___.

"‘“I—

III

I
l

I
I

IIIII

It

‘

 

AN INVESTIGATION OF THE

BLUEGILL POPULATION IN FORD LAKE,
MICHIGAN

Thesis for the Degree of M. S.
MICHIGAN STATE COLLEGE

MichaeI WiIIiam Fabian
' I954

"HESI‘:

0-169

I|llllll|lIIIIIIIIIIIIHIlllllllllllllllHlHllllllllllllllll I

3 1293 10490 9555

This is to certify that the I

thesis entitled
A Fisheries Investigation of the

Bluegill in Ford Lake, viichigjen.

presented by

Michael Fabian

has been accepted towards fulfillment
of the requirements for

__l_{_.__S_._ degree in M

QM QB;

Mainr nrn‘pccnr

Date May 199 1953.

 

 

 

AN INVESTIGATION OF THE BLUEGILL POPULATION
IN FORD LAKE, MICHIGAN

by

MICHAEL WILLIAM FABIAN

A THESIS

Submitted to the School of Graduate Studies of Michigan
State College of Agriculture and Applied Science
in partial fulfillment of the requirements

for the degree of

MASTER OF SCIENCE

Department of Zoology

1951;

43M claw

7 5/. 5'“

ACKNOWLEDGEMENTS

The writer wishes to extend his thanks to Dr. Robert C.
Ball, Zoology Department, Michigan State College, who has
directed this study, and to whom the results are herewith
dedicated.

Thanks are expressed to the personnel of the Pigeon
River Trout Experimental Station for the collecting and
recording of data and bluegill scales.

Grateful acknowledgement is also due to Dr. Roger Keller
for his assistance in the statistical analysis of the trap
not catch, and to Dr. Peter I. Tack for his help in interpre-
tation of the scale data.

Thanks are also due to the author's wife for her
typing of the thesis, and her patience and encouragement
throughout the entire investigation.

331.3 11

I.

II.

III.

Iv.

V.

VI.
VII.

TABLE OF CONTENTS

INTRODUCTIONOOOOOOOOO...

A.
B.

Description of Ford Lake . .
History 0 O O O O O O O O O O

FIELD PROGRAM . L . . . . . . . . .

A.
B.
C.

0

Recovery of Poisoned Fish in 1952 .
U86 Of Trap Nets e e e e e e e 0
Scale Sampling 0 e e e e e e e e

O O

COMPARISON OF THE STANDING CROP IN THE 1936,
19u6, AND 1952 FISH POPULATIONS . .

UTILIZATION OF TRAP NETS IN FORD LAKE

IN 1952 e ee 0 e e e e e e e e e e

A.
B.

U36 0 e e e e e e e e e e 0

Construction . . . . . . .

SCALE ETHOD 0 O O O O O O O O O O O

O 0

O 0

Sex Differences of Ford Lake Bluegills.

Growth Increments . . . . . .
Calculated Growth Rates .'. .
Variation in Growth Rates . .

Statistical Test for Pepulation

Differences e e e e e e e e 0
Condition and Length-weight

Relationships . . . . . . . .
Time of Annulus Formation . .

DISCUSSION . . . . . . . . e . e .

SW 0 O O O O O O O O O O O O 0

VIII. LITERATURE CITED . . . . . . . e e e

O
O

O

Page

GHD‘J 'Q UH»

11

17

17
17

23
26

#7

ti

63
66
67

INTRODUCTION

The total fish population in lakes has been of increasing
interest to the practical fish manager in recent years as a
knowledge of the species composition, abundance, size and
growth rate is of value in fisheries management. Powdered
derris root has been used most effectively in gaining infor-
mation on these factors by removing undesirable species or
reducing an overpopulated area.

Studies made by Beckman (1950) to determine the effect
of reduction in numbers of fish by winterkill found that the
increase in the rate of growth was not maintained for longer
than a year in most species.

Ford Lake, in the north central part of lower Michigan,
is an example of one of the several Michigan lakes which was
poisoned and stocked with trout, only to become repopulated
with warm-water fish. This may have been due to incomplete
kill or unauthorized introduction of live fish. From 19M:
to 1952 the population of Ford Lake became predominantly one
of stunted bluegills (Lepomis Erochirus macrochirus
Rafinesque). Ford Lake was poisoned for the third time in
August, 1952, offering an Opportunity to study the total
pepulation in comparison with other years.

Trap nets play an important part in fisheries research
and certainly affect the analysis of any data resulting
from the catch. In this investigation the results of the

catch from.three types of nets were analysed to determine
the effect of net construction and size on the number and
size of bluegills caught.

Data on the growth of the bluegills were obtained from
those bluegills caught in the trap nets during 1952. This
information was used to study the effect of increasing
pepulation density on the growth rates of an almost pure
bluegill pepulation with.little if any predation to reduce
the population.

An attaMpt was made to determine the effect of size on
the time of annulus formation and also to determine the date
at which.half the pepulation had formed the annulus.

Description of Ford Lake

In 1931 and 1932, a physical, chemical, and biological
survey was made of Ford Lake. According to Eschmeyer (1937),
the surface area is 11.7 acres with no inlet or outlet.
Vegetation on the shoal areas is abundant. The dominant
soil types were found to be: sand, peat, and marl in the
shoal areas; marl on the slope areas, and peat in the deep
zones.

The north and north-east end of the lake has a peat
bottom with Scigpus and beds of 93533. The west end is
very shallow with beds of Scirpus.

Field work by Schneider in 1939 showed the dominant soil
condition in Ford Lake region to be sand on the surface with
a sub-stratum of brownish-yellow sand with occasional gravel
pockets. The major soil types are Rubicon and Roselawn sand.

Soil analyses revealed the drainage to be extremely
rapid. The physicgraphy of the region is pitted outwash
plains and subdued moraines with local relief of twenty to
fifty feet. Eighty per cent of the area has up to seven
per cent slopes with twenty per cent of the area having
slopes from 7-25 per cent.

The original vegetation was white (Pinus strobus, L.)
and red pine (Pings resinosa, Ait.) with second growth aspen
(Populus 32.), fire cherry (Prunus zensylvanica), service
berry (Amelancher 52.), and Jack pine (M banksiana, Lamb.).

b.

There are present large open areas of bracken fern lPteriduim
92.), sweet fern (Comptonia _s_p_.), bluegrass (£92 s .), and
blueberries (Vaccinium gp. ). This area was given a general
agricultural rating of fourth class land because it was

very droughty and has low natural fertility.

History

Ford Lake lies in the Pigeon River State Forest area
in the north central part of the Lower Peninsula of Michigan.
It is located in Otsego County, (R. l W., T. 32N., Section 8)
and seems to have been formed either from the isolation of an
ice block or from the dissolving away of limestone beneath
the soil. Physical, chemical, and biological inventories in
1931 and 1932 by the Institute for Fisheries Research,
revealed that several pit lakes in the area were suitable
for trout production. At that time the species composition
of Ford Lake was limited to a stunted population of yellow
perch.(§gggg flavescens).

Ford Lake, like the others in the area was found to be
alkaline in nature, thermally stratified, with abundant
vegetation, and sufficient oxygen for fish life available
below the thermocline in warm weather.

A program for experimental management, as stated by
Eschmeyer (1937), was set up to improve fishing by stocking
the lake in 1933 with.brook trout. In l93h when it was
found that the stocked fish still were not doing well, the
perch.population was heavily netted. In 1934 and 1935, the
lake was stocked with brook, brown, and rainbow trout. In
1936, due to the poor condition of the trout, it was decided
to remove the fish by poison and dynamite. The lake was
then restocked in October, 1936 with 5000 Montana grayling

fingerlings, (Thymalluszmontanus).

6

The experiment (Leonard, l9h0) on feeding habits of the
grayling was complicated by the unauthorized introduction
of bluegills. It was shown that the grayling were not able
to compete for food with the more aggressive bluegills.

In 19m, plantings of 5000 fingerling brook trout,
(Salvelinus fontinalis), proved to be unsuccessful as none
were recovered in gill nets set in l9h5.

With the possibility that a predatory fish.might reduce
the bluegill population, walleyes, (Stizostediog vitreum),
were introduced in 19MB (Ball, 1948).

On August 26, l9h6, Ford Lake was again poisoned with
rotenone in order to compare the standing crop with that
recovered in 1936. In the fall of l9h6, brook trout were
again introduced. In 19h7, bluegills, believed to have
survived the l9h6 poisoning, were found to be present in the
lake. Karvelis (1952) found that the majority of fish that
survived the l9h6 poisoning were of the l9hb year class.

Plantings of 5,800 three inch brook trout were made
each fall from.l9h? to 1951 with each planting being
identified by removal of a particular fin.

Due to the large numbers of stunted bluegills and very
poor survival of brook trout, Ford Lake was again poisoned
on August 22, 1952. During the several days following,
every effort was made to recover all fish that came to the
surface or were washed up on shore. On September 5th the
count was discontinued when there were only nine bluegills

found on the entire lake shore.

FIELD PROGRAM

Materials and Methods

Recovery of Poisoned Fish in 1952.

In order to compare the brook trout-bluegill relation-
ships, Ford Lake was poisoned with rotenone on August 22,
1952. It was desirable to obtain a complete pickup of fish
following the poisoning to compare with previous studies.

In order to check the recovery, 3h2 marked bluegills were
placed in the lake prior to poisoning. A test cage with a
few bluegills were place in the lake just before poisoning
to test the toxicity at the twenty feet level. On August
29, the test cage was lifted and all the fish.were dead. It
is not known whether there was a complete kill at the twenty
foot level but it is possible that the repeated lifting of
the trap through the surface layers killed these test fish.
The personnel of the Pigeon River Trout Research.Area quit
picking up fish on September 5th when the count reached nine
bluegills for the entire lake shore. Very few fish were
still visible on the bottom but the known recovery rate was
little less than 75 Per cent.

Only five species of fish were recovered after the lake
was poisoned: bluegills, brook trout (Salvelinus fontinalis),
bluntnose minnow (Hyborhlnchus notatus), mudminnow (m 1351;),

and the shiner (Notropis 32.). All but one brook trout
recovered were characterized by removal of the right pec-
toral fin. This would indicate that the brook trout
recovered were those planted in l9h7. One brook trout was
recorded as having the dorsal fin removed, this fish then
belonged, presumably, to the l9h6 planting. In the test
trap nets one fish.was alive four days after application of

the poison.

Use of Trap Nets

From February through August, 1952, the personnel of
the Pigeon River Trout Research.Area maintained and checked
the trap nets set in Ford Lake. The results of the metal
trap net catch.were tabulated and an attempt was made to
determine the effect of net construction on catch per net
hour. The method used was the analysis of variance test as
given by Snedecor (1950). Most of the scale sampling date
were obtained from.these trap nets although a few were

caught by hook and line.

Scale Sampling

The scales used in the age and growth studies were
obtained largely from fish caught in the trap nets. The
scale data from.the trap nets were recorded in the metric

system, in grams, and millimeters. The length data obtained

\

from anglers were recorded in the English system, and con-
verted to millimeters by use of a conversion table (Lagler,
1952).

The scale data were obtained from January 28, through
August 1h, 1952.

It should be noted that the scale data do not represent
a random.samp1e because of the selectivity of gear used.

The larger fish were caught by anglers and no fish from.year
classes l9h6, 1951, or 1952 were collected.

The ages 0, 1, 2, 3, etc., refer to the number of
winters through which.the fish have lived. Thus, a fish in
the summer in which it has been hatched belongs to the 0 age
group, for it has passed no winters and shows no annuli. In
the second summer after hatching, it has passed one winter
and therefore belongs to the age group one.

The scales obtained were cleaned in water with a stiff
bristled brush.and.mounted on slides in a gelatin-glycerin
media. The scales were then enlarged h5.5 X on the scale
projection machine and the annuli recorded on Keysort cards.
In every case the scale was read from the focus to the ante-
rior edge of the scale. The annuli were recorded on the
cards at the point a complete circulus was being formed.

The growth rates were then calculated by means of a nomo-
graph as described by Carlander and Smith (l9hh).

In order to use the nomograph it is necessary to know

the length.of the fish at the point the scales begin to fepm.

10

Potter (1925) found the standard length of bluegills at
the time of scale formation to be 17 millimeters. Using the
conversion factor as presented by Beckman (19h8) the total
length was found to be twenty millimeters at the time of
scale formation. Twenty millimeters was then used as the
point at which the scale began to form.

The "K", or condition factor was computed from the
alinement chart as developed by Phenicie and BishOp (1950).
The alinement chart used was a graphical, mechanical rep-
resentation of the relationship between length and weight.
This chart proved convenient as the condition index could
be read directly at the point the straight edge crossed the

calibrated line.

11

COMPARISON OF THE STANDING CROP IN THE
1936, 19kb, AND 1952 FISH POPULATIONS

According to Ball (19h8) a complete kill of the fish
pepulation was reported for 1936. All fish were accounted
for by counting or close estimates. In l9h6, every effort
was made to recover all fish that came to the surface or
were within reach of the surface, but apparently some of the
younger fish survived. The poisoning in 1952 was believed
to have been a complete kill as no fish were found in trap
nets set as soon as the waters became non-toxic.

The fish population of Ford Lake as determined in 1936
consisted of brook trout, four species of minnows, and a
stunted population of perch. The weight of the total fish
pepulation in 1936 was about 521 pounds. The total number
of fish present was hl,703.

At the time of the 19h6 poisoning the bluegill was the
dominant species with no yellow perch present. The only
brook trout present were those stocked immediately prior to
poisoning. Only 17 walleyes were recovered from the young
planted in 19h3. The total number of fish recovered in the
second poisoning was h1,693 with a total weight of 1,293
pounds.

The population in 1952 differed from.the previous two
poisonings as would be expected. Only six years had elapsed

since the previous poisoning and there were 11,622 fish

12

TABLE 1

A COMPARISON OF THE STANDING CROP OF FISH
RECOVERED AT THREE POISONINGS

 

.1/ 2/
1952 3/fi19h6 1936
Total number recovered 11,622 hl,693 h1,703
Total weight recovered [4/
(pounds) 726.8 1,293 521
Percentage by number of
bluegills recovered 9A.? 89.6 --
Percentage by weight of
bluegills recovered 79.9 9h.5 --
Number of bluegills
recovered 11,001 37.383 ~-
Bluegills per acre 1,028 3rh9h» "
Total number of fish
per acre 1,086 3,897 3,567
Weight of bluegills
per adre (pounds) 5h.3 11h.2 ,-
Pounds of fish per acre 67.9 121 uh.

Number of legal sized

bluegills recovered

per acre 2h 1.68 --
Average weight of the

bluegills recovered

(ounces) 0.85 0.52 ~-
;/ Ball (1948)
g/ Ball (19h8)

‘3/ Doesn't include the number of small fish recovered.

14/ Includes weight of the small fish.

13

recovered as compared to approximately h1,700 recovered the
previous two poisonings. Ball (19h8) stated that the average
length of the bluegills recovered in 19h6 was 3.9 inches and

the average weight about one~half ounce. No data were

TABLE 2

WEIGHT AND NUMBER OF BROOK TROUT AND
OTHER FISH RECOVERED AT POISONING
IN 1952

Brook Trout Small Fish

J

Total weight (pounds) 2h.h 121.3
Pounds per acre 2.3 11.3
Per cent of total weight 3.3 _ 16.6
recovered
Total number 621 --
“assists/“mar °f 5‘3 --
Number per acre 58 --
Average weight (ounces) .628 ~-

 

il/Excluding the numbers of small fish

available on the average length of the bluegills recovered
in the 1952 poisoning but the average weight was 0.85 ounces.
The average weight of the bluegills from the scale data was
35.2 grams as compared to the average weight of Zh.grams for

those recovered in the poisoning operations. This is

 

 

on do Amvuzowv swam Hanan

o o w ma om Ob no bwm mad ‘ Amousomn
maaflmosap Hosea pom

ea we or mmm mmm mama bow owmm maom Amomssmv
maawmmSHn Ahmed 95m
0 H o a HH mm on son mma Ammoudmv pdoap Mooam

o o o m b ca om wad mm , Anonfidav
maaflmodap vmmflm Hmmmq

H mm mm mm mm mm mm mm mm
.pmom undead

W49 mmm Dmmlroomm HmHh QWEomHom ho BmemB and mmmzpz

m

HAMTB

probably due to the size selectivity of the trap nets.
There were 11,001 bluegills recovered with a total weight
of 581.1 pounds. Six hundred and twenty one brook trout
weighed 2h.h pounds. Approximately 9A.? per cent of the
number of fish recovered, i.e. brook trout and bluegills,
were bluegills. By weight, bluegills consisted of 79.95
per cent of the total weight. The minnows that were
recovered during the poisoning Operation were weighed but
not counted. In 1952, 257 legal sized bluegills were
recovered as compared to 18 in 19h6.

Within ten days prior to the poisoning 3h2 bluegills
were marked and returned to the lake. After the poisoning
254 were recovered which would indicate that there was
approximately 7h.3 per cent recovery of poisoned fish in
the lake, presuming the mortality was very low. Ball (1948),
after the poisoning of Ford Lake in 19h6, reported a 58.9
per cent recovery of all marked bluegills, and hh.7 per cent
of the marked trout were recovered.

A study by Krumholz (19ml) estimated the fish popu-
lation in Twin Lake, Michigan, by means of recovery of
marked fish in nets. The lake was then poisoned and 86 per
cent of the marked fish presumed to be alive were recovered.
One of the main items of uncertainty in such an operation
is the completeness of recovery of poisoned fish.

Day Lake, a small soft water lake in Wisconsin, that

is naturally divided into two basins by a shallow narrow

16.

constriction, was considered ideal for a pepulation and
growth study. The fish.population was considered stunted
and to increase the growth rate, the population from one
basin was removed by fyke nets and rotenone. The left fins
of numerous fish.were clipped and of the fish known to be
present in the lake shortly before poisoning, only h7.5 per
cent were recovered (Williamson and Brusch, l9h7).

This would seem to indicate that the recovery at Ford

Lake was higher than the recovery in most lakes.

1?

UTILIZATION OF TRAP NETS IN FORD LAKE IN 1952

Use

From.February 27 through August 20, trap nets were set
in Ford Lake to obtain scale samples and lengthrweight data
for growth analysis. These nets were maintained, checked,
and moved about the lake periodically by personnel of the

Pigeon River Trout Research Station.

Construction

Eight nets were used during the entire netting operation
in 1952, but only three nets were used from March.through
July 26.

Net No. 1 was constructed of one inch chicken wire mesh.
The not had a length of 52 inches with 36 inch triangular
sides. Funnel depth was 20 inches with a 3% inch Opening.
The funnel was reconstructed June 25th with a new depth of
38 inches, and replaced on June 28. Nets 2, h, 5, 6, 7, and
8 were each constructed of one inch chicken wire mesh with
a length of AB inches and 36 inch triangular sides. Funnel
depth was 20 inches with a 3% inch opening.

Net No. 3 was constructed ofifi inch.mesh.hardware
cloth--length AB inches with 36 inch triangular sides. The
funnel depth was 20 inches with a 3% inch opening.

The data on the metal trap nets indicated that there

18

‘was a difference in the catch.due to net construction. To
substantiate this assumption a statistical test was made to
determine whether or not the traps had the same catchrability.
Bets 1 and 2 have the same size wire mesh but each.has a
different length. The funnel depth was the same until it

was changed on June 25th and the not reset on June 28. Nets
2 and 3, although of the same dimensions, are constructed
respectively of one inch.chicken wire mesh and one half inch

mesh.hardware cloth.

TABLF.A
CATCH PER NET PER 100 HOURS

 

Note No. l I No%:g_r No. 3
March 2.8 5.0 5.2
April 2.6 6.9 . 11.6
May 0.8 21.3 13.8
Through June 25 1&2 ‘l§;g '42:;
Totals 7.h. 51.h. 39.7

The statistical test was the variance ratio, ”F", as
shown by Snedecor (1950). If the "F" test showed Signifi-
cant differences, there was a difference in.the catch per
net hour. The value of the variance was calculated for nets
1, 2, and 3 from.March through June 25 (Table four). The

value revealed a significant difference in catch for the

19

three note, at the five per cent level. That is, up to June

25, net 2 was the most effective trap net.

TABLE 5

COMPARISON OF CATCH FROM JULY 28
THROUGH AUGUST 20

 

Nets Hours Fished Fish per 100 Net Hours
1 600 18.2
11 600 111.2
5 600 11.0
6 600 11.2

From July 28 through August 20 (Table 5), a comparable
number of hours were fished. The data from Table 5 showed
that not No. 1 seemed to have a substantially increased catch
over previous months. The catch was also greater than in
nets 1;, 5, and 6. This increase is thought to be due to the
new funnel depth of 38 inches, as compared to 20 inches

previ ous 1y .

Nets l, 2, and 3 seem to show a declining catch per
unit of time set toward summer which might be accounted for
by the increased water temperature. Perhaps the increased
yield of not No. 1 can be explained in that it may be an

increase due only to net construction and comparison with

previous months.

TABLE 6 20

COMPARISON OF THE MONTHLY TRAP NET CATCH
IN FORD LAKE IN 1952

 

 

 

 

Total Hrs. Total No. Catch per 100 Size Ran e
Month Fished Fish Net Hrs. (Inches
Net No. 1
Feb. 96 Ill 11,. 5 ll. 3-6.0
Mar. 672 19 2. 8 he3‘802
April 768 20 2.6 Ink-7.0
May 62A 5 0.8 hA2-h.7
June 50h 6 1.2 h.2-h.5
July 720 71 9.9 11.2-8.1;
Aug. 552 102 184; IN 1-6.%
393 .2??- 00 e 1" 0
Net No. 2
Mar. 672 3’4. 5.0 I-l-eS‘7e7
April 768 53 6.9 Ins-8.1
Nay 62h. 133 21.3 I); Z‘Beh»
June 720 131 18.2 ~-
July 672 o 0.0 --
Aug. 6 1 1.0 .0
3552 3'52 9.9 .2- .
Net No.g3
Mar—Eh 672 35 50 2 he1‘6e7
April 768 89 11.6 3.5-6.1
May 600 83 13.8 3. li-6.1
June 720 “.6 6eI+ 3. 3'509
JUly 720 3 Och. (+0 1‘508
August 96 O ‘QLQ ~-
3 7 235 7.2 2.5-5.7

21
TABLE 7

A COMPARISON OF THE CATCH OF NETS
WITH THE SAME CONSTRUCTION

Total Hours Total No. Catch per 100 Size H e

 

Nets Fished Fish Net Hours (Inches

It 696 128 18.I|. 11.2-8.9

5 696 106 15.2 halt-6. 8

6 696 100 111.1; I1. 2,-6.6

7 192 52 27 . 1 A. 1-6. It

8 __9_§ _13 _13_.5_ 11. 3-6. 7
2376 399 16.8

As water temperature increases during the spring, the
fiSh become more active and.more food is required to main-
tain bodily demands. Morgan (1951) found that extreme rises
in temperature may also cause bluegills to stop eating.

He also found the test not catch was a good record of when
the fish were biting. In Buckeye Lake, Ohio, the average
number caught increased rapidly from March to May when the
temperature rose to 70 degrees Fahrenheit but declined
sharply from.June to August when the temperature rose as
high as 80 degrees Fahrenheit.

This assumption does not always seem to hold true as
Balding (1928) stated that trout decreased their activity
as the water temperature rose into the seventies whereas

the bullheads did not seem to mind the increase.

22

TABLE 8
TOTAL CATCH, SIZE RANGE FOR EACH TRAP NET

 

Catch per Size
Net. ”RAISE“ TESS“ 132.32“ £238.13
1 3936 237 6.0 h.1-8.u
2 3552 352 9.9 h~2-8-h
3 3576 256 7.2 2.6-6.7
n 696 128 18.h. 4.2-8.9
5 696 106 15.2 h.h-6.8
6 696 100 lh.h h.2-6.6
7 192 52 27.1 h.l-6.h.

8 ____2§ ___;3 ggggg . -6.
13,hh0 1,2hh. 9.3 2.6-8.9

Table 6 and Table 8 show that not No. 3 had the
smallest size range of all the nets. This is believed to

be due to the one half inch.mesh.hardware cloth construction.

23

SCALE METHOD

Scales are a protective exoskeleton found on fish which
until recently were not studied extensively. Ctenoid scales,
found usually in the higher teleosts, such as the bluegill,
and perch, are similar to cycloid scales, but the part which
extends out from neighboring scales has small spines.

Creaser (1926) found that tested scale data might be
used effectively in the study of the life history of fishes.
Three types of marks have been described in the fixation of
the pattern on scales, those of the cessation of scale growth,
those of variation in the rate of scale growth, and those of
regeneration.

Van Oosten (1928) reported that it was possible to deter-
mine by scale analysis the approximate length attained by the
fish at the end of each year of its life, and its rate of
growth.for each year of life.

The age of bluegills in this study was obtained by
counting the annuli, which appear to be visible marks pro-
duced at about the time growth was resumed following semi-
dermancy. The use of the scale method is based on the assump-
tion that the scale length increases directly proportional to
the length of the fish. In order to check this for Ford Lake
bluegills, the data were grouped in ten.millimeter intervals

(Table 15) and plotted as seen in.Figure l.

 

.mmma as emposaaoo madnmmeae was ac

mennmqonpsamn nausea nmaeunpmqma masom one H mhzmam

on." . can

 

 

(mm) m was

26

Sex Differences of Ford Lake Bluegills

A comparison of the sex ratio of bluegills in Ford Lake
(Table 9) showed that there were 107 females for every 100
males.

Beckman (l9h9) in a study of 8,159 bluegills, had a ratio
of 120 females for every 100 males.

Hansen (1951) in a study of the white crappie, (Pomoxis

annularis, Rafinesque), found 105 females for every 100 males.

TABLE 9
SEX RATIOS OF BLUEGILLS IN FORD LAKE IN 1952

 

Number Number of Number of Females
Annulus of Males Females per 100 Males
2 19 23 121
3 77 126 16h
h 60 2o 33
5 __2 ._J: .21
TOTALS 159 170 107

In the Ford Lake samples most of the young bluegills
were females (Table 10), and most of the older ones were
males. The sex ratio was equal, apparently, between the
third and fourth year of life. The unbalanced sex ratio may
have been due to the selectivity of the trap nets for a par-
ticular year class, or variation in the natural mortality for

each sex.

.mmma mmflnzw ompomaaoo mmmao amen come you

msaszus note we mpmmamhozfl Spaces wmpwazoawo mwwmoaw on?

 

 

 

 

 

 

 

8
(mammal) summer: We

TABLE 10

29

AVERAGE CALCULATED TOTAL LEINGTHS (MILLIMETERS)
OF MALE AND FEMALE BLUEBILLS

 

Year Annulus
Class Sex 1 ”gr 3 5
1911? Male Total length 38.1 88.7 1211.0 m8.2 158.7
Number
examined 29 29 29 29 3
Female Total length 38.1; 88.9 126.6 11111.7 211.0
Number
examined 7 7 7 7 1
19118 Male Total length 11.1.Lt 92.1; 128.5 151.2
Number
examined 89 89 89 31..
Female Total length 112.11 911.1 133.1; 161.2
Number
examined 70 70 70 111
1919 Male Total length 12.3 91.2 127.3
Number
examined to to 22
Female Total length 112.7 87.0 116.6
Number
examined 90 90 70
1950 Male Total length 53.0 120.0
Number
examined 1 l
Fanale Total length 1.16.0 89.3
Number
examined 3 3

—.

.0—- ..

~ - -...,_I

o...

 

.mmmao meek meme pom msadumm

some pm summed umpwadoawo mmmnm>m 039 m onsmflm

 

 

 

15°

 

 

8

(W'IITIDI) mm

 

 

 

 

 

 

32

Beckman (19h9) found that in Michigan waters there was a
general trend toward a decreased percentage of male bluegills
with increase in age. Hubbs and CoOper (1935) found that
data on the sex ratio in the green sunfish (Apomotis cyannellus),
show an increasing percentage of males among the older fish,
thus constrasting with the condition found in the long-cared
sunfiSh (Xenotis megalotis peltastes).

A comparison of the growth rates of females and males
was of particular interest. The total lengths of each sex,
‘Iithin each year class or brood, were calculated for each
annulus. The l9h7 brood, the oldest in the sample, shows
that the female was larger at each annulus except the fourth.

Morgan (1951), combining year classes, found that the
average length of the female bluegill was consistently larger
than the.male.

The females from.the l9u8 year class were larger at each
annulus, whereas the males from the l9h9 and 1950 year class

showed a more rapid growth than the females during 1951 and
1952.

Growth Increments

Table 11 and Figure 2 were obtained by determining the
length of the fish at each annulus and subtracting the
previous calculated length from.it. For example, if the

calculated lengths at each annulus were 35. 80, and 100

 

.mdaducm some pm mmmao nmoh

some you mnpmmea demeanoamo owmnmpm one o enswwh

35

mdllimeters, then the fish grew 35 millimeters to the first

annulus, A5 millimeters to the second, etc.

TABLE 11

AVERAGE GROWTH INCREMENTS (MILLIMETERS) FOR THE

DIFFERENT YEAR CLASSES OF BLUEGILLS

 

Annulus
Year Class 1 2 3 5
19t7 Growth 38.3~ 50.0 35.6 23.1 19.0
No. or fish 39 39 39 39 it
l9h8 Growth hl.8 50.3 37.1 23.6
No. of fish 187 186 186 56
1949 Growth 42.6 hl.0 27.9
No. of fish hoo too 327
1950 Growth Q6.2 N7.h
No. of fish 6 5

Table 11 shows that the 19h7, 19h8, and 1950 year class

reached their maximum growth during the second year of life,

thereafter the decline is rapid.

no fish in the samples from the l9h8 year class.

Unfortunately there were

However,

the growth of the 19h? year class closely approximates the

growth of bluegills from.Batteese Lake, Michigan, following

winterkill (Bedtman, 1950).

During the winter of l9hh.and

l9u5, a severe winterkill reduced th: population of bluegills

in Batteese Lake, subsequently, the growth of the fish

36

increased sharply immediately following the winterkill and

then slowed down.

Year

AVERAGE CALCULATED LENGTHS (MILLIMETERS) OF
BLUEGILLS FOR EACH YEAR CLASS

TABLE 12

Annulus

 

Class 1 2 3 A. El
19h7 Average
length 38.3 88.h 123.9 lh6.9 171.8
Number
of fish 39 39 39 39 h
l9h8 Average
length hl.8 92.0 129.1 151.8 --
Number
of fish 186 186 186 56 --
19h9 Average
length (4.2.6 8307 110.8 '"" --
Number
of fish hoo hoo 327 -- --
1950 Average ,
length h6.2 9h.2 -- -- --
Number
of fish 6 5 -- -- --

the l9h8 year class during the third year of life.

Figure 2 shows that the 19h? year class grew less than
Also it

was noted that the l9h9 year class, though having an initial

years growth larger than the preceding two year classes,

declined much more rapidly.

It should be noted that the 1950

 

 

.mmma ca cepomaaoo mmmao peek some you

emanate me asap one pm mnpwnea Hmpop ewmnerm m eesmam

. . Isrull. jam-WI, . urn-.11! VII-Sal“
a. . IE “t Pt.

u u

I

 

32 \\

Ag

mg

.5»

 

OOH

on."

(“SMITH“) 3mm 'IVIOI

VARIATIONS IN GROWTH RATES DUE TO THE TIME OF THE YEAR

TABLE 13

39

 

Month Year Class
19117 19118 19119 1950
Jan. Average Total
Length (111111.) 1115.8 1117.11 117.0 ~-
No. of Fish 5 17 1 --
Feb. Average Total
Length.(mm.) 1h7.5 139-0 11h.7 "
No. of Fish 2 3 ' lO --
March Average Total
Length (mm) 160.9 150.6 109.9 --
No. of Fish 10 37 39 --
April Average Total
Length (nuns) 16h03 155.1%- 12603 ‘-
No. of Fish 3 3h 15 --
May Average Total
Length (111111.) 1611.0 157.6 136.2 69
No. of Fish 7 211 22 1
June Average Total
Length (mm.) 172.0 156.5 1211.11 --
No. of Fish 9 22 18 ~-
July Average Total
Length (mm) 180.3 156.1; 1211.5 111;
No. of Fish 3 33 1115 1
.Ans. Average Total
Length (mm.) -- 150.11 121.11 121.3
No. of Fish -- 16 150 A
{TOTALS Average Total .
Length (m.) 163.2 153.5 122.3 111.3
No. of Fish 39 186 1100 6

 

 

 

L10

year class, whose growth.increments were approximately the
same at each annulus, were above the state average for age

group II at time of capture.

Calculated Growth Rates

Figure 3 shows that the average growth of the l9h8 year
class to the first annulus was greater than the 19A? year
class. They maintained this initial growth through.the for-
mation of the third annulus. The l9h9 year class, though
having an initial growth at the first annulus larger than the
previous two, grew much less from the second to the third
annulus. The 1950 year class had a calculated growth rate
slightly higher for the first two annuli. This may be due
to the type of food eaten by the various year classes.
Bennett, Thompson, and Parr (l9h0) stated that the older
bluegills were less active than the yearling fish in seeking
the animal foods.

In an effort to determine whether the growth rates of
the 19h9 and 1950 year classes were declining, the average
total lengths for August were plotted in Figure 3. Spoor
(1938) found that suckers (Catostomus commersonnii) in
.Muskellunge Lake, Wisconsin completed 92 per cent of their
growth by mid-July. Karvelis (1952) found that the growth
of the 1949 and 1950 year classes in Ford Lake would be less

than the growth of the 19117 or 19118 year class at the third

Ill

and fourth annuli. It is believed the 1950 year class does

not represent a true sample because of the small numbers.
Variation in Growth Rates

Figure 5 and Table 13 show the differences in monthly
average total lengths. From this table it is shown that the
average total length of each year class increases as the
summer progresses. The fish caught during January, February,
and March were smaller than those caught in June, July, and

 

August.
TABLE 1h
AVERAGE WEIGHT 0F BLUEGILLS AT THE TIME OF
CAPTURE IN 1952 FOR EACH YEAR CLASS
Number Wei t (Grams

T9E7"'T9HB""T9E§"-"T935 9 19 19
Jan. 5 17 1 -- 38.A h1.1 19.0 ~--
Feb. 2 3 10 -~ h2.5 33.7 18.3 ~-
March 10 37 39 -- 6h.6 50.9 16.2 --
April 3 3h 15 -- 62.3 56.7 28.h ~-
May 7 2h 22 l 70.h 59.9 Al.h. .h
June 9 22 18 -- 75.1 50.9 27.5 --
July 3 33 lhs 1 10h.3 56.2 2h.0 19.0
mfihmz._l_é .152 1 ...-.-..-:... 12.1. as 21.11

0‘

39 186 hoo 66.5 52.2 2h.3 19.7

 

 

 

 

.mmea as saneeoa eoeeoaaoo

mmeao use» more new pnmfima thop mmnmm>e the o masmwm

 

 

.qu

 

 

ow

OOH

(SFNHD) mew mew

 

 

8.! will.“ gratin... Hashim-«4‘
H “M al' n .I. a...

TABLE 15

THE RELATIONSHIP OF TOTAL LENGTH AND AVERAGE
WEIGHT T0 THE LENGTH 0F THE SCALES 45.5x

 

Class Number Average AveEige Average
Interval of Length Length of Weight
_(mm.) Fish (mm.) Scales (mm.) (grams)

81-90 3 82.3 50.7 6.7

91-100» 8 95.5 73.3 11.6
101-110 27 107.1 79.1 15.8
ill-120 178 116.5 86.5 20.2
121-130 149 124.9 92.6 24.3
131-11:0 4.1 135.0 ‘ 99.9 31.3
141-150 81 146.4 110.4. 41.9
151-160 68 155.6 116.2 51.7
161-170 51 165.7 127.6 66.1
171-180 9 173.1 127.1 74.2
181-190 2 182.5 139.0 96.0
191-200 _ 8 194.3 148.8 89.9
201-210 2 206.0 162.5 137.5
211-220 5 215.0 163.6 176.0
221-230 1 226.0 167.0 195.0

The average weight of the bluegills showed a corre-
sponding increase in length with several exceptions. The
19h7, l9h8, and l9h9 year classes showed a decrease in average
'weight during June (Table 1h). This decrease may have been

115

Figure 7 length-weight relationships of the Ford Lake
bluegills collected during 1952.

 

 

 

175

15°

135

man! '91111113)
8

75

25

 

200
w A! 160 )
120 mm (lemmas

80 Tom.

0

1+7

due to spawning activities since Karvelis (1952) reports that
the peak of the bluegill spawning had passed as of June 18,
in Ford Lake.

Statistical Test for Pepulation Differences

An effort was made to determine whether there was a
difference between the average total lengths of the 1948 and
the 1949 year classes during June. The "T" test as given by
Snedecor (1950) was 6.46 with 38 degrees of freedom. This is
statistically significant at the one per cent level. In June
the standard deviation for the 1948 year class was 11.6 milli-
meters and 19.3 millimeters for the 1949 year class. A
simdlar test was used for the March catch which was also
significant at the one per cent level.

The 1949 population had an average deviation in June from
105.1 to 143.7 millimeters, whereas the average deviation for
the 1948 year class varied from.144.9 to 168.1 millimeters.

The "T" test was used to determine whether the 1948 and
1949 year classes were essentially different populations. In
June, for example, a bluegill approximately 124.millimeters in

length probably belonged to the 1949 year class.

Condition and Length-weight Relationships

Table 15 shows that over 50 per cent of the fish caught

 

.mmmao meek nose new name one no

camp esp op esp neposm :M: mmp EH nOHpmHmsb m ensmflm

 

 

\
\
no N ~o in .e n on
C O C C C C O
H H H .4 H H .4

1103011 .10 [m7

APRIL

MARCH

JAN.

50

were from 111 to 130 millimeters in length and these weighed

about 22.3 grams.

of the sample were from the 1949 year class.

TABLE 16

VARIATION IN "K" FACTOR DUE TO THE TIME OF

THE YEAR FOR EACH YEAR CLASS

Year Class

It should also be noted that two-thirds

 

Month 1947 1948 1949 1950
January 1.25 1.30 1.19 --
February 1.48 1.40 1.22 --
March 1.54 1.48 1.23 --
April 1.40 1.49 1.44. --
May 1.59 1.50 1.67 1.21
June 1.48 1.31 1.44 --
July 1.78 1.46 1.25 1.28
August _:;_ 1:26 1. 2 1:32
TOTAL AVERAGE 1.50 1.40 1.34 1.27

length.

Weight in fishes may be considered a function of the

The values of "K" have been used to express this

relative well~being of the fishes. As fish grow older they

tend to gain proportionately more in weight than in length.

Abrupt changes occur in the condition of a fish at spawning.

Preceding spawning there is a rise in the "K" factor due to

 

 

I“
‘46

mma mzflnzd empomaaoo npmsma 2H Hm>empnfl

mmeao smashes some new Hoposm :M: mmuHe>E m mnsmflh

“33:83 Baa «Sun:

8H

9:

OOH

 

OJ

Hen

«A

n..—

a..."

“A

men

5.4.

can

a.

ROI-DYE

53

enlarging gonads. Following spawning there is a rapid
decrease in the "K" factor due to loss of weight. It has
also been noted that the "K" values increase with age because

the older fish tend to gain in weight faster than length(Hile,

1936).

TABLE 17

AVERAGE "K" FACTOR FOR EACH CLASS INTERVAL
IN LENGTH COLLECTED IN 1952

 

_glass Interval (mm.) Average "K" Factor Number of Fish
81-90 1.21 3
91-100 1.34

101-110 1.26 27
111-120 1.30 178
121-130 1.24 149
131-140 1.27 41
141-150 1.37 81
151-160 1.35 68
161-170 1.45 51
171-180 1.45 9
181-190 1.61 2
191-200 1.23 8
201-210 1.58 2
211-220 1.77 5
221-230 1.69 l

54

Table 16 shows that the "K" factor is greater for the
older age groups although the value for each year class is
less than the Michigan average. Each year class, except 1950,
showed a decline in condition during June, probably due to
spawning activities. The 1949 year class continued to decline
in condition in July, possibly meaning that spawning took
place in July. Bluegills of the 1949 year class averaged 4.9
inches in length during June and July. The females outnumbered
the males 2%:1 in the collections of this period. It is
believed that the 1948 year class increased in condition in
July because of an increase in weight, whereas the average
length.did not increase.

Table 17 shows that the average "K" factor for over
fifty per cent of the bluegills was approximately 1.28.

Figure 9 shows a drop in the "K" factor for those fish in the
191-200 millimeter group. AlthOugh the sample was taken
throughout the collection period, seven out of the eight fish
in this grouppwere females. It is believed that this sample

was not representative of the group.

Time of Annulus Formation

An effort was made to determine the relationship of the
length and the weight to the time of annulus formation. Table
18 shows that there was not much difference in the average

weight at each collection date. In most cases, however, it

5
mm
2
ma
.Ho
>
.HwM
E
on
.H
do
pm
m
p4

\w

.mm
ma
on
w
.8
ma
:
H
o
pm
0
soap
oo
Ha
oo
o
5
an
9
deep
0
m

\H.

ad a O
.D
a
w
0
5.9
mm
db
0
Q
m
HH
Hm
0.9
H H
mm
M.
H a pd H
00
.Hm
Q
m
S
H.
OH
0H
3w
rm

57

was the longer fish, during each collection period, that had
formed the annulus. Table 19 shows that for three collection
periods out of four, the average weight of the bluegills
having the annulus formed was larger than those not having

the 1952 annulus formed.

TABLE 18

THE RELATIOHSHIP 0F LENGTH AND WEIGHT TO THE TIME OF THE
1952 ANNULUS FORMATION FOR THE 19u8 YEAR CLASS

 

 

Average Average Per Cent No.

Weight (gramsl Length.(mm.) with Fish

Collection Without With Without ‘With Annulus Exam-

Date Annulus Annulus Annulus Annulus IFonned _;iged
h/23-E/27 56.0 62.2 153.0 160.7 20.7 29
5/1-5/16 49.6 9u.8 1h8.8 183.3 35.0 1h
5/17-6/1 5h.5 50.0 15u.5 155.0 11.1 9
6/2-6/17 56.0 53.5 15h.o 151.5 50.0 a
6/18-7/2 h9-5 51.8 156.6 160.3 22.2 18
7/3-7/18 L2.5 u1.0 1h5.5 150.0 66.7 6
7/19-8/2 35.6 63.5 1A6.2 159.5 72.7 33
8/3-8/1h- -- uu.3 -- 153.3 100 10

A comparison of Table 18 and Table 19 shows that the

majority of the l9u9 year class formed the annulus sooner

than the l9h8 year class.

increased growth of younger age groups.

This is believed to be due to the

pdfipmmviar esp pm wopnooma fluflmsxonfleev

mmjpstmazmp Ham smflpnn:.unmnm>m mQB AH mnzmflh

60

TABLE 19

THE RELATIONSHIP OF LENGTH AND WEIGHT TO THE TIME OF THE
1952 ANNULUS FORMATION FOR THE 19h9 YEAR GLASS

Average Average Per Cent No.
Weight (gransl Length 1mm.) with Fish
Collection Without With Without With Annulus Examr
Date Annulus Annulus Annulus Annulus Formed ined

h/23-h/30 26.5 -- 126.h -- 0.0 11
5/1-5/16 82.8 56.7 162.3 153.4 42.9 7
5/17-6/1 18.7 37.0 115.0 135.1 53.3 15
6/2-6/17 -- 50.0 -- 155.0 100 l

6/18-7/2 18.0 27.3 110.0 12h.3 88.8 17
7/3-7/18 17.0 25.1 llh.0 123.0 95.0 20
7/19-8/2 -- 23.9 -- 123.3 100 180
8/3-8/lh -- 23.9 -- 122.h 100 95

Figure 10 compares the time of annulus formation for all
fish collected in 1951 and 1952. Table 20 shows that approxi-
mately 50% of the fish collected in 1952 had formed the
annulus before June 23. Karvelis (1952), working on Ford
Lake in 1951, found that 52.h per cent of the fish had formed
the annulus by June h, 1951. It should also be noted (Figure
10) that the average monthly air temperature in the vicinity
of Ford Lake in May, 1951, was 5.3 degrees above that in
May, 1952. This early increase in temperature for 1951 may
partly account for the rapid increase in annulus formation

in early June. The average monthly air temperature during

61

TABLE 20

PERCENTAGE OF BLUEGILLS HAVING FORMED THE ANNULUS
BY EACH COLLECTION DATE IN 1952

Percentage Having

 

Date #fif Number EXamined Annulus Formed
4/23 '38 15.8
M27 Ll- 25.0
5/2 3 0.0
S/LL 16 31.3
5/9 10 , h0.0
5/22 19 MA»
5/25 6 33.3
6/h 5 hO-O
6/19 28 32.1
6/23 16 81.3
7/12 9 88.9
7/lh 16 87.5
7/21 2 100
7/26 155 98.1

June was higher in 1952, which.may possibly account for the
rapid increase in annulus formation from June 19 to June 23.
The average air temperature was computed for the period
preceding each collection date in 1951 and 1952. The only
similarity between 1952 and 1951 was a period of average air

temperature of 55 degrees Fahrenheit for a period of

62

approximately 12 days preceding the June h, 1952 collection
period. By this time ho per cent of the bluegills had

formed an annulus. For ten days preceding the May 19, 1951
collection, the average air temperature was also 55 degrees
Fahrenheit and hl.6 per cent of the bluegills had formed an

annulus.

TABLE 21

AVERAGE MONTHLY.AIR TEMPERATURE (FAHRENHEIT) AT THE
VANDERBILT TROUT RESEARCH STATION

 

 

Year Month
April May June Jugy August
1951 h2.0 56.3 60.6 65.2 61.8

1952 h3.u. 51.0 63.5 68.6 63.8

DISCUSSION

Ford Lake was one of the lakes that became part of a
fish.management plan to expand trout production in Michigan.
This planning began in 1931 and extends through the present.

In twenty years Ford Lake has been stocked with brook,
brown, and rainbow trout, and Montana grayling. The lake
has been poisoned three times, the last in August, 1952.
This poisoning offered an opportunity to compare the standing
crop with that found following previous poisonings.

Data on the trap nets used in Ford Lake were suitable
for an analysis of variance test to determine whether small
differences in construction would alter the catch. The test
indicated that the funnel depth influenced the number of
bluegills caught.

Karvelis (1952) found insects to be the predominant
food of the brook trout in Ford Lake. He also found that
over half the food of the larger bluegills was insects.

This competition for the food utilized by trout was evident
by the relatively few numbers and low weight of brook trout
during poisoning. At least 29,000 fingerling brook trout

had been planted in Ford Lake since 19h? but only 621 were
recovered following poisoning in 1952. In 19h9, 1950, and
1951, a total of 197 brook trout were caught by anglers.

This relatively low return seems to indicate that brook trout

cannot survive in competition with the bluegill.

61+

aAlthough a few small bluegills were found in trout
stomachs, the bluegills were not limited in pepulation by
predation. Essentially the main species in Ford Lake was
the bluegill, limited in growth and population by food and
natural mortality. It was found that the average bluegill
from the l9h8 brood reached the legal length of 6 inches
in four years. The bluegills from.the 19h? and 19h9 year
classes averaged respectively, 6.h and h.8 inches in 1952.

It was found that the bluegills grew faster during the
first year or two of life, but the growth rate declined
rapidly in later years.

The biOlogical pattern of Ford Lake indicates several
possibilities or combination of possibilities. Sexually
mature or near mature bluegills survived the l9h6 poisoning
and Spawned in 19h? or later years. This would probably
mean a very large population survival of bluegills from the
19k? year class. It is also possible that some "young of the
year" fish survived the poisoning and spawned in 1949, Which
may have resulted in the very large sample of the l9h9 year
class. Morgan (1951) proposed that the date of spawning,
whether it was the third or fourth summer, depended on the
hatching date being early or late in the summer.

The average total lengths of age groups 3, h, and S
were below the Michigan average total length at time of

capture. The average weight of the bluegills recovered from

65

poisoning in 1952 was little more than 0.3 of an ounce larger
than those recovered in 1946. It is believed, therefore, that
the period of time from the last poisoning was adequate to
produce stunting tendencies in an almost pure bluegill

pOpulation.

l.

2.

3.

10.

ll.

66

SUMMARY

The known recovery rate at time of poisoning of bluegills
marked before poisoning was slightly less than 75 per cent.
Bluegills constituted 80 per cent of the total weight and
95 per cent of the number of fish recovered.

The average weight of the brook trout was slightly more
than half an ounce.

The funnel depth of a trap not influenced the yield of
bluegills.

The wire mesh on trap nets apparently was a selective
factor in the size of catch.

The sex ratio revealed that the majority of the younger
bluegills were females while the older ones were pre-
dominantly males.

The average calculated total length of the l9h8 year
class showed that the female was larger than the male at
each annulus formation.

The growth rates of the l9h9 and 1950 year classes were ”
declining following formation of the first annulus.

Over 50 per cent of the bluegills caught were from 111

to 130 millimeters in length.

During each collection period it was the larger and
heavier bluegill that had formed the 1952 annulus.

The l9h9 year class formed the 1952 annulus earlier

than the l9h8 year class.

67

LITERATURE CITED

Ball, Robert C.
l9h5 A summary of experiments in Michigan lakes on the

elimination of fish pOpulations with rotenone,
lain-1952. Trans. Am. Fish. Soc., l9k5, 75: 139-

l9h8 Recovery of marked fish following a second poisoning
of the population in Ford Lake Michigan. Trans.
Am. Fish. Soc., 1945, 75: 36- .

Beckman, William C.
l9k8 The length-weight relationship, factors for con-
versions between standard and total lengths, and

coefficients of condition for seven Michigan fishes.
Trans. Am. Fish. Soc., l9h5, 75: 237-256.

l9h9 The rate of growth and sex ratio of seven Michigan
fishes. Trans. Am. Fish. Soc., 19A6, 76: 63-81.

1950 Changes in growth rates of fishes following reduc-

tion in pOpulation densities by winterkill. Trans.
Am. Fish. Soc., 1948, 78: 82-90.

Balding, David.

l9h8 Water temperature and fish life. Trans Am. Fish.
Soc., 1928, 58: 98-105.

Bennett, George W., D. H. Thompson, and S. A. Parr.
l9k0 A second year of fisheries investigation at Fork

Lake, 1939. Illinois Natural History Survey Lake
Management Reports A, 1-24.

wCarlander, Kenneth D., and L. L. Smith Jr.

19hh Some uses of nomographs in fish growth studies.
Copeia, No. 3: 157-162.

Chanley, Paul

1950 Attainment of sexual maturity and growth studies of

the bluegill of Buckeye Lake. Presented 12th Mid-
west Wildlife Conference, Dec., 1950.

68

Creaser, Charles W.

1926 The structure and growth of the scales of fishes in
relation to the interpretation of their life history
with special reference to the sunfish (Eupomotis
gibbosus). Misc. Pub, No. 1?, Univ. of MlChigan,
Museum of Zoology.

Eschmeyer, R. William.
1937 EXperimental management of a group of small Michigan
lakes. Trans. Am. Fish. Soc., 1937, 67: 120-129.

Hansen, Donald F.
1951 Biology of the white crappie in Illinois. Bull.
of the Illinois Natural History Survey, Vol. 25,
Article A: 211-265.

Hile, Ralph.

1936 Age and growth of the cisco, (Leucichthys artedi)
(Le Sueur), in the lakes of the northeastern highs
lands, Wisconsin. Bull. U. S. Bur. Fish., k8:
211-317 0

Hubbs, Carl L., and G. P. COOper.
1935 Age and growth of the long-eared and the green sun-
fishes in Michigan. Pap. Mich. Acad. Sci. Arts,
and Lett., 193R, 20: 669-696.

Karvelis, Ernest Genrick.
1952 Growth characteristics of a bluegill pOpulation in
a Michigan trout lake. Unpublished M. S. thesis.
Michigan State College, 1952, 72 numb. leaves,
6 figures.

Krumholz, Louis A.
l9kh A check on the fin-clipping method for estimating
fish populations. Pap. Mich. Acad. Sci. Arts,
and Lett., l9h3, 29: 281-291.

Lagler, Karl F.
1952 Freshwater fishery biology. Wm. C. Brown Co.,
First Ed., Dubuque, Iowa, 99-lhl.

Leonard, Justin W.
1939 Feeding habits of the Montana grayling (Thymalus
montanus Milner) in Ford Lake, Michigan. Trans.
Am. Fish. Soc., 1938, 68: 188-195.

V

69

Further observations on the feeding habits of the
Montana grayling (Thymallus montanus) and the
bluegill (L_pomis macrochirugg in Ford Lake, Michi-
gan. Trans. Am. Fish. Soc., 9: 2kh-256 .

Morgan, George D.

1951

Phenicie,
1950

The life history of the bluegill sunfish, Lepomis
macrochirus, of Buckeye Lake, (Ohio). Denison
University Bull., Journal of the Scientific Labora-
tories, 1951, Vol. h2, No. R.

 

Charles K., and C. G. BishOp.
Condition factor alinement charts. Prog. Fish.
Cult., 12(3): 163-168.

Potter, George.

1925

Scales of the bluegill, (Lepomis pallidus)(Mitchell).
Trans. Am. Micros., Vol. XLIV, No. 1: 31-37.

Schneider, Ivan F.

1939

Snedecor,

1950

Otsego County preliminary natural land type legend.
Agr. Exp. Station. Michigan State College Con-
servation Institute and Soil Science Section.
Revised Sept. l9h9. Mimeographed.

George W.
Statistical methods. Iowa State College Press,
Ames, Iowa, 21h-252.

Spoor, William A.

1938

1929

19h?

Age and rowth of the sucker, (Catostomus corner-
sonnii) %Lacepede), in Muskellunge Lake. Wisconsin
Academy of Sciences, Arts, and Letters, Vol. XXXI:

#57- 505

Van Oosten, John.

Life history of the lake herring (Leucichth ye
artedi) (Le Sueur) of Lake Huron as revealed by
its scales with a critique on the scale method.
Bull. U. S. Bur. Fish. Ah: 2 65-uh.8. kg. -

Williamson, Lyman 0., and John Brasch. \

Experimental poisoning of Day Lake,L Vilas County,
Wisconsin. Section of Fishery Biology, Investi-
gational Report No. 516, Wisc. Conserv. Dept.,

Madison, Wisc., 1- 3h.

‘—

ROOM USE ONLY

0611636

.4- 5.” “ ':
|.‘._. - ' N: I 1

ROOM USE ONLY

 

 

 

 

 

 

 

HICHIGQN STATE UNIV. LIBRQRIES

31293104909555