CONTRIBUTION TO THE ECOLOGY OF THE WHITEFISHES

'Prosopium cylindraceum AND Coregonus clupeaformis

OF ALGONQUIN PARK, ONTARIO

by

FREDERICK KEITH SANDERCOCK B.Sc, The University of Toronto, 1962

A THESIS SUBMITTED IN PARTIAL FULFILMENT OF

THE REQUIREMENTS FOR THE DEGREE OF

MASTER OF SCIENCE

in the Department

of

. Zoology

We accept this thesis as conforming to the required standard

THE UNIVERSITY OF BRITISH COLUMBIA October, 1964 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 per• mission for extensive copying of this thesis for scholarly purposes may be granted by the Head of my Department or by his representatives. It is understood that, copying or publi• cation of this thesis for financial gain shall not be allowed without my written permission...

Department of Z7~ The University of British/Columbia,

Vancouver 89/Canada

Date / ii

ABSTRACT

The distribution of Prosopium cylindraceum (Pallas) and Coregonus

clupeaformis (MLtchill) in Algonquin Park, Ontario, suggested that there

may be some interaction between these species. In large lakes where both

species are present the C_. clupeaformis population is always dominant; in

small lakes only, one species is present. During the summer of 1963 the

ecological relationships between these species were studied. Lakes Opeongo

and Lavieille each contained both species, while in Lakes Redrock and

Happy Isle only P. cylindraceum was present.

Gill nets were set at frequent intervals, to determine the depth range occupied by the two species and to provide material for stomach analysis and age and growth data. Temperature and dissolved oxygen levels were recorded regularly using standard limnological techniques. The depth range occupied by both species was not strongly correlated with the thermal structure or oxygen level of the lake.

P. cylindraceum in sympatric situations invariably occupied a shallower depth range than did C. clupeaformis. Where the latter species was absent P. cylindraceum were frequently found in a wide range of depths.

P. cylindraceum from Lake Opeongo fed heavily on larval insects and to a lesser extent on bottom-dwelling Crustacea. C_. clupeaformis from the same lake fed mainly on bottom-dwelling Crustacea plus some insects and molluscs. P. cylindraceum- in Lakes Redrock and Happy Isle fed almost entirely on plankton Crustacea. Zooplankton was of importance as a primary food source for whitefish.

Age and growth data have shown that there is a direct correlation iii

between the relative importance of plankton in the diet and the rate of growth of the fish.. Fish from Lakes Redrock and Happy Isle had a much higher growth rate in both length and weight than the two species in Lake

Opeongo. In the latter lake C. ..clupeaformjs grew faster than P. cylind• raceum.

Large lakes with adequate zooplankton production will support both

P. cylindraceum and C_. clupeaformis. but the better adaptation of

C..clupeaformis to plankton feeding may account for its greater success as indicated by its wide distribution, large numbers, and high rate of growth. viii

ACOOWLiiDGEMENTS

I wish to thank Mr. N.V. Ifertin, director of the Harkness Memorial

Fisheries Research Laboratory, Algonquin Park, Ontario, for his continuing

guidance throughout all stages of this study. Also Mr. K. Loftus, head of

Fisheries Research Branch, Ontario Department of Lands and Forests, for

providing all the necessary facilities and equipment, without which the

problem could not have been undertaken.

I am indebted to Dr. G.C. Lindsey, Institute of Fisheries, University

of British Columbia, who supervised the writing of the thesis, and whose

criticisms and advice have proven invaluable. Dr. N.J;. Wilimovsky and Dr.

I.E. Efford critically reviewed the manuscript and made many helpful

suggestions.

The author wishes to express his thanks to the Institute of Fisheries,

University of British Columbia, and The Fisheries Association of British

Columbia for their financial assistance. iv

TABLE OF CONTENTS

Page

ABSTRACT .ii

LIST OF TABLES . .y

LIST OF FIGURES. .vii

ACMOWLEDGEMENTS viii

INTRODUCTION. 1

DISTRIBUTION. 3

LAKE DESCRIPTIONS.... .9

METHODS OF OBTAINING FISH ....i.l5

DEPTH DISTRIBUTION. .17

FOOD HABITS, ...... 17

Opeongo Lake .27

Happy Isle Lake and Redroek Lake. 28

AGE AND GROWTH . .29

Lengths-weight relationship. .3.0 Calculated growth..;....."." .34 Growth in Length 37 Growth in Weight. .40

DISCUSSION 44

SUMMARY ••••56

LITERATURE CITED...... 58

APPENDIX. .62 V

LIST OF TABLES Page I. Distribution records of P. cylindraceum in Ontario excluding Algonquin Park. .7

II. Distribution of P. cylindraceum and C. clupeaformis in Algonquin Park. 8

III. A list of all food items found in the stomachs analysed, along with a comment on their relative abundance. .22

IV. Equations for length-weight relationship...... 30

V, Length-weight relationship of P. cylindraceum from Redrock Lake...... 31

VI. Length-weight relationship of P. cylindraceum from Happy Isle Lake. 7....v...... v...... 33

VII. Length-weight relationship of P. cylindraceum from Opeongo Lake. ..33

VIII. Length-weight relationship of G. p.1np

IX. Relation between standard length and magnified (x35) scale diameter of P. cylindraceum from Redrock Lake. 35

X. Relation between standard length and magnified (s35) scale diameter of P. cylindraceum from Happy Isle Lake .35

XI. Relation between standard length and magnified (x35) scale diameter of P. cylindraceum from Opeongo Lake. 35

XII. Relation between standard length and magnified (x35) scale diameter of C. clupeaf ormis from Opeongo Lake. 36

XIII. Equations for length-scale diameter relationship 37

XIV. Calculated standard length at the end of each year of life of each age group of P. cylindraceum from Redrock Lake ....38

XV. Calculated standard length at the end of each year of life of each age group of P. cylindraceum from Happy Isle Lake 38

XVI. Calculated standard length at the end of each year of life of each age group of P. cylindraceum from Opeongo Lake. 39

XVII. Calculated standard length at the end of each year of life of each age group of £. clupeaf ormis from Opeongo Lake. 39 vi

Page XVIII. Summary of the calculated growth in length of whitefish from Lakes Redroek, Happy Isle and Opeongo 42

XIX. Summary of the calculated growth in weight of whitefish from Lakes Redroek, Happy Isle and Opeongo .42

XX. Levels of food consumption by the major fi3h species in four Algonquin Park lakes. .51

XXI. The food of P. cylindraceum and C. clupeaformis from three Ontario lakes. ...62 vii

LIST OF FIGURES

IMS.

1. Map of Ontario showing distribution of Prosopium cylindraceum .. 5

2. Map of Algonquin Park showing distribution of Prosopium cylindraceum and Coregonus clupeaformis. .. 6

3. Contour map of Opeongo Lake, Ontario 10

4. Contour map of Happy Isle Lake, Ontario...... 11

5. Contour map of Redrock Lake, Ontario 13

6. Contour map of Lavieille Lake, Ontario...... 14

7. Depth distribution of Prosopium cylindraceum and Coregonus clupeaformis in Opeongo Lake. 18

8. Depth distribution of Prosopium cylindraceum in Lakes Happy Isle and Redrock. 19

9. Summary of the depth range occupied by sympatric pairs of whitefish. 20

10. Bimonthly food index values for P. cylindraceum and C. clupeaformis in Opeongo Lake...... 24

11. Bimonthly food index values for P. cylindraceum in Lakes Happy Isle and Redrock. 25

12. Summary of food index values. 26

13. Length-weight relationship of whitefish from Lakes Redrock, Happy Isle and Opeongo, based on calculated Weights. .32

14. Calculated growth in length of whitefish from Lakes Redrock, Happy Isle and Opeongo. .41

15. Calculated growth in weight of whitefish from Lakes Redrock, Happy Isle and Opeongo .43 INTRODUCTION

During the course of an aquatic faunal survey of Algonquin Park,

Ontario, it became apparent that the distribution of the Coregonine fishes contained some unusual features. The lake whitefish, Coregonus clupeaformis

(Mitchill) in this area occurs in almost all lakes that are sufficiently deep to support a cold-water species. However the distribution of the round whitefish Prosopium cylindraceum (Pallas) is more restricted and reflects its rather sporadic North American distribution on a smaller scale.

An examination of the lakes in which these species occur revealed the following: (l) that both species may occur separately in relatively small lakes (one-half square mile in area) in which the maximum depth does not exceed sixty feet; (2) that where these species occur together the lakes are for the most part greater than five square miles in area and have a maximum depth of over one hundred feet. It was also observed in the study area that in lakes where both species are present C. clupeaformis is much more common than P. cylindraceum.

Cooper and Fuller (1945) determined some of the aspects of the. ecology of the aboye species in Moosehead Lake, Maine. Studies on other sympatric pairs of whitefish have been made by Godfrey (1955), Lindsey (1963), and

Fenderson (1964). Similar investigations by Svardson (1953), Lindstrom and Nilsson (1962) and Nilsson (1958) have been made on European species of whitefish.

Due to the commercial importance of C. clupeaformis a large number of papers have been published on this species, many of which deal with certain aspects of their ecology. Hart (1931), Qadri (1961), Watson (1963) and 2

others have described the food habits, age and growth and other factors.

Kennedy (1943) examined the C. clupeaformis populations of Lake Opeongo,

Algonquin Park, but restricted his work primarily to morphology.

Although P. cylindraceum is widespread, it is only recently that much work has been done on this species. Other than Cooper and Fuller's

(1945) paper, only Kennedy (1949), Rawson (1951), Bailey (1963) and Mraz

(1964) have made detailed studies on the round whitefish. The latter two confined their work to Lakes Superior and Michigan respectively.

Papers by McKugh (1939, 1940), Northcote (1957), Sigler (1951) and others have dealt with the related form,.the.mountain whitefish, P. williamsoni. while Eschmeyer and Bailey (1955) have treated the pygmy whitefish, P. coulter!.

In view of the peculiarities in the local distribution of C. clupea• formis and P. cylindraceum. plus the fact that so little was known about the food habits of P. cylindraceum. a study was begun to determine the ecological' relationshipexisting between these fishes. The study was confined essentially to four lakes, Opeongo, Layieille, Happy Isle and

Redroek, all of which are located in Algonquin Park. In the first two lakes, Opeongo and Lavieille, C. clupeaformis and P. cylindraceum are both present, however in Lakes Happy Isle and Redroek P. cylindraceum is the sole whitefish species.

Other lakes were examined briefly during the summer months but the data presented here are based primarily on work completed on the above lakes. The information on depth distribution, food habits and parasitism was obtained almost entirely during the months of May to September, 1963. 3

DISTRIBUTION

C. clupeaformis is broadly distributed over much of North America, frequently occurring in such Large quantities as to make it a commercially important species. Smith (1957) has pointed out that the probable origin of the Coregonus complex was in north-central Europe and that C. clupea• formis is merely the most easterly representative of this group. It is thought that the Coregonines were confined to Northern Europe and Asia prior to crossing the Bering Strait area in the early Pleistocene.

Although these fish are normally found only in fresh waters their ability to withstand high salinities under certain conditions has been well documented (Dymond 1933, Wynne-Edwards 1952, Walters 1955). Periods of glacial advances and retreats with the associated pro-glacial lakes undoubtably provided the means by which these fish moved in an eastward direction across North America (Radfprth 1944).

The present range of this species is from the Yukon and northern

British Columbia, across Canada to Quebec, Labrador and New Brunswick.

The southern limit of their distribution roughly parallels the Canadian -

United States border but also includes most of the states within the Great

Lakes drainage system.

Evidence suggests that the southern limit of their distribution has always been close to that exhibited at present (Rostlund 1952), For although the waters of the upper Mississippi were probably cool enough to support this species during the last glacial advance it is assumed that other factors in the environment must have proved unsuitable, for there is no evidence to suggest that whitefish ever occupied this southern area.

The northern limit of their range is poorly defined but extends close 4

to the edge of the Canadian Archipelago.

The range of P. cylindraceum in North America roughly parallels that

of C. clupeaformis with the exception that the range does not extend further

south than the Great Lakes. The number of localities from which this species

is known is far fewer than that of C. clupeaformis. Only rarely does this

fish occur in sufficiently large numbers to make it of any commercial value.

It appears to have originated in the moutainous country of northwestern

North America and. subsequently extended its range eastward across Canada

and westward across Asia and Europe (Smith 1957). It is presumed that the

same means of dispersal was.utilized by Prosopium as by Coregonus. that of

the pro-glacial waterways.

The distribution of C. clupeaformis is so wide in Ontario that no

attempt has been made to indicate the innumerable inland lakes in which it

occurs. The distribution of P. cylindraceum (Table I) is based mainly on

published reports and information obtained from district offices of the

Ontario Department of Lands and Forests. Although all known localities

in which P. cylindraceum occurs are shown in Figure 1., there is no doubt that more will be added at a later date as lake surveys are completed in northern areas.

Algonquin Park (Figure. 2.) is situated on a height of land bounded by the Ottawa River, Georgian Bay, and Lake Ontario drainage systems. Geol•

ogically it is part of the Canadian Shield. Extensive lake surveys of this area have been conducted by the staff of the Fisheries Research Branch of the Ontario Department of Lands and Forests since 1948. For this reason the knowledge of the detailed distribution q£ P. cylindraceum and C. clupeaformis in Algonquin Park is quite complete. In the forty-one lakes in which at 5 6

Figure 2. Map of Algonquin Park showing distribution of Prosopium cylindraceum and Coregonus clupeaformis. 7

TABLE I. Distribution records of P. cylindraceum in Ontario excluding Algonquin Park.

Map Lake Name: Location: Reference: Number (with location on lake for Great Lakes)

SUPERIOR 1. 'Apostle Island 47°00'N, 90°30»W Bailey (1963) 2. isle Royaie 48 00»N, 88 40'W

MICHIGAN 3, ; Sturgeon Bay Ship 44°00«N, 87°15'W Mraz (1964) Canal

HURON 4. North Channel 46°00'N, 83°00'W D. Cucin (1) 5. Dorcas Bay 45^0'N, 81 40'W

ONTARIO 6. Oakville 43°25'N, 79°40'W Radforth (1944) •7. Picton 43°53'N, 77°00'W W.J. Christie (2)

8. LIMERICK 44°55'N, 77°38'W Tweed D.O. 9. PAPINEAU 45°20'N, 77°50«W ii 10. Algonquin Park .for list of localities see Table II 11. CLEAR 45°28«N, 78°55'W Parry Sound D.O. 12. LA CLOCHE 46°0?!N, 82°04'W D. Cucin (1) 13. MOCCASIN • "? 46°45'N, 82°33'W Sault Ste. Marie D.O. 14. RANGER 46°55'N, 83°35'W '.. •. II • . -•' " 15. TORRANCE 47°I3»N, 83°31*W II 16. • CLOVE' -47°15?N, 83029'W ' M tt 17. MEGISAN 47°15'N, 83°31*W 18. GORD : 47°19!N, 83°32«W 19. COMO 47°55>N, 83°30!W Chapleau D.O. 20. DOG 48°25«N, .84°15'?W K.H. Loftus (3) 1 21. PUKASKWA 48°02,N, 85°50>W f ••• ti 22. HELEN 49°05'N, 88°15'W R. Ryder (3) O 88°15 23. POLLY 49 08'N, 'W II • S ' 88°30 24. NIPIGON 50°00«N, *W Dymond (1926) 90o40.'W 25. ST. "JOSEPH 51°05'N, R. Ryder (3) 26. WINISK : 52°55'N,. 87°20'W il ' - • 27. BIG TROUT 53°45'N, 90°00»W

Ont. Dept. of Lands and Forests Research Stations: (1) South BayMouth* Manitouiin Island. (2) Lake Ontario Research Station, Picton, Ontario. (3) Southern Research Station, Mapie, Ontario.

D.0.= District Office, Ont. Dept. of Lands and Forests. 8 least one of these species is known there are only seven localities in which P. cylindraceum and C. clupeaformis occur sympatrically (Table II).

TABLE II. Distribution of P. cylindraceum and C_. clupeaformis in 'v ": Algonquin Park. ' • "

Both species present:

Map Lake Name: Location: Drainage System: Number:

1. BLACK BEAR 45°38'N, 78°44»W OXTONGUE RIVER 2. VICTORIA 45°37'K, 78°02«W OPEONGO RIVER 3* BOOTH 4539'N, 78^12 «.W • v ' • • 4. OPEONGO 45„42'N, 78.22 «W 5. BIG CROW 45°50;'N, 78„26»W CROW RIVER II 6. LAVIEILLE •45053,'N, 78015>W 7. CATFISH 45 56»N, 78 33'W PETAWAWA RIVER

One species present:

Prosopium cylindrac eum

8. TWO RIVERS 45D35'N, 78028'W MADAWASKA RIVER 9. KEARNEY 45°35% 78 26'W II 10. CROTCH 45_39'N, 78 06»W OPEONGO RIVER 11. ALSEVER 45°41'N, 78 00»W II 12. HAPPY ISLE 45~45'N, 78°30»W II 13. ANIMOOSH 45°46'N, 78^08'W CROW RIVER 14. REDROCK 45146'N, 78°28'W II 15. DICKSON 45°48'N, 78°12'W n 16. MERCHANT 45°46'N, 78°32W PETAWAWA RIVER 17. ROSEBARY 45 46'N, 78 55'W II

Coregonus clupeaformis

18. SMOKE 45031«N, 78"41«W OXTONGUE RIVER 19. TEPEE 4536 »N, 78^44»W II 20. LITTLE JOE 4537'N, 78Q42'W 21. BURNT: ISLAND 45°39'N, 78"38'W «'

22. SPROULE 45°36'N, 78023»W OPEONGO RIVER, 23. BRIDLE 45^40 «N, 78^08«W n 24. PROULX 45°46»N, 78.24'W CROW RIVER 25. ALLURING 45.47'N, 78^08»W •'.. n - 26. WHITE 45°44% 78°40'W PETAWAWA RIVER 27. BIG TROUT 45°46N, 78 30'W ti 9

Coregonus clupeaformis continued:

31. GRAND 45 53'N, 77 50»W PETAWAWA RIVER 32. ST. ANDREWS 45 50;«N, 77 41'W ii 33. CEDAR 46 01»N, 78 30»W ii 34. LAURA 46 04*N, 78 36»W it 35. WASKIGOMOG 45 57*B, 79 02«W AMABLE DU FOND RIVER 36. ERABLES 46 00'N, 78 48»W II 37. MAPLE •• 46 01% 78 49'W II 38. WILKES 46 00% 79 OO'W II 39. KIOSHKOKWI 46 05% 78 52'W it 40. LAUDER 46 08% 78 50'W II

LAKE DESCRIPTIONS

Opeongo Lake (Figure 3.) is the largest lake in Algonquin Park, with

an area of 20.5 square miles. The lake is divided into three major basins, the South, North and East Arms, the latter having an additional basin associated with it. These Arms are interconnected by a narrow channel and shallow sills (ten feet). Despite the shallowness of the sills there is an active exchange of fish between the basins particularly during the periods when the basins are isothermal, in Spring and Autumn. All parts of the lake are classified as oligotrophic, although in recent years some eutrophication of the South Arm has occurred. The shoreline is rocky and precipitous in most areas with the occasional sandy beach in protected bays. As Kennedy

(1943) has pointed out, virtually all lake bottom at depths greater than fifteen feet is covered by a soft black ooze consisting of a mixture of organic debris and soft clay. Maximum depth in this lake is one hundred and sixty feet.

Happy Isle Lake (Figure 4.) is located one and a quarter miles due west of the North Arm of Opeongo Lake. The total area of the lake is 2.3 square miles, with a maximum depth of 138 feet. The shore of this lake is

11

Figure 4. Contour map of Happy Isle Lake, Ontario (Contour interval 20 feet, dots indicate netting sites.) 12

quite rocky with a few sand beaches. The littoral zone is not extensive since large boulders dominate the narrow shallow-water zone. In some areas dead trees line the shore area. The bottom materials in deeper water consist of organic debris and clay.

Redrock Lake (Figure 5.) is situated about one mile north-west of the

North Arm of Opeongo Lake and is separated from it by a height of land.

Martin (1952) described the lake as having a. total area of 1.1 square miles, a maximum depth of 70 feet and a mean depth of 29 feet. A broad littoral zone lines the shore area of much of the lake. Beyond the littoral zone there is a narrow area of rocky bottom which gives way to a soft mud bottom in depths greater than fifteen to twenty feet.

Lake Lavieille (Figure 6.), located eight miles northeast of Opeongo

Lake is the third largest lake in Algonquin Park, with a total area of

9.3 square miles and a maximum depth of 165 feet. Much of the shoreline of this lake is rocky with sand beaches in protected bays. The littoral zone is broad in many areas but the rooted vegetation is quite sparse.

Like the above lakes, the bottom at depths ..greater than twenty feet consists of black mud with a high organic content.

During the course of the study certain physical features of the above four lakes were measured. Thermister readings were taken at weekly intervals in Lake Opeongo, but were recorded less frequently in the three other lakes.

By June 15th a well-developed thermocline had appeared at the 20 to 30 foot level in each of the lakes. The maximum surface temperature of 24°C was reached in all of the four lakes during the period July 1st to 7th.

Temperatures in the hypolimnion were consistently in the 7 - 10°C range.

The effects of temperature are discussed more fully under the topic of Figure 5. Contour map of Redroek Lake., Ontario. (Contour interval 15 feet, dots indicate netting sites.) Figure 6. Contour map of Lavieille Lake, Ontario, (Contour interval 20 feet, dots indicate netting sites.) 15

vertical distribution of whitefish.

Measurement of the level of dissolved oxygen in the four lakes was

found to be close to saturation at all depths during the summer months and

so did not appear to be a controlling factor in fish distribution. "'1

Lakes Opeongo and Happy Isle are situated at the head waters of the

Madawaska River, while Lakes Lavieille and Redroek are in the upper reaches

of the Petawawa River. Both the Madawaska and the Petawawa Rivers drain

into the Ottawa River.

METHODS OF OBTAINING FISH

During the summer of 1963, netting at about weekly intervals was

conducted in Opeongo Lake. Nets were also set in Lakes Happy Isle and Red-

rock at about monthly intervals over the period May to September inclusive.

The netting in Lavieille Lake was conducted at irregular intervals during

the summer months of 1962 and 1963. The purpose of the netting was to

determine the normal depth range occupied by the fish as well as to collect

specimens for age and growth data and stomach analysis. Standard sets of

gill nets were used at various sites in the above lakes, all of which were placed at right angles to the shoreline and over a variety of gradients. A

standard set consisted of four hundred and fifty feet of net, this being

comprised of three, one hundred and fifty feet by six feet lengths of two

inches and two and a half inches, stretched mesh, braided nylon nets. A

single two and a half inch monofilament net, fifty feet in length and twenty-

five feet in depth was also used. Previous work on gill net selectivity in this area had indicated that the greatest numbers of whitefish, as well as representatives of all size ranges were taken by the two inch and two and a 16

half inch mesh nets. The inshore end of the net was held in place by tying

a twenty foot length of quarter inch rope from the float-line to some object

on shore. Each gang of nets was anchored at the offshore end. The lower

edge of the net rested on the bottom throughout its length. Since the two

species of whitefish had been shown earlier to be closely associated with

the bottom, no offshore diagonal or floating sets were used. Some experiment•

al use of a vertical set in fifty and one hundred feet of water proved quite unsuccessful. In this case a six foot wide, two and a half inch mesh nylon net, was suspended vertically from the surface by two styrene floats and weighted at the bottom by a six foot length of galvanized pipe which also

served to keep the net spread uniformly. The only fish taken with this net were a few Leucichthys artedi.

In order to determine the depth at which any particular fish was caught,

soundings were taken along the length of the net site. As the net was lifted

(from the inshore end) the number of fish per float interval (approximately five feet) was recorded. In this way the distribution of the fish over the entire length of the net could be determined. These data were later plotted on a scale drawing of the net showing its position relative to the bottom profile. From this plot the number of fish per float interval could be converted directly into the number per five foot depth interval, and so give their distribution in respect to the bottom contours. All of the net settings were overnight sets, with an average duration of thirteen to fourteen hours. 17

DEPTH DISTRIBUTION

By using a mesh size known to take the largest numbers as well as the

greatest size range of whitefish it was possible to determine with reasonable

accuracy the depth distribution of both P. cylindraceum and C. clupeaformis.

The method by which the depth of capture was determined has been outlined

above. It has been assumed that the susceptibility to the nets was the same

at all depths and that the relative number in a given depth zone is indicative

Of the abundance of the fish at that level. The bimonthly averages of dist• ribution for Opeongo Lake are based on several nettings and have been plotted along with the temperatures at various depths (Figure 7.).

A noticeable feature of the depth distribution is the uniformity throughout the summer months. It is not until the surface temperatures approach 21°C that the zone of maximum abundance is shifted downward from the 10 - 20 foot zone to the 20 - 30 foot zone. In the present study there appears to be no correlation between the observed depth of the fish and any particular isotherm.

Similar results were observed in Lakes Happy Isle and Redroek for

P. cylindraceum (Figure 8.).

Depth distribution data from other studies have been summarized (Figure

9.).

FOOD HABITS

In order to obtain information on the food habits of the whitefishes being studied, an average of twenty stomachs per species was preserved from each catch for later analysis. The number of stomachs examined was as 18

Figure 7. Depth distribution of Prosopium cylindraceum and Coregonus clupeaformis in Opeongo Lake. Aid-eu ssjprT. ur tuneaeopurxAo mnraTSsojjf jo uoxq.nqfjq.sTp uqctaQ- »g eanSfj

DEPTH IN FEET 8 c* * IU . . Q • O . O Q >

Oiu-M> co O 20

7 o

20

40

80 Q_

Q 100

120

I401—

Figure 9. Summary of the depth range occupied by sympatric pairs of white- fish. (1 ^ Opeongo Lakej 2 — Lavielle Lake; 3 Moosehead Lake, Cooper and Fuller, 1945J 4 = Okanagan Lake, McHugh, 1939; 5 = Babine Lake, Godfrey, 1955; 6 = Tacheeda Lake, McCart, 1963; 7 =• Cluculz Lake, McCart, 1963.)

0* clupeaformis P. •wi.n.iamaoni

P. cylindraceum P. coulteri 21

follows;

C. clupeaformis Opeongo Lake 280

P. cylindraceum Opeongo Lake 160

" Happy Isle Lake 120

" Redroek Lake 80

The stomachs were removed by severing the oesophagus and the posterior section of the pyloric sphincter. The open ends of the oesophagus and pylorus were effectively closed by a brass safety-pin which also held an individual label. The stomachs were then preserved in 755^ alcohol. This manner of preservation completely retarded any further digestion of the stomach contents.

Subsequently the contents of each of the stomachs was identified and counted.

A visual estimate of percentage of total volume was made for each type of food organism present. The total volume of food material in the stomach was then measured by displacement in alcohol. Any non-edible material such as sand, pebbles, caddis-cases or hemlock needles, etc., that were found in the stomachs were excluded from the volumetric analysis. Actual counts were made on all organisms with the exception of some Cladocerans. Where large numbers of Cladocera were present, the volume displacement of a subsample

(100 Cladocera) was determined and then compared with the total volume displacement of all Cladocera in the stomach. In this way the approximate number of Cladocera consumed could be calculated. Table III outlines the organisms that were present as food in the 640 stomachs that were analysed.

In most papers dealing with food studies on various species of fish, the measure of importance of a particular food organism may be given as the percentage volume, including or excluding the empty stomachs in the sample, 22

TABLE III. A list of all food items found in the stomachs analysed, along with a comment on their relative abundance (C» common, F m few, R ~ rare, A-absent).

CRUSTACEA Coregonus Prosopium Cladocera Sida crystallina C C Ophryoxus gracilis c C Eurycercus lamellatus c C Latona setifera c A Daphnia so. F C Acantholeberis curvirostris R A Bosmina sp.' R A Holopedium gibberum R A Leptodora kindtii R A Polyphemus pedicuius R R

Amphipoda Hyalella azteca R R

Copepoda Cyclops sp. c A

INSECTA Ephemeroptera (nymphs) c C Odonata Gomphidae A F Hemiptera Corixidae (instars) F A Neuroptera Sialidae (nymphs) F • F Trichoptera (larvae) '•. - . Molannidae c C . Leptoceridae ' • c • v C Phryganeidae • c '••'.:c '•' '• Coleoptera R V"' R "'. .Hymenoptera

A Formicidae (adults) ' R ' Diptera Chironomidae (larvae and pupae) c C Ceratopogonidae (larvae & pupae) R R Culicidae (larvae and pupae; Chaoborus sp. c

MQLLUSCA Amnicola limosa c C Valvata sincera F A Planorbula sp. R A Physa sp. A R 23

MOLLUSCA continued: Heli8oma sp. A R Pisidium sp. c C

OSTRACODA C A

WATER MITES c c

FISH Perca flavescens R R

or the percentage frequency of occurrence. However, as Godfrey (1955) and others have pointed out neither of these values taken alone Is an adequate measure of the food intake, for example, "if a single or few fish have ingested a large volume of some food organism, or when all or many fish have each consumed very small amounts of some organism" then either of the above values would be misleading. One way of overcoming this difficulty is to plot graphically the percentage volume against percentage frequency as Korthcote

(1954) did in his work on sculpins. In this way the importance of a food organism may be determined by comparing the relative areas of the graphs.

Godfrey (1955) in an effort to minimize this difficulty utilized,a

"consumption index" derived from the square root of the product of the number of fish in the sample that consumed a specific organism times the average volume of that organism in all stomachs. The present author has used a similar method in deriving "food index" values (FI). These values are found by taking the square root of the product of percent volume times percent frequency (Table XII) which has the advantage over the above method in that

It restricts the range of values to between zero and 100. Thus the magnitude of the value indicates the "rank" or relative importance of a food organism.

Figures 10., 11., and 12., are a summary of the food index values for the four populations studied. Figure 10. Bimonthly food index values for P. cylindraceum and C. clupeaformis in Opeongo Lake. 25

R CYLINDRACEUM HAPPY ISLE LAKE so J A

AUG 16 31

l_-J

P CYLINDRACEUM REDROCK LAKE

2 o

Figure 11. Bimonthly food index values for P. cylindraceum in Lakes Happy Isle and Redrock. „ 26

Figure 12„ Summary of food index values. (Average bimonthly F.I. value of food items grouped by type; Misc. = miscellaneous, includes water mites, ostracods and fish.) 27

Opeongo Lake:

In Lake Opeongo, both P. cylindraceum and C. clupeaformis are essentially

bottom feeders, consuming bottom-dwelling crustaceans as well as insect larvae and molluscs (Figure 10}. This pattern of feeding appears to be quite fixed during the summer months. In P. cylindraceum the emphasis is decidedly upon

insect larvae. In the latter part of May, caddis-fly larvae are the most

important food organism with dragonfly naiads being somewhat less so. As the

summer progresses caddis-fly larvae become less important and the emphasis is

shifted towards chironomid larvae and pupae, and to a lesser extent the mayfly nymphs (mostly Hexagenia). Only during June and July are the bottom- dwelling plankters consumed in any quantity and even then their relative importance does not exceed that of the insect larvae. As far as molluscs and other food items are concerned their importance to individual fish may be

significant but to the population as a whole, represent a rather minor element of the diet.

The food habits of C. clupeaformis are however in sharp contrast to those of the P. cylindraceum population. Purely superficial examination of the,stomach contents would indicate a marked similarity between these species but as in so many other food studies the detailed analysis reveals signifi• cant differences. During the latter part of May larval insects form a major part of the diet of both C. clupeaformis and P. cylindraceum but there is a distinct difference. The lake whitefish feed almost entirely on mayfly nymphs, while the emphasis in the round whitefish is divided between caddis- fly larvae and dragonfly naiads.

! Beginning in June and throughout the summer months, bottom-dwelling

Crustacea and other organisms such as ostracods and water mites make up a 28

major portion of the diet of the lake whitefish only. In both species it is interesting to note the almost complete absence of any mid-water plankters in

the stomachs of these fish. The reason for this, it is believed, is the

presence in Lake Opeongo of the cisco, Leucicthys artedi. A number of papers

(Clemens and Bigelow 1922, Langford 1938b) have well documented the plankton

feeding habit of this species. It would seem then that the mid-water plankton

feeding niche is being occupied by this species.

Happy Isle Lake-and Redroek Lake:

In these lakes P. cylindraceum is the only whitefish species present.

Stomach analysis of fish taken from these lakes during the summer months

revealed a situation quite different from that of Lake Opeongo. As shown in

Figure 11. the major element in the diet of the round whitefish is Daphnia

longispina. Although these fish do feed on insect larvae as well, this food

material is of much less importance compared to its role in the diet of round

whitefish in Lake Opeongo.

, The question then arises as to whether the observed difference is due to

a lack of bottom fauna in Lakes Happy Isle and Redroek. Miller (1937$ in:

Martin 1952) stated that the bottom fauna of Redroek Lake was the richest of

any lake studied by him in Algonquin Park. Wood (1953) published a value of

63.5 individual organisms per square foot of bottom area for Redroek Lake.

Similar work by Webb (pers. com.) gives values of 38 and 43 individual

organisms per square foot for Lakes Happy Isle and Opeongo respectively.

Since the relative abundance of the bottom fauna in Lake Opeongo is inter• mediate between the values for Lakes Happy Isle and Redroek, it must be

concluded that the plankton-feeding habit of the P. cylindraceum populations 29

of the latter two lakes is related to some factor other than the availability

of the bottom fauna as food.

AGE AND GROWTH

Fish collected by methods outlined above were measured in the field tcu

the nearest millimetre of standard length, this measurement being defined by

Hubbs and Lagler (1958) as the distance from the tip of the snout to the

posterior end of the vertebral column. Fresh weights were determined by a

spring balance to the nearest 0.1 pound.

The sex and state of maturity of the gonads were determined by gross examination; Any fish captured that was judged to be ready to spawn during the fall of the same year was considered mature. Scales were removed from the left side of the fish midway between the mid-dorsal line and the lateral line at a point below the origin of the dorsal fin. The scales were preserved dry by placing them in small envelopes. Prior to reading the scales, a few were taken from the envelope, cleaned and dry mounted between glass slides. The slides were then placed on the stage of a Bausch and Lomb Microprojector, and the images of the scales (magnified x35) projected ongrid. By positioning the focus of the scale on the centre of the grid it was possible to accurately measure in millimetres the annuli diameters along the dorso-ventral axis of the scale as suggested by Smith (1955). The validity of age determination from scales of Coregonines has been amply demonstrated in numerous papers:

Van Oosten (1923), Van Oosten and Hile (1949), Eschmeyer and Bailey (1955),

Bailey (1963), Mraz (1964) and others. 30

Length-weight relationship;

In order to express the length-weight relationship of the whitefish b

studied the general equation of a parabola, W » aL was used, where W«=-

weight, L «= length, and a and b are empirically determined constants. The

values of a and b were derived from data collected during the period May to

September, 1963. Empirical weights and scale diameters are averages for 1 cm.

intervals of length. As the differences in weight between a male and a female

of a given length were small, the" data were combined without regard to sex or

state of maturity.

TABLE IV. Equations for length-weight relationship. ¥ «• weight in poundsj

L * standard length in cm. j tooSsb= standard error of slope b at 95% confidence limits.

P. cylindraceum

Redroek Lake log W= -4.93656-H 3.3179 log L b + 0.3215 W- 1.157 x 10~5 L3*3179

Happy Isle Lake log W = -4.I696O +- 2.7665 log L b 0.3984 W~ 6.767 xlO^L2-7665

Opeongo Lake log W = -4.67478 +• 3.1122 log L bt 0.1524 W = 2.1146 x 10"5 L3'1122

C. clupeaformis

Opeongo Lake log W a, -4.82693 +- 3.2536 log L h± 0.1083 V ~ 1.4896 x 10~5 L3*2536

Using a standard linear regression analysis, with length and weight data transformed to logarithms, the equations representing each of the four 31

populations of whitefish were determined (Table IV).

From the above equations the theoretical weights for each unit of

standard length were determined (Tables V - VIII). The calculated weights are the basis for the curves shown in Figure 13.. In the normal size range

of whitefish observed in the three lakes studied, the length-weight relation•

ship is quite similar, however if the curves for the three populations of

Prosopium are extrapolated to a value equal to the maximum size of Coregonus observed in Lake Opeongo, the differences become apparent. In the larger sizes a £. clupeaformis of a given standard length from Lake Opeongo, will be heavier than a fish of similar length from any of the three populations of

P. cylindraceum. It may also be seen that within the three populations of

Prosopium there is a distinct order. The round whitefish from Opeongo Lake are intermediate to those from Happy Isle Lake and Redrock Lake.

TABLE V. Length-weight relationship of P. cylindraceum from Redrock Lake.

STANDARD WEIGHT (lbs.) NUMBER LENGTH - of (cm.) EMPIRICAL CALCULATED FISH

26 0.56 0.57 1 2? 0.61 0.65 8 28 0.78 0.73 6 29 0.83 0,82 9 30 0.94 0.92 10 31 1.09 1.03 9 32 1.13 1.14 6 33 1.25 1.26 3 34 1.34 1.40 6 35 1.53 1.49 5 32

10 2.0 30 ••' 40 50 . LENGTH IN CM. . . . • . • • \ •• Figure 13. Length-weight relationship of whitefish from Lakes Redroek, Happy Isle and Opeongo, based on calculated weights. (Dotted sections represent extrapolations? 1 •= C. clupeaformis from Opeongo Lake j 2= P. cylindraceum from Redroek Lake; 3 = P• cylindraceum from Opeongo Lake; 4 = P. cylindraceum from Happy Isle Lake.) 33

TABLE VI. Length-weight relationship of P. cylindraceum from Happy Isle Lake.

STANDARD WEIGHT (lbs.) NUMBER LENGTH of (cm.) EMPIRICAL CALCULATED FISH

21 0.29 0.31 1 23 0.39 0.40 1 24 0.44 0.45 5 25 0.49 0.50 5 26 0.59 0.56 1 27 0.62 0.62 2 28 0.68 0.68 5 29 0.83 0.75 8 30 0.85 0.82 11 31 0.92 0.91 10 32 1.03 0.99 10 33 1.05 1.08 11 34 1.16 1.17 11 35 1.19 1.27 16 36 1.30 1.37 10 37 1.47 1.48 2

TABLE VII, Length-weight relationship of P. cylindraceum in Opeongo Lake.

STANDARD WEIGHT (lbs.) , NUMBER LENGTH of (cm.) EMPIRICAL CALCULATED FISH

24 0.46 0.42 3 25 0.44 0.47 3 26 0.55 0,54 6 27 0.60 0.66 17 28 0.67 0.67 13 29 0.72 0.75 13 30 0.82 0.84 11 31 0.91 0.93 21 32 1.00 1.02 19 33 1.13 1.12 17 34 1.23 1.23 11 35 1.37 1.35 8 36 1.56 1.48 4 37 1.63 1.61 4 38 1.67 1.75 1 39 1.94 1.89 i 34

TABLE VIII. Length-weight relationship of C. clupeaformis from Opeongo Lake.

STANDARD WEIGHT (lbs.) NUMBER LENGTH of (cm.) EMPIRICAL CALCULATED FISH

16 0.13 0.12 2 17 0.14 0.15 10 18 0.16 0.18 7 19 0.22 0.22 4 20 0.28 0.25 10 21 0.31 0.30 34 22 0.37 0.35 38 23 0.41 0.40 37 24 0.47 0.46 42 25 0.53 0.53 28 26 0.61 0.60 33 27 0.64 0.68 23 28 0.77 0.76 8 29 0.79 0.85 7 30 0.90 0.95 2 31 1.07 1.06 4 32 1.24 1.17 2 33 1.26 1.30 3 34 "1.37 1.43 i 35 1.36 1.57 I 36 1.71 1.73 2 37 1.96 1.89 3 38 2.15 2.66 2 39 2.36 2.23 2 43 3.32 3.08 4 44 3.17 3.31 1 45 3.69 3.57 1

Calculated Growth;

Preparatory to making back calculations for the size of fish at various

ages it was first necessary to establish the relationship between body length

and scale diameter. The maximum scale diameter as well as the diameter of

each annulus was measured as outlined above. Scale diameters were taken only

from scales used in age determination. The mean scale diameter (magnified)

for each cm. of standard length was computed (Tables IX - XII). These values

were then plotted on a logarithmic scale and the line of best fit determined 35

TABLE IX. Relation between standard length and magnified (x35) scale diameter of P. cylindraceum from Redroek Lake.

STANDARD AVERAGE SCALE NUMBER LENGTH DIAMETER of (cm.) (cm.) FISH

26 18.8 1 27 20.2 8 28 21.4 7 .2.9 -22.8 13 30 22.7 11 31 24.3 13 , 32 . 25.3 11 33 25.5 6 34 27.8 7 35 27.9 7

TABLE X. Relation between standard length and magnified (x35) scale diameter of P. cylindraceum from Happy Isle Lake.

STANDARD AVERAGE SCALE NUMBER LENGTH • DIAMETER of (cm.) (cm.) FISH

21 15.2 1 23 17.3 1 24 17.6 5 25 17.6 6 26 20.4 1 27 18.6 2 28 21.3 7 29 21.4 8 30 21.9 13 31 22.3 10 32 21.8 7 33 22.7 9 34 23.3 9 35 25.3 19 36 26.9 11 37 28.8 2

TABLE XI. Relation between standard length and magnified ,(x35) scale diameter of P. cylindraceum from Opeongo Lake.

STANDARD AVERAGE SCALE NUMBER LENGTH : DIAMETER of (cm.) (cm.) FISH

24 15.4 3 25 16.1 3 26 19.2 6 27 18.7 17 36

TABLE XI. continued:

28 20.0 14 29 20.0 13 30 20.9 12 31 21.1 21 32 21.6 19 33 23.0 17 34 24.2 11 35 24.5 8 36 24.1 4 37 27.0 4 38 25.4 1 39 29.5 1

TABLE XII. Relation between standard length and magnified (x35) scale diameter of C. clupeaformis from Opeongo Lake, y

STANDARD AVERAGE SCALE NUMBER LENGTH DIAMETER . of (cm.) (cm.) FISH

16 10.7 • 2 17 11.7 10 18 12.5 7 19 14.7 4 20 14.2 10 21 14.5 34 22 15.4 38 23 15.2 37 24 16.9 42 25 17.0 28 26 19.6 33 27 20.0 23 28 21.4 8 29 22.2 7 30 21.8 2 31 23.4 4 32 24.9 2 33 24.4 3 34 25.4 1 35 22.9 1 36 27.7 2 37 26.2 3 38 28.5 2 39 29.5 2 43 31.7 4 44 34.1 1 45 30.0 1 37

by regression analysis. The equations expressing the body length to scale diameter relationship (Table XIII) are of the form, S *=• aLb , where S = magnified (x35) dorso-ventral scale diameters, L = standard length of the fish, and a and b are empirically determined constants.

TABLE XIII. Equations for length-scale diameter relationship. S = scale

diameter (x35) in cm. ; L = standard length in cm. ; to sfe standard error of slope b at 955^ confidence limits.

P. cylindraceum

REDROCK LAKE S = 0.2800 L1,2977 bt 0.1567

HAPPY ISLE LAKE S =0.7935 L°*9739 b i 0.1951

OPEONGO LAKE S = 0.4638 L1'1169 b ± 0.1562

C. cluDeaformis 1.0856 OPEONGO LAKE S = 0.5434 L bt 0.1026

Growth in Length;

From the above equations the previous growth histories were calculated

(Tables XI? - XVII). Examination of these values indicates some small discrepancies, both random and systematic. For instance, the random discrep• ancies observed in the back calculations of growth in fish from Lakes Redroek and Happy Isle are probably due to the relatively small sample size. However it appears that the discrepancies observed in the growth history of the two species of fish from Lake Opeongo are systematic in origin.

The P. cylindraceum population of Lake Opeongo exhibit Lee's phenomenon to a marked degree. This phenomenon was described by Lee (1912) as the

"apparent change in growth rate from the calculated values of lengths of fish of different age at corresponding years of their existence, by which it appears 38

TABLE XIV. Calculated standard length at end of each year of life of each age group of P. cylindraceum from Redrock Lake.

NUMBER AGE GROUP I II III IV V VI VII of FTSH II 12.4 17.2d 2 III 12.8 19.0 22.3* 4 IV 12.3 18.5 23.4 26.8' 9 V 12.3 18.9 23.7 27.6 30.3 55 VI 12.4 18.8 23.8 28.3 31.4 33.5 . 19 VII 13.1 18.9 24.5 28.5 31.3 34.0 36.4" 2

AVERAGE CALCULATED LENGTH 12.6 18.8 23.9 28.1 31.4 34.Q 36.4

INCREMENT OF - AVERAGE 12.6 6.2 5.1 4.2 3.3 2.6 -

TABLE XV. Calculated standard length at end of each year of life of each age group of P. cylindraceum from Happy Isle Lake.

NUMBER AGE GROUP I II III IV V VI VII of

III 9.2 17.8 23.5* • 11 IV 9.3 18.0 25.2 28.2 24 V 9.3 17.9 25.2 29.5 31.7* 54 VI 8.8 16.7 24.2 29.9 33.6 35.7* 20 vii 9.2 16.7 23.6 29.6 34.1 38.0 40.9* 3

AVERAGE CALCULATED LENGTH 9.2 17.4 24.6 29.7 33.9 38.0 40.9

INCREMENT OF AVERAGE 9.2 8.2 7.2 5.1 4.2 4.1 -

size at capture not included in calculation of mean. 39

TABLE XVI. Calculated standard length at end of each year of life of each age group of P. cylindraceum from Opeongo Lake.

AGE GROUP I II III IV V VI VII VIII IX X XI XII NUMBER of

TV 9.0 16.2 19.1 24.1* 5 V 8.7 15.5 20.3 24.1 26.5* 12 VI 9.3 15.7 20.3 24.0 26.7 28.4* 30 VII 9.2 15.4 19.8 23.3 26.1 28.2 29.3* 40 VIII 8.9 14.8 19.2 22.6 25.7 28.3 30.5 32.3* 40 IX 8.9 14.7 19.2 22.4 25.7 28.3 30.5 32.4 33.7* 17 X 9.1 15.2 19.5 23.3 26.5 29.0 31.4 33.5 34.9 36.3* * 9 XII 8.9 15.1 19.1 22.7 25.8 28.8 30.9 32.8 34.7 36.3 38.3 39.8* 2

A.C.L. 9.0 15.3 19.6 23.2 26.1 28.5 30.8 32.9 34.8 36.3 38.3 39.8

I.O.A. 9.0 6.3 4.3 3.6 2.9 2.4 2.3 2.1 1.9 1.5 -

TABLE XVII. Calculated standard length at end of each year of life of each age group of C. clupeaformis from Opeongo Lake.

AGE GROUP I II III IV V VI VII VIII IX X XI NUMBER of FTftH II 11.4 15.6" 4 III 10.3 15.0 17.9 14

IV 9.6 14.6 18.1 20.4* # 26 V 10.1 15.1 18.6 21.4 23.0 28 VI 11.0 15.8 19.5 22.8 25.6 27.4 35 VII 11.1 15.6 19.4 23.0 26.3 29.1 31.0 16 VIII 10.9 15.7 19.7 23.4 27.0 30.6 33.7 35.7* 9 ix 11.1 16.4 20.6 23.7 27.2 30.7 33.9 37.1 39.0*" 3 X 9.3 13.1 17.9 21.2 24.5 28.8 31.3 34.2 37.7 40.5 „. 2 XI 10.2 16.6 20.4 24.4 27.5 30.7 33.7 36.6 39.4 42.1 43.7 3

A..C.L. 10.5 15.3 19.3 22.8 26.4 30.0 33.2 36.0 38.6 42.1 43.7

I.O.A. 10.5 4.8 4.0 3.5 3.6 3.6 3.2 2.8 2.6 3.5 -

A.C.L.™ Average Calculated Length; I.O.A.m Increment of Average: * size at capture not included in calculation of mean. 40

that in older and older fish less growth is attained in each year of their

existence". Although this decrease in calculated lengths is not apparent in

the age group I, or in the oldest age groups, it is however quite obvious for

fish in the II - V age groups.

Examination of the calculated values for C. clupeaformis from Lake

Opeongo indicates that they do not exhibit Lee's phenomenon but show what appears to be a reversal of this tendency, that is the lengths calculated from older fish seem to increase in size as compared with lengths calculated from younger fish.

The rate of increase in length (Figure 14, Table XVIII) among the four populations studied is quite distinct. The maximum size reached by round whitefish from either Redrock Lake or Happy Isle Lake is not as great as that in either of the two species from Lake Opeongo, but it is achieved in little more than half the time. For example the largest fish collected in Redrock

Lake had completed its sixth annulus and had a calculated length of 34*0 cm..

A fish of similar size from Lake Opeongo would be just completing its ninth annulus. The difference between the growth rate in Happy Isle Lake and

Opeongo Lake is even more significant. A 38.0 cm. fish from Happy Isle Lake would have completed its sixth annulus but in Lake Opeongo would have reached this size only after completion of the eleventh annulus.

Growth in Weight;

Calculated values for increase in weight, derived from length-weight equations show precisely the same sort of pattern as demonstrated in the length data (Figure 15, Table XIX). The rate of growth in terms of weight is much greater for fish from Redrock Lake and Happy Isle Lake as compared with 41

AGE

Figure 14. Calculated growth in length of whitefish from Lakes Redroek, Happy Isle and Opeongo. (1 =- C. clupeaformis from Opeongo Lakej 2— P. cylindraceum from Redroek Lake; 3 *=* P. cylindraceum from Opeongo Lakej 4 =• P. cylindraceum from Happy Isle Lake.) 42

TABLE XVIII. Summary of the calculated growth in length of whitefish from Lakes Redroek, Happy Isle and Opeongo.

REDROCK LAKE HAPPY ISLE LAP OPEONGO LAKE P. cylindraceum P. cylindraceum P. cylindraceum C. clupeaformis

AGE Average Incre• Average Incre• Average Incre• Average Incre• length" ment length ment length ment length ment GROUP (cm.) (cm.) (cm.) (cm.)

I 12.6 12.6 9.2 9.2 9.0 9.0 10.5 10.5 II 18.8 6.2 17.4 8.2 15.3 6.3 15.3 4.8 111 23.9 5.1 24.6 7.2 19.6 4.3 19.3 4.0 IV 28.1 4.2 29.7 5.1 23.2 3.6 22.8 3.5 V 31.4 3.3 33.9 4.2 26.1 2.9 26.4 3.6 VI 34.0 2.6 38.0 4.1 28.5 2.4 30.0 3.6 VII 30.8 2.3 33.2 3.2 Vltl 32.9 2.1 36.0 2.8 IX 34.8 1.9 38.6 2.6 X 36.3 1.5 42.1 3.5

TABLE XIX. Summary of the calculated growth in weight of whitefish from Lakes Redroek, Happy Isle and Opeongo.

REDROCK LAKE HAPPY ISLE LAKE OPEONGO LAKE P. cylindraceum P. cylindraceum P. cylindraceum C. clupeaformis

AGE Average Incre• Average Incre• Average Incre• Average Incre• weight ment weight ment weight ment weight ment GROUP (lbs.) (lbs.) (lbs.) (lbs.)

I 0.05 0.05 0.03 0.03 0.02 0.02 0.03 0.03 II 0.20 0.15 0.18 0.15 0.10 0.08 0.11 0.08 III 0.43 0.23 0.48 0.30 0.22 0.12 0.23 0.12 IV 0.74 0.31 0.80 0.32 0.38 0.16 0.39 0.13 V 1.07 0.33 1.16 0.36 0.71 0.17 0.95 0.32 VII 0.91 0.20 1.33 0.38 VIII 1.12 0.21 1.73 0.40 •' IX : .. '>;•, 1.31 0.19 2.16 6.43 X 1.51 0.20 2.87 0.71 43

AGE

Figure 15. Calculated growth in weight of whitefishes from Lakes Redroek, Happy Isle.and Opeongo. (l = C. clupeaformis from Opeongo Lakej 2 = P. cylindraceum from Redroek Lakej • 3 •= P. cylindraceum.. from Opeongo Lake; 4 •= P. cylindraceum from Happy Isle Lake* )

the whitefish from Lake Opeongo. It is particularly interesting to note the

close similarity in the growth history of C. clupeaformis and P. cylindraceum

in Lake Opeongo especially during the first 4-5 years, however after this period the growth rates diverge. Comparing the rates of growth for the three populations of P. cylindraceum it is important to note how much slower

the growth rate is in fish from Opeongo Lake. In this lake, a weight of 1.5

pounds is reached only after ten years of growth, whereas in Redroek Lake and Happy Isle Lake the same weight is reached in less than half the time. 44

DISCUSSION

One of the most noticeable features of the distribution of whitefish in

Algonquin Park is the apparent relationship to lake size. Routine sampling indicates that lakes with a total surface area of more than 5 sq. mi. and a maximum depth of more than 100 feet frequently contain two or more species of whitefish, while relatively small lakes, those less than one-half of a square mile in area, possess no more than one whitefish species. Work by

Godfrey (1955) showed similar results.

It is obvious though, that it is not strictly the physical dimensions of the body of water involved but is related to the presence or absence of a particular factor in lakes of different sizes. Whether a given body of water will support one or more species of fish, especially closely related ones, will likely be related to the availability of food, or space, or some other habitat requirement. As Odum (1953) has pointed out the larger the habitat size the greater the number of niches available and hence the greater the number of species it will support.

One interesting aspect of the sympatric occurrence of P. cylindraceum and C. clupeaformis is that the latter species is almost invariably the more successful one. The sole exception to this appears to be the findings of

Cooper and Fuller (1945) in Maine. In Opeongo Lake it was estimated that the lake whitefish outnumbered the round whitefish in the order of six to one, and were found to have a higher rate of growth.

An essential part of the present study was to determine if possible the presence of any interaction between the above two species. Attempts to determine the temperature preferences, if any, for the two species met with rather poor success. Although a slight seasonal downward shift did occur, the 45

fish did not appear to be confined to a narrow temperature zone as might be

expected.

Qadri (I96I) observed in his depth distribution data for 1954, that the

G. clupeaformis of Lac La Ronge, Sask., did not migrate downward but appeared to stay up in the warmer water throughout the summer. However in the years

1948, 1949, 1950 and 1953 a distinct downward migration was observed. The fish appeared to be following the 18°C isotherm with maximum concentrations occurring at the 12°C isotherm. No explanation for the 1954 data was offered.

Other studies such as that by Kennedy (1943) have not observed this rather diffuse vertical distribution in regard to temperature but found it to be more distinct. Kennedy noted that the common whitefish of Opeongo Lake did not move above the 18°C isotherm and that they seemed to be "concentrated at about 15°C".

It would appear then that under certain conditions a species that is normally considered a cold-water form may be found in a zone of high tempera• ture. An example of this is to be found in the work by Martin (1952) on the lake trout of Redrock Lake. He observed that the trout were most frequently found below the 18°C isotherm, but noted that they were also "in much shallower water than it is commonly believed the species will enter at this time".

Since most of the depth distribution data in the above papers and in the present study are based on overnight sets, it is possible that those fish caught in areas of high temperature do not reflect their normal distribution, but represent the temporary excursion of some individuals into the epilimnion.

The presence of terrestrial insects and the emerging adult stages of some aquatic forms in the stomachs of these fish would seem to support this idea.

According to Cooper and Puller (1945) these excursions may be more frequent 46

than is realised. They stated that "the designation of even surface waters as 'non-trout • is probably erroneus'', due to the fact that salmon and trout were observed feeding at the surface during the midsummer when the lake temperature exceeded 21°C.

However on the basis of the present study and the work of others it may be assumed that the distribution of these cold-water whitefish species is below the 18°G isotherm in a stratified lake, and and that those fish caught in shallower depths were taken only during periods of feeding activity. This assumption could be tested by extensive netting on a diel basis.

Another interesting feature of the depth distribution of Coregonus and

Prosopium is the range of depth occupied by each of the species, in a number of cases where two species of whitefish occur sympatrically it may be demonstrated that the maximum depth range of the former is consistently greater than that of the latter. The following are some examples of this relationship: in Opeongo Lake during the summer months, _C. clupeaformis was caught in al depths ranging from 0-80 feet, while P. cylindraceum was found only between 10 - 55 feet. In Lavieille Lake an almost identical depth range relationship is observed. During the summer of 1962, extensive netting in this lake showed that in the months of May and June C_. clupeaformis were frequently caught at depths to 55 feet while the maximum depth at which

P. cylindraceum was taken was 45 feet. In July 1963 the results were again similar: lake whitefish down to 75 feet, and round whitefish down to 55 feet.

Other studies in sympatric pairs of whitefish show comparable results.

Cooper and Fuller (1945) observed a maximum depth of 120 feet for lake whitefish and a maximum of 75 feet for round whitefish in Moosehead Lake,

Maine. McHugh (1939) in his work on Okanagan Lake, British Columbia, found 47

that C. clupeaformis were caught in depths ranging from 20 feet to 138 feet,

whereas the mountain whitefish, P. williamsoni. were never taken at depths

over 50 feet. Godfrey (1955) studying the above two species in Babine Lake,

B.C., observed much the same type of distribution; the lake whitefish ranged

from the surface to 70 feet, but only one mountain whitefish was captured in

more than 55 feet of water.

McCart (1963) also found an apparent shift in depth range when three

species of whitefish were present. In Tacheeda Lake, B.C., P. williamsoni

ranged from the surface to 40 feetj C. clupeaformis down to 55 feet while

the pygmy whitefish, P. coulteri. ranged in depth from 35 feet to over 100

feet. In Cluculz Lake, B.C., a similar type of distribution was observed;

P. williamsoni and C. clupeaformis from the surface to 35 feet, while

P. coulteri were caught only between 35 and 125 feet. In two other British

Columbia lakes, McLeese and MacLure, where P. coulteri is the only whitefish present, the apparent depth range was between 15 to 70 feet and 15 to 50 feet respectively. Since the presence of the other two species of whitefish appeared to have a depressing effect on the pygmy whitefish it was concluded

by McCart that the absence of this species in the upper levels of Lakes

Tacheeda and Cluculz, "may be largely the result of competitive exclusion by the other two whitefish". (A summary of the above data is shown in Figure 9.)

Examination of the depth distribution data for Lakes Happy Isle and Redrock

(Figure 8.) suggests that P. cylindraceum may also range over greater depths when it is the sole whitefish species present.

Just what biological significance of this relationship is can only be left to speculation. It is possible that the difference in depth distribution between the two species is simply due to a preference by P. williamsoni or 48

P. cylindraceum for the littoral and sublittoral zones, although the latter have been recorded at depths greater than 175 feet in Lake Michigan (Koelz

1929). On the other hand this difference may be due in fact to some inter• action between the two species as McCart has suggested. It appears that a definite answer to this problem is not possible until more is known about the biology of these species.

Another insight into the ecological relationship between P. cylindraceum and C. clupeaformis can be gained by detailed analysis of the food habits of the two species. Much has been written about competition between fish species

(Larkin 1956, Lindstrom and Hilsson 1962 and others) but only rarely can it be accurately demonstrated. One of the basic problems, as Larkin has pointed out, is the difficulty in determining the availability and the limits of a particular resource, like food, that is possibly being competed for. By definition, interspecific competition is the interaction between two species that have demands on the same resources of the environment in excess of the immediate supply.

Whether such an interaction exists in the present study is open to quest• ion. However one thing is certains as. much as P. cylindraceum and C_. clupea• formis consume essentially the same organisms, they do so either at different times of the year or else in vastly different quantities. Compare for example the consumption of chironomid larvae and pupae during the month of July

(Figure 10.). In the first half of the month, chironomid larvae are an important food item to C. clupeaformis whereas in P. cylindraceum the emphasis is on chironomid pupae. In the latter half of the month when the consumption of chironomid larvae and pupae by C. clupeaformis is low, the values for these food items are high in P. cylindraceum. This and other examples 49

illustrate the distinct difference in the food habits of these two species in

Lake Opeongo. Nilsson (195$) also demonstrated similar food relationships

with other species of sympatrically occurring whitefish.

In general then, P. cylindraceum feed mainly on larval insects while

C. clupeaformis feed primarily on littoral and bottom-dwelling Crustacea.

As has been discussed previously the Cisco, Leucichthys artedi, occupies the

mid-water plankton feeding niche. Also present in Lake Opeongo are lake

trout, Salvelinus namaycush. which in this lake are essentially piscivorous

in nature^ Compare this situation with that found in Lakes Happy Isle and

Redrock. It has been noted earlier that neither Leucicthys artedi nor

C. clupeaformis are present in either of the above lakes. It would appear

then that P. cylindraceum has shifted its feeding habits to occupy the niche

normally held by the other two species. Likewise the trout in these lakes

appear to have shifted away from their normal piscivorous habit to a mixed

diet consisting of fish, insects and plankton. Martin (1952) stated that the

diet of S. namaycush in Redrock Lake was as follows; 7Q# (frequency of occur• rence) fish, 53# insect larvae, and 8% plankton Crustacea. Baldwin (1948) in his study on S. fontinalis of the same lake, found that in the early summer months the frequency of occurrence of insects in this species was 31# while

during July and August the perch fry comprised almost 98^ of the total volume.

Preliminary work on the lake trout of Lake Happy Isle shows an even greater

shift away from the piscivorous habit (frequency of occurrence of fish in lake

trout stomachs is about 30j£).

One might ask what would be observed if only the lake trout were present.

Martin (1952) studied the ecology of a lake trout population in this type of

situation in Louisa Lake. This lake is located in the south-central area of 50

Algonquin Park and in limnological features is not unlike the four lakes

examined in the present study. Analysis of. lake trout stomachs during the period May 20th to October 31st showed that plankton had a frequency of occur• rence of 73$ while insects and fish had values of 25% and 23$ respectively.

In the cold-water species of the above four lakes there appear to be distinct niches based on food, habits (Table XX) which may be occupied by a particular species in one lake and by another species jLn a second lake. It is not known if similar relationships are present between the warm-water species. The validity of comparisons such as that between the trout and white- fish is open to question, due to a lack of information about so many other factors. For example the plankton feeding habit of the Louisa trout is possibly the end result of being forced into this niche by the absence of forage fish such as the whitefish. In the other lakes the availability of a food type may not be the same, resulting in food habit differences. Only by experimental feeding under conditions such as those described by Fabricius and Lindroth

(1954) might a more conclusive answer be provided for this problem.

:; Another aspect of the feeding habits of whitefish yet to be considered is the conspicuous absence of copepods in the diet of round whitefish. In many lakes, including those studied in Algonquin Park, the numerous species of copepods make up a significant part of the planktonic Crustacea. These forms are generally found quite uniformly distributed in all regions of the lake, with the possible exception of the deep water zones (Langford 1938a). In view of the fact that such large quantities of plankton are consumed by round white- fish, particularly by those fish in Lakes Happy Isle and Redroek, the absence of copepods in all stomachs is surprising. The small size of the copepods would seem to preclude any selective feeding against these organisms, yet work 51

TABLE XX. Levels of food consumption by the major fish species in four Algonquin Park lakes.

SPECIES LAKE Salvelinus Prosopium Coregonus Leucichthys sp. cylindraceum clupeaformis artedi

LOUISA S. namaycush

P 732 "(F) i 252 (F) f 23% (F) - - -

'CD

HAPPY ISLE S. namaycush

P 5$ .(F) p 88% (FI) i 21$ '(F) i 33% (FI) - - f 30%' (F)

(2)

REDROCK S. namaycush

p 70$ (F) i 53% (F) f 8% (F)

(1) P 75% (FI) S. fontinalis i 34^ (FI) -

i 98% (V) f 315 (F)

(3)

OPEONGO S. namaycush

i 1035 .(F) p 282 (FI) P 532*(FI) p 902 (E) f 80$ (e) i 80% (FI) i 442 (FI)

(4)

(1) Martin (1952); (2) Martin and Sandercock (unpub.); (3) Baldwin (1948); (4) Fry and Kennedy (1937)°° (F) =• percent frequency of occur• rence; (V) = percent volume; (FI) = food index value; (E) = estimated value; *- = mean value for period June 1st to September 1st; - - species not present in lakes p ^.plankton; i = insects; f = fish. 52

by McHugh (1940) showed similar results in the food habits of P. williamsoni.

Although routine plankton sampling generally indicates that these plankters

occur quite randomly, it has been observed in littoral and sublittoral zones

that there is frequently a "bunching" of plankters. It is possible that there

is some kind of avoidance reaction to these "clouds" of copepods on the part

of Prosopium. a reaction that is not exhibited in Coregonus; in fact Cyclops

sp. were found to rank third in importance among plankters as food in C. clup•

eaformis of Opeongo Lake. It is equally possible that slight variation in the manner of feeding, or of site, may also account for the observed differences.

The fact remains that P. cylindraceum does not normally feed on copepods while the opposite is true for C. clupeaformis.

Since Cyclops sp. are well known as the intermediate hosts for a variety of parasites, it is of interest to examine the parasitic fauna of P. cylind• raceum and £. clupeaformis of Algonquin Park. Bangham (1940) published such

a list for this area and indicated the frequency of occurrence of each of the parasites:

Coregonus clupeaformis % 10 fish examined.

Protocephalus laruei Faust (in 9 fish) Leptorhynchoides fhecatus (Linton) (in 3) Crepidostomum cooperi Hopkins (in 2) Spinitectectus gracilis Ward and Magath (in l)

Prosopium cylindraceum % 10 fish examined.

Crepidostomum farionis (Miller) (in 6) Protocephalus laruei Faust (in 4) Crepidostomum cooperi Hopkins (in 2)

Subsequent work by Bangham and Venard (1946) revealed two other features about the distribution of parasites; first that Protocephalus laruei is only found very rarely in P. cylindraceum, and second that Crepidostomum farionis 53

may occasionally be found in C. clupeaformis. These findings have been

confirmed more recently by Dr. R.S. Freeman, Ontario Research Foundation

(pers. com,), who has been working in the same area. Freeman (1961)

demonstrated experimentally that Cyclops bicuspidatus is probably the most

important intermediate host in the life cycle of Protocephalus laruei. This

then would explain the presence of this parasite in £. clupeaformis and its

great rarity in P. cylindraceum.

The fluke, Crepidostomum -farionis, is by far the most important parasite

found in the round whitefish population of Algonquin Park. According to

Dogiel et al (I96l) the parasite is most probably acquired by consuming

infected larval Ephemeroptera. This however, raises the question of host

suitability since more Ephemeroptera are consumed by £. clupeaformis than by

P. cylindraceum and yet the incidence of parasitism is much higher in the

latter species. This problem.also invites further study.

A comparison of the age and growth data of the round whitefish from the

three lakes studied can be made with the work by Bailey (1963) and Mraz (1964)

on Lakes Superior and Michigan respectively. The growth rate of the round whitefish studied by Bailey was comparable to that of the same species from

Lake Opeongo. Another similarity is the presence in both populations of Lee's phenomenon. However as Bailey has suggested,, there is a strong likelihood that the observed discrepancy in the back calculations is due simply to the

selectivity of the nets used. Gill nets of a given size always have a tendency to select only the larger, faster growing fish of the younger age groups. For this reason it is possible that the back calculations from these younger fish

in the sample are an over-estimate of size, rather than the figures derived

from older fish being an under-estimate. 54

The fast rate of growth of round whitefish from Lakes Redrock and Happy

Isle is similar to that found by Mraz in the whitefish of Lake Michigan. In

these three populations no evidence of Lee's phenomenon was observed* The

growth data for C. clupeaformis from Opeongo Lake showed a reversal of Lee's

phenomenon, that is, there was an apparent increase in the calculated lengths

from older fish as compared with younger fish. Kennedy (1943) observed the

same apparent increase in calculated lengths, but demonstrated that this

relationship was merely a function of sample size.

The growth patterns of the whitefish from Algonquin Park reflect the

previously described differences in food habits. There appears to be a distinct

correlation between the amount of plankton eaten and the rate of growth. For

example, of the four populations of whitefish studied, the P. cylindraceum of Happy Isle Lake, consume the largest amount of plankton; they also have the highest growth rate. At the lower end of the scale are the P. cylindraceum from Opeongo Lake. Here it was observed that these fish fed primarily on insects and only to a small degree consumed any plankton. Their growth rate was only half that of the fish from Happy Isle Lake. The growth rates of round whitefish from Redrock Lake and the lake whitefish from Opeongo Lake are intermediate between the P. cylindraceum of Happy Isle and Opeongo Lake, as are the consumption levels of plankton.

Studies by Cooper and Fuller (1945) in Moosehead Lake, Maine, demonstrate a similar relationship between food and growth rate. In this lake the P.

cylindraceum reach a weight of one pound in their tenth year of growth, whereas the slowest growing fish in the present study, the P. cylindraceum from Opeongo

Lake, reach this same weight before their eighth year. Stomach analysis of round whitefish from Moosehead Lake showed that these fish fed entirely on 55

larval insects and snails. It appears then, that the availability of plankton as a food source for whitefish is of prime importance to their relative success.

Since C. clupeaformis are better adapted to plankton feeding than the

P. cylindraceum, by virtue of the large number of fine gill rakers, it is not surprising that in any situation where £. clupeaformis and P. cylindraceum occur sympatrically that the lake whitefish are almost invariably the dominant species* 56

SUMMARY

The distribution and relative abundance of Prosopium cylindraceum (Pallas) and Coregonus clupeaformis (Mitchill) in Algonquin Park, Ontario, suggested that some interaction may be present between these two species.

A study of the ecological relationship of these two species was conducted in four Ontario lakes: Opeongo, Layieille, Redrock and Happy Isle. In the first two lakes P. cylindraceum and C. clupeaformis occur sympatrically. In the latter two lakes only P. cylindraceum is present.

Gill nets were set at regular intervals to determine depth range of the two species and at the same time sample stomachs to determine food habits.

Scale samples plus length and weight data were collected in the field.

In the presence of C. clupeaformis it appears that P. cylindraceum occupy a shallower depth range. When the lake whitefish are absent the round white- fish are found in a wide range of depths.

A detailed examination of .640 stomachs was made. P. cylindraceum from

Lake Opeongo were found to consume mainly larval insects plus some bottom- dwelling Crustacea. G clupeaformis from Lake Opeongo fed mostly on bottom- dwelling Crustacea but also included a variety of other bottom organisms. The diet of both populations of P. cylindraceum from Lakes Redrock and Happy ,Isle consisted primarily of planktonic and bottom-dwelling Crustacea.

The growth rate for the four populations of fish appeared quite distinct.

The rate of increase of both length and weight of the P. cylindraceum from

Lakes Redrock and Happy Isle was much greater than that observed for the two whitefish populations from Lake Opeongo. However when C. clupeaformis is present, as in Lake Opeongo, the growth rate of P. cylindraceum is markedly reduced. 57

It is concluded that the better adaptation of C. clupeaformis to plankton

feeding may in part account for its success and at the same time provide an insight into its dominance over P. cylindraceum. 58

LITERATURE CITED

Bailey, M.M. 1963. Age, growth and maturity of round whitefish of the Apostle Islands and Isle Royale regions, Lake Superior. Fish. Bull., U.S. Fish and Wildlife Service, Department of Interior, 6_3_(l)s 63=75.

Baldwin, N.S. 1948. A study of the speckled trout, Salvelinus fontinalis (Mitchill) in a Precambrian lake. M.A. Thesis, Department of Zoology, University of Toronto.

Bangham, R.V. 1940. Parasites of fish of Algonquin Park lakes. Trans. Am. Fish. Soc, 20s 161-171.

Bangham, R.V. and C.E. Venard. 1946. Parasites of fish of Algonquin Park lakes. Pub. Ont. Fish. Res. Lab., No. 53, pp.'33-46.

Clemens, W.A. and N.K. Bigelow. 1922. The food of ciscoes (Leucichthys) in Lake Erie. Pub. Ont. Fish. Res. Lab., No. 3, pp. 41-53. "

Cooper, G.P. and J.C. Fuller. 1945. A biological survey of Moosehead Lake and Haymoch Lake, Maine. Fish. Survey Rept. No. 6, Maine Department of Inland Game and Fisheries, 160 pp.

Dogiel, V.A., Petrushevski, G.K. and I.I. Polyanski. 1961. Parasitology of fishes. Edinburgh, Oliver and Boyd, 384 pp.

Dymond, J.R. 1926. The fishes of Lake Nipigon. Pub. Ont. Fish. Res. Lab., No. 27, pp. 1-108.

Dymond, J.R. 1933. Qoregonine fishes of Hudson and James Bays. Contr. Can. Biol., N.S., 8s 1-12. -

Eschmeyer, P.H. and R.M. Bailey. 1955. The pygmy whitefish, Coregonus coulteri in Lake Superior. Trans. Am. Fish. Soc, 84_s 161-199.

Fabricius, E. and A. Lindroth. 1954. Experimental observations on the spawning of whitefish, Coregonus iavaretus L., in the stream aquarium of the Holle laboratory at River Indalsalven. Rept. Inst. Freshw. Res. Drottningholm, 21% 105-112.

Fenderson, O.C. I964. Evidence.of subpopulations of lake whitefish, Coregonus clupeaformis„ involving a dwarfed form. Trans. Am. Fish. Soc, 93(2)s 77- 94.

Freeman, R.S. 196I. Annual report of the Ontario Research Foundation, Department of Parasitology.

Fry, F.E.J, and W.A. Kennedy. 1937. Report on the 1936 lake trout investig• ation, Lake Opeongo, Ontario. Pub. Ont. Fish. Res. Lab., No. 54, pp. 3=20. 59

Godfrey, H. 1955. On the ecology of Skeena River whitefish, Coregonus and Prosopium. J. Fish. Res. Bd. Can., 12.(4)s. 499=542.

Hart, J.L. 1931. The food of the whitefish Coregonus clupeaformis (Mitchill) in Ontario waters, with a note on the parasites. Contr. Can, Biol., N.S. 6(21)s 447-454.

Hubbs, C.L. and K.F. Lagler. 1958. Fishes of the Great Lakes region. Bull. Cranbrook Institute of Science, 26s 213 PP«> revised edition.

Kennedy, W.A. 1943. The whitefish, Coregonus clupeaformis (Mitchill), pf Lake Opeongo, Algonquin Park, Ontario. Pub. Ont."Fish. Res. Lab.,,No. 62, pp. 23-66.

Kennedy, W.A. 1949. Some observations on the coregonine fish of Great Bear Lake, North West Territories. Bull. Fish. Res. Bd., 82s 1-10.

Koelz, W. 1929. Coregonid fishes of the Great Lakes. Bull. U.S. Bureau of Fisheries, 43.(2)s 297-643.

Langford, R.R. 1938a. Diurnal and seasonal changes in the distribution of the limnetic Crustacea of Lake Nipissing, Ontario. Pub. Ont. Fish. Res. Lab., No. 56, pp. 1=142.

Langford, R.R. 1938b. The food of the Lake Nipissing Cisco, Leueichthys artedi (Le Sueur) with special reference to the utilization, of the limnetic Crustacea. Pub. Ont. Fish. Res. Lab., No. 57* pp. 143-190.

Larkin, P.A. 1956. Interspecific competition and population control in freshwater fish. J. Fish. Res. Bd. Can., 1,2(3)* 327-342.

Lee, R.M. 1912. An investigation into the methods of growth determination in fishes. Conseil permanent international pour 15exploration de la mer. Pub. de Circ. 63.

Lindsey, C.C. 1963. Sympatric occurrence of two species of humpback white- fish in Squanga Lake, Yukon Territory. J. Fish. Res. Bd. Can., 20(3)s 749-767.

Lindstrom, T. and N.A. Nilsson. 1962. On the competition between whitefish species. In: Exploitation of natural animal populations. Edited by E.D. LeCren and M.W. Hodgate, Oxford, Blackwell Sci. Pubs., pp. 327-340.

McCart, P.J. I963. Growth and morphometry of the pygmy whitefish, (Prosopium coulteri) in British Columbia. M.Sc. Thesis, Department of Zoology, Univ•

ersity of British Columbias 98.pp.

McHugh, J.L. 1939. The whitefishes C. clupeaformis (Mitchill) and P. williamsoni (Girard) of the lakes of the Okanagan Valley, British Columbia. Bull. Fish. Res. Bd. Can., 5j>s 39-50. 60

McHugh, J.L. 1940. Food of the Reeky Mountain whitefish. J. ..Fish. Res. Bd. Can., j>(2): 131-137.

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

Mraz, D. 1964. Age and growth of the round whitefish in Lake Michigan. Trans. Am. Fish. Soc, 23.(1): 46^-52.

Nilsson, N.A. 1958. On the food competition between two species of Coregonus in a North-Swedish lake. Rept. Inst. Freshw. Res. Drottningholm, 3_?J 146- 161.

Northcote, T.G. Observations on the comparative ecology of two species of fish, Cottus asper and Cottus rhotheus. in British Columbia. Copeia 1: 25-28.

Northcote, T.G. 1957* A review of the life history and management of the mountain whitefish, Coregonus williamsoni Girafd. Fish. Management Div., British Columbia Game Commission. Mimeo., 6 pp.

Odum, E.P. 1953. Fundamentals of ecology. Philadelphia and London, W.B. Saunders Co., 384 pp.

Qadri, S.U. 1961. Food and distribution of lake whitefish in Lac La Ronge, Saskatchewan. Trans. Am. Fish. Soc, £0(3): 303-307.

Radforth, I. 1944. Some considerations on the distribution of fishes of Ontario. Contr. Royal Ontario Museum, No. 25, 116 pp.

Rawson, D.S. 1951. Studies of the fish of Great Slave Lake. J. Fish. Res. Bd. Can., 8(4): 207-240.

Rostlund, E. 1952. Freshwater fish and fishing in native North America. University of California Publications (Geography), Vol. 9, pp. 1-313.

Smith, S.B. 1955. The relation between scale diameter and body length of Kamloops trout, Salmo gairdneri kamloops. J. Fish. Res. Bd. Can., 12(5): 742-753.

Smith, S.H. 1957. Evolution and distribution of the coregonids. J. Fish. Res. Bd. Can., 1^(4)s 599-604.

Sigler, W.F. 1951. The life history and management of the mountain whitefish, Prosopium williamsoni (Girard) in Logan River, Utah. Utah State Agriculture College Bull., 3_4_2s 1-21.

Svardson, G. 1953. The coregonid problem; V. Sympatric whitefish species of the lakes Idsjon, Storajon, and Hornovon. Fish. Bd. Sweden, Rept. Inst. Freshw. Res. Drottningholm, 3JfcS 141-166. 61

Van Oosten, J. 1923. The whitefishes (Coregonus clupeaformis). A study of the scales of whitefishes of known ages. Zoologiea, New York, 2(17)? 380- 412.

Van Oosten, J. and R. Hile. 1949. Age and growth of the lake whitefish, Coregonus clupeaformis (Mitchill) in Lake Erie. Trans. Am. Fish. Soc.j 22 s 178-249.

Walters, V. 1955. Fishes of western arctic America and eastern arctic Siberia? taxonomy and zoogeography. Bull. American Museum of Natural History, 106(5)s 257-368.

Watson, N.H,F. 1963. Summer food pf lake whitefish, Coregonus clupeaformis (Mitchill), from Heming Lake^ Manitoba. JV Fish. Res. Bd. Can., 20(2)% 279-286.

Wood, K.G. 1953. The bottom fauna of Louisa and Redrock lakes, Algonquin Park,'Ontario. Trans. Am. Fish. Soc, 82s 203-212.

Wynne—Edwards, V.C. 1952. Fresh-water vertebrates of the Arctic and Suba: Bull. Fish. Res. Bd. Can., No. 94, pp» 1-28. 62

APPENDIX

TABLE XXI. The food of P. cylindraceum and C. clupeaformis from three Ontario lakes.

Prosopium cylindraceum : Lake Opeongo MAI 15 - 31 JUNE 1 - 15 JUNE 16 - 30 AUGUST 1-15 AUGUST 16 - 31 FOOD ITEM %V J6F FI %V %F FI %V %¥ FI %¥ FI %F FI %y %¥ FI #V %F FI Sida 12.2 39.0 21 22.1 42.9 31 25.3 44.4 34 10 3.5 6.3 Ophryoxus 4.1 39.0 13 1.1 .20.0 5 0.1 11.1 1 3.5 6.2 Eurycercus 2 34.2 9 42.9 .5 1.7 9 0.7 22.2 4 13 Polyphemus 0.2 11.1 2 Hyallela 0.1 2.9 X

Ephem. 1.6 100 13 6.0 36.6 15 5.4 28.6 13 21.5 22.2 22 25.4 18.2 22 0.1 16.1 9.1 12 Odonata 31.4 50 40 0.1 2.4 X 15.1 2.9 7 Sialidae 0.1 2.4 X 0.2 2.9 X 8.5 18.2 13 13.8 9.1 11 Triehop. 64.3 100 80 8.9 46.3 20 9.8 37.1 19 44.9 33.3 3.9 24.9 63.6 40 25.4 62.5 40 21.8 36.4 28 Coleop. 1.4 2.9 2

Chiron. L. 2.1 100 14 52.5 75.6 63 11.3 51.4 24 1 0.5 11.1 2 21 .4 45.5 31 0.8 37.5 5 14.1 24.2 19 Chiron. P. 7.2 75.6 23 20.1 57.1 34 5.9 77.8 21 8.3 63.6 23 66.2 50.0 58 25.4 30.3 28 Chaob. L. 0.8 7.3 2 0.1 5.7 X 0.3 11.1 2 Chaob. P. 2.5 3.0 3 Amnicola 0.8 50 6 1.1 9.8 3 0.5 11.1 3.8 6.1 5 Valvata 0.3 12.2 2 Pisidium 0.4 9.8 2 0.1, 2.9 X 1.9 3.0 2 Helisoma 0.1 7.3 X Physa 3.6 2.4 3

Hydracar. 0.2 7.3 1 0.0 5.7 X 0.3 11.1 2 0.6 6.3 2 0.6 3.0 1 Perca 11.5 2.4 6

Coregonus clupeaformis Lake Opeongo MAY 15 - 31 JUNE 1 - 15 JUNE 16 - 30 JULY 1 - 15 JULY 16 - 31 AUGUST 1-15 AUGUST 16 - 31 %V %F $V %F FI %¥ FI FOOD ITEM FI %V %F iFI %Y %F FI %V %F FI %V %F FI

Sida 2.8 29.7 9 6.4 50.0 18 16.1 61.9 32. 18.0 60.0 33 10.0 31.6 19 35.2 50.0 42 Ophryoxus 5.7 48.6 17 5.4 47.4 16 1.8 47.6 9 1.6 30.0 7 0.2 8.8 1 0.2 10.0 2 Eurycercus 3.0 37.8 11 13.2 55.3 27 7.1 71.4 23 43.-5 40.0 42 0.4 5.3 1 0.8 3.3 2 Latona 12.6 26 15.8 6 52.7 2.3 0.1 9.5 x 0.1 3.5 x 3.5 15.0 7 Daphnia 0.0 2.5 x 0.0 3.3 x Acantho. 0 4.1 1 .4 0.1 2.5 x 0.1 3.5 0.2 11.7 2 Bosmina 0.2 1.4 X 0.1 6.7 x Holopedium 3.9 8.1 6 Leptodora 0.1 2.7 X 31.5 26.3 29 0.3 3.3 X Hyallela 0.1 3.9 X 0.1 41.0 X 0.1 2.6 X 0.1 3.3 X Cyclops 1.7 50.0 9 9.1 68.4 25 6.6 81.0 >' 23. 3.7 52.5 14 2.0 33.3 8 5.9 48.3 17 63

TABLE XXI. continued:

Coregonus clupeaformis : Lake Opeongo MAY 15 - 31 JUNE 1 - 15 JUNE 16 - 30 • JULY 1'-. 15 JULY 16 - 31 AUGUST 1 - 15 . AUGUST 16 - 31 FOOD ITEM %V %F FI %V %¥ FI %V %F FI %V %F FI 2v %¥ FI %'V %F FI JbV %F

Ephem. 95.3 76.9 86 12.4 37.5 21 9.0 18.4 13 3.4 9.5c . 6 0;1 2.5 X 2.2 3.5 2 5.2 6.7 6 Corixidae 0.0 3.9 X 1.9 22.6 6 0.8 4.8; 2 0.3 2.5 X 0.3 3.5 1 0.5 6.7 2 Sialidae 1.9 19.2 6 Trichop. 0.0 3.9 X 0.7 22.6 4 1.4 15.8 5 2.1 4.8. 3 0.1 5.0 X 0.6 3.5 2 1.6 10.0 4 Coleop. 0.1 1.4 X 0.3 1.7 X Formicidae 10.1 5.4 7 0.4 2.6 X 2.0 5,0 3 Chiron. L. 1.1 26.9 6 1.6 46.9 9 5.2 63.2 18 17.0 61.9- . 33 4.3 42.5 4. 11.2 33.3 19 20.0 55.0 33 Chiron. P. 0.3 11.5 2 2.2 43.2 10 2.4 39.5 10 1.1 33.3 6 2.9 30.0 9 3.2 26.3 9 2.2 20.0 7 Chiron. A. 0.4 3.3 1 Chaob. L. 0.2 8.1 1 1.1 23.7 5 .. 3 1.5 17.5 5 1.6 0.6 15.0 0.7 14.3 u.o 5 3 Chaob. P. 0.3 1.4 X 1.6 28.6 7 1.9 15.0 5 0.9 14.0 4 0.1 1.7 X

Amnicola 0.7 19.2 4 29.9 46.9 37 3.3 7.9 5 1.6 4.8 3 0.3 7.5 2 1.1 7.0 3 1.6 8.3 4 Valvata 1.2 8.1 3 0.2 2.5 X 1.2 5.3 3 0.2 1.7 X Pisidium 0.5 7.7 2 2.4 19.9 7 3.5 36.8 11 36.8 57.1 46 16.7 45.0 27 9.2 17.5 13 10.3 36.7 20 Planorb. o.i 4.1 X

Ostracods 0.5 .28.4 4 0.2 7.9 1 0.0 19.1 X 0.1 2.5 X 0.1 10.5 X 1.3 36.7 7 Hydracar. 0.1 19.2 2 5.6 72.6 20 5.7 55.3 18 3.1 76.2 15 4.9 52.5 16 8.2 38.6 18 7.9 45.0 19 Perca 47.4 5.3 16

Prosopium cylindrac eum : Lake Happy Isle Prosopium cylindraceum : Redrock Lake MAY 16 - 31 JUNE 16 - 30 JULY 16 - 31 AUGUST .16 - 31 JULY 16 - 31 AUGUST 16 - 31 FOOD ITEM 2v %F FI %M %F FI 2v %F FI %V %F FI %! %F FI JfeV FI

Sida 20.2 41.2 -29 Ophryoxus ' 2.0 10.0 5 0.7 11.8 i 3- Eurycercus 4.7 50.0 15 41.1 45.0 3 4.8 35.3 13 Daphnia 88.5 88.0 88 93.8 75.0 84 28.4 85.0 49 70.6 74.3 72 82.6 89.5 86 62.6 81.0 71

Ephem. 0.9 8.8 3 . 4.9 15.0 9 1.3 11.8 • 4 2.1 5.3 3 0.5 4.8 2 Odonata 2.1 5.3 3 Trichop. 4.3 12.0 7 1.3 25.0 6 0.9 10.0 3 8.6 29.4 16 5.1 10.5 7 4.5 9.5 7 Chiron.. L.. 0.3 8.8 .2 4.0 50.0 14 5.8 29.4 13 0.1 5.3 X 32.1 38.1 35 Chiron. P. 5.5 88.0 2 0.2 25,0 2 14.7 80.0 34 1.8 23.5 7 5.1 10.5 7 Chaob. L. 2.8 15.8 7 0.2 9.5 1

Amnicola 0.3 4.0 1 3.0 10.0 6 1.5 11.7 4 Pisidium 0.6 5.0 2 0.1 9.5 X

Hydracar. 0.2 4.0 X 0.4 5.0 1 . 0.1 5;9 X