the scale, representing the growth which took
place during the first few years of lake life, was very compressed.
This has made the age determination less acurate than was desir•
able. Scales of fingerlings taken from the lake and the outlet
stream were read so that a knowledge of the number of. years growth
that is compressed in the central part of the scale might be det•
ermined. The results indicated that the males spawned for the
most part at five years of age. However, first spawning occurred
in the sixth and seventh years of life.
The number of times that a particular fish had spawned was
difficult to determine for the longnose suckers. No distinctive
spawning check comparable to that in steelhead trout, Salmo
gairdneri, and described by Maher and Larkin (1955)? was found.
In this species - 27 - only two instances of a scale pattern which might be called a spawning check were observed. The possibility existed that these fish only spawned once, but work at Baker Lake in the summer of 1957 showed that this was not the case. In the run to the inlet stream of Baker Lake in that year ¥*$ of the fish taken in the ascending trap were fish which were marked as spawners in that stream the year previous. This demonstrated that longnose suckers do spawn more than once. Spawning checks on the scales, if they exist, are difficult to discern.
Female longnose suckers in Baker Lake spawned primarily in their sixth year. However, some fish spawned at five, seven and eight years of age. Rawson and Elsey (19^8) have studied the longnose sucker in Pyramid Lake in the Jasper area. Their results indicate that kO% of the males and 12$ of the females mature in their fifth year. 65$ of the males and 20$ of the females were mature in their sixth year. All were mature by their seventh year. Sex Ratio of Spawners Ascending Baker Lake Inlet.
Data have been collected on the sex ratio of longnose suckers spawning in Baker Lake inlet in the spring of 1956 and 1957. Of the 1,269 adults ascending the inlet in 1956, 873 were females and 376 were males (a ratio of 2.*f females: 1 male). A chi-square test indicated that the difference was a significant departure (p<.01) from an expected 1:1 ratio.
A similar difference in sex ratio was noted in the 1957 run, in which 6*f7 of the 1,053 fish were females (1.6 females: 1 male).
Gill net sets in these two years also took a great majority of - 28 -
| | New Females 80- Marked Females
60
40-
20-
r_sm,
f~~| New Males
Marked Males n 60-
40
20
400
j?ig. 7. Length-frequency distributions of marked and unmarked spawning longnose suckers in Baker Lake inlet. 1957. Marked fish returning as multiple spawners. - 29 - females, although some selective action of the nets may have influenced these results.
Determinations of the length-frequencies of males and fe• males which entered the spawning stream in 1957 as unmarked fish, i.e. fish which were not handled in 1956*were made. Length- frequency determinations were also made on the fish returning to the inlet as marked fish. These fish had been marked in 1956 and were returning to spawn for at least the second successive year. The results are indicated graphically in Fig. 7.
Of the unmarked fish entering the stream there were 280 fe• males and 2H-3 males, which is not a significant departure from a
1:1 ratio. The presence of some precocious males in the stream may have masked the ratio. The size distribution indicated that many of these fish were probably first spawners although some of the larger ones have probably spawned previously. Females were slightly larger than males.
Marked fish were on the average much larger, although the males were smaller than females. This group composed of 367 females and 163 males, departed significantly (p<.01) from 1:1.
The method of marking used in this study was very satis• factory. - kh% of the fish which migrated up through the trap on the inlet of Baker Lake in 1957 were marked. This was also kh% of the total number that returned marked to the lake in 1956.
For the most part the marks were still very clear and readily recognizable. In the cases where there was some doubt, probing with the point of a knife was usually sufficient to reveal the spot of latex. - 30 -
Not only was the mark recognizable for a period of at least
one year, but also there was no noticeable mortality associated
with this means of marking. Markus (1933)? Ricker (1956) and
other workers have recognized that many types of marking do
increase the mortality of fish. It did not appear that the dif•
ference in the sex ratio was due to any marking mortality. Very
few dead fish were found in the spawning stream. There was no
apparent sexual difference in spawning mortality. All fish
returning to the lake appeared to be in good condition.
The difference in the sex ratio which has been noted in the
spawning run may be explained by differential mortality of males
and females between first and second spawning. As no appreciable
mortality occurred in the spawning stream, this mortality must
occur in the lake after first spawning.
Differential mortalities have been noted in other fish.
Foerster (195^) noted that the Cultus Lake sockeye run was com•
posed predominantly of females. He postulated a differential
ocean mortality as the cause as the sex ratio of the smolts
leaving for the sea was approximately 1:1.
Probably the sex ratio of longnose sucker fry entering the
lake was 1:1 as there was no significant difference in the sex
ratio of unmarked fish entering Baker Lake inlet in 1957*
There is possibly some selective advantage in a differential
rate of natural mortality between the two sexes. Male suckers,
according to Reighard (1920) are able to fertilize the eggs of
several females. Thus, relatively fewer males would be adequate
for reproductive purposes. - 31 -
In addition, various workers have demonstrated a positive cor• relation between body length and egg number (Foerster and Pritchard).
If such is the case for suckers, the production of large females would be of advantage in propogation of the species.
If such a selective advantage does exist, it is probably
genetically induced. Possibly it is a sex-linked character which does not operate till after first spawning. Alternately, the rate of natural mortality of males may be greater from hatching.
If this were the case, the number of spawning males might be
equal to the number of one-year-older spawning females.
Baker Lake data, Fig. 8, indicates that male and female
longnose suckers entered the spawning stream at the same time.
Although the number of females migrating upstream at Baker Lake was much higher than males, the proportion of the two sexes remained relatively constant throughout the upstream migration.
Differences in the time of entry into the spawning stream have
been noted in the other species of sucker at Baker Lake and the rainbow trout in the Loon Lake inlet. (T.G. Northcote. Personal
communication).
Length of Time Spent in the Inlet at Baker Lake.
Longnose suckers were present in the inlet for approximately
one month. The data were examined to determine which segments
of the spawning run comprised the fish remaining in the stream
till the end of the run. Fig. 9 indicates the results as det• ermined by the passage of marked fish down to the lake. Fish marked at the beginning of the run remained for the longest - 32 -
19 5 6 Fig. 8. Daily number of male and female longnose suckers moving upstream in Baker Lake inlet during 195§> spawning run. Male catch superimposed on female catch. - 33 -
10 T Marked May 12, 13
No. • • of Fish
r—1 0 1
Mart ted K Ha 1 16, 17 1
fU1-
Marked May 2 0, 21
rLr"Lr-
Marked May 24,25
" I • 1 1 1—i • 1 1—n 1 1—i1 1 1 l 1—i 1 ( 1 1 1 1 1 1—r—i—r—* 16 20 25 30 1 5 10 14 Date May 16- June 14, 1956 Fig. 9. Length of time spent by portions of longnose sucker run in the inlet spawning stream at Baker Lake as determined from date of marking and dates of return through descender trap. 1956. - 3k - period of time. The last fish to return through the traps in any numbers were fish marked during the period of May 12 -
13. As the run progressed the length of time spent in the stream became shorter. Fish marked on May 2k and 25, which was the last period when large numbers of fish moved upstream, had all returned to the lake by June 5.
It will be noted in Fig. 9 that, in some instances, fish returned through the descender trap a day or two after first being marked. This was perhaps due to the shock of handling during the marking operation. These fish were put back upstream if they had been marked with the spot which was currently in use.
If the mark on the fish was no longer being used, the fish was put downstream. Many of these fish which were put down, for the most part still unspawned, returned through the ascender trap within a few days.
Sex Ratio of Fish Descending to Baker Lake After Spawning.
Within a few weeks of the time the fish migrate upstream to spawn, all have returned to the lake. In 1956 the majority of fish had returned to the lake by June 10. The data have been examined with a view to indicating which sex, if either, returned to the lake first. Fig. 10 shows that a far greater proportion of females migrated lakeward during the first half of the period of descent to the lake than during the last half. From May 10 to 2k 66.2% of the descending fish were females. During the period May 25 to June 7 only kk.3% were females. The difference is especially marked when the difference in the sex ratio of the - 35 -
• ?
T 50
N o. of •• 25 Fis h
J- 0
uaTe May 14- June 7, I9S6 Fig. 10. Movement of male and female longnose suckers through Baker Lake inlet descending trap as measured by daily catches. 1956. Male catch superimposed on female catch. - 36 - males and females in the spawning run is taken into considera•
tion; about two females entered the spawning stream for every male.
Sexual Condition of Fish Migrating Upstream.
Male longnose suckers were usually mature when they entered
the spawning stream. This was the case not only in Baker Lake
but also in the other lakes in the Quesnel area which were exam•
ined. Maturity was indicated by the well developed tubercles on
the anal fin and the flow of milt when a gentle pressure was
exerted on the belly of the fish.
Females on the other hand, as is shown in Fig. 11, were
generally quite green when they first entered the spawning stream.
In other words, no eggs could be extruded from the body by
exerting pressure on the belly. The ratio of green to ripe fe•
males changed throughout the duration of the spawning run.
During the first part of the run the majority of the females were
green. In the latter stages of the run however, the number and
proportion of ripe females increased considerably. This, as dis•
cussed below, is possibly correlated with the distribution of the
fish within the stream.
Distribution of Spawners in Baker Lake Inlet Creek.
Preliminary work on this subject in 1956 failed to reveal
any information, as the surveys were carried out after the peak
of spawning was passed and large numbers of fish had returned to
the lake. Surveys of the spawning grounds were carried out during
the length of the 1957 spawning season. - 37 -
Dote May 1956
Fig...11. Daily numbers of green and ripe female longnose suckers in Baker Lake inlet trap. May 1956. Ripe fish superimposed on green fish. - 38 -
On May 8, 1957 a survey was carried out to determine the distribution of longnose suckers in the stream at the first part of the spawning run. The stream was divided off into one hundred yard sections and the numbers of fish in each section estimated by seining fish wherever possible. Only five fish were seen in the first three hundred yards of stream. In the fourth section however, which was probably the upper limit of the spawning area, forty-three fish were caught and examined.
Large numbers were also seen in a pool in this area but they could not conveniently be seined. The results strongly indicated that the first segment of the run moved to the upper reaches of the spawning grounds.
A second survey was carried out on May 13, 1957. The fish appeared more evenly distributed in the creek than they had been previously. Moderate numbers of suckers were obtained in the second and third sections of the stream, while only a few fish were obtained in the fourth section where the largest numbers were seen previously.
On May 20, a third stream survey revealed very few fish of this species in the stream. Those present were found in the first two hundred yards above the trap. Observations at the end of the 1956 run indicated that the majority of longnose suckers were also in the lower part of the spawning stream.
The results of these stream surveys indicated that the first longnose suckers migrated to the upper reaches of the spawning grounds, while those which entered as the run progressed moved - 39 - shorter distances upstream. As previously mentioned this behaviour may be related to the sexual development of the fish entering the stream. Fish which were not completely mature on entering the stream migrated to the upper reaches of the spawning grounds. Those which were mature on arrival at the spawning grounds spawned in the area Immediately above the fish traps.
Two common salmonids exhibit a similar pattern of behaviour. Unpublished data on the rainbow trout (Salmo gairdneri) in Loon Lake inlet indicated that the first fish to enter the stream were green and that these migrated to the upper reaches of the spawning area while ripe fish migrated into the lower spawning areas. The sockeye salmon, Oncorhvnchus nerka. also exhibits a similar pattern of behaviour. First fish entering the vast Fraser River system are relatively undeveloped sexually. They migrate to Stuart Lake which is in the upper area of the system. Late runs of near mature fish migrate to streams less than one hundred miles from salt water. This behaviour in sockeye is also cor• related with the temperature cycle. Spawning occurs in streams at temperatures between *+5 and 55°F. with peak spawning at approx• imately 50°F. This happens whether the distance is 30 or 730 miles from salt water (Int. Pac. Salmon Fish. Comm. Ann. Rept. 1950). Rainbow trout and longnose sucker migrations may also be correlated with temperature in this manner. - ko -
Survival in Baker Lake Inlet.
The survival of adult longnose suckers which migrated into the stream to spawn, as judged by the numbers of marked fish returning later through the descender trap, was very high. The average return during the 1956 spawning run was 88.6$. 90.8$ of the individuals tagged during the first part of the run returned, while 80.7$ and 85.2$ of the fish marked during the two middle periods of the run returned through the trap. All of the fish marked during the last eight days of the upstream mig• ration returned to the lake.
Sucker survival in Baker Lake is higher than that exper• ienced by rainbow trout in Loon Lake Inlet near Clinton. Many of the trout died before returning to the lake. Possibly this was due to the difference in behaviour which the two species exhibit. Rainbow trout often migrate as much as several miles to the spawning grounds, and exhibit a very marked territorial behaviour on the spawning grounds. This results in bodily damage. Consequently, fish returning to the lake were usually in poor condition and appeared more susceptible to fungus development and predation. Personal observations indicated that the longnose suckers migrated only a few hundred yards upstream and did not exhibit any marked territorial behaviour.
Extent of Utilization of Same Spawning Stream by Longnose Suckers in Successive Years.
In 1957 traps were operated on the outlet and two inlet streams. Table 3 indicates the return of marked and unmarked - hi - longnose suckers to the various spawning streams. All fish had been marked in the main inlet in the spring of 1956. The results, therefore, indicate the degree to which these fish return to the same spawning stream in successive years. This might also indicate the degree of homing, but no data on the stream of origin of these fish are available.
TABLE III. Numbers of marked and unmarked longnose suckers in Baker Lake spawning streams in 1957. Inlet A (main inlet in Fig. 1) was site of 1956 marking.
Inlet A Inlet B Outlet
Unmarked fish 523 79 3 Marked fish 503 103 10 A "two-by-two" chi-souare test indicated that a signi• ficantly higher proportion of marked fish (p<".05) occurred in the outlet and inlet "B" than in inlet "A" which was the main inlet in which the fish were marked in 1956. There does not appear, on the basis of this information, to be any tendency for fish to return to the spawning stream they had used the year pre• vious .
Possibly the low water levels of the inlet "A", in 1957 was a deterrant to upstream migration of the relatively larger marked fish and consequently, they may have moved into the other two available streams. This might account for the proportionately higher number of marked fish in inlet "B" and the outlet. - 1*2 -
The sex ratio of the fish which "strayed" was nearly the same as that of those fish which returned to inlet "A". The sex ratio of marked fish in inlet "B" was 3 females : 1 male while 2.3 females : 1 male were observed as marked returns in inlet "A". ^ Incubation Period. Unsuccessful attemps were made to culture longnose sucker fry at Baker Lake. However, Mr. P. Canagaratanam of the Institute of Fisheries raised some eggs of this species which had been sent by air from Baker Lake to the University of B. C. His results of controlled temperature experiments are shown in Table IV.
TABLE IV. The incubation period of longnose sucker eggs at three temperatures.
Temperature Days to Hatching 10°C- 50°F. 11 15°C- 59°F. 8 20°C- 68°F. 5 days to eyed eggs
After hatching, the fry at Baker Lake remained in the gravel of the stream bed until the yolk sac was absorbed. Time spent in the gravel after hatching was approximately a week to ten days. The Early Life of the Fry and Fingerlings.
The. behaviour of the fish after emergence from the gravel will be discussed in detail in a later section under the factors influencing migration. Fry which hatched in the inlet moved into - ^3 - the lake almost immediately after emergence from the gravel.
Fry which hatched in an outlet stream remained there for some time.
The fingerlings ascending the Baker Lake outlet were aged
by scale reading. Most of these fingerlings were from 100 to
160 mm. long and were from two to four years old. The majority were three years old. The outlet stream flowed over a beaver dam and this may have presented a serious obstacle to the young fish moving lakeward. Possibly they were not able to swim over the dam until they had reached a certain critical size which was somewhat larger than normally, attained by these fish at the
time of migration towards the lake.
Longnose suckers from the unobstructed outlet of Bouchie
Lake were examined. Of the twenty Bouchie Lake suckers examined, twelve were two years old and eight were three years old. No four year old fish were examined. This suggests that the dam on
Baker Lake outlet may present a barrier to upstream migration of longnose sucker fingerlings and delay their upstream migration
as much as one or two years. V. THE WHITE SUCKER
The white sucker, Catostomus commersoni?is the best known species of this genus. Several detailed studies have been carried out on this species in Eastern North America.
However, little of its biology in British Columbia lakes and streams is known.
The distribution of the white sucker in North America is slightly more restricted than that of the longnose sucker. It is found across North America from the Rocky Mountains to
Labrador and the Gulf States. Only recently has this species been reported in the upper regions of the Fraser River watershed.
It is now known to extend as far south in this system as Quesnel.
Previously its known British Columbia distribution had been limited to the Mackenzie and Skeena drainages. Lindsey (1956b) believes that, judging from its restricted distribution in the
Fraser River, it has only recently crossed the Continental
Divide to the Pacific.
Economically this species is important as it is the most commonly utilized food fish of this genus. In addition, Forney
(1957) mentions that this species is of some value as a bait fish.
Data on the reproduction of this species have been obtained and are presented and discussed below. - \5 -
Spawning Localities*
Observations on spawning streams revealed that white suckers spawned primarily in the inlet streams, as did the long• nose sucker. The great majority of white suckers spawned in the inlet stream at Baker Lake. Very few passed into the trap on the outlet stream, although some were observed spawning in the current of the outlet immediately above the beaver dam and the spillway to the trap. Varying sized runs of white suckers were also observed in the inlets to Cluculz and Summit Lakes as well as Shelley's Slough.
Although inlet spawning is usual, some exceptions have been noted. Outlet spawning is known to take place in the outlet of
Cluculz Lake, and has been reported by a local resident in the
Crooked River, which is the outlet of Summit Lake north of
Prince George. Dence (19^8) noted that C. commersoni utawana migrated into inlet streams for spawning. Scott (19$+) states that C. commersoni moves from the lake to the streams to spawn.
He also says that spawning may take place in the shallow water of the lake shores. Eddy and Surber (19^7)j Hankinson (1919),
Adams and Hankinson (1928), and Harlan and Speaker (1956) all men• tion migrations upstream for spawning.
Although lake spawning was not observed during this study, it has been reported in the literature, and must occur in some cases as the only spawning areas available are in the lake.
Smith (1938), Spoor (1938), Eddy and Surber (19^7), and Scott
(.199+) all report instances of lake spawning by C. commersoni. - k6 -
"White suckers have been noted spawning in inlet and out• let streams at Cluculz Lake. Outlet spawning took place prior to inlet spawning. This difference is possibly associated with the temperature of the streams in question.
The white sucker, then is quite adaptable as far as its> ability to spawn in a series of different habitats. While inlet spawning occurred most commonly, runs of spawning fish to outlet streams were not uncommon and in some instances lake spawning must take place in order that the species is perpetuated in cer• tain landlocked bodies of water.
Timing and Duration of the Spawning Run.
Data on the timing and duration of the white sucker spawning runs have been obtained from Baker Lake (Quesnel), Shelley Slough,
Cluculz Lake and Summit Lake, all in the Prince George area.
Table V indicates the timing and duration of the white sucker spawning runs in the Quesnel and Prince George area.
TABLE V. Timing and duration of 1956 white sucker runs in Four Lakes in Quesnel-Prince George area. Dates approximate. Temperature approximately daily maximum.
Lake & Locality Stream Beginning Peak of End of Temp, at of Run Run Run Peak-°F. Baker Lake Quesnel ' ' Inlet May ih May 2h June 1 60
Shelley Slough Prince George Inlet May 15 May 23 May 31 56 Summit Lake Prince George Inlet May 2k- May 30 — 55 Cluculz Lake Inlet May 10-15 May 2h May 31 Prince George Outlet May 1 May 10 — 51* - k? -
As was noted for longnose suckers, the white suckers appeared to enter outlet streams before inlet streams. This is indicated from observations at Cluculz Lake west of Prince
George.
There was some suggestion of latitudinal variation in the time of spawning. Runs were somewhat earlier at Baker Lake than at Summit Lake, which is 115 miles north of the former. Local climatic variability also appeared to govern the time of spawning migrations. Summit Lake is only thirty miles north of Cluculz
Lake, but the ice left Summit a week later in 1956 and as a result the runs were correspondingly later.
Yearly variation in climate also governed the migration time.
The weather warmed up earlier in 1957 and consequently the spawn• ing runs of white suckers were earlier than they had been in 1956.
Runs of white suckers extended over a period of a month.
The peak of migration was usually reached a week or ten days after the appearance of the first fish. y Some information on the timing of the white sucker spawning runs has been noted in the literature. It is generally agreed that white.suckers spawn in the spring months. Stewart (1926) noted that the breeding season extended over a period of 29 days during May and June. Adams and Hankinson (1928) reported that white suckers ascended the streams to spawn soon after the ice has left the lake. Carl and Clemens (1953) report that spawning in the Peace River District takes place about the middle of May.
Dence (19^8) working in the Adirondacks in New York, reported - h8 -
that the dwarf sucker, C. commersoni utawana. spawned three weeks after the ice left the lake which was generally around
the latter part of May. Other workers have presented evidence
to show that C. commersoni spawns in the spring from April to
June. The greater number of published records however, indi•
cate that May is the main month of spawning. Spawning runs of
white suckers in B. C. were in the streams from two weeks to a
month during May and early June.
Characteristics of Spawning Grounds.
Observations on the spawning grounds of Baker Lake have
indicated the type of regions which white suckers utilize for
spawning. Samples were made with a Surber stream sampler. An
indication of the use made of a particular area for spawning was
determined by examining the fry and eggs taken in each sample.
The yellowish eggs, readily distinguishable from the white
eggs of the longnose sucker, were found only in the portions of
the stream which had a gravelly bottom. Generally the water in
these areas was less than six inches deep and was moving fairly
rapidly. No eggs or fry were found in areas where large stones
predominated and only dead eggs were found in the sandy portions
of the stream. White suckers appear to have two main spawning
requirements:
a) Running water less than 12 inches deep.
b) Gravel bottom. - h9 -
These are the requirements as indicated by personal obser• vations. Reighard (1913) mentioned that C. commersoni breeds in streams where there is swift water and gravel bottom.
Huntsman (1935) noted that suckers ran up to the rapids of streams to spawn. Dence (19^8) stated that clean coarse sand or gravel was an essential element of the spawning habitat. Further• more, fish did not spawn in deep pools and were found only in areas of good cover. Scott (195L0 » Reighard (1901+), and Harlan and Speaker (1956 have mentioned the need for gravelly stream bottoms and running water.
Reighard (1913) maintained that possibly a suitable bottom was the main requirement for successful spawning and running water was not essential. This seems to be reasonable in view of the fact that spawning does occur in lakes. Possibly lake spawning takes place in lakes only on the gravel substrate in the shallow parts of the lake where wave action or seepage could have some influence in oxygenating the eggs.
The areas of stream used for spawning by longnose and white suckers did not appear to be markedly different.
Age at Spawning.
The age of spawning suckers in Baker Lake was determined by means of scale readings. The procedure has been described in an earlier section. Scale samples from twenty fish of all sizes of spawning fish were read. Of this number fifteen were seven year olds, two were eight, two were six and one was five years old. The majority of fish of each sex were seven year olds. - 50 -
Unlike those of the longnose sucker, scales of white suckers were easily read. The scales were large and the annuli were well defined, even in the early years of life. Spawning checks were also quite pronounced. Of the twenty scales which were read, eleven were second spawners. The fact that a great number of the fish were multiple spawners was well borne out by the number of fish marked in 1956 which returned in 1957 to the same spawning stream. Approximately k-5% of the 1957 run was made up of such fish.
The results of the Baker Lake work agree with those of Stewart (1926) who stated that white suckers, to his knowledge, did not spawn before age six. Spoor (1938) stated that males mature at five or six years and females at six or seven years.
Size Distribution of Spawners.
A significant difference (p <.01) was found using the "t" test between the average size of male and female spawners. The average size of the l^t-l females in the run was 338.5 mms. as compared with an average size of 291.h mms. for the males. A
"t" test applied to the size distribution of the males and fe• males indicated that the differences were significant at the p<.01 level. Spoor (1935, 1938) discussing the sexual dim• orphism and growth of Catostomus commersoni noted that the females in the spawning runs were larger than the males. Dence
(19*+8) noted that females of C. commersoni utawana were somewhat larger on the average than the males. Raney and Webster (19*f2) also noted that female white suckers were larger than males. - 51 -
All! evidence suggests that males are generally smaller (in the
spawning run at least) than the females. Fig. 12 shows the size distribution of the fish which were taken in the inlet trap at Baker Lake in 1956.
The Sex Ratio of White Suckers Ascending the Baker Lake Inlet.
The only stream v/here sufficient numbers of fish were
sampled to give an indication of the sex ratio of spawning white
suckers was the Baker Lake inlet. The overall sex ratio of the run in 1956 was not significantly different from 1:1. Over the length of the run there were l6k females and 159 males. How• ever, the sex ratio was not consistent throughout the run. Up
to June 25 the run was predominantly composed of males. During that period 132 males and 91 females were taken in the trap.
A "chi-square" test indicated that the difference was signi• ficant at the p< .01 level. However, the proportion of females
increased in the latter half of the spawning run. During this time, as can be seen from Fig. 13, 73 females and 27 males moved upstream into the trap. This difference also proved sig• nificant (p <.01).
Mottley (1933) noted that male rainbow trout, Salmo gairdneri, were the first to move into the spawning stream. He suggested that males were more active in their random movement and therefore were the first to locate the spawning stream and move into it.
Spoor (1938) noted that the sex ratio of spawning suckers was 1:1. The same results were obtained by Raney and Webster (19^2). - 52 -
220 250 300 350 400 Length { 10 mm. group )
Fig. 12. Length frequency of spawning male and female white suckers in Baker Lake inlet. 1956. - 53 -
20 T
No.
10 .. of
Fish
I »
i T—i 1—r 15 20 25 30 I 5 10
Date May 14— Jane 7, 1956
Fig. 13. Daily numbers of male and female spawning white suckers ascending Baker Lake inlet trap. 1956.
J - 9+ -
Dence (19^8) however, noted that males predominated in spawning runs of the dwarf sucker, C. commersoni utawna. He may have been dealing with a run of precocious fish however, in which case the males would probably predominate. The possibility of precpciousness among these dwarf fish is discussed in a later section.
A marked difference in the sex ratio was noted in the two years. In 1956 nearly equal numbers of the two sexes were caught in the inlet trap. However, in 1957, the new fish included 59 females and 91 males, while marked fish returning as multiple spawners numbered *+l females and 80 males. The length-frequen• cies of these two groups of fish are plotted in Fig. 1*4-. While the differences in the length-frequencies of the new and marked fish of each sex do not appear to be as large as those exhibited by the longnose suckers, there are more small fish in the group handled for the first time in 1957• The sex ratio of 2 males
: 1 female that was noted in 1957 was much different than that in 1956 when equal numbers of each sex were present in the spawning stream.
The change in the sex ratio cannot be accounted for by a differential mortality as the sex ratio of the new and marked fish is practically identical. Possibly fewer white sucker females migrated into the inlet trap in 1957 because of the low water levels. Females of this species are larger than the males and presumably experience more difficulty in migrating upstream during low water. Approximately one hundred yards of spawning - 55 -
59 New Females
41 Marked Females
91 New Mafes
80 Marked Males 10 -
i 1 1 1 «- i 1 r 250 ~i 1 1 r 350 400 300 LENGTH - MM*
Fig. Ik-. Length-frequency of marked and unmarked spawning white suckers passing through ascender trap in Baker LakV inlet. May 1957. Marked fish returning as multiple spawners. - 56 - area was available between the trap and the lake. It is possible that a large number of females spawned in this area.
However, no evaluation of the population below the trap was made.
Possibly a large percentage of the females do not spawn in two successive years. If such were the case some of the fe• males marked in 1956 may be found when the traps are operated in the spring of 1958.
Length of Time Spent in the Spawning Stream.
Analysis of marking data indicated that the first portion of the spawning run remained in the stream for the longest period of time. This is illustrated in Fig. 15* Some of the first spawners to enter the stream remained over three weeks.
Fish marked on May 2h and 25 had returned to the lake in two weeks, while those marked on May 30 and 31 returned for the most part within one week. All but a few spawners had returned to the lake by June 10. This may simply have been a reflection of the onset of low water levels or increasing stream temperatures.
No records of similar observations have been noted in the literature.
In 1956 the sex ratio of descending spent fish was 1:1, similar to that of ascending fish, indicating that no differen• tial mortality existed on the spawning grounds. Fig. 16 indicates some difference in the time at which the two sexes leave the spawning stream. The majority of the females returned to the lake before the males. - 57 -
Marked May 16, 17
n r~i m
Marked May 20, 2 I
Marked May 24, 25
0 •
3
Marked May 28, 29
0 •
-i—i—i—i—i—i—i—i—i—i—i—1—i—i—i—i—i—i- "i—i r 20 25 30 I 5 10 May 18 - June II, 1956
.g. 15. Time spent by portions of the white sucker run in the inlet spawning stream at Baker Lake as determined from the date of marking and dates of return through descender trap. 1956. - 58 -
-• 30
o -• 20 d
30 -- 10
20
10 •-
i— T 1 f 1 1 I 1 1 1 1 r i 1 T T 1 I » 1 » I I 20 25 30 I 5 10
May 16 — June 14
Fig. 16. Daily number of spent male and female white suckers in Baker. Lake inlet descending trap. 1956.' - 59 -
Survival of Spawning Adult White Suckers in Baker Lake Inlet Stream.
The survival of the adult white suckers in the spawning run was determined by comparing the number of fish which were marked and put upstream with the number that returned as marked spent adults through the descender trap. This method of det• ermining the survival is reliable as all adult fish moving up• stream were marked.
Of the 322 fish which were marked, 271 returned to the descender trap in the inlet. This represents a survival of Sk.lfo.
As pointed out previously, no evidence indicated a differential mortality of the two sexes in the spawning stream.
The range of survival is shown below in Table VI. Mortality in the stream varied between 65$ and 92$ except during the last few days of the run when the non-return of one fish could alter the survival figures as much as 50$.
TABLE VI. Survival of marked white suckers in Baker Lake inlet during the 1956 spawning run. The two day periods were indicated by dis• tinctive marks.
Date Marked No. Marked Total Return $ Survival
May 16 - 17 18 13 72 May 18 - 19 52 3k 65 May 20 - 21 k5 35 77 May 2k - 25 85 7k 8k May 26-27 7 5 71 May 28 - 29 56 k7 83 May 30 - 31 27 25 92
This indicates that no appreciable differential mortality exists between portions of the run. - 60 -
Distribution of Spawners in the Inlet Stream.
Some work on this subject was conducted in 1956. However, only the limits of the spawning migration were determined as the survey was carried out late in the spawning run. From this work it appeared that the upper limit of spawning was some four hundred yards above the traps.
The areas of the stream used by various portions of the spawning run were determined by periodic seining over the length of the stream. The results of studies in 1957 indicated that the white suckers which entered the stream first moved to the upper areas of the spawning grounds. Fish entering the stream later in the run spawned in areas of the stream progressively closer to the mouth of the creek. The longnose suckers exhibit a similar pattern of behaviour. Raney and Webster (19^2) noted that some of the first white suckers migrated as much as four miles upstream but the majority moved only a few hundred yards upstream.
Extent of Utilization of the Same Spawning Stream by White Suckers in Two Successive Years.
Table VII indicates the numbers of white suckers marked in the main inlet "A" in 1956 and recaptured in the spawning streams of Baker Lake in 1957. - 61 -
TABLE VII. Numbers of marked and unmarked white ^ suckers in Baker Lake spawning streams. 1957. Inlet "A" was site of 1956 marking.
Inlet "A" Inlet "B" Outlet
New fish 150 1 9 Marked fish 120 2 3
No significant difference was noted between the proportion of marked and unmarked fish in the inlet streams (p = .80).
Furthermore, no significant difference was noted between the proportion of marked and unmarked fish in inlet "A" and the out• let (pf .20). The difference is approaching a significant level and may indicate, that white suckers tend to return to an inlet stream in preference to an outlet. The low water conditions in the "home" stream may have had some inhibiting influence on fish returning to the same stream in successive years.
Dence (19^8) has reported that the dwarf white sucker,
C. commersoni utawana. returned to the same spawning stream year after year.
Incubation Period of Eg;gs.
Data on incubation were obtained by placing fertilized eggs in a jar anchored in the outlet stream of Baker Lake in 1956.
Circulation was facilitated by introducing a rubber tube into the jar and running water through it from a flume. In this way the water was oxygenated and the temperature was maintained at the level of the stream. - 62 -
White sucker eggs were placed in the jar on May 29. Some hatched on June 3» a total of six days after fertilization. The remaining eggs hatched, for the most part two days later. The average stream temperature during this time was 53°F. This is 126 units in terms of the heat units commonly used in hat• chery practice. At hatching, the fry were in a very undeveloped state. They were approximately 15 mm. long and had a large globular yolk sac in the head region and extending along much of the body in the form of a small band. Stewart (1926) has done some work on the white sucker and maintains that the normal incubation period is twelve days. Dence (19^8) reports a normal incubation period of eight days at a tem• perature of 60 - 70°F. for the dwarf sucker. Catostomus commersonii utawana. Raney and Webster (19^2) give the incubation period for .white -suckers in Skaneateles Lake inlet, New York as follows: . 70°F. - \ days 65°F. - 5 days 60°F. - 7 days 50°F. - 7 days 1 HO°F. -Ik days These data on the'incubation periods agree with those col• lected on the white sucker in British Columbia.
Early Life of White: Sucker Fry and Fingerlings.
After hatching, the fry remained in the gravel until the yolk sac was practically absorbed. This, as shown by bottom samples collected at regular intervals, was evidently the case for both white sucker and longnose sucker fry. After emergence the fry - 63 - moved down the inlet streams towards the lake.
Studies on the streams in the Quesnel area in the summer of 1956 indicated that the sucker fry left the inlet spawning streams by the middle of July. Hubbs and Creaser (19^2) have stated that a passive downstream movement following hatching is a general rule in many fishes and is probably true for the white sucker. This supports the work carried out on the downstream migration of these fish which is discussed in detail in the section dealing with factors influencing migration.
White suckers spawned primarily in inlet streams. However, some spawning did take place in outlets. On hatching the fry in outlets did not immediately enter the lake. They remained in quiet backwaters of the stream and were displaced downstream when they entered the main velocities of the stream. However, these fish remained in the stream for as long as four years even though they are presumably capable of moving upstream a few weeks after hatching. Some behavioural differences, probably related to the temperature of outlet streams, results in the white sucker finger- lings remaining in the stream for some time. Runnstrom (1957) has reported that brown trout juveniles grow as rapidly for the first three years in an outlet stream as the lake. Possibly there is no selective advantage to lake residence till this age. A com• parable situation might exist with white suckers. - 6>+ -
VI. THE LARGESCALE SUCKER
i The largescale sucker, Catostomus macrocheilus Garard, while a common British Columbia species, was studied relatively little as it did not occur frequently in the lakes of the
Quesnel area. However, some data, while less complete than on the other two species, are presented below.
Until recently this species has been found only on the
Pacific slope. According to Carl and Clemens (1953) it is found in the Skeena, Fraser, Columbia, Puget Sound drainages, coasts of Washington and Oregon, east at least to the headwaters of the
Salmon River in Idaho and south at least to the Sixes River in
Oregon.
The species occurs most abundantly in the southern parts of
B. C. including the Kootenays, Okanagan, Lower Mainland and
Southern Cariboo areas. It has been mentioned as having some food value to the Flathead Indians by Jordan and Evermann (1903)•
Lindsey (1956b) describes the occurrence of this species in
Summit and McLeod Lakes which are the headwaters of the Peace
River. He maintains that this species is a recent invader of that drainage judging from its rather limited distribution in the system.
Hybridization between the white sucker and the largescale sucker is known to occur in at least one lake in British Columbia. - 65 -
Spawning Locations.
All information on this subject suggests that largescale
suckers spawn primarily in outlet streams, but if these are not present, spawning does occur in inlet streams.
In Cluculz and Summit Lakes, as well as in some of the lakes in the Merritt-Kamloops and Okanagan areas, spawning has
been noted in outlets. Moderate numbers of fish descend into
the outlet of Cluculz each year to spawn and return after spawn•
ing through a weir operated by the B. C. Game Commission. No fish of this species have been noted in the inlet streams of this
lake. A similar situation probably exists in Summit Lake.
Although the Crooked River which is the outlet of Summit Lake was never examined, large numbers of this species were reported
to spawn in the river. Although taken by gillnetting in the lake, none were ever taken in the inlet streams in spite of fairly
intensive collecting in these streams during the spawning season.
Large numbers of largescale suckers spawn in the San Jose River,
the outlet of Lac La Hache, and Sweltzer Creek, the outlet of
Cultus .Lake, near Chilliwack.
However, largescale suckers do spawn in locations other than
outlet streams. 108 - Mile Lake, near Lac La Hache, has only an inlet stream. Each spring a small run of these fish moves into
the stream for spawning. 'Weisel (1957) reports that suckers spawn along lake margins, in ox bows of rivers, or up smaller streams.
Carl and Clemens (1953) noted that the spawning runs of largescale
suckers takes place in May following the runs of fine scale
suckers into the streams. Weisel (1957) has mentioned lake - 66 - spawning. However, no instance of this was noted in British
Columbia. The only indication of possible lake spawning was seen at Ellison Lake, near Kelowna, where dead largescale suckers were seen at various points along the beach. These fish were spent, but could conceivably have been carried down from the inlet stream.
Largescale suckers are evidently able to spawn in lakes and streams. However, when available, outlet streams are utilized in preference to inlet streams.
Comparative Dates and Duration of Spawning Runs.
In British Columbia there is a great difference in the time of spawning depending on the locality. Largescale suckers enter
Sweltzer Creek, the outlet of Cultus Lake, around the first of
April and the run continues until May. On May 15> 1956, the largescale suckers in 108 - Mile Creek in the Cariboo were still green for the most part, but a week later the majority had spawned and returned to the lake. The same situation prevailed in this stream in 1955 and 1957• The run in 1957 was somewhat earlier, probably as the result of an early spring. Many large- scale suckers were seen in the outlet of Sheridan Lake on
May 8, 1955. Ripe males and females were taken from ripe fish
collected in the inlet of Ellison Lake, near Kelowna, on June k-9
1955» Dead fish were found in the inlet of Monte Lake near
Westwold on June 16, 1955 and in the inlet of Box Lake near
Nakusp the following day.
The spawning migration of large numbers of this species has - 67 - been observed in the outlet of Cluculz Lake in May, usually beginning the first and second weeks of that month. Return of these spawners to the lake continues till after mid-June.
Weisel (1957) states that largescale suckers spawn in the spring, usually April and May. Carl and Clemens (1953) mention spawning runs in Lac La Hache in May.
The spawning migrations of largescale suckers takes place during April and May depending on the locality. Observation on several streams indicate that the spawners remain in the stream for a period of three weeks to a month.
The time of the spawning migration depends on the locality of the spawning stream. Spawning runs in the more moderate climatic areas of the province such as the Lower Mainland, are considerably earlier than those in the more rigorous climatic areas such as the Kootenays and the Cariboo. In these regions runs are often a month or more later than those of the Lower
Mainland. Undoubtedly this is associated with the altitudinal and latitudinal position of the area. The Kootenay region has much the same latitude as the Lower Mainland but is far removed from the climate-moderating influence of the ocean, and con• sequently runs are a few weeks later.
Hybridization of Largescale White Suckers.
The timing and the location of the various spawning runs of the white and largescale sucker may account for the hybridization which apparently occurs between these two species in Cluculz and > Summit Lakes. The taxonomic counts of these supposed hybrids are - 68 - definitely intermediate as is generally the case -with hybrids.
Table VIII indicates the results of counts on the hybrids and parental species.
TABLE VIII. Counts on white, largescale and hybrid suckers from Summit Lake indicating the intermediacy of the taxonomic Character• istics. Counts by CC. Lindsey.
Catostomus Catostomus commersoni macrocheilus Hybrid Dorsal Rays 11, 12 12 13, lh Scales above lateral line 8, 9 10, 12 11, 13 Scales along lateral line 65, 66 69, 72 71
Dorsal to vent, ht. 2.1+2 2.62 Peduncle ht. 2.78
Only two hybrids were examined. 'Both'followed C commersoni with respect to the number of dorsal rays. One followed each of the parental species with respect to scales along the lateral line and both were intermediate in peduncle height compared to body depth. One specimen was intermediate in number of scales above the lateral line while the other was similar to
C. macrocheilus. Hubbs, (1955) has discussed the subject of natural hybridization in fishes and maintained that the following factors are important prequisites to its occurrence.
1. Limited spawning area which brings the fish into
close proximity thereby increasing chances of acci•
dental meeting of eggs and sperm. - 69 - (
2. Co-habitation of a few individuals, especially those
which have been introduced, with a multitude of a
related species. When ready to breed the species that
is rare may outcross if proper mates are not at hand.
3. Intergradation of habitat is conducive to the produc•
tion of hybrids. Overlap of breeding seasons is an
important factor as is overlap of response to chemical,
organic and physical environments.
The conditions conducive to hybridization described by Hubbs would seem to be applicable in the Cluculz and Summit Lakes in the Prince George area.
Limited spawning area was possibly a factor resulting in the production of C. commersoni and C. macrocheilus hybrids. Large numbers of both species have been noted in the outlet of Cluculz
Lake at different times in the spring, and possibly the stream may have been crowded. Overlapping of the white and largescale sucker runs was conceivably responsible for the production of hybrids. The white suckers entered the outlet stream earlier than the largescales. .r
Observations on Clucluz River on May 10, 1957 revealed large numbers of mature white suckers and small numbers of largescale suckers in the stream at the same time.
Furthermore, a collection of fingerling suckers from this same river in 1950 was composed primarily of largescale suckers.
However, some white suckers and fish with intermediate dorsal ray count, peduncle height and number of scales above that lateral - 70 -
line were also in the collection. These may have been hybrids
between the two species, indicating that hybridization did occur
in the outlet stream. The condition of the specimens was such
that precise taxonomic examination was difficult.
The co-habitation of a rarer species, in point of time only, with a multitude of a related species, brought about by the over•
lap of breeding seasons may possibly govern hybridization in these
two lakes.
In Cluculz Lake, at any rate, hybridization could conceivably
occur in the inlet streams where white suckers are frequently found, and where largescales may occasionally occur. However, largescale suckers were never found in these areas. The former explanation seems more plausible at this time.
Lindsey (1956b) has suggested that the white sucker is a relatively recent Invader of the Pacific watershed. If this
assumption is correct, further agreement with the conditions con• ducive to natural hybridization as discussed by Hubbs is obtained.
Size Distribution.of - Spawners.
Insufficient data were collected from any one stream during
the spawning season to indicate the size distribution of the
spawning fish of this species. Some indications were obtained however, by measuring and sexing the fish collected in the spawn• ing streams and now in the Museum at the Institute of Fisheries,
University of B. C. Although the samples were fairly small, it appeared that the females were larger than the males.
The indications were that the females were larger than the - 71 -
males. This was the case in samples from Harrison Lake, 108 -
Mile Lake, Rail Creek, Shumway Lake outlet and Cultus Lake out•
let. However, Clemens (1939) in work on Okanagan Lake made no
mention of differential growth of male and female largescale
suckers.
Age of Spawning Largescale Suckers.
Here again, insufficient numbers of fish from any one loc•
ation were available to determine the age of spawning large-
scale suckers. However, scale samples of fish from 108 - Mile
Lake were examined by placing the scale on a glass slide in a
drop of water and placing a cover slip over it and then examining
in the usual manner with a microprojector. A general trend was
indicated by the fifteen scale samples examined. Six of the
eight females from this particular stream were six years old,
while the other two were five years old. All except one of the
seven males was a five year old. One small male was four years
old. 1
Survival of Adults.
No mention of the survival of largescale suckers has been
noted in the literature. Very little data have been collected
in this study.
Observations at Cluculz Lake however, indicated that the sur•
vival was high. Large numbers of adult suckers return through a
weir on the river each year in June. No dead fish have been
observed and it would seem that, as with white and longnose suckers,
a high rate of survival of spawning fish is usual. Very few dead suckers were seen in the Shumway-Trapp-Napier Lake chain near
Kamloops or 108 - Mile Creek, although moderate sized runs were present in these locations.
Characteristics of Areas Utilized for Spawning.
A few observations of the spawning streams utilized by largescale suckers indicated that the requirements for spawning were much the same as for the other two species already dis•
cussed. Spawning took place on shallow riffle areas in Ellison
Lake inlet. Similar areas were utilized for spawning in 108 -
Mile Lake inlet. Eggs were deposited primarily in gravel areas
of these two streams. Very few eggs were found in sandy or rocky areas of these streams.
Incubation Period of the Eggs.
No data have been collected on this subject during the course
of this study. However, Weisel (1957) reports that the normal
incubation period for this species is about two weeks.
Early Life.
Although factual data available on this subject are limited,
certain conclusions can be drawn on the basis of information .
gathered for the other species. Since some spawning does occur
in inlet streams, the fry must migrate down to the lake shortly after emergence from the gravel much as longnose and white sucker fry. This is essential as many of the streams in the areas where these fish occur dry up completely in mid-summer. In a lake such as 108 - Mile Lake, where no outlet stream is present, this would be essential for preservation of the species. The - 73 - mechanism of downstream migration of the fry may be similar to that described by Hoar (1953) for pink and chum salmon fry. The same behaviour pattern probably exists for fry and finger- lings in outlet streams as is the case with white and longnose sucker juveniles. This is indicated from a collection of juvenile largescale suckers made in the outlet of Cluculz Lake in 1950. These fish ranged in size from two to four-inches. The ages of these fish, as determined by scale reading, were one to three years. The majority of the fish were one and two year olds.
Evidently largescale suckers spend a considerable period of time in the lake before migrating into the lake. A similar behaviour pattern has been demonstrated for longnose and white suckers. - 7k -
VII. FACTORS INFLUENCING MIGRATIONS
Detailed data have been collected at Baker Lake with a
view to indicating the factors which are important in influ-
encing the upstream and downstream migration of longnose and
white suckers.
Literature Review.
Various authors have suggested some of the factors which
influence spawning migrations of adults and lakeward migra•
tions of fry and fingerlings of these species. Dence (19^8)
found that a sharp increase of temperature at the approach of
the spawning season usually caused a great influx of spawning
dwarf suckers, Catostomus commersoni utawana, from the lake.
Abnormal decreases of temperature were, on the other hand,
associated with abnormal curtailment of the spawning migrations.
He also noted a marked correlation between the dates the ice
left the lake and the date which marked the beginning of the
spawning migration. Shetter (1938) noted that heaviest move•
ment of suckers (not classified as to species) into an outlet
stream was at a temperature of k$ degrees F. No movement took
place until the temperature was 38.3 degrees. Rawson and Elsey
(19^8) working on Pyramid Lake in the Jasper area stated that
the longnose sucker in spawning condition moved freely into the
streams at temperature of 11 - lk degrees Centigrade. They remained near the stream mouths when the temperature was nine
degrees or lower. Brown and Graham (1953) working on the long•
nose suckers in Yellowstone Lake noted that marked increases or - 75 - decreases in water temperature were associated with similar increases or decrease in the number of suckers in the traps.
> Wescoatt and Moore (195*+) working on West Beaver Creek, the inlet stream to Skaguay Resevoir in Colorado, noted that the main factor that appeared to increase the number of fish trapped daily was the maximum stream water temperature. The largest catches were made when the temperature was 56°F. or higher. Stream temperature increased from *+2°F. on May k- to a maximum of 58°F. on May 7 when the first catch of any size was made. They noted no relationship between the water level or the surface temperature of the reservoir and the numbers of fish taken in the trap. Wescoatt (1955) noted a similar response of spawning fish to temperature in 1955. He stated that suckers and trout con• gregate at the head of the lake in shallower water and move up with a rise in temperature. His results showed a definite cor• relation between temperature and the number of suckers caught in the trap. Pew workers have mentioned the effects of current on migrations of spawning fish. However, Mottley (1933) con• sidered the factors which influence the migration of rainbow trout, Salmo gairdneri into the inlet streams of Paul Lake in the interior of British Columbia. He maintained that with the onset of maturity the current from the stream was the most impor' tant factor governing the migration of fish. He considered that all other factors were subsidiary in importance.
Current is undoubtedly an important factor associated with - 76 -
the spawning migrations of suckers but judging from the pub•
lished results of other workers, temperature is apparently one
of the more important factors influencing the migration into
the stream.
The data on factors influencing the upstream migration of
the two species of suckers in Baker Lake have been analyzed and
the results presented below. Only the inlet stream was con•
sidered as the numbers of fish moving into the outlet stream were
so small as to be of insignificant value in indicating any
physical factors which were associated with migrations.
"White Suckers.
The conclusions drawn from this work support the findings
of other workers. The two factors which appeared to be most
critical in controlling the upstream migration of this species
were water levels and stream temperatures. These data are
related to the numbers of fish migrating upstream and are
depicted graphically in Fig. 17 and 18. Special mention of the
method of graphical presentation is necessary. The traps were
generally checked in mid-afternoon. However, as will be shown
later, the white suckers moved upstream primarily at night, and
as a result the fish in the trap on any one afternoon were
largely the results of the previous days temperatures. Therefore
the number of fish taken in the trap on any particular day was
compared with the daily temperature of the previous day and is
presented graphically in this manner. - 77 -
40 .
30
in
o 20, z
ro
"T" —r —r- -4 -3 -2 -I 0 I 2 3 4
°F Temperoture Change From Previous Day
Pig. 17. Number of white suckers migrating up Baker Lake in relation to the change in daily maximum temperature from previous day. 1956. - 78 -
May I
Fig. 18. Relationship of daily maximum temperature change, water levels and number of white suckers moving into Baker Lake inlet. May 1957. - 79 -
In 1956 a fairly clear relationship existed between the daily increase or decrease in temperature and the number of fish in the trap the following day. The data are presented graph• ically in Fig. 17. The number of fish taken in a day is com• pared with the temperature change from the previous day. While some variability existed, especially with small temperature increases, the largest number of fish were associated with the greatest change in temperature. A decrease in temperature over that of the previous day resulted in smaller numbers of upstream migrants.
Only 95% of the fish were considered in.this treatment.
Fish migrating at the extreme ends of a run are not necessarily present in sufficient numbers to demonstrate the relationship with temperature change. At the end of a run, temperatures can increase markedly, as they did in 1956. However, since the run was practically over, the increase in temperature was not reflected in a large number of upstream migrants.
The data for 1957 have been treated in a similar manner.
However, the results did not appear at all comparable to those of 1956. As can be seen from Fig. 18, an increase or decrease in the number of fish in the trap.
The other physical data which were collected were examined in the hope that some explanation of this difference in response to temperature might be obtained. The water levels in the stream during the height of the 1956 and 1957 runs were very different.
In 1956 the ice left Baker Lake about the 10 of May, which is - 80 - consistent with other years.
As a result the main run-off period coincided with the normal spawning times of the two species of suckers. This, coupled with high precipitation in May and June, maintained the water flow at a high level. In 1957 however, the ice had left the lake by the 1st of May. As there was an unusually small amount of snow during the previous winter, the run-off did not last long. In addition, very little rain fell' during the first two weeks of May. At times the stream flow was so reduced that less than two inches of water flowed over the sill of the trap.
(Fig. *0.
The only pronounced migration of white suckers into the inlet stream followed a heavy freshet which brought the water level up fifteen centimeters. As can be seen in Fig. 18, this- increased migration occurred at the time when both temperatures and water levels rose. Thus it may have been the combination of the two factors which controlled the migration. Krohkin and
Krogius (1937) have mentioned that the low water and falling tem• peratures decrease spawning migration of sockeye salmon. This species migrated on increased water flows and temperatures.
Apparently water level did have a definite influence on the run of fish. Fig. 18 shows that on May l'+th, water temperature fell, while the water level rose. Migrations were not usually initiated by falling temperatures. However, the first large upstream mig• ration of the season occurred at this time. It is likely that water level, as shown by the 1956 data, does not generally affect - 81 - the number of fish moving upstream. However, in this case, the water level reached a critical point and hindered the mig• ration into and up the stream.
Evidently temperature plays an important role in influenc• ing migration. If it did not, large numbers of fish might be expected to move upstream during the spring run-off when the water temperatures were low and the water levels high. This has not occurred during the course of the present study.
Longnose Suckers.
Data obtained on the factors associated with the upstream migration of longnose suckers into the inlet stream concur only in a general way with those presented by other workers.
The first few days of the runs of longnose suckers in both of the years studied failed to follow what had come to be the i expected temperature relationship. The data on other physical factors were thus examined in the hope that they might provide an indication of the factors which were affecting this portion of the run. (
Water levels in the stream appeared to have no effect on the numbers of fish moving into the stream. They were adequately high so that they would not be a limiting factor and were no higher than other portions of the run when large numbers of fish were taken in the trap.
The runs of longnose suckers started shortly after the ice had left the lake in both 1956 and 1957. Instability of the lake which had not yet stratified, or some associated condition, may - 82 - possibly have influenced migration of fish into the stream.
Detailed limnological studies were carried out on Baker
Lake in the spring of 1957 with the hope of answering some of
these questions. The direction and velocity of winds and cur• rents in the lake, and temperature series were taken frequently.
Oxygen samples were also taken at regular intervals.
Lake temperature might have some effect as it would det•
ermine the level at which the inlet stream flowed out into the
lake. The temperature, and hence density of the stream, would
govern the level at which the stream currents would be detected
in the lake as the water from the creek would "seek out" its own
density level. Winds might influence the numbers of fish mig• rating upstream, particularly in an unstratified lake where com• plex currents might be set up. If the wind were blowing directly
onshore, the influence of the stream might be restricted to a
smaller area than it would if the wind were blowing offshore and
in a sense reinforcing the effects of the stream current in the lake. This effect has been noted in Nicola Lake where the thermal
influence of a creek which discharge 5 cubic feet per second,
could not be detected 10 feet from shore when a strong wind was
blowing directly towards the mouth of the creek. (T.G. Northcote personal communication).
Extensive data on winds and lake currents were taken between
the time when the ice' left the lake and the thermocline was established. Current vanes on the surface and at 15 foot depth
suggested substantial "turning-over." - 83 -
It appeared that large numbers of fish migrated into the stream when the winds were blowing directly out from the mouth of the creek or were up and down the lake. During the period before establishment of a thermocline, only 13 fish moved into the inlet stream when the wind was blowing directly onshore. k larger number of fish might have been expected as the temp• erature on that date (May 6th) was slightly higher than the day previously when 69 fish moved upstream. After establishment of the thermocline no further effects of winds or currents on the movement of fish into the inlet stream could be determined. How• ever, further more detailed work will be necessary to clarify the situation.
Mottley (1938) has considered the effect of wind on the
"intensity of migration" of spawning rainbow trout in Paul Lake, near Kamloops, B. C. He found that the greatest migration occurred on days when the wind blew directly towards the inlet stream which the fish used for spawning. He maintained that the migration to the creek was related to a complicated inter• action of wind-driven lake currents, the stream current and temp• erature acting in a dual capacity; first through the effect on the fish themselves, and secondly in its effect on the density of"the water and through density on the linking up of the currents.
Comparisons of maximum, mean and minimum temperature with the number of fish taken in the trap were made. However, no definite relationship was evident. An increase or decrease in , the daily temperature did not necessarily result in a corres• ponding change in the numbers of fish as it did in the white - 8»+ -
suckers. At times no temperature change from one day to the
next resulted in a sharp increase or decrease in numbers of
migrating fish. A decrease in temperature also resulted in an
increase in the numbers migrating. The same situation prevailed
during the 1956 and 1957 seasons.
Various authors have noted however, that an increase or
decrease in temperature influences the numbers of fish migrating upstream and for that reason a further examination of the temp•
erature data was made.
This further work was based on the hypothesis that longnose
suckers move into the area of the creek mouth and remain there
until favorable conditions stimulate them to move into the stream.
If, because of unfavorable conditions, the fish congregated off
the mouth of the creek, did not move into the stream, they would
be joined by additional numbers of fish which were attracted to
the sphere of influence of the creek.
Although congregation off the mouth of the spawning stream has
not been reported for suckers, other species of fish do exhibit
this behaviour. Salmon, in particular, are known to delay off
the mouth of a river until the necessary stimuli for upstream move•
ment occur (Huntsman 193^ and Poerster 1937)•
On the further assumption that the frequency of fish mig•
ration into the stream follows the pattern of a normal distribu•
tion, the data can be treated by probit analysis.
Probit analyses are carried out by calculating the cumula•
tive percentage of the total run of fish which have arrived at a
particular date. These data are plotted on probit paper and a - 85 -
straight line is fitted to the points. The theoretical cum•
ulative percentage of the run which should have arrived to any
date can be determined from this graph and from this the theore•
tical daily percentage which should arrive can be calculated.
The number of fish which actually arrived each day can then be
expressed as a percentage of the expected number of fish. If
more fish arrived than were expected it is assumed that condi•
tions were very favorable and if fewer than calculated arrived,
then conditions were unfavorable. If fewer arrived than calculated,
then it was assumed that the theoretical remainder were still in
the vicinity of the stream mouth and would enter the stream with
the next days number of migrating fish. On the other hand, if
conditions were favorable, then perhaps part of the succeeding
days run would be stimulated to migrate into the stream. Thus
the total available to migrate into the stream the following day
would be lessened.
The data were treated by probit analysis in an attempt to
, clarify any relationship which existed between temperature and
the numbers of migrating fish entering the stream. The white
sucker data were not treated in this manner as the temperature
relationship was fairly clear.
The results of the probit analysis are compared with the
daily maximum temperatures in Fig. 19 and 20. Examination of
the graphs indicates a positive relationship between temperature
change and numbers of fish moving upstream during the middle period
of the run. However, factors other than temperature are operative
during the beginning and end of the run.
c. - 86 -
200
150
100.
50
Temp. ° F
k 0 6o\
% ^ Expec t e d Arrivals 50
40
• i —i— 12 15 20 25 Date May 1956
Fig. 19. Probit analysis of arrival frequencies of longnose suckers in Baker Lake inlet com• pared with daily maximum temperature. May 1956. - 87 -
50
100
50 J
0 1 % Expec ted Arrivals
0 15
Date May 1957
Fig. 20. Probit analysis of arrival frequencies of longnose suckers in Baker Lake inlet com• pared with daily maximum temperature. May 1957. - 88 -
Only in the middle stage in the two years is there any degree of consistency of the relationship.
Possibly the limnological conditions in the lake account for some of the discrepency in the relationship in the early stage of the run. A factor which must also be considered is the availability of fish during the beginning and end of the up• stream migrations. In some instances such small numbers are available to move into the stream that a relationship can be dis• torted by the presence or absence of a very few fish.
To date this study has indicated the factors which appear to control the upstream migration of longnose and white suckers but the exact relationship of each factor has not been determined.
Temperature has some influence on the stimulation of migration into the stream but its effect can be controlled by water flows.
Conditions in the lake appear to govern the availability of fish to the spawning stream. Complex currents resulting from the effects of discharge into the lake and wind-driven currents may determine the numbers of fish which arrive at the mouth of the stream in any one day. Further work on this aspect of the pro- blem is to be done in the summer of 1958.
Diurnal Movement of Longnose and White Suckers.
Indications from the data obtained over two seasons at Baker
Lake were that both longnose and white sucker adults exhibited marked diurnal variation in movement when entering the inlet spawning stream. '
In 1957 the traps were emptied three times a day, as regu• larly as is possible under field conditions, at 0900, 1600 and 2100 hours. - 89 -
The great majority of fish of both species moved into the traps between 1800 hours and 0600 hours following morning, pointing very definitely to a nocturnal migration. 65% of the white suckers and 50% of the longnose suckers moved into the stream during this period. 28% of the white suckers and 35% of the longnose suckers moved into the trap in the late afternoon-early evening period.
The remaining fish (7% of the white suckers and lk% of the long• nose suckers) moved into the traps during mid-day.
In an attempt to define this movement more precisely, the traps on the inlet stream were emptied every hour from May 13 to
May 16 during the 1957 spawning run. The results are shown in
Fig. 21. The diagram includes only the data collected from
May 1*+ - 16. Very few fish were taken on May 13. The results demonstrate the predominantly nocturnal movement of these two species of suckers. The daily movement of the longnose suckers up into the spawning stream extended over a greater number of hours than it did for the white suckers.
Various other workers including Raney and Webster (19^2),
Dence (19^8), Hankinson (1919) and Adams and Hankinson (1928) have noted a nocturnal migration to the spawning grounds by the white sucker.
The nocturnal migration of the suckers may have been in response to water temperatures. The migration took place on fal• ling water temperatures. However, the rising temperature of earlier periods of the day may have stimulated the fish to move into the stream from the lake. If this were the case, they might - 90 -
1 1 1 —i •—r
Fig. 21. Dxurnal movement of longnose and white suckers in Baker Lake inlet compared with stream temperature and periods of daylight and darkness. May lk- - 16, 1957. - 91 - not reach the trap till such time as the temperatures had begun to fall off. The data on water levels for this period indicated no relationship between the flows and the nocturnal migration of these fish. The migratory behaviour may also be related to falling light intensity. Fig. 21 illustrates that the numbers of migrating fish gradually increase as the light intensity falls.
Greatest numbers of fish were taken in the traps during peak hours of darkness- Although several workers have noted this noc• turnal behaviour, none have discussed its possible causes.
Some data on the downstream movement of the spent longnose suckers were also obtained in the course of the hourly clearing of the traps. Downstream movement of spent white suckers had not begun by this time. It appeared that the bulk of the long• nose suckers returning to the lake after spawning moved down during the hours from noon to midnight, with the peak of down• stream movement occurring about 10:00 p.m.
Factors Associated with the Return of Juvenile Longnose and White Suckers to the Lake.
Two distinctly different situations existed with respect to the problem of juveniles of these two species and factors assoc• iated with their return to the lake. Fish hatching in inlet streams moved downstream shortly after emerging from the gravel.
However, fish in outlet streams remained there for a year or more.
The factors which influenced their return were also markedly dif• ferent and will be discussed separately. The inlet stream will be considered first.
Results of the work carried out on Baker Lake inlet in 1957 I - 92 - indicated that the young of both species of suckers migrated downstream shortly after emergence from the gravel. Fry were sampled by means of a Surber stream sampler which was emptied every hour for several successive days. The data collected indicated a very marked nocturnal downstream migration of the fry of both species. The migration was limited to the hours of darkness with a peak of migration occurring in the hours from
11:00 p.m. to 2:00 a.m. Migration dropped off sharply with the first light and was limited to a few fish throughout the remainder of the daylight hours.
The mechanism of this behaviour is not known but an explana• tion as suggested by Hoar (1953) for pink and chum salmon fry seems probable. He maintained that the pink salmon drifted pas• sively downstream during the hours of darkness as a result of a loss of visual contact with the surroundings. When sufficient light was present to permit visual recognition of the environment, the fish were able to hold position in the streams. Hubbs and
Creaser (192^) mention that a passive downstream movement following hatching is probably the case for the fry of Cj. commersoni.
The importance of light in maintaining position was clearly shown by a special experiment carried out in the Baker Lake inlet on June 8, 1957* A Coleman gasoline lantern was hung over the stream above the sampling gear. During hours of darkness the lamp was turned on and off on alternate hours. When the light was on, very few fish were taken in the stream sampler. When the light was turned off for the following hour, the usual large number of fish were captured. Indications were that the down- - 93 - stream movement of these fish is controlled to a large extent by light.
Data were not graphed or tabulated because identification of the fry of the two species was uncertain. Longnose and white sucker fry migrated to the lake at a size of approximately one- half inch. The fish were in a very undeveloped stage at this size and separation of the two sucker species was difficult.
Shiners and squawfish could readily be separated from the two sucker species as the former two were considerably smaller.
Attempts to separate the two species of suckers were not success• ful. Since the longnose suckers spawned first? the fry pre• sumably hatched and migrated downstream first. Samples from the first part of the downstream migration were examined. The maj• ority of the suckers at this time were heavily pigmented, while those at the end of the run were less heavily pigmented. It was assumed that these other fish may have been white sucker fry.
However, there appeared to be a large amount of intermediacy in pigmentation and separation was not certain on this basis alone.
Examination of known longnose sucker fry from Bouchie Lake revealed that a great deal of variation in pigmentation existed in the one species in one stream. Meristic characters were not sufficiently developed to permit separation on that basis.
Because this problem of separating the two species existed, absolute counts of each species moving downstream were not made.
However, examination of the samples revealed that the pattern of migration was similar for both species as the bulk of fry were - 9^ -
captured during the hours of darkness.
The second phase of the juvenile sucker behaviour deals
with the fish which hatch in the outlet stream. Observations
on Baker Lake and Bouchie Lake indicated that outlet fry
remained in the stream for a period of one to four years.
The explanation of this behaviour is purely speculative.
It does seem possible that fry are physically incapable of swim• ming upstream into the lake during their first summer due to
their small size. However, they remained in the stream after
they reached a size when they would presumably be able to swim
up into the lake. Some change in behaviour must exist to explain
the continued stream residence.
The results which are presented here deal with the longnose
suckers only as very few white sucker fingerlings were taken in
the ascender trap on Baker Lake outlet. Work carried out during
the summers of 1956 and 1957 indicated that longnose sucker
fingerling movement upstream into the lake was associated with
temperature. In Pig. 22 the daily numbers, of fish moving up
into the lake were compared to the change in mean temperature
from the previous day. Results are variable but it appeared
that an increase in the temperature resulted in a greater upstream
migration while very few fish were taken in the traps when the
temperature dropped from that of the previous day. A sharp rise
in temperature seemed to initiate the large upstream movements.
In 1956, the largest number of fingerlings was taken on a day
when the temperature rose 12°F. above the previous day's temp•
erature . - 95 -
40 -
30
w 20 « .0 E 3 Z
10 -
o o o o I I 1 1 1 I 1 1 1 1 1 1 1 I I < r——I— 5_4_3_2^| 0123456789 10 II 12
°F Temperature Change From
Previous Day
Fig. 22. Relationship of temperature change from previous day to the numbers of longnose sucker fingerlings moving up the Baker Lake outlet. 1956. - 96 -
The 1957 data did not reveal any distinct relationship between fingerling upstream movement and daily change in max• imum temperature. However, there were no sharp increases or decreases in temperature during the upstream migration.
Runnstrom (1957) maintained that a sharp increase in temperature resulted in a marked increase in the upstream movement of brown trout. This relationship also appeared to exist during the 1956 upstream migration of longnose sucker fingerlings. The absence of a sharp change in temperature may account for the lack of a clear relationship in 1957.
The relationship of temperature and the number of juvenile longnose suckers moving into the lake is fairly well established.
As the temperature rises, the number of fish migrating upstream increases. In 1956 a sharp decrease in temperature resulted in a small number of upstream migrants.
The migration of the fingerlings was not limited to the number of days depicted in Fig. 22. Approximately 70% of the fish moved upstream during these few days. The remainder moved into the lake sporadically over the remainder of the summer.
As mentioned previously, the outlet of Baker Lake spills over a beaver dam. The possibility of this barrier seriously hindering the upstream migration fish existed and therefore observations on Bouchie Lake outlet were conducted to determine the age at which the fingerlings moved upstream.
Two-way conical minnow traps were placed in the outlet stream of Bouchie Lake. They were arranged in pairs with one - 97 - opposite lead on each trap closed so that an indication of upstream and downstream movement could be obtained. The results suggested that the migration was primarily upstream. In two days, the traps sampling upstream migration captured *+2 fish while no fish were taken in downstream traps. The majority of these fish were two years old. Since the majority of fish taken in the Baker Lake outlet were three years old it is possible that the dam on the outlet of Baker Lake prevented the migra• tion of the longnose sucker fingerlings into the lake for a year or two. - 98 -
VIII. CONCLUSIONS AND SUMMARY
Much of this study, because of its nature, has been discussed under each section. However, the following section considers some of the more general relationships existing between the three species.
It is recognized that all of these three' species may live sometimes entirely in rivers and large streams. However, this study has dealt with those fish which spend the majority of their life in lakes and move into the streams at maturity for the purpose of spawning. Spawning Localities of Suckers.
Extensive observations throughout B. C. in 1956 and 1957 have revealed the primary spawning localities of each of these three species. The longnose sucker and the white sucker spawn primarily in inlet streams. Small numbers of longnose suckers have been observed spawning in outlet streams in the Quesnel area, but the numbers were generally insignificant compared with those spawning in the inlet streams. White suckers, although spawning chiefly in inlet streams, were found in some outlet streams in moderate numbers.
The largescale sucker, on the other hand, spawned chiefly in outlet streams. In lakes where both inlet and outlet streams were available, migrations were generally to the outlet. At
108 - Mile lake, however, only an inlet stream was present, and the largescale suckers utilized this stream for spawning.
The three lake-dwelling species can therefore be divided into two groups; the longnose and white suckers which spawn - 99 - primarily in the inlet streams and the largescale suckers which usually migrate at maturity to the outlet streams.
Timing and Duration of'Spawning Runs.
Not only do differences exist in the streams used for spawning by these species, but also differences in the time of spawning have been noted. Comparable data are available only from the Cariboo area. Longnose suckers migrated to the inlet streams before the white and largescale suckers. The peak of the longnose sucker migration was generally a week or ten days before the white sucker run at Baker Lake. Longnose suckers appeared in the inlet to 108 - Mile Lake two weeks before the largescale suckers.
White suckers and largescale suckers were observed in the same outlet stream at Cluculz Lake. Observations there indi• cated that the white suckers spawned sometime before the large- scale suckers.
Outlet-spawning largescale and inlet-spawning white suckers were noted in different streams of this lake at the same time.
Evidence suggests that the white suckers spawned in the outlet before the inlet stream. Observations have been made in other places, including Loon Lake, near Clinton, where rainbow trout spawned in the outlet stream considerably before the inlet stream. The same situation was noted in the longnose suckers of Bouchie Lake, in which the few fish which migrated to the outlet stream were nearly a month ahead of those migrating to the inlet. - 100 -
The spawning'runs of the three species of suckers take
place, in most parts of British Columbia, during the month of
May. In the Lower Mainland, runs of largescale suckers are
during April. This is probably related to climatic conditions
which are a function of the latitude and altitude.
In most streams there was no significant spawning migra•
tion of any of the three species after June 1. The most not•
able exception was in a small stream in the East Kootenays, where
a small run of small mature longnose suckers made up primarily
of males was noted in mid-June. Examination of a sample of these
fish indicated that they were probably precocious.
In summary, spawning migrations of longnose suckers to inlet
streams are earlier than those of white suckers which in turn are
earlier than largescale sucker migrations to inlets. Comparable
data from the Cariboo area indicat that longnose and white
suckers spawn at similar times in outlet streams and are followed
by largescale suckers. Runs of these species to outlets pre•
cede those to inlets. The runs of suckers studied in British
Columbia extended over a period of a month.
Size and Sex Ratio of Spawning Fish.
Spawning females in the three species studied were larger
than the males. Significant differences were noted in the size
of males and females of both the longnose and the white sucker.
Examination of largescale suckers in the Institute of Fisheries
collection indicated that probably the females of the species
were also larger than the males, although insufficient numbers - 101 - were present to demonstrate this conclusively. Hubbs and Cooper (1936) discussing the minnows of Michigan, maintained that it is common in those cyprinid species which exhibit no parental care for the females to be larger and live longer than the males.
The sex ratio of the two species of suckers migrating into the Baker Lake inlet was noted. In 1956 the sex ratio of the white suckers was not significantly different from an expected 1:1 ratio. However, in 1957> twice as many males as females passed through the ascender trap. As the sex ratio of the fish entering the traps for the first time, was the same as that of the marked fish, it was assumed that there was no apparent dif• ferential sexual mortality. Water levels were unusually low in the spring of 1957 and possibly the larger females were unable to migrate into the traps and remained in the stream below the trap or spawned in one of the other two creeks.
In the two years the sex ratio of the longnose suckers was approximately 2 females : 1 male. Analysis of the 1957 data revealed that the sex ratio of the fish moving into the traps for the first time In 1957 was 1:1. However, the ratio of marked fish returning to the same spawning stream as they had been marked in during 1957 was nearly 3 females to 1 male. Differential mortality of the sexes apparently occurs between subsequent spawnings. There is possibly some selective advant• age in such a mechanism. It has been shown by some workers that egg production is correlated with the size of the fish (Foerster - 102 - and Pritchard 19^1)• Large females produce relative more eggs and since one male is apparently able to fertilize the eggs of several females, there would be some selective advantage to the species in the production of a predominance of large females. Age of Spawning Suckers.
The age of spawning suckers has been determined for the three species under consideration. Adequate numbers of scale samples from spawning longnose and white suckers were available to enable a reasonable statement about the age of spawners of these fish, but only small numbers of scale samples were avail• able from spawning largescale suckers. The white suckers examined from Baker Lake indicated that the majority of spawning fish were seven years old, with a range of from five to eight years. Pish over seven years of age were females.
Some longnose sucker males spawned in Baker Lake for the first time at five years although the great majority spawned at age six. Some seven year old males were noted. The females of this species appeared to mature a year later than the males. First spawning of females was at six years, while it occurred predominantly at seven years with some at ages eight and nine.
The same differences in spawning age appeared to exist for the males and females of the largescale suckers. Females spawned primarily at six years and the males at five years.
A parallel is noted in the life history of cyprinids. Hubbs and Cooper (1936) have shown that those species which exhibit no parental care the females generally live longer than the males. - 103 -
In some cases spawning checks on the scales of fish
indicate the number of times that a fish has spawned. The
indications of such checks in these three species of suckers were so slight that no confidence could be placed in this method of determining the number of previous spawnings.
Sexual Differences in the Movement into and out of the Stream.
Differences in the time of movement into and out of the
streams were noted during the 1956 and 1957 spawning runs of
longnose and white suckers., 'V "•
White sucker males preceded the females into the spawning
stream. However, no differences were noted in the time of the migration upstream of male and female longnose suckers. The majority of the males of both species remained in the spawning
stream after the females had moved back into the lake. Observa•
tions on the squawfish, Ptychocheilus oregonense. in Baker Lake
indicated much the same behaviour. The males entered the stream much earlier than the females and remained there much longer.
In some cases, large females would move into the stream one day,
and the next day return spent to the lake. Unpublished data on
the rainbow trout in Loon Lake revealed a similar difference in
the time spent by males and females in the spawning-stream.
Survival of Spawning Fish.
The work at Baker Lake has shown that the survival of
spawning fish is high. In 1956, approximately 85 percent of both white and longnose suckers which had been marked and put upstream returned through the descender as spent fish. - 10*f -
Distribution on Spawning Grounds.
The distribution of spawning fish has been studied at
Baker Lake. The first fish move up the stream the farthest and later fish move into the lower reaches of the spawning stream, even though the densities of fish by that time are quite low and the upper areas would be available for spawning.
This behaviour was noted in both the white and longnose suckers.
Distributions of runs of rainbow trout and sockeye salmon are comparable to these species in this respect as the first fish move into the upper areas of the spawning grounds. This behav• iour pattern may be related, as it is in sockeye, to the temp• eratures of the streams.
All species of suckers observed spawning in inlet streams returned to the lake by the middle of June. Possibly there is some selective advantage in this behaviour pattern as streams in the study area often dry up or have very reduced flows and high temperatures during the summer months.
Nature of Spawning Grounds.
The nature of the spawning grounds is remarkably similar for the three species studied. Observations indicated that suckers are selective in the nature of the areas chosen for spawning.
Eggs were deposited by the three species of suckers pri• marily in areas of the stream where the water was less than a foot deep and the velocities moderate. Usually the gravel size in spawning areas was not more than four inches. Some deposition of - 105 - eggs did occur in regions where the water was deep and slow moving, and where the substrate was sandy. The majority of eggs found in such areas were dead. Suffocation as a result of poor subsurface flows through the substrate and resultant deple• tion of oxygen may have been important factor in such mortality.
Although lake-spawning must occur in certain instances to permit the maintenance of populations in lakes with no streams, it was not observed for any of the species during the course of this study. "When it does occur, possibly a relatively exposed beach where the wave action keeps the eggs well oxygenated is required. Lake spawning may take place in areas where the see• page would be sufficient to supply the necessary oxygen to the eggs. Published results from other areas indicate that suckers spawn for the most part in areas similar to those described for the three British Columbia species.
Streams Used for Successive Spawnings.
In 1956, white sucker and longnose sucker adults were marked in the spawning stream. Examination of fish recaptured in the three streams of the lake was conducted in 1957• The results indicate that there is very little tendency for either the white sucker or longnose suckers to return to the same spawning stream year after year. The greatest numbers of marked fish returned to the inlet stream in which they had been marked. However, the proportion of marked longnose suckers to unmarked fish was lower in the stream where these fish had been marked than it was in the second inlet and the outlet stream, suggesting if anything, - 106 - a tendency not to return to same stream two years in a row.
The white suckers showed no significant differences between the proportion of marked and unmarked fish in the various streams in the lake.
The two species of suckers considered here may, in reality, return to the same spawning stream in consecutive years to a much greater degree than was demonstrated during the 1957 obser• vations. Water flows in the main inlet were abnormally low that year. This may have prevented the larger marked fish from moving upstream into the traps. A number of these marked fish may have remained in the stream below the trap and others may have moved out and into another stream. Further information on this subject will be gathered in 1958.
Factors Influencing Spawning Migration of Suckers.
The question of the factors influencing the spawning mig• ration of suckers into the streams is one which has been dealt with in some detail. The results are not clear, but do indicate those factors which are important.
Current, as Mottley (1933) stated, is the most important factor influencing spawning migrations in salmon and trout. He maintained that this is the fishes main compass and no matter what other factors come into play, their importance is subsi• diary to the effect of current. He maintained that all salmon and trout are susceptible to current with the onset of maturity and it is the chief direction finder at the time of maturity.
The above can probably be applied to the species of suckers - 107 - which have been studied. While current may attract fish to the stream mouth, it is apparent that other factors actually trigger-off the migration into the stream.
Temperature appears to be the most important factor which
brings about their movement into the inlet stream. The rela• tionship which was found to exist, while not precise, did
indicate a correlation of temperature and numbers of suckers migrating into streams. Many other workers have shown similar relationships and the tendency of fish in general and suckers in particular to move into streams on rising temperature seems well established. A decline in temperature results in a decrease in the number of fish moving into the stream.
The results of this investigation suggested that the abso•
lute temperature was not the important factor, but rather the
change in temperature from day to day seemed to control migra•
tion. A lack of change of the maximum temperature over two days resulted in a decline of the number of fish moving into the
traps. This was especially true for the longnose suckers.
The temperature relationship \^as more precise for the. .white
suckers than it was for longnose suckers. During the first part of the run of longnose suckers in both 1956 and 1957? the numbers
of this species moving into the stream could not be closely cor• related with temperature. As this run began shortly after the ice left the lake, and before the lake became stable on the establishment of a thermocline, it is proposed that some facet
of the limnological condition of the lake may in some way - 108 - influence the upstream migration of these fish. Mottley (1933) has suggested that migration of trout into inlet streams at
Paul Lake was controlled to a certain extent by the water temp• erature of the creek. When ..the temperature was such that the water flowed out into the lake at a density level which was coincident with the level at which the fish occurred, then mig• ration increased.
Intensive work was carried out at Baker Lake in an attempt to demonstrate any such relationship which might exist, but it did not result in any conclusive evidence. In the period before a thermocline was set up in the lake, which was about a week after the ice left the lake, the direction of the wind and lake currents appeared to be associated with differences in the number of fish which were moving into the stream. During this period, a wind blowing directly towards the mouth of the creek was associated with a decline in the number of migrating fish moving into the stream. When the wind was blowing offshore, larger numbers of fish were taken in the traps. This wind dir• ection may possibly have reinforced the effects of the current from the stream and in this way enlarged the sphere of influence of the stream and resulted in the attraction of more fish to the
stream.
Stream temperatures, which would govern the level at which the influence of the current would be felt in the lake, might also be important. However, more work on both these subjects is necessary before anything more than conjectural statements may be made. -109 -
Creek water level was also an important factor influencing
the upstream migration of suckers. The effect was primarily
that of limiting, rather than influencing migration. Wo rela•
tionship existed between water level and the number of fish
entering the stream when the flows were substantial. However,
in 1957 by the beginning of the white sucker run, the stream
level had dropped very sharply and no substantial upstream mig•
ration took place until the water level increased. The 1956
run was not affected in this way as the water levels were high
till mid-June.
Factors Associated with Lakeward Migration of Fry and Fingerlings.
Adults suckers spawn in the month of May. The eggs are
deposited in medium size gravel, where they are incubated for a
period of one to two weeks, depending on the water temperature.
Experiments on the incubation time of white and longnose
suckers indicated that the incubation period was similar for these
species. Contributions from the literature support the fact that
a relatively short incubation period is common.
After the eggs hatch, the fry remain in the gravel till such
time as the yolk sac is practically absorbed. They then emerge
from the gravel. Their fate after this depends on the stream in which they hatch.
Good data on the life history of these fish after they hatch from the gravel have been obtained for the white and longnose
suckers, but the evidence on the largescale suckers is largely
circumstantial. - 110 -
Young longnose and white suckers which hatch in inlet streams leave shortly after they emerge from the gravel. There is no reason to suspect that the largescale sucker fry do not follow the same general behaviour pattern. There must cer• tainly be some selective advantage to the fry moving into the lake shortly after they hatch, as many of these streams dry up during the summer months. If the fry remained in the streams for any length of time they would undoubtedly experience a very heavy mortality. Selection would be in favor of those fish which developed some mechanism permitting their early departure from 'the stream. Apart from the streams drying up, conditions are probably more favorable in lakes as inlet streams are generally poor in food.
The downstream migration of these fry into inlet streams takes place for the most part during the hours of darkness.
This was shown very clearly at Baker Lake where traps designed to capture downstream migrants were placed in the stream. Hourly checks on the number of fish in these traps were carried out over a period of three days, and while the longnose and white sucker fry could not he readily distinguished, it was evident that the same behaviour pattern for both species existed, as all downstream migration of any importance was during the hours of peak darkness.
Hoar (1953) has suggested that the downstream migration of chum salmon at night is the result of falling light intensity, which influences the rheotactic responses which are largely dependent on vision. As the light decreases the response decreases and - Ill - the fish pass downs-tr-eam in shoals. Pink salmon behaviour is much the same. Such an explanation seems very likely for the downstream., migration of the white and longnose sucker fry.
These fry moved down in increasing numbers as the hours of mid• night to 2:00 a.m. approached and fell off till dawn when prac• tically no fish moved into the traps.
The effect of light in controlling this migration was indicated when a Coleman lantern was set out over the trap during the evening. When the lamp was on, the number of mig• rants taken in the trap was reduced to virtually none. "When the lamp was shut off, migration resumed. This would seem to support the hypothesis that the migration is a result of loss of visual contact with the surroundings. As long as the fish are able to orient themselves relative to the stream bottom, migration does not occur but when they are no longer able to do this, they slip downstream.
Fry4which hatch in the outlet have a different behaviour pattern than those fish in the inlet. On emerging, the longnose and white sucker fry remain in the quiet side waters of the streamjitand as they grow they gradually move out into the faster water of the stream.
Migration does not occur upstream in their first summer, however, instead they remain in the stream for a period of two to four years before moving up into the lake. The reasons for this behaviour are mainly conjectural. It seems plausible that the fish are physically incapable of moving upstream into the - 112 - lake during their first summer due to their small size. How• ever, after they reach a certain size, this would no longer be the case. Some factor must alter their behaviour. The dif• ference in the temperature between the inlet and outlet stream which exists has been suggested as causing this behavioural difference.
The migrating fingerlings appear to move into the lake in response to an increase in temperature. During the period of the migration, an increase in temperature resulted in an increase in the number of fish taken in the trap while a fall in temp• erature resulted in a decline of the numbers of fish moving upstream. - 113 - IX. LITERATURE CITED
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