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AGE AND GROWTH OF THE COMMON WHITEFISH.
mflEGBNUS CLUPEAFORM'IS (MITCHiLL), 0F NORTHERN [ME
MICHIGAN AND BAY DE NOD AREAS

Thesis for the Degree: of M. S.
MICHIGAN STAIE UNIVER§ITY
GLENN R‘ PiEHLER
1967

 

 

E W“

 

 

 

ABSTRACT

AGE AND GROWTH OF THE COMMON WHITEFISH:
COREGONUS CLUPEAFORMIS (MITCHILL),
OF NORTHERN LAKE MICHIGAN AND
BAY DE NOC AREAS

by Glenn R. Piehler

This study was done in order to update age and growth
data on lake whitefish (Q. clupeaformis) as they relate to
fisheries management.

Scale samples and certain morphometric data on white-
fish were collected during 1965 and 1966 by members of the
Fish Division, Michigan Department of Conservation, for
portions of northern Lake Michigan and the Bay de Noc area.

The data indicate a dominance of the commercial
fishery by age groups II and III. Currently, the 1964 year
class appears to be the most important in the Bay de Noc
area, while the 1963 year class is generally the most abundant
in northern Lake Michigan. An exception to this is the 1965
Hog Island sample, which is dominated by fish of the 1962
year class. Some possible causes of year-class dominance
are discussed.

Fish taken in the Bay de Noc area and west of Seul
Choix Point have higher absolute sizes at each age than those

east of Seul Choix Point and SSE of Naubinway.

Glenn R. Piehler

Condition factors and length-weight relationships
are highest for fish taken just west of Seul Choix Point, and
lowest for Bay de Noc Whitefish.

Data for this study indicate an earlier maturity of
males than females, this occurring approximately simultaneous-
ly with the attainment of legal size (17 inches). Non-
parametric statistical tests show no differences between
males and females with respect to growth in length. Mature
females of a given age tended to be slightly heavierthan

their male counterparts.

AGE AND GROWTH OF THE COMMON WHITEFISH,

COREGONUS CLUPEAFORMIS (MITCHILL),

 

OF NORTHERN LAKE MICHIGAN AND

BAY DE NOC AREAS

BY

Glenn R. Piehler

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

MASTER OF SCIENCE

Department of Fisheries and Wildlife

1967

ACKNOWLEDGEMENTS

This study was made possible through the fine coopera-
tion of Myrl Keller and other membens of the Fish Division,
Michigan Department of Conservation.

I would like to extend my sincere appreciation and
gratitude to Doctors E. W. Roelofs, P. I. Tack,and W. E.
Cooper, for their many helpful suggestions throughout this
study.

Thanks go also to my wife Karen for her patience and

encouragement during this entire period.

CONTENTS

INTRODUCTION . . . . . . . . . . . . . .
MATERIALS AND METHODS . . . . . . . .
Historical Background
Sampling Data
Growth Analyses
AGE COMPOSITION . . . . . . . . . . . .

Collections from the Hog Island Area

Collections from the General Area South and

Southeast of Naubinway
Collections West of Seul Choix Point
Collections East of Seul Choix Point
Collections from Bay de Noc Areas
Miscellaneous Collections

Sand Bay of Beaver Island
1/2 Mile SSE of Whiskey Island
1/2 Mile NE of North Fox Island
Discussion of Age Composition
LENGTH-FREQUENCY DISTRIBUTIONS . . . . .
GROWTH IN LENGTH . . . . . . . . . . . .

LENGTH-WEIGHT RELATIONSHIP AND CONDITION

COMPARISON OF THE SEXES . . . . . . . .
SUMMARY AND CONCLUSIONS . . . . . . . .
.LITERATURE CITED . . . . . . . . . . . .
APPENDICES . . . . . . . . . . . . . .

ii

Page

15
21
22
24
24
25
25
26
26
26
27
33
37
45
49
52
56

59

Table

7a.

7b.

.10.

LIST OF TABLES

Lake Whitefish production (in pounds) by

statistical districts MMrl,

MM-3 in the commercial fisheries of the

State of Michigan waters of Lake Michigan
and Green Bay,

Particular information as to date,

1942-1965 . . . . . . .

locality,

gear, and depth (where reported) for
the samples taken . . . . . . . . . . .

Age composition of the different samples

Salient features

of the analysis of variance

on spring precipitation for the years

1960 to 1964

Salient features
on length at
year class

Salient features
on length at
year class

of the analysis of variance
age 2 for fish of the 1963

of the analysis of variance
age 2 for fish of the 1964

Analysis of variance on July-August precipi-
tation for 1960-1965 as reported by two

stations each for Bay de Noc and northern

Lake Michigan . . . . . . . . . . . . .

Table of deviations (observed — eXpected)
associated with the analysis of variance
given in Table 7a. . . . . . . . . . .

Length at each age for Whitefish of this,
and other studies . . . . . . . . . . .

Ninety-five percent confidence intervals
around "Y" (weight) for the mean (X)

and two end-point values of "X"

(length)

for each length-weight relationship . .

Condition factors for Bay de Nbc and Lake
Michigan Whitefish . . . . . . . . . .

iii

Page

12

17

32

39

40

43

43

44

47

48

Table Page

11. Comparison of males and females with regard
to percent maturity in the legal and
sublegal portions of the commercial catch . 50

12. Comparison of Whitefish sexes with respect

to average length, average weight, percent
mature, and condition . . . . . . . . . . . 50

iv

LIST OF FIGURES
Figure Page
1. Commercial fish production in State of
Michigan waters of Lake Michigan,

1942-1965 0 o o o o o o o o 0 Q o o o o o o 5

2. Statistical districts of Lake Michigan and
Green Bay . . . . . . . . . . . . . . . . . 7

3. Areas from which samples were taken . . . . . . 11

4. Summary of Whitefish length-frequency
distributions . . . . . . . . . . . . . . . 36

5. Comparative total lengths at each age . . . . . 41

6. Calculated logarithmic length-weight
relationships . . . . . . . . . . . . . . . 46

Appendix

Hgomqmmbwmw

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Hra
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1.14
1.15
1.16.
1.17
.l.18
1.19
1.20

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when)
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|-'

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NNNNNNNNNNNNNN N

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b

2.15
'2.16
2.17

LIST OF APPENDICES

LENGTH-FREQUENCY DISTRIBUTIONS . . . . .

Oct.,

April,

Oct.,
May,

June,
Oct.,
Oct.,
Oct.,
Oct.,
Oct.,
Oct.,
Oct.,
Oct.,
June,
Oct.,
Oct.,
Oct.,
Feb.,
Oct.,
Oct.,
July,
Ju1y,
July,

1966:

1965 Hog Island .
1966 Hog Island

1965 between Naubinway and Hog Is.

1966, Pelkie Reef
24,
28,
24,
24, 2 miles
6 miles
2 miles
of Seul
of Seul

of Seul

1966,
28, 1966,
28, 1966,
1965 east
1965 west
1966 west
26, 1966,
26, 1966,
26, 1966,

25,
25,

1966:

1966, 3 miles

1966 Sand Bay of Beaver Island .
1966, Whiskey Island . . . . . .
Island . . . . . .

1966, Nbrth Fox

10 miles South of Naubinway .

1966 Pelkie Reef . . . . . . .
1966, 2-5 miles E. of Naubinway
1966 Biddle Point off Naubinway

SSW of Epoufette
SW of Epoufette .
S. of Epoufette .
Choix Point . .
Choix Point . .
Choix Point . . .

1 mile SW of Port Inland
1 mile SW of Port Inland
1 mile SE of Port Inland
1965 Little Bay de Noc . . . . .
Blacksnake HDmp . . . .

NW of Fairport

CALCULATED GROWTH IN LENGTH . . . . . . .

Oct.,

April,
Oct., 1965, between Naubinway and
1966.

May,

JUne,
Oct.,
Oct.,
Oct.,
Oct.,
Oct.,
Oct.,
Oct.,
Oct.,
June,
Oct.,
Oct.,
Oct.,

1965 Hog Island .
1966, Hog Island

1966, Pelkie Reef
24, 1966,
28, 1966,
24, 1966,
24, 1966,
28, 1966,
28, 1966,
8, 1965,

8, 1965,

1966:
26,
26,
26,

2 miles
6 miles
2 miles

1966:
1966:
1966a

vi

10 miles south of Naubinway

east of Seul Choix Point
west of Seul Choix Point
west of Seul Choix Point .
1 mile SW of Port Inland
1 mile SW of Port Inland
1 mile SE of Port Inland

Hog Is

Pelkie Reef . . . . . . .
2-5 mileer. of Naubinway .
Biddle Point off Naubinway.

SSW of Epoufette
SW of Epoufette
S. of Epoufette

Page

60

61
62
63
64
65
66

68
69
7O
71
72
73
74
75
76
77
78
79
80
81
81
82

83

84
84
85
85
86
86
87
87
88
88
89
89
9O
90
91
91
92

Appendix

2.18
2.19
2.20
2.21
2.22
2.23

Feb.,
Oct.,
OCtol
July,
July,
July,

1965, Little Bay de Nbc . . .
25, 1966, Blacksnake Hump . . . .
25, 1966, 3 miles NW of Fairport

1966:

Nbrth Fox Island . . . .

1966, Whiskey Island . . .

1966,

Sand Bay of Beaver Island

vii

Table

92

94
94

INTRODUCTION

The common Whitefish, Coregonus clupeaformis
(Mitchill), is the most widely known and economically per-
haps the most important Species of the coregonoid group.
Its range extends throughout the Great Lakes region and
central and eastern Canada. Koelz (1929), gives a general
account of the distribution and natural history of coregonoid
species in the Great Lakes.

The relative economic importance of the lake
whitefish to the commercialfilher’iefl of Lake Michigan
and adjacent waters of Green Bay has in the past been
subject to considerable fluctuation. A substantial treat-
ment on the economic aspects of the Great Lakes fisheries
has been presented by Frick (1965). The comparably high
market price drawn by this species makes it worthy of
study.

There is available a relatively large volume of
literature concerning age and growth of whitefish. Several
of the more extensive investigations on the Great Lakes
whitefish include the following: van Oosten (1939),

Lake Huron: van Oosten and Hike (1949), Lake Erie;
Dryer (1963, 1964), Lake Superior; Caraway (1951), Barker
(1953), Roelofs (1958), and Mraz (1964), Lake Michigan

and/or Green Bay areas. As far as the author can ascertain

there have been no major investigations dealing with growth
of Lake Michigan whitefish within the last decade. Roelofs
(op. cit) and Mraz (op. cit.) based their papers upon data

collected during the late 1940's and early 1950's.

The present study was conducted therefore to update
information concerning age and growth of Q, clupeaformis.
The significance of this type of knowledge in fisheries
management has been reviewed by Lagler (1956). It is
hoped that this report will stimulate further research on

g, clupeaformis in order that this species may assume a role

 

of integral importance in Michigan fisheries.

MATERIALS AND METHODS

HistoricaliBackground

Figures compiled by the Michigan Department of
Conservation (Keller, pers. comm.) indicate that for the
period 1942-1965 the lake whitefish made up from 0.10
percent (1957) to 38.44 percent (1947) of the total commer-
cial catch in State of Michigan waters of Lake Michigan.
Data presented in Figure 1 illustrate the yearly fluctua-
tions in commercial production for the period aforementioned.

The Great Lakes and related waters have been sub-
divided into statistical districts (see Smith, et. a1. 1961
for a concise review of this subject). Districts for Lake
Michigan and Green Bay are shown in Figure 2. Data on white—
fish production have been obtained from the U.S. Bureau of
Commercial Fisheries at Ann Arbor (Buettner, pers. comm.)
for those districts pertaining to this study (i.e., MM-l,
MMrZ, and MMr3), and are given in Table 1. Analysis of the
data has shown that during the years 1942-1946 district
MM93 accounted for 73.6 percent of the total whitefish pro-
duction of northern Lake Michigan and Green Bay. District
NmFl produced 75.6 percent of the total catch during 1947-
1954, while district MM~3 took the lead again for the
period 1955-1965 (71.5 percent accounted for). District
MMr2 was a consistently poor producer, taking only 4.5, 0.4,

3

Figure 1. Commercial fish production in State of Michigan
waters of Lake Michigan, 1942-1965.

Total production; __ _ Whitefish production
..... Production of all other Species.

m4m> .. 250:

000. N00. ¢om_ .00. otm. o¢m_ NVQ.
b ill-I b b + bl # + L D b P b P F -

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- n p n p P b p F b p h b p P P h b p p p 0000—

SGNnOd :IO SGNVSflOHJ.

Figure 2. Statistical districts of Lake Michigan and Green
Bay (from Hile, 1962).

 

Gulliver Lake

M ck' ac
Bridge
MANISTIQUE

    

 

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PI. ' D
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— — — INTERSTATE BOUNDARY
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Ind 150316;: ' Statute Miles

 

 

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FIGUI E 2.

Table 1. Lake whitefish production (in pounds) by statistical
districts MMLl, MMLZ, and MML3 in the commercial
fisheries of the State of Michigan waters of Lake
Michigan and Green Bay, 1942-1965.

 

 

YEar MMrl MM—2 MNFB
1942 92:456 60:494 715}986
1943 141,222 81,605 774,255
1944 232,494 48,062 806,364
1945 233,787 31,415 721,868
1946 513,782 26,993 1,050,434
1947 2,427,087 32p020 1,400,664
1948 3,066,290 12,302 1,070,298
1949 2,262,963 9,302 537,269
1950 1,493,564 5,873 218,205
1951 441,042 .228 167,730
1952 933,047 1,188 212,702
1953 635,769 --- 98,152
1954 501,904 5,872 16,490
1955 69,771 4,093 82,797
1956 11,284 --- 15,326
1957 3,767 --- 5,975
1958 2,057 6,423 30,354
1959 505 155 10,356
1960 8,424 7,879 11,186
1961 48,793 10,480 103,301
1962 34,179 14,789 114,901
1963 73,636 11,275 146,322
1964 81,478 15,142 453,292
1965 117,560 96,785 376,463

 

and 7.7 percent, respectively, for the above periods.

The catastrophic decline in abundance of white-
fish in Lake Nuchigan following the peak production of
1948 is presumably attributable to predation by the sea
lamprey. Petromyzon marinus Linnaeus, although documentation
on this subject Specifically in reference to the whitefish
has been scarce compared to that for the lake trout
(Salvelinus namaycush). Studies by Caraway (op. cit.)

on a total of 684 whitefish taken from areas of northern

Lake Michigan and Big Bay de Noc showed an average of 7.89
percent exhibiting lamprey scars.

The sea lamprey, however,,may not be entirely
responsible for the reduction of whitefish stocks in
Lake Michigan. Erick (op. cit.) makes reference to the
gradual warming of some of the Great Lakes and the in—
creasing fertilization by commercial fertilizers leached
from the soil, as environmental factors adversely affecting
the populations of higher-value species (lake trout, whitefish,
etc.), and promoting the growth of the less-valuable but more
resistant species such as chubs (Coregonus Spp.), yellow
perch (§g£g§_flavescens), smelt (Osmerus mordax), and
alewife (Alosa pseudoharengus). It has been reported
(Tody and Tanner, 1966) that the alewife, a competitor of
the whitefish in feeding habits, may now comprise 90 percent
or more of the total fish population by weight in Lake
Michigan.

More recently, however, whitefish production seems
to be on the upswing, reaching 1.2 million pounds in 1966

(Borgeson and Tody, 1967).

Sampling7Data

The present study is based on 1,408 whitefish cap-
tured within the areas shown in Figure 3 by certain of the
commercial fishing vessels operating on northern Lake
Michigan and Green Bay. Information as to specific date,

locality, and gear is given in Table 2. Fishing depth is

Figure 3. Areas from which samples were taken.

Key:

 

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maonumm him mum: many nmmflnoflz axon .mmscansmz mmo .um mappflm em .uuo
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II mum: HHHm :~\Hlv pamHmH uw>mmm mo >mm pcmm ma aapb
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u: Ana: nnna =m\nuv camnnasz axmn .ooanan mom an.uoa
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13

included where reported. Samples of the total catch from each
area were taken by fishery biologists affiliated with the
Michigan Department of Conservation. Total length (inches)
and weight (pounds) were recorded, and the fish were sexed
when not sold "in the round." Scale samples were taken

from each fish, but apparently many of these samples did not

include ”key scales" (see Rounsefell and Everhart, 1953).

Growth Analyses

The method used in age determinations was that of
scale interpretation. The validity of the Scale method for
determining the age of whitefish has been demonstrated by
Van Oosten (1923). Scale impressions were made in cellulose
acetate (Smith, 1954) and magnified approximately 22
diameters by means of a microprojector. Examination of
several scales per sample were made in order to select the
one most representative and easily interpreted for each
fish. Information on approximately two percent of the
total number of fish was discarded due to complete regeneration
or extreme difficulty in interpretation. From the magnified
impressions of the chosen scales, positions of radii and annuli
were marked on graduated scale cards from focal midpoint
to anterior margin as outlined by Caraway (op. cit.). The
scales were examined carefully, and consultation was obtained
where difficulty was encountered in distinguishing true annuli
from false cheeks. "Crossing-over" of circuli in the lateral

scale fields was used as a criterion for identification of

14

true annuli. A nomograph was employed for back-calculations
of length at each annulus. Length-weight relationships and
condition factors have been determined empirically from data
recorded by the collectors. Growth data have been analyzed
statistically in order to determine the significance of
growth differences within and among sampling areas. Such
differences, if significant, may be indicative of descrete
subpopulations within the total body of Lake Muchigan white-
fish. The one (1) percent level of significance was used
throughout these and any other associated analyses in this

paper.

AGE COMPOSITION

In general, data for this study were collected at
the docks, thereby representing mainly the legal portion
(fish larger than 17 inches) of the catch. HoWever, several
samples were taken on board the commercial vessels and do
include some sub-legal fish.

Most of the samples thus made available to the
author contained only one or two age groups, indicating a
complete dominance of the fishery by these few year classes
and the virtual absence of all others. A similar situation
has been reported by Mraz (op. cit.), who mentions the fact
that dominance of samples by one age group is common among
coregonines. Indeed, this dominance has been very well
documented, and attempts have been made to ascribe the
phenomenon to various meteorological conditions including
temperature, wind, turbidity, and so forth.

The extent to which certain age groups are exploited
in the commercial fishery is influenced considerably by
gear selectivity. Thus, 4-1/2 inch gill nets would tend
to capture fish of similar size, rejecting most of the
very large fish and permitting the majority of smaller fish
to pass freely through the mesh. Hence, the very young and
the very old fish would tend to be excluded from the samples,

the catch therefore being represented mainly by the few

15

16

intermediate age groups within the population. The tables in
Appendix 1 do not show any substantial trend with respect

to differential exploitation of age groups by the several types
of gear.

Specific age composition of the individual samples
will be considered at this point. A partial summary of the
information discussed below is given in Table 3. The col-
lections from Little Bay de NOC have been combined here due
to the small sizes of the individual samples.

Age determinations in this study assumed the fol—
lowing criterion: a fish whose scale showed one annulus
belonged to age group I; a specimen with two annuli in
evidence belonged to age group II, and so on. Several of
the scales examined here exhibited distinct "checks" unusually
near to the focus, which superficially resembled annuli.
Closer inSpection revealed, however, that these checks almost
invariably occurred only on one side of the scale rather than
more or less circumscribing an area around the focus. This,
along with the fact that the marks were not continuous with-
in the same samples, gave reason for disregarding them as true
annuli. In view of the fact that whitefish eggs develop
during the winter and hatch in early spring (Eddy, 1957),
the possibility exists that scales marked in this fashion
represent earlier-hatching individuals within the population.
Conceivably then, these checks could have occurred in the
transition from late winter to spring. This point is

mentioned merely as one possibility for the slight growth

17

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II II ma NFL

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. .mmmucmouwm
qu85:
Anna: amuuv
aaam anxnwm no am manna «\nun o» «\nll m acpo
mmmucmouwm
Hanan:
Lana: nawm

 

 

 

 

 

 

 

 

 

 

 

=~\4I¢v >m3cwnsmz mo m mmane OH I moon .ma an:
mmmuamouma
Honfiss
Amuse

 

 

.an aoMlaa sazannoaz I moan .m .umm
"sasaammaz no mm sea a aaonwaannoo

many mecv

 

mmmuumuumm
HwQESS
Aaaao nnnmd acananxaom u moon .anlnnmmm.
mmmucmoumm
Maniac
36 RENE aoanan mom . maoln 1a Mono.

Amman pcmamH mom scum acomuomaaou

 

 

 

 

 

 

 

 

.H

 

H> > >H , HHH

macaw mam

m>ma 002 on ham MHUDHA mo mcowuomaaoo

HH

.mmamEmn uc0H0NMH© any mo coauflaomfiou 00¢

Hmuou mo mmmusouumm

0cm .Hmam .uwnfiss .wumc .mamm mcwuuaaaoo

.omcflnfioo swan

 

 

om GHQMB

18

II 0.m¢
II 0v

II m.¢®
II mw

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o¢

m.mm
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mg

5.00
on
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m.hh_
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ma

ammucmoumm
Manes:

Amps: vasomv

 

USMHSH uuom mo 3m mafia H I mmma .mN
ammunwoumm
Manes:

.uUO

 

Anna: vasomv

 

.uo xnono nsam no 3.anns «\n I moon .n acne

ammucmohmm
Hanan:

 

Amumc vasoav

 

.um xflonu Hamm m0 u made a I mood .m
ammusmoumm

Hanan:

.uUO

 

Lava: nnnmv .ao xnono

 

Hsmw mo 3 mmHflE VA OH H I moma .m

.uUO

 

"unflom Macao Adam canons mGOHuomHHOU .m

mmmucmouwm
Hanan:

 

Anna: assay

 

wuummsomm mo m mmHHE N I mmma .mN
mmmucwoumm
Hanan:

.000

 

Awnmcxmmnwv

 

wuummsomm mo 3m mmHHE m I mmma .mm
mmmucmuuom

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.d amwamoomm no 3mm aanmaIm I moon .am

.UUO

 

.pmsaflucoo .N

 

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>

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Hmuou mo ammusmoumm

macaw am< new .Hmwm .Hwnfisc .mumo .mwum mcwuumaaoo

 

lilhlllh W

 

 

.wassamdou .m magma

19

0.0m II 0.0m II II II II mmmuswouwm
H II H II II II II H0955:
Aanac nnnmu scanan
Mom nunoz mo m2 mHHE N\H I mmma .MH >th
umconuoannoo asoanmnnaomnz .m

 

 

 

II II II II m.¢ ¢.mm II ammusmonmm
II II II II o omH II nmnsss
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on anomnnaa.no zz mansaIm I moan .mm .nao
II II II II N.m maam II ammucwunmm
II II II II mI mm II Hanan:
Anus: ccsomu 002 00
>am mam .stm axmcmxomam I moma .mm .900
II II II II II m.¢ m.mm mmmusmonmm
II II II II II n_ am Hanan:
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"mmmnm 002 an wwm CH mcofluoaammw .w

II II II as.m ao.am a~.oa II amanoaanao
II II II a mm mm II nansnc
Amuwc nanny
acanan anon no ma anne n I moan .am .nao
II II II mm.a Na.oo mm.mm II amancaanao
II II II m am on II naneoo
Anna: amnuv
aoancn anon no em anns n I moon .amwuao
.pascwucoo .m

 

 

 

 

 

 

 

 

 

 

 

 

nn> n> > >H nnn an n nauou no ammucaanao
macaw 00¢ 0cm .Hmmm .nwnfisc .mumo .mmnm mcwuomaaou

 

 

 

 

.pmsswucoo .m magma

20

 

II II 5.00 momm II II II OUMUCOUHQQ
II II N H II II II Hmnfisc
II Aanaa nnnm =~\nIao
MGMHmH nmbmmm mo hmm Guam I mmmH .oH >HSb
II II II II 0.0m 0.0m II mmmusmonwm
II II II II H H II nmnEsc
Lanac nnna .mo aoanmm
mmmeSS mo mmm mHHE N\H I momH .mH mHsb
.nmssHucoo .m

Hg 5 > 5 HHH nn H Hauou no amaucaunam
, muonw 0mm cam .nmmm .Hwnfioc .mum0 .mmnm mcHuomHHOU

 

 

 

 

 

 

 

.pmanucoo .m aHnma

21

disruptions evident, and need not be pursued further in this
discussion.

The following analysis includes the dates of sampl-
ing in each case to avoid confusion as to the assignment

of similar age groups to different year classes and vice

versa .

Collections from the Hongsland Area

Two collections (October, 1965, and April, 1966)
were made in the vicinity of Hog Island. The October
collection proved to be the most diversified of the
collections with respect to age composition. This sample
consisted of 60 fish, one of which was discarded due to
scale regeneration. Age groups II through VI are repre-
sented, group III comprising 81.3 percent of the sample.
IHence, the 1962 year class, of which these 3-year-olds are
a.part, could well be considered the "strongest" year class
Inithin the sample. The year classes 1963 and 1961 (age
saroups II and IV) are represented to a lesser extent. The
Slibstantial percentage drop between age groups III and IV may,
35! Roelofs (op. cit.) suggests, be indicative of significant
HKthality from age III to age IV. Age groups V and VI,
frWJm year classes 1960 and 1959 respectively, are each
represented by a single fish. The scarcity of these older
fiJBh in the samples is fairly understandable considering
the record low parent stocks in Lake Michigan during the

late 1950's.

22

Collections of April, 1966, provide little compari-
son with the previous sample due to the circumstance that
the 1966 collection is composed entirely of sublegal fish,
whereas the 1965 collection includes 98.3 percent legal fish.

Annulus formation had not yet occurred in April,
so the age groups denote the same year classes in both
samples. Here though, the 1963 year class (age group II)
accounts for 77.8 percent of the total, while the 1962 year
class comprises only 16.7 percent. The 1964 year class (age
group I) is represented in this sample by one individual.
Possible factors involved in this change of year class
representation may include such things as mortality of
older fish during the fall fishing season, migration of
certain size groups, bathymetric differences, and so forth.

Collections from the General Area South and
Southeast of Naubinway.

The geographical proximity of these sampling areas
warrants their inclusion in one section in order that
correlations in age composition from year to year may be
more conveniently discussed.

The initial sample (October, 1965) from the area
between Naubinway and Hog Island (see Figure 3) was composed
100 percent of fish belonging to age group II, or the 1963
year class. Subsequent samples taken during May and June
of 1966 attest to the strength of this year class. Scale
samples from the May collection showed no evidence of new

annulus formation. Scales from fish in the June collection

23

did exhibit the beginnings of annulus formation, but pre-
cise delineation of the new annuli was impossible. As
shown in a later section dealing with annual length in—
crement, fish of the latter sample had all but finished
their previous season's growth, but the determinate crossing-
over had not quite been completed.

The year class of greatest strength in the May
1966 collection is again the 1963 class. This year class
accounts for 50 percent of the sample. Age group III
(representing the 1962 year class) comprises 41.67 percent
of the sample, while age group IV (1961 year class) is
represented by one specimen.

The Pelkie Reef collection of JUne, 1966, was again
dominated by the 1963 year class (listed as age group II
but actually having almost completed the third season's
growth). This year class is represented to the extent
of 77.8 percent, while the 1964 year class, not repre—
sented in either of the previous samples, is present as 22.2
percent of the total.

In the October, 1966, collections from areas south
of Naubinway, Epoufette, etc., the 1963 year classflpresent
here as age group III, makes up approximately 85 percent
of the various samples taken in totality for this month.
Inspection of the individual sampling data (Table 3)
gives evidence of this substantial dominance in all but one
of the samples, that taken 6 miles southwest of Epoufette.

However, this sample was taken only from the sublegal

24

portion of the catch and therefore cannot be considered
representative. The 1962 and 1964 year classes were repre-
sented in varying proportions within these samples. The
reader is referred to Table 3 for specific age compositions

of the six individual samples.

Collections West of Seul Choix Point

Two collections were made in the areas west of Seul
Choix Point. The first collection (October, 1965) was taken
by gill net, the Second (JUne, 1966) by pound net. Here
again, in both of the samples, the 1963 year class was the
most abundant. Fish of this year class comprised 98.7
percent of the October sample, and 64.7 percent of the l
JUne, 1966 collection. A single age group III fish (1962
year class) was taken in the October sample. The JUne
sample contained, in addition to the strong 1963 year
class, 6 individuals (35.3 percent) from the 1964 year
class.

Only one fish in the June sample showed evidence
of recent annulus formation. This fish is included in
the 1963 year class by reason that the amount of growth
achieved since the formation of the third annulus does not

seem to warrant its inclusion in the 1962 year class.

Collections East of Seul Choix Point

The first sample from this area was obtained on 8
October 1965 by means of pound nets. The sample consisted

of 43 whitefish, 100 percent of which belonged to the 1963

'25

year class (age group II). Additional samples taken during
October, 1966, also indicated the strength of this year
class, althOugh not of the same magnitude as the previous
years' sample.) When considered as a whole, the 1966
Samples taken in the vicinity of Port Inland were composed
of 53.5 percent 1963'year class, 40 percent 1964 year 7
class, 4.9 percent 1965 year class, and 1.6 percent 1962

year class.

Collections fromkgay de NOC Areas

Four samples, totalling 22 fish, were taken in
Little Bay de Noc during.February, 1966. These samples
have been combined as stated previously. WAgeyGroup I,
representing the 1964 year Class, made up 95.5 percent
of the total sample. _The 1963 year class was represented
by one fish.. The strength of this 1964 year class is
evidenced also in the October, 1966, samples from Big Bay
de Noc, where the fish were taken as two—year-olds. Here
this age group accounts for 94.4 percent of the combined
samples, theremaining portion representing the 1963 year

class.

Misgellageous'Collectigns

The last three collections are for convenience
groupedunder this category. The individual samples
obviously are too small to facilitate extensive discussions,
soIthe reader is merely introduced here to situations which

may exist in each of the areas.

26

Distinct new annuli were present on the Scales of

all seven fish.

Sand Bay of_§eaver Island.—-This sample (taken on
16 Ju1y 1966) consisted of three fish, two belonging to
age group V, and one in age group IV. These age groups

represent respectively the 1961 and 1962 year classes.

112 Mile SSE_gf Whiskey Island.--A sample of two
fish was obtained from the commercial catch here on 15
Ju1y 1966. Included were one fish representing the 1964
year class (age group II), and one representing the 1963

year class (age group III).

1/2 Mile NE of North Fox Island.--The sample here
(taken 13 Ju1y 1966) seems to present a special situation.
A 5-year-old (year class 1961) and a 7-year old (year class
1959) were included in this sample. HoWever, the sizes of
these fish were 17.2 and 16.2 inches, respectively, a size
which most of the other whitefish studied here have attained
by the end of their third growing season. Dwarf whitefish
populations have been described in several localities, but
these fish have not attained an age which would justify
categorizing them as such. Roelofs (op. cit.) has shown
a similarly slow rate of growth for fish taken around

South Fox Island.

27

Discussion of Age Composition

The preceding data indicate the presence of two
year classes which could be considered generally "dominant"
in these samples, with a third year class of less wide—
spread occurrence but nevertheless dominating one of the
collections. Currently, with the exception of the 1965
Hog Island sample, the northern Lake Michigan whitefish
fishery seems to be dominated by the 1963 year class.

The strength of this year class is shown by the good
correlation of age groups in samples of the two consecu—
tive years, age group II comprising the bulk of the 1965
samples and age group III those of 1966.

The 1965 Hog Island sample was dominated by the
1962 year class. Scarcity of the 1963 year class in
this sample seems reasonable in view of the large-mesh
gill nets employed, which presumably would not capture
many age group II fish. However, other samples taken
by similar means (e.g., the 8 October 1965 sample west
of Seul Choix Point) include a large number of these fish.
In the latter samples it is difficult to explain the absence
of age group III (1962 year class) individuals. These
facts tend to indicate then, at least from the standpoint
of age composition, the existence of a separate stock of
whitefish in the Hog Island area. The April 1966 sample
from this area was composed mainly of fish of the 1963 year
class, but this sample was taken entirely from the sub—

legal portion of the catch while the first sample contained

28

only one sublegal fish. No collections were made here
during Fall 1966.

Most of the fish studied here apparently enter
the fishery near the end of their third growing season
(II year-olds) and make a significant contribution as III
year-olds. Van Oosten and Hile (op.'cit.,) found that age
group III was "typically dominant" in the whitefish fishery
of Lake Erie, as did Roelofs (op. cit.) for Big Bay de NOC.
Dominance of the fishery by this age group in western
Lake Michigan and Green Bay has been reported more recently
by Mraz (op. cit.).

A high continuity of age composition exists also
for the Bay de Noc samples, this time confirming the strength
of the 1964 year class. Thus it appears that Bay de Nbc
whitefish have been subject to different conditions than
those of northern Lake Michigan. It has been reported
(Roelofs, op. cit.) that Bay de Noc whitefish do not mix
extensively with Lake Michigan fish. This information,
along with the results of other studies (notably Smith and
Van Oosten, 1940, and Dryer, 1964) and the age composition
of samples used in the present investigation, implies the
existence of separate whitefish stocks in northern Lake
Michigan and the Bay de Nocs.

I think it should be pointed out that the term
"dominance" as used here simply refers to those year
classes contributing the majority of whitefish to the

fishery, and is not meant to infer any phenomenally strong

29

year class such as that of 1943 which was responsible for

the fantastic production of the late 1940's. At this point,
while such is not the primary purpose of this paper, it

seems advantageous to present a brief discussion concerning
some of the causes of year class dominance as reported in
the literature, bearing in mind the fact that the dominant
year classes of this study may represent nothing more unusual
than those which may generally typify a formerly depleted
population. It is possible under the existing situation
that this low age composition may in fact be indicative

of a further declension of the fishery rather than a
population renewal. Miller's (1966) work concerning the
collapse and recovery of a small Canadian whitefish fishery
fits nicely in here. He notes that during the years of

high exploitation there was a corresponding period of de-
creasing age structure, i.e., the percentage of young

fish increased and the percentage of older fish decreased.
Subsequently, during the recovery phase of the fishery,

this situation was reversed. While commercial fishing
intensity for Great Lakes whitefish has been relatively
ineffective in recent years, it may be possible that selective
mortality by the lamprey upon older whitefish could well have
produced an analogous situation. If such is the case then,
perhaps the whitefish fishery could now be adequately
managed to produce maximum growth and biomass if commercial
fishing intensity is adjusted for a period. The relatively

large proportion of young fish now in Lake Michigan and Bay

30

de Noc seems incongrous with the low parent stocks of the
early 1960's. It has been pointed out, however (Ricker, 1954),
that density dependence may be reflected in strong year
classes arising from low parental numbers and vice versa.
This relationship seems to be true of the strong 1943 year
class referred to earlier (Roelofs, op. cit.). On the other
hand, Ricker (1958) states "the biggest difficulty in examin-
ing the effect of stock density upon net production is that
year to year differences in environmental characteristics
usually cause fluctuations in reproduction at least as

great as those associated with variation in stock density
over the range observed. . . ."

Temperature as a factor of primary importance for
survival of whitefish eggs and young in Lake Erie has been
reported by Lawler (1965). Price (1940) has conducted
laboratory experiments on whitefish development which have
shown both mean survival of eggs and mean length of hatched
larvae to be affected by temperature. I don't think we can
attribute fluctuations in year class composition in
northern Lake Michigan to temperature, however, as water
temperatures here are apparently close to freezing during
a large portion of the year and indeed the water remains
ice-covered all winter. Lake Erie on the other hand is

considered to be the southernmost extreme for Q, clupeaformis,

 

and is subject to more drastic temperature changes and with-
out the benefit of ice cover during the critical developmental

period in many years (Lawler, op. cit.).

31

Miller (1952) has not found any significant relation-
ship of temperature to spawning success, but has found wind
velocity of importance in that large windrows of eggs are
occasionally blown ashore. Larkin (1956) cites Langlois
(1954) as attributing fluctuations in Lake Erie cisco popu-
lations to changes in turbidity. This would apparently
be due to siltation of eggs. Dymond (1948) has suggested
that food and nutrients during larval stages are important.
In regard to both turbidity and nutrients then, it may be
that precipitation during early life-history stages is of
importance. Data obtained from the United States Weather
Bureau do not indicate any such relationship for the
period in question, however. A two-way analysis of variance
was carried out on total precipitation (inches) over the
three month period April through June for the years 1960
to 1964 as reported by four stations, two around northern
Lake Michigan and two in the Bay de Noc vicinity. The
salient features of this analysis are presented in Table 4.
It is interesting to note that precipitation for spring, 1963,
is significantly lower than all other years but 1962. Thus
I think we can safely exclude any hypothesis based upon
unusually high nutrient content during this period. Other
factors, including various biotic ones, have been referred
to in the literature but further analyses will not be

attempted here as this could constitute a thesis in itself.

32

Table 4. Salient features of the analysis of variance on
spring precipitation for the years 1960 to 1964.

 

 

 

Source d.f. ss iss F

Areas 1 0.0042 0.0042 0.0036
(P > .10)

Years 4 268.3435 67.0859 57.6290**
(P < .01)

Interaction 4 6.2633 1.5658 1.3451
(P > .10)

Error 10 11.6408 1.1641

Total 19 286.2518

 

Table of means:*
1960 1961 1964 1962 1963

16.78 8.74 8.61 8.43 6.06

 

 

*Least Significant difference (LSD .01) = 2.4084

LENGTH - FREQUENCY DISTRIBUTIONS

Most of the samples here exhibit tight unimodal or
bimodal length distributions in accordance with year class
structure. These length-frequency data are presented in
Appendix I. A summary of the data is given in Figure 4.
The situation existing in this study would seem to provide
an ideal opportunity to examine the effects of gear selecti-
vity, as all three main types of gear were employed. It
should be noted again, however, that many of these collec-
tions were made at dock, thereby biasing the frequencies
toward legal-size fish and underestimating the abundance
of sublegals. Commercial fishermen report the approximate
proportions of legal and sublegal whitefish in an average.
catch as 75 and 25 percent respectively (Moffit and Wilson,
pers. comm.).

Inspection of the data for the larger samples
shows no evidence of any substantial gear selectivity.

Gill nets and trap net types are apparently taking similar
size fish, although in some cases the trap and pound net
samples include borader size ranges. Few of these samples
should be considered truly representative of a typical
commercial catch, since most were taken strictly from either
the legal portion or the sublegal portion of any given

catch.

33

34

Considerable overlap of age groups in the majority
of samples renders questionable the use of length as an
accurate index of age, although some general approximations

may be extended according to averages given in the tables.

Figure 4.

35

Summary of whitefish length-frequency distribué.
tions. The solid line represents the total
range of lengths: the short horizontal line de-
notes the mean (i). The white portion enclosed
by dashes represents one standard deviation on
either side of the mean (X). NUmbers to the
left of each distribution indicate the total
number in the sample. Depth is in fathoms.

Abbreviations are: F - fall season:
S — spring season;
GN — gill nets;
TN - trap nets;
PN — pound nets.

36

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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I. I. 9 I. 9 L
I. 9 o
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N N N
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. L. s.a£u.aam 3.1 ..t Ease-sen .0 3
no: 00 >0. a... as! 00 >0. 0...... .t .

 

GROWTH IN LENGTH

Growth in length has been calculated according to
the scale method used in conjunction with a nomograph. In
using this method it was necessary to assume a mathematical
relationship described by the formula

L = a + cS
Where L = body length, S = scale radius, c = a constant,
and a = a constant. The vertical intercept, "a", has long
been considered as that body length at which scales first
appear on the fish. Van Oosten (1923), through direct
observation of whitefish, has placed this value at 35 to 40
millimeters. Barker (op. cit.) and Caraway (op. cit.) ar-
bitrarily placed the value at 40 millimeters in their theses.
Dryer (1963) found the value of "a" to be 0.04 inch for
Lake Superior whitefish, a value he considered insignifi-
cantly small, thereby justifying use of a direct-proportion
formula. While Dryer (op. cit.) found use of "key scales"
(those taken from a precisely delineated spot on each fish)
of little consequence in his work, such does not appear to
be true here. In this study a patch of scales was taken from
the same general area of each fish, but variability in scale
radii for given lengths was tremendous. This, along with
the limited length distribution, rendered calculation of
an accurate body length — scale radius relationship futile.

37

38

Data have been analyzed for a random sample of the total,
yielding an "a" value of approximately 260 millimeters.
Such a value makes little sense biologically, and if used
would introduce substantial error in the back-calculations
to follow. It is on this basis that a value of 40 milli-
meters (reported originally by van Oosten, 1923) was used.
Since most of these fish are in the II - III year-old class
(central portion of the T.L.-S.R. regression), there has
undoubtedly been some error in the estimation of length at
each annulus. This error is probably more pronounced for
the very young, and also the older ages. Subsequent statisti—
cal analyses should still be valid however, as it is assumed
that these errors are distributed randomly throughout the
samples.

Calculated growth in length for fish of all samples
is presented in Appendix 2. Statistical analyses have
been conducted in order to determine the significance of
observed growth differences among the several sampling
areas. Parametric one-way analyses of variance using length
at age 2 as a criterion were carried out on fish of both
the 1963 and 1964 year classes. Length at age 3 would
perhaps have been a more accurate index under the circum-
stances, but would have excluded many of the samples used
in comparison. Random subsamples were taken from those
collections for which there were at least 40 fish in the
particular year class. A table of random numbers was

employed in the selection of these fish. Collections from

39

the area one mile southwest of Port Inland have been com-

bined in view of similar locations, gear, fishing depth, and

dates. Comparison of growth between different year classes

within the same collections was not feasible due to low

numbers of the non-dominant year classes in most instances.
Important features of the analysis of variance are

given in Tables 5 and 6. Inspection of the two tables and

their reSpective listings of mean lengths for whitefish of

the various areas indicates the following generalized relation-

ship: growth west of Seul Choix Point > Bay de Noc > east

of Seul Choix Point > south and southeast of Naubinway.

Table 5. Salient features of the analysis of variance on
length at age 2 for fish of the 1963 year class.

 

— m

 

 

 

Source of 3:32.23 3:325:32. e Ratio
Among areas 8 79,681 9,960.12 ll.74***
Within areas 216 183,112 847.74 (p < .001)
Total 224 262,793

 

(NSD.01 = 21.200)
Observed means:

*W. Seul Choix *E. Seul Choix SW Port In. SE Port In.
378.64 339.8 329.16 326.04

 

Bid. Pt. Pelkie R. SSW EP. 2-5 E. Naub. S.E.P.
3;4.52 319.6 317.96 316.68 314.2

 

 

— W

*1965 Collections.

40

Table 6. Salient features of the analysis of variance on
length at age 2 for fish of the 1964 year class.

 

m

Sums of Mean Sums fi Ratio

 

 

Source df ISquares of Squares
Among areas 3 8,229 2,743.0 9.329***
Within areas 116 34,104 294.0 (9 < .001)
Total 119 42,333
LSD .01 = 11.567
Observed Means:
N.W. Fairport Blacksnake Hump SW Port Inland SE Port Inland

 

 

 

361.77 354.50 1. 344.67 340.63

 

 

 

Further inspection of the tables shows that while
differences among the major sampling areas (i.e., south and
southeast of Naubinway, east of Seul Choix Pt., west of
Seul Choix Pt., and Bay de Nec) are Significant, differences
within each of these main areas are not. It is on this
basis that grand averages of length of each age have been;
compiled for comparative purposes as shown in Figure 5.
Data for the Hog Island samples are included in this figure
for interest. The latter samples, being composed mainly
of 1962 year class fish, were not compared statistically
with other areas as there are no large counterparts for
this year class among the rest of the collections.

It should be noted that the significantly greater
amounts of growth exhibited by Bay de Noc and West Seul

Choix Pt. whitefish may in fact be artifacts resulting from

 

41

   
  
  
   

 

25
*
23 Hoe ISLAND
21‘? wear
or
e SEULCHOIX PT.
“K
0 _
219
o I ,
517-— BAY 0! N00
v
I I. \SAST 0F sew. CHOIX PT.
._1sL—
‘29 I-
IIJ1aiI— \
_I _ as”. or NAUBINWAY
.J
11—
<
I- n
O
I- 9—
r.
7r-
r
5 I I I I J J
1 2 3 4 5 6
AGE
Figure 5. Comparative total lengths at each age.

*Less than 5 fish

42.

systematic error associated with the back—calculations of
length at each age, commonly referred to as "Lee's phenomenon."
In such a situation the calculated lengths are higher in
early years for younger fish than for older ones. This
relationship seems to hold true also for the Port Inland
collections, in that 2 year—old fish of the 1964 year

class have higher mean calculated lengths at age 2 than 3
year olds of the 1963 year class (see Tables 5 and 6).
However, there are still some significant differences
between Bay de Noc and Lake Michigan whitefish growth

even for fish of the same age group (Table 6). The implied
higher growth-rate shown by the Bay de Nbc whitefish has
been noticed by Mraz (op. cit.) and is also evident in
Caraway's (op. cit.) data.

Examination of Appendix 2 does not reveal any
general applicability of Lee's phenomenon, although a few
samples seem to exhibit a tendency toward it. Most of
these, however, do not include many of the younger (ages I
and II) fish. hence containing a bias strongly in favor of
the faster-growing legal-sized individuals within the age
groups. Lee's phenomenon has been reported by Van Oosten
and Hile (op. cit.) for Lake Erie whitefish.

Van Oosten and Hile (op. cit.) have found growth
of whitefish in Lake Erie to be positively correlated
with amount of rainfall during Ju1y and August. A three-
way variance analysis with replication in this regard has

shown no significant differences (.01 level) either between

43

the two main areas or among years (see Table 7a). The
interaction of years with months is significant however,
the nature of which is shown in Table 7b. In very simple
terms this interaction merely points up a change in the

monthly rainfall pattern over the years studied.

Table 7a. Analysis of variance on JUly-August precipitation
for 1960-1965 as reported by two stations each
for Bay de Nbc and northern Lake Michigan.

— —
— _—

 

...... .. 2332.2: Sia2.::$:. Raii. PrzfiaBilitY
A (areas) 1 4.928 4.928 4.794 ..10>p>.05
a (months) 1 2.803 2.803 2.727 P>.10
I (years) 5 23.139 4.628 4.502 .10>p>.01
A x a 1 4.877 4.877 4.744 ..10>p>.05
A x I 5 1.883 0.377 0.367 p>.10
a x 1 5 29.173 5.835 5.676**v .01)?

A x a x I 5 7.812 1.562 1.519 8>.10
Error A *21 21.583 1.028

Total 44 96.198

 

*reduced by 3 since 3 missing observations were
generated.

Table 7b. Table of deviations (obs.-exp.) associated with
analysis of variance given in Table 7a.

 

=—

 

 

 

 

;_§ay.de Noc” " Northern Lake Michigan

Ju1y August JUly August
1960 + - + -
1961 + - + -
1962 - + - +
1963 + - - +
1964 - + + -
1965 - - + —

 

Growth in length in all five of the main areas

44

illustrated in Figure 4 is apparently much greater than that

previously reported in the literature.

in this study is compared with that reported in other

studies in Table 8.

An increase in growth would be ex-

Growth of fish used

pected in accordance with reduced intraspecific competition,

and indeed complies well with observations on other declining

populations of commercial importance.

 

 

 

 

 

Table 8. Length at each age for whitefish of this,
other studies.
'Ifl: _r
Calculated T.L. (inches) at age:

Location 1 2 3 4 5 6
w. of Seul Choix Pt. 8.3 14.7 18.6
Bay de Noc 7.9 14.1 18.3
E. of Seul Choix Pt. 7.5 13.1 17.2 19.3
sass. of Naubinway 7.3 12.6 16.7 19.3 21.6*
Hog Island 7.1 12.8 17.5 19.2 22.3* 24.2*
Green Bay1 1 6.6 11.8 16.0 18.9 20.6 22.0
N. Lake Michigan 5.6 9.8 13.8 17.2 19.6 21.2
Big Bay de Noe2 5.1 9.8 14.1 18.0
High Is1and2 5.4 9.1 12.8 17.0
Lake Huron3 5.0 8.9 12.3 16.1
Lake Erie4 6.9 12.7 16.1 18.1
Lake Superior

Whitefish Pt. 6.6- 11.2 14.7 17.6 20.4 21.7

Bayfield 5.1 8.0 10.9 13.3 15.0 16.7

 

*Fewer than 5 fish.

1.
2.

3.
4.
5.

Mraz (op. cit.)

Roelofs (op. cit.) after Barker (op. cit.) and

Caraway (op. cit.)
Van Oosten (1939)

Van Oosten and Hile (op. cit.)

Dryer (1963)

LENGTH-WEIGHT RELATIONSHIP AND CONDITION

Length-weight relationships have been determined
for the combined samples of each of the main areas discussed
in the previous section. Random subsamples of 75 fish were
taken from each collection in these major areas in proportion
to the individual collection sizes. Equations were derived
by fitting straight lines by least squares to the logarithms
of the lengths and weights. A CDC 3600 was used here.
The calculated linear regressions, along with their
respective coefficients of correlation are shown in Figure 6.
Ninety-five percent confidence levels are given in Table 9.
Equations describing the length-weight relationships are as
follows:
Bay de Nbc areas
w = 1.057 x 10‘2 L 2°78°
Areas south and southeast of Naubinway
w = 1.429 x 10'2 L 2°?13
Areas east of Seul Choix Point
w = 2.506 x 10a2 L 3°}20

Areas west of Seul Choix Point
3 3.862

w = 1.963 x 10' L
Where

W = weight in ounces
and

L = length in inches.

45

46

.l r - 0.943

bli— W. of SeulChoix .’
Point \ /

 

*' /
. I.’ ,°r=0.966
. _ E. 1 s 1601 I ' .°
‘7 0961;“ o x \ -’ ,’l'-O.946
L. o/\..° /,
' r-o.s15
.-
I
01.6
a use.“ Naubinway
3
.9
0
9.1.5
1.4
|.3__|__[ I I I I I I I I J L I 1

 

 

1.20 1.22 1.24 T5 1.2. 1.30 1.32
lOGw lENGTH

Figure 6.Colculoted logarithmic length—weight
relationships

47

 

 

 

 

 

Table 9. Ninety-five percent confidence intervals around
y (weight) for the mean and two end-point values of
x (length) for each length-weight relationship.
L at. Log10 Log10 95
0C ion Length Weight Percent Conf. int.
Bay de Nbc Areas 1.204 1.323 1.237 1.409
1.240* 1.430* 1.346 1.514
1.322 1.651 1.435 1.867
Areas South and 1.204 1.352 1.300 1.404
Southeast of 1.280* 1.580* 1.508 1.652
naubinway 1.322 1.696 1.584 1.808
Areas East of 1.204 1.357 1.283 1.431
Seul Choix Point 1.250* 1.510* 1.426 1.594
1.322 1.726 1.580 1.872
Areas west of 1.204 1.357 1.211 1.503
Seul Choix Point 1.250* 1.520* 1.434 1.606
1.322 1.813 1.619 2.007

 

*Regression mean (2).

These equations exhibit much more variability than

the ones derived by Mraz (op. cit.) for similar study areas.

Indications are that Seul Choix Pt. whitefish increase

considerably more in weight than Bay de Noc whitefish with

increased length.

Mraz (op. cit.) found the opposite re-

lationship for fish collected during the period 1948-1952.

Differences in the slopes of the regressions (powers of L

in the above equations) between Bay de Noc and west Seul

Choix Point are significant at the one percent level, others

are not.

Condition factors,6

ness" are given in Table 10.

 

6 =wx105

KTL

L = total length in centimeters.

Where W

or indices of relative ”plump-
In order to make more valid

weightuin kilograms, and

48

comparisons, only the October collections were used in

these computations. Differences among age groups within
each area with respect to condition do not seem of great
consequence. Instances in which greater variability occurs
are associated with small numbers of fish in some of the

age groups. The less robust condition of the Bay de Noc
fish is again apparent. Average weights cf whitefish in all
collections are much higher for any given age group than the
weights reported by Mraz (op. cit.) or Van Oosten and

k I

Hile (op. cit.).

TableilO. Condition factors for Bay de Nbc and Lake Nuchigan

 

 

 

 

 

 

 

 

 

-whitefish.
Age \ No Average T.L. Average weight
Group " ' Inches cm. Ounces Kg. Condition(KTL)
1. .gay de Noc
II 186 17.7 45.0 28 0.794 0.871 .
III 11* 20.7 52.6 45 1.276 0.876
2. South and Southeast of Naubinway '
I 5 13.3 33.8 13 0.369 0.955
II :89 16.4 41.7 25 0.709 0.977
III 533 19.4 49.3 40 1.134 0.946
7 IV 33 21.0 53.3 53 1.503 0.992
3. East of Seul Choix Point
I ;13 "12.7 32.3 12 0.340 1.008
II 157 17.1 43.4 .28 0.794 0.971
III 151 19.7 50.0 43 1.219 0.975
IV 7 21;; 53.6 60 1.701 1.104
4. west of Seul Choix Point.
II 76 17.9 45.5 36 1.021 1.083

III 1 21.2 53.8 64 1.814 1.164

 

COMPARISON OF THE SEXES

Data pertaining to sex in this study are relatively
sparse and do not readily lend themselves to statistical
treatment. Information has been collected however on those
fish which were not sold in the round. In general, males
outnumbered females in these samples, although the ratio
approaches 50:50 in the H09 Island sample, and sways in
favor of females in the west Seul Choix Pt. sample. The
fact that the majority of samples for which sex data have
been recorded were taken during October makes this
general relationship understandable in that male whitefish
reportedly arrive on the shallower Spawning grounds earlier
than females (Van Oosten, 1939).

Inspection of Tables 11 and 12 reveals an earlier
maturity of males, this occurring somewhere in the range
of 2-1/2 to 3-1/2 years. Females appear to mature toward
the end of the third year. Taking all of these samples
in totality, the smallest mature male was one 14.5 inches
in length belonging to age group II, and the largest
immature male was a 23.3 inch 3-year-old. The latter
fish is a rare exception however, as 98 percent of the
males were mature prior to 18 inches. Comparable lengths
for mature and immature females are 16.8 and 19.6 inches,
respectively, both belonging to the second age group.

Mraz (op. cit.) also found the minimum lengths of males

49

50

 

 

 

 

 

 

 

 

 

 

 

Table 11. Comparison of males and females with regard to
percent maturity in the legal and sub-legal
portions of the commercial catch.

Sub-legal Legal
number % mature number % mature

Males 113 61.1 192 86.0

Females 43 2.3 146 52.1

Table 12. Comparison of whitefish sexes with respect to
average length, average weight, percent mature, and
condition.

Av. Av.
Age T.L. Weight ‘% KTL

Group Location Sex No..(cm.) (Kg.) Mature

II Blacksnake Hump M 45 44.7 0.766 64.4 0.857
in Big Bay de F 10 45.5 0.879 20.0 0.933
Noc '

NW Fairport in M 103 45.0 0.766 97.1 0.840
Big Bay de NOC F 26 45.5 0.879 76.9 0.933
Naubinway to M 26 40.6 0.680 92.3 1.016
Hog Island F 3 40.9 0.680 0 0.993
2 mi. S. M 17 40.9 0.624 17.6 0.912
Epoufette F 78 40.9 0.624 0 0.912
6 mi. SW of M 10 41.1 0.652 10.0 0.939
Epoufette F 7 41.9 0.709 0 0.963
East of Seul M 31 41.4 0.709 96.8 0.999
Choix Point F 12 41.1 0.709 0 1.021
1 mi. SW Port M :7 41.9 0.652 28.6 0.886
Inland F 2 40.9 0.595 0 0.869
W of Seul M 20 45.2 1.021 55.0 1.105
Choix Point F 56 45.5 1.049 1.8 1.113

III 2-5 mi. East M 2 51.8 1.247 100.0 0.897
of Naubinway F 21 .50.8 1.332 100.0 m.Ol6
Hog Island M 22 49.5 1.247 90.9 1.028

F 21 50.8 1.503 100.0 1.146 -

 

51

and females at maturity to be 14.5 and 16.5 inches, respective-
ly. Dryer (1963) reports similar sizes for Lake Superior
whitefish, but his fish were one or two years older at these
lengths. From the data at hand, it seems that whitefish of
Bay de Noc apparently achieve maturity sooner than those in
other areas studied. The deviations shown by these Bay de Nbc
fish with reSpect to most of the previous parameters could
be due to a variety of things, among which include certain
population interactions, genetic factors, and limnological
conditions.

Differences in growth between sexes with reference
to length are not significant (non-parametric tests),
but in samples containing a large proportion of mature
females, the females are somewhat heavier (see Table 12).
Van Oosten (1939) and Barker (op. cit.) also have not found
any significant differences in length increment, but do
report a slight weight advantage on the part of the
females. Condition factors for samples with a substantial

percentage maturity also support this contention.

SUMMARY AND CONCLUSIONS

The commercial whitefish catch in northern Lake
Michigan and Bay de Noc is currently dependent almost
wholly upon the second and third age groups. Those age
groups dominating the 1965 and 1966 collections from the
Bay de Nbcs and the major portion of northern Lake Michigan
represent the 1964 and 1963 year classes, respectively,
as indicated by the good correlation of successional age
groups within the samples. The fall 1965 HOg Island
sample consisted mainly of 1962 year class individuals,
while the spring 1966 sample included a majority of 1963
year class fish. A variety of factors in addition to
inherent sampling error could have produced this situation.
No correlation of year class strength with spring precipi-
tation was found over the period 1960 through 1964.

Length-frequency analyses in this paper show con-
siderable overlap in length for fish of different ages.

It has been mentioned that a typical commercial catch may
be composed of approximately 75 percent legal and 25 per-
cent sublegal whitefish.

Experience in this study with regard to the "Y"
intercept ("a" value) in the body length - scale radius
relationship indicates a need for "key scales" taken from

exactly the same location on each fish. A value of 40

52

53

millimeters has frequently been referred to in the litera—
ture as the ”a" value in this linear model, and for this
reason was used in the present study.

Analysis of variance on length at age II for fish
of the various samples has shown the following general
relationship for growth in length: west of Seul Choix
Point > Bay de Noc > east of Seul Choix Point ) south and
southeast of Neubinway. Fluctuations in growth increment
for different year classes within each sample could not be
treated statistically due to the low numbers of the non-
dominant year classes. Growth differences among the major
areas could not be attributed to JUly—August precipitation.
Van Oosten and Hile (op. cit.) had previously reported a
positive correlation of precipitation during these months
with growth fluctuations in Lake Erie. Growth in length
in all areas was greater than that previously reported for
Great Lakes whitefish.

Length-weight relationships and condition factors
show Baysde Noc whitefish to be less robust than fish of
the other main areas. The slope of the Bay de Noc regres-
sion differs statistically (.01 level) only from the one
for fish west of Seul Choix Point.

In general, males outnumbered females in these
prespawning-season samples. Growth in length does not
differ statistically between the two sexes, although mature
females tended to be slightly heavier than males. The

males in these sampling areas apparently begin maturation

54

early in their third growing season (in the 16-17 inch
range). Females mature somewhat later at lengths of 17-18
inches for the most part.

We can summarize briefly then, that the commercial
whitefish fishery of northern Lake Michigan and the Bay
de Necs depends mainly upon a few low age groups, the fish
of which are growing faster and maturing at an earlier age
than those previously reported in the literature. Such
conditions have characteristically been associated with
declining populations, hence indicating a strong need for
further research leading towards formulation of effective
restoration and management programs.

If the differences in growth observed in this study
are truly indicative of separate sub-populations, it may
become necessary to handle each main area individually.
Previous experiments (notably Smith and Van Oosten, op. cit.:
Dryer, 19647 Roelofs, pers. comm.) have indicated limited
migrational patterns for whitefish, giving evidence of
descrete population entities among these fish. In order to
institute management programs whereby population equilibrium
and maximum sustained yield are maintained, it will be
necessary to conduct carefully planned migration and popu-
lation studies. As these are probably not immediately
feasible, easily administered temporary management proce-
dures should be undertaken just to insure survival and

spawning of a good portion of the present stock.

55

When the results of other more detailed investigations
are available then, it should be possible to evaluate the
economic, sociological, and physical aSpects of the situation
and bring into effect some sophisticated programs with limits
on catch quotas, numbers of commercial vessels, fishing
grounds, and so forth. Thus it may be possible to recreate
a once lucrative whitefish industry in this area barring

any further destruction of the ecosystem.

Barker, As Mo 19530

Borgeson, D. P.,

Caraway, P. A.

Dryer, W. R. 1963.

. 1964.

 

Dymond, J. R. 1948.

Eddy, S. 1957.

Frick, H. C. 1965.

Hile: R. 1962.

and W. H. Tody, eds. 1967.

1951.
formis (Mitchill),

LITERATURE CITED

A study of the age, growth, and
year class abundance of the white-
fish, Coregonus clupeaformis (Mit-
chill), from Big Bay de Noc, Delta
County, Michigan. Thesis. Michigan
State University. Unpublished.

 

Status
report on Great Lakes fisheries.
Fish. Div.,Mich. Dept. of Cons.
Fish. Mgt. Rept. no. 2. 35 p.
The whitefish, Coregonus clupea-
of northern Lake
Michigan, with Special reference to

age, growth, and certain morphometric
characters. Thesis, Michigan State
University. Unpublished.

Age and growth of the whitefish in
Lake Superior. U.S. Fish. and Wildl.
Serv. Fish. Bull. 63 (1): 77—95.

Movements, growth, and rate of re-
capture of whitefish tagged in the
Apostle Islands area of Lake Superior.
U.S. Fish. and Wildl. Serv. Fish.
Bull. 63 (3) : 611-618.

European studies of the populations
of marine fishes. In: Symposium on
fish populations. Bull. Bingham
Ocean. C011. 11 (4): 55-80.

How to know the freshwater fishes.
Wm. C. Brown Co., Dubuque, Iowa. 253 p.

Economic aSpects of the Great Lakes
fisheries of Ontario. Bull. Fish.
Res. Ed. Can., No. 149. 160 p.

Collection and analysis of commercial
fishery statistics in the Great Lakes.
Great Lakes Fish. Comm. Tech. Rept.

No. 5. 31 p.

56

57

Koelz, W. 1929. Coregonoid fishes of the Great Lakes.
Bull. U.S. Bur. Fish., 43 (1927),
Pt. 2: 297-643.

Lagler, K. F. 1956. Freshwater fishery biology.
wm. C. Brown Co., Dubuque, Iowa. 421 p.

Langlois, T. H. 1954. The western end of Lake Erie and
its ecology. Ann Arbor, Michigan.
479 p. (From Larkin, 1956)

Larkin, P. A. 1956. . Interspecific competition and
population control in fresh-water fish.
J. Fish. Res. Ed. Can. 13(3): 327342.

Lawler, G. H. 1965. Fluctuations in the success of year
classes of whitefish populations with
special reference to Lake Erie.

J. Fish. Res. Ed. Can. 22(5): 1197-1227.

Miller, R. B. 1952. The relative strengths of whitefish
year classes as affected by egg plantings
and weather. J. Wildl. Mgt. 16(1): 39-50.

. 1956. The collapse and recovery of a small
whitefish fishery. J. Fish. Res. Ed.

 

Mraz, D. 1964. Age, growth, sex ratio, and maturity
of the whitefish in central Green Bay
and adjacent waters of Lake Michigan.
U.S. Fish. and Wildl. Serv. Fish. Bull.
63(3):619-634.

Price, J} W. 1940. Time-temperature relations in the
incubation of whitefish. J. Gen. Physiol.
23 (4): 449-468.

Ricker, W. E. 1954. Stock and recruitment. J. Fish.

. 1958. Handbook of computations for
biological statistics of fish populations.
Bull. Fish. Res. Ed. Can., No. 119.
300 p.

 

Roelofs, E. W. 1958. r‘Age and growth of the whitefish,
Coregonus clupeaformis (Mitchill),
in Big Bay de Nbc and northern Lake
Michigan. Trans. Am. Fish. Soc.
87: 190-199.

58

Rounsefell, G. A., and W. H. Everhart. 1953. Fishery
science - its methods and applications.
Jehn Wiley & Sons, Inc., New York. 444 p.

Smith, 0. H., and Jehn Van Oosten. 1940. Tagging experiments
with lake trout, whitefish, and other
species of fish from Lake Michigan.
Trans. Am. Fish. Soc. 69:63-83.

Smith, Stanford H. 1954. Method of producing plastic
impressions of fish scales without
using heat. Prog. Fish-Cult., 16(2):
75—78.

., H. T. Buettner, and Ralph Hile. 1961.
Fishery statistical districts of the
Great Lakes. Great Lakes Fish. Comm.
Tech. Rept. No. 2. 24p.

 

Tody, W. H., and H. A. Tanner. 1966. Coho salmon for the
Great Lakes. Fish Div.,Mich. Dept.
of Cons. Fish Mgt. Rept. No. 1. 38 p.

Van Oosten, Jehn. 1923. The whitefishes (Coregonus
clgpeaformis). A study of the scales
of whitefishes of known ages. Zoologica:
Sci. Cont. of the New York Aool. Soc.
2(17):380-412.

. 1939. The age, growth, sexual maturity,
and sex ratio of the common whitefish,
Coregonus clupeaformis (Mitchill),
of Lake Huron. Pap. Mich. Acad. Sci.,
Arts and Lett. 24:195-221.

 

., and Ralph Hile. 1949. Age and growth
of the lake whitefish, Coregonus
clupeaformis (Mitchill), in Lake Erie.
Trans. Am. Fish. Soc. 77:178-249.

 

APPENDICES

APPENDIX 1

LENGTHFFREQUENCY DISTRIBUTIONS

1.1. Length-frequency distribdzion of whitefish in the
October 1965 sample from Hog Island (4-1/2" gill

 

 

 

 

 

nets).
Age Group

T.L. Average II III IV V VI
Interval T.L. Year Class

(mm.) (in.) 1963 1962 1961 1960 1959
420-429 16.7 1
430-439 17.19 1 3
440-449 --
450-459 17.7 1
460-469 18.35 1 1
470-479 18.6 4
480-489 19.07 7 1
490-499 19.44 5 1
500-509 19.88 7
510-519 20.28 8
520-529 20.6 6
530-539 21.09 2 1
540-549 --
550-559 22.0 2
560-569 22.2 1 1
570-579 22.5 1 l 1
580-589 --
590-599 23.3 1
600-609 --
610-619 --
620-629 --
630-639 24.8 1

Number 4 48 5 1 1
Average Length 17.49 19.88 20.87 22.5 24.8
(in.

 

Percent legal 75.0 100.0 100.0 100.0 100.0

 

62

1,2. _Length-frequency distribution of fish in the April
1966 sample from Hog Island (4-1/2"_gill nets).

 

 

 

 

Age Group
T.L. Average I II III
Interval T.L. Year Class
(mm.) (in.) 1964 1963 1962
360-369 14.2 1
370-379 --
380-389 15.2 1
390-399 15.6 1
400-409 15.93 8 1
410-419 16.28 4 2
Number 1 14 3
Average length (in.) 14.2 15.95 16.16

 

Percent legal 0.00 0.00 0.00

63

1.3. Length-frequency distribution of fish in the
October 1965 sample between Naubinway and HOg
Island (deep trap nets in 60 feet).

 

 

 

 

Age Group
T.L. Average _ .II
Interval T.L. Year Class
(mm.) (in.) 1963
350-359 14.1 1
360—369 --
370-379 --
380-389 --
390-399 15.56 5
400-409 16.09 9
410-419 16.26 14
Number 29
Average length 16.01
(in.)
Percent legal 0.00

 

64

 

 

 

 

 

 

1.4. Length-frequency distribution of fish in the
May 1966 sample from the area 10 miles south of
Naubinway (4-1/2" gill nets in 7-14 fathoms).
Age Group

T.L. Average II ~III IV
Interval T.L. . Year Class

(mm.) (in.) 1963 1962 1961
420-429 16.8 1 1
430-439 17.2 1
440-449 —-
450-459 17.81 3
460-469 18.21 1 1
470-479 --
480-489 19.15 2
490-499 --
500-509 --
510-519 --
520-529 20.6 1
530-539 --
540-549 21.4 1

Number 6 5 1
Average length (in.) 17.61 18.78 21.4
‘Percent legal 83.33 80.00 100.0

 

65-

1.5. Length-frequency distribution of fish in the
Pelkie Reef sample of June 1966 (trap net in 9-10

 

 

 

 

 

fathoms).
Age Group
T.L. Average I II
Interval T.L. Year Class
(mm.) (in.) 1964 1963
350-359 14.1 1
360-369 14.5 1
370-379 --
380-389 --
390-399 --
400-409 16.1 1
410-419 16.5 2
420-429 16.77 4
Number 2 7
Average length (in.) 14.30 “ 16.60

 

Percent legal 0.00 0.00

 

66

 

 

 

 

 

 

1.6. Length-frequency distribution of whitefish in the
October 24, 1966 sample from Pelkie Reef (trap nets
in 5-1/2-6 fathoms).

Age Group
T.L. Average II III IV V
Interval T.L. Year Class
(mm.) (in.) 1964 1963 1962 1961

430-439 17.1 1

440-449 --

450-459 18.0 2

460-469 --

470-479 18.64 1 1

480-489 19.15 8

490-499 19.42 18

500-509 19.86 9

510-519 20.20 5

520-529 20.60 2 1

530-539 20.9 1

540-549 21.3 1

.NUmber l 46 2 1

Average Length 17.1 19.55 20.95 18.64
(in.)

Percent Legal 100.0 100.0 100.0 100.0

 

67

1.7. Length-frequency distribution of whitefish in the
October 28, 1966 sample 2-5 mi. east of Naubinway
(4-1/2" gill nets in 2-4 fathoms).

 

 

 

 

Age Group

T.L. Average II III IV V
Interval T.L. Year Class

(mm.) (in.) 1964 1963 1962 1961
450-459 18.0 1
460-469 18.26 1 8
470-479 18.62 1 17
480-489 19.07 32
490-499 19.46 62 1
500-509 “19.87 46
510-519 20.26 32 2
520-529 20.58 18
530-539 21.08 3 3
540-549 21.48 2 3
550-559 21.88 3
560-569 22.1 1
570-579 --
580-589 23.0 1

Number 2 221 13 1
Average Length 18.44 19.62 21.18 23.0
(in.)
Percent Legal 100.0 100.0 100.0 100.0

 

68

1.8. Length-frequency distribu:ion of whitefish in the
Octéber 24, 1966 sample from Biddle Point off
Naubinway (4-1/2" mesh trap nets in 6-7 fathoms).

 

 

 

 

 

Age Group

T.L. Average 1' II III IV
Interval T.L. . . ,. Year Class

(mm.) (in.) ..‘3 1964 .."? 1963 ;.'l962
390-399 15.7 1
400-409 --
410-419 --
420-429 --
430—439 17.17 4 1
440-449 17.55 2 5
450-459 17.94 4 5
460-469 18.23 1 13 1
470-479 18.68 31
480-489 19.06 1 29 1
490-499 19.45 38
500-509 19.87 27 2
510-519 20.25 16 1
520-529 20.60 1 2
530-539 21.03 5 1
540-549 21.36 1 1
550-559 21.90 3
560-569 --
570-579 22.66 2
580-589 23.0 1

Number 13 172 15
Average Length 17.58 19.24 20.99
(in.)

111

Percent legal 92.31 100.0 100.0

 

69

1.9. Length-frequency distribution of Whitefish in the

October 24,

1966 sample 2 mi. SSW of Epoufette

(trap nets - 4-1/2" mesh - in 5-7 fathoms).

 

 

 

 

 

Age Group
T.L. Average II III IV
Interval T.L. Year Class
(mm.) (in.) 1964 1963 1962.
430-439 17.15 1 1
440-449 --
450-459 --
460-469 18.33 2 1
470-479 18.70 4
480-489 19.11 7
490-499 19.50 7
500-509 19.81 16
510-519 20.22 6
520-529 --
530-539 21.04 3 1
540-549 21.4 1
Number 1 46 3
Average Length 17.15 19.57 20.26
Percent Legal 100.0 100.0 100.0

 

70

1.10. Length-frequency distribution of whitefish in the
Octdber 28, 1966 sample 6 mi. SW of Epoufette
(4-1/2” mesh trap nets in 30-50 feet).

 

 

 

 

 

Age Group
T.L. Average I II III
Interval T.L. Year Class
(mm.) (in.) 1965 1964 1963
300-309 11.8 1
310-319 --
320—329 12.8 1
330-339 13.1 1
340-349 --
350-359 --
360-369 --
370-379 --
380-389 15.2 1
390-399 --
400-409 16.02 5
410-419 16.42 7 1
420-429 16.79 4 l
NUmber 3 l7 2
Average Length 12.57 16.32 16.61
(in.

 

Percent Legal 0 0 0

 

71

 

 

 

 

1.11. Length-frequency distribution of whitefish in the
October 28, 1966 sample 2 mi. S of Epoufette
(4-1/2" mesh trap nets in 40 feet).

Age Group
T.L. Average II III
Interval T.L. Year Class
(mm.) (in.) 1964 1963

380-389 15.3 1

390-399 15.57 6 1

400-409 15.94 6

410-419 16.32 8

420-429 16.71 3

430-439 17.2 1

440-449 17.56 1 1

450-459 17.90 4

460-469 18.32 4

470-479 18.6 1

480-489 19.07 11

490-499 19.48 6

500-509 19.76 7

510-519 20.26 3

520-529 20.59 10

26 48
Average Length 16.15 19.34
(in.)
Percent Legal 7.69 97.92

 

72

1.12. Length-frequency distribution of whitefish in the
Octdber 1965 collection east of Seul Choix Point
(pound nets in 26 feet).

 

 

 

 

 

Age Group
T.L. Average II
Interval T.L. Year Class
(mm.) (in.) 1963
360-369. 14.5 1
370-379 14.9 1
380-389 --
390-399 15.58 5
400-409 15.97 8
410-419 16.40 16
420-429 16.68 9
430-439 --
440-449 17.4 2
450-459 17.9 1
Number 43
Average Length 16.29
(in.)

 

Percent Legal 6.98

 

1.13. Length-fre uenc

73

distribution of fish in the
October 19 5 co lection west of Seul Choix
Point (4-9/16" gill nets in 6-8 fathoms).

 

 

 

 

 

 

Age Group

T.L. Average II III
.Interval T.L. Year Class

(mm.) (in.) 1963 1962
420-429 16.8 3
430-439 17.14 13
440-449 17.48 13
450-459 17.86 18
460-469 18.25 14
470-479 18.76 13
480-489 18.9 1
490-499 19.6 1
500-509 --
510-519 --
520-529 --
530-539 21.2 1

NUmber 76 1
Average length 17.89 21.2
(in.)
Percent Legal 96.05 100.00

 

74

1.14. Length-frequency distribution of fish in the June
sample west of Seul Choix Point (pound nets in 30

 

 

 

 

 

 

feet).
Age Group
T.L. Average I II III
Interval T.L. Year Class
(mm.) (in.) 1964 1963 1963*
350-359 13.92 2
360-369 14.5 2
370-379 14.7 1
380-389 15.0 1
390-399 15.5 1
400-409 --
410-419 16.4 1
420-429 16.7 2
430-439 17.1 1
440-449 --
450-459 18.0 1
460-469 18.2 1
470-479 18.8 1
480-489 --
490-499 --
500-509 19.74 2
510-519 20.1 1
Number 6 10 1
Average Length 14.42 17.82 18.8
Percent Legal 0.00 60.00 100.00

 

*Considered in this year class on the basis of grOWLh
achieved since third annulus (as explained in text).

75

 

 

 

 

 

 

1.15. Length-frequency distribution of whitefish in the
October 26, 1966 sample 1 mi. SW of Port Inland
(4-1/2" mesh pound nets in 5-6 fathoms).

Age Group
T.L. Average I II III
Interval T.L. Year Class
(mm.) (in.) 1965 1964 1963

270-279 11.3 1

280-289 --

290-299 11.7 1

300-309 12.0 1

310-319 12.30 2

320-329 12.6 2

330-339 13.12 3

340-349 13.64 2

350-359 --

360-369 --

370-379 14.7 1

380-389 --

390-399 --

400-409 15.94 2

410-419 16.46 4

420-429 16.77 4

430-439 17.11 7 1

440-449 17.50 10

450-459 17.86 9 2

460-469 18.29 2 1

470-479 18.69 1 5

480-489 19.06 1 8

490-499 19.54 3

500-509 20.0 3

510-519 20.29 8

520-529 20.68 5

530-539 21.04 2

540-549 21.4 1

550-559 21.7 1

Number 13 40 40
Average Length (in.) 12.78 17.37 19.66
Percent Legal 0.00 75.00 100.00

 

76

1.16. Length-frequenc distribution of whitefish in the
October 26; 196 sample 1 m1. SW of Port Inland

(trap nets in 5-6 fathoms).

 

 

 

 

 

fige Group

T.L. Average II III IV
Interval T.L. Year Class

(mm.) (in.) 1964 1963 1962
430-439 17.15 5
440-449 17.51 3
450-459 17.81 2 1
460-469 18.23 2
470-479 18.54 4 2
480—489 19.15 5
490-499 19.45 4
500-509 19.96 3
510-519 20.26 2
520-529 20.60 6
530-539 21.02 2 1
540-549 21.36 1 1
550-559 21.9 1
560-569 22.4 1
570-579 --
580-589 23.1 1
590-599 --
600:609 ---
610+619 24.0 1

Number 16 29 3
Average Length 17.78 20.14 21.83
(in.)

 

Percent Legal 100.00 100.00 100.00

 

77

 

 

 

 

1.17. Length-frequency distribution of whitefish in the
October 26. 1966 sample 1 mi. SE of Port Inland
(trap nets in 5 fathoms).
Age Group:
T.L. Average II III IV
Interval T.L. Year Class
(mm.) (in.) 1964 1963 1962
410-419 16.5 1
420-429 16.80 3
430-439 17.13 29
440-449 17.53 6 1
450-459 17.88 13 2
460-469 18.19 6 3
470-479 18.72 9
480-489 19.06 12
490-499 19.45 19 1
500-509 19.86 12 1
510-519 20.26 11
520-529 20.67 7
530-539 21.01 5 1
540-549 --
550—559 21.7 1
560-569 22.2 1
Number 58 82 4
Average Length (in.) 17.42 19.60 20.63
Percent Legal 93.10 100.00 100.00

 

78

1.18. Length-frequency distribution of fish in the Feb.,
1965 Little Bay de Noc samples (pound nets).

 

Age Group II

 

 

 

T.L. Average I
Interval T.L. Year class
(mm.) (ing) 1964 1963
330-339 13.0 2
340-349 13.54 4
350-359 13.91 4
360-369 14.27 5
370-379 14.72 5
380-389 --
390-399 15.6 1
400-409 --
410-419 --
420-429 —-
430-439 --
440-449 --
450-459 --
460-469 --
470-479 --
480-489 18.9 1
Number 21 1
Average Length (in.) 14.11 18.9

 

Percent Level 0.00 100.00

 

79

1.19. Length-frequency distribution of whitefish in the
October 25, 1966 sample from "Blacksnake Hump," Big
Bay de Noc (4-1/2" mesh pound nets in 5-6 fathoms).

 

 

 

 

Age Group
T.L. Average II III
Interval T.L. Year Class
(mm.) (in.) 1964 1963
410-419 16.3 1
420-429 16.72 5
430-439 17.17 13
440-449 17.49 14
450-459 17.86 8
460-469 18.16 8
470-479 18.70 7
480-489 --
490-499 19.51 2
500—509 19.70 1
510—519 --
520-529 20.55 .2
56 5
Average Length (in.) 17.63 19.96
Percent Legal 89.29 100.00

 

80

1.20. Length-frequency distribution of whitefish in the
October 25, 1966 Sample 3 mi. NW of Fairport in
Big Bay de Noc (pound nets in 3-3-1/2 fathoms).

 

 

 

 

 

Age Group
T.L. Average II III
Interval T.L. Year Class
(mm.) (in.) 1964 1963
420-429 16.85 9
430-439 17.18 27
440-449 17.50 27
450-459 17.83 31
460-469 18.22 21
470-479 18.58 11
480-489 19.00 3
490-499 19.3 1
500—509 20.0 1
510—519 20.26 2
520-529 20.7 1
530-539 21.0 1
540-549 --
550-559 --
560-569 --
570-579 -—
580-589 --
590-599 --
600—609 —-
610-619 --
620-629 -—
630-639 25.0 1
Number 130 6
Average Length (in.) 17.72 21.20

 

Percent Legal 93.08 100.00

 

81

1.21. Length-frequency distribution of fish from Sand Bay
of Beaver Island (4-1/2" gill nets).

4— L
—; -

 

 

 

 

Age Group
T.L. Average IV V
Interval T.L. Year class
(mm.) (in.) 1962 1961
550—559 21.7 1
560-569 --
570-579 —-
580-589 23.0 1
590-599 --
600-609 23.8 1
Number 1 2
Average Length (in.) 21.7 23.4
Percent legal 100.00 100.00

 

1.22. Length-frequency distribution of fish from Whiskey
Island (3" gill nets).

 

 

 

Age Group
T.L. Average II III
Interval T.L. Year class
(mm.) (in.) 1964 1963
380-389 15.2 1
390-399 --
400-499 --
410-419 --
420-429 --
430-439 --
440-449 --
450-459 17.7 1
Number 1 1
Average Length (in.) 15.2 17.7

 

Percent Legal 0.00 100.00

 

82

1.23. Length-frequency distribution of fish from North
Fox Island (3” gill nets).

 

 

 

 

 

Age Group
T.L. Average V VI VII
Interval T.L. Year Class
(mm.) (in.) 1961 1960 1959
410-419 16.2 1
420-429 --
430-439 17.2 1
Number 5 l 1
Average Length (in.) 17.2 16.2

 

Percent Legal 100.00 0.00

 

APPENDIX 2

CALCULATED GROWTH IN LENGTH

84

2.1. Growth data for fish in the October 6, 1965 sample
from Hog Island.

 

 

.Calculated Total Length (mm.) at age: Average

 

 

 

AV. cal-Co T.L. (mm.)
Av. Calc. T.L.(in.)
Av. increment (mm.)
)

,Age Year No. T.L.

Gr. Class 1 2 3 4 5 6 at Cap.
II 1963 4 192.0 357.8 445.0

III 1962 48 178.6 333.9 455.9 504.8
IV 1961 5 161.4 280.2 403.8 477.6 530.8
V 1960 1 192.0 302.0 419.0 480.0 540.0 572.0
VI 1959 1 187.0 352.0 468.0 543.0 592.0 614.0 630.0

1 2 3 4 5 6

178.4 330.7 450.7 487.3 566.0 614.0

7.02 13.02 .17.?4 .19.18 2

2.28 24.17

178.4 152.3 120.0 36.6 78.7 48.0

 

 

 

 

 

Av. increment (in. 7.02 6.00 4.72 1.44 3.10 1.89
Rel. Growth (%J 100.00 85.47 36.25 8.12 16.16 8.48
2.2. Growth-data for fish in the April 14, 1966 sample
from Hog Island.
Calc. T.L. (mm.) at age: Av.

Age Year No. T.Li
Gr. Class 1 2 3 at Cap.

II 1963 14 185.7 308.9* 404.9

III 1962 3 174.7 264.7* 346.7* 412.3

1 2 3

Av. Calc. T.L.(mm.) 185.5 301.1 346.7
Av. Calc. T.L.(in.) 7.30 11.85 13.65
Av. increment (mm.) .185.5 115.6 45.6
Av. increment (in.) 7.30 4.55 1.80
Rel. Growth 0%) 100.00 62.33 15.19

 

*Underestimates growth since only from sublegal portion.

85

 

 

 

 

 

2.3. Growth data for fish in the October 8, 1965 sample
between Naubinway and Hog Island.
Calc. T.L. (mm.) at age: Average
Age ,Year T.L
Group Class No. 1 2 at Cap.
II 1963 29 181.7 322.8 406.7
1 2
Av. calc. T.L. (mm.) 181.7 322.8
Av. calc. T.L. (in.) 7.15 12.71
Av. increment (mm.) 181.7 141.1
Av. increment (in.) 7.15 5.56
Rel. growth (%) 100.00 77.76

 

 

 

 

 

 

2.4. Growth data for fish in the May 13, 1966 sample 10
mi. South of Naubinway.
Ca1c.-T.L. (mm.) at:ge: AV'
(Age Year T.L.
Group Class No. l 2 3 4 at Cap.
II 1963 6 196.0 327.7 446.8
III 1962 185.2 327.8 427.6 477.6
IV 1961 1 230.0 370.0 464.0 511.0 544.0
1 2 3 4
Av. Calc. T.L. (mm.) 194.3 331.3 433.7 511.0
.Av. Calc. T.L. (in.) 7.65 13.04 17.07 20.12
Av. increment (mm.) 194.3 ” 137.0 102.4 77.3
Av. increment (in.) 7.65 5.39 4.03 3.05
Rel . Growth (76) 100.00 70.46 30.92 17.33

 

2.5.

86

Growth data for fish in the June 3, 1966 sample 1/2 -

1-1/2 mi. SW of Pelkie Reef.

 

 

 

 

 

 

Age Year Calc. T.L. (mm.) at age: Avgrige

Group Class No. 1 2 at Cap
I 1964 2 213.5 363.0
II 1963 7 184.4 307.1 421.6

1 2

Av. Calc. T.L.(mm.) 190.9 307.1

Av. Calc. T.L. (in.) 7.52 12.09

Av. increment (mm.) 190.9 116.2

Av. increment (in.) 7.52 4.57

Rel . Growth (76) 100 .00 60. 9

2.6. Growth-data for fish in the October 24, 1966 sample

from Pelkie Reef.

 

 

 

: A .
Age Year Calc. T.L. (mm.) at age T E
Group Class No. 1 l 2; 3 4 5 at Cap
II 1964 1 166.0 329.0 434.0
III 1963 46 181.4 315.4 427.9 496.5
IV 1962 2 175.0 323.5 426.0 482.5 535.5
V* 1961 1 161.0 261.0 358.0 400.0 448.0 472.0
1 2 3 4 5
AV. calc. T.L. (mo) 18008 31600 42798 48205 “--
AV. calc. T.L. (in.) 7012 12044 16084 19.0 “--
Av. increment (mm.) 180.8 135.2 111.8 54.7 --
Rel. Growth (76) 100.00 74.78 35.38 12.79 --

 

*Not used in calculations of average growth.

87

2.7. Growth data for fish in the October 28, 1966 sample
2-5 mi. east of Naubinway.

 

 

 

 

Age Year Calc. T.L. (mm.) at age: Av.
Group Class No. . T.L.
l 2.. , 3 4 5 ' at Cap.
II 1964 2 194.0 355.5 " - 465.0
III 1963 22 190.1 325.4 428.9 ' ' ‘ 498.3
IV 1962 13 171.8 320.6 431.3 492.5 ”’ . 537.3

V .1961 1 182.0 322.0 448.0 509.0 549.0 584.0

 

1 2 3 4 5

Av. calc. T.L. (mm.) 189.1 325.0 429.1 493.7 . 549.0
Av. calc. T.L. (in.) 7.44 12.79 16.89 19.44 21.61
Av. increment (mm.) 189.0 135.9 104.1 64.6 55.3
Av. increment (in.) 7.44 5.35 4.10 2.55 2.17
Rel. Growth (%9 100.00 71.9 132.03 15.05 11.20

 

2.8. Growth data for fish in the October 24, 1966 sample
from Biddle Pt. off Naubinway.

 

 

 

 

Age Year Calc. T.L. (mm.) at age: Téz:
Group Class No. 1 2 3 4 at Cap.
II 1964 13 188.3 340.7 446.3
III 1963 172 185.9 316.2 420.2 488.9
IV 1962 15 176.5 315.3 422.3 487.1 532.9

 

1 2 3 4

Av. Calc. T.L. (mm.) 185.4 317.7 420.4 487.1
Av. Calc. T.L. (in.) 7.30 12.51 16.55 19.18
Av. increment (mm.) 185.4 132.3 102.7 66.7
Av. increment (in.) 7.30 5.21 4.04 2.63
Rel. Growth (%) 100.00 71.36 32.33 15.87

 

88

2.9. Growth data for fish in the October 24, 1966 sample
2 mi. SSW of Epoufette.

 

 

 

 

 

Calc. T.L. (mm.) at age: ZAv.
Age Year T.L.
Group Class No. l 2 3 4 at'Cap.
II 1964 1 169.0 324.0 434.0
III 1963 46 187.8 322.1 426.0 497.2
IV 1962 3 184.0 311.0 429.7 478.3 515.0
1 2 3 4

Av. Calc. T.L. (mm.) 187.2 321.5 426.2 478.3
Av. Calc. T.L. (in.) 7.37 12.66 16.78 18.83

Av. increment (mm.) 187.2 134.3 104.7 52.1
Av. increment (in.) 7.37 5.29 4.12 2.05
Rel . Growth (96) 100.00 71 .74 32 .57 12 .22

 

2.10. Growth data for fish in the October 28, 1966 sample
6 mi. SW of Epoufette (taken from sub-legal catch).

 

 

 

 

. Average
Age Year Ca1c.4ggln (nghlpat age. T.L.
Group Class No. 1 2 3 at Capture
I 1965 3 178.0 319.3
II 1964 17 170.5 305.9 414.2
III* 1963 2 154.5 238.5 339.0 423.0
1 2 3
Av. calc. T.L. (mm.) 170.1 298.8 339.0*
Av. calc. T.L. (in.) 6.70 11.76 13.35*
Av. increment (mm.) 170.1 128.7 40.2
Av. increment (in.) 6.70 5.06 1.59
Rel . Growth (96) 100 .00 75.66 13.45

 

*Underestimates growth at this age, since only slower-
growing ones of this age group are represented in sub-
legal portion of catch.

89

 

 

 

 

 

 

 

 

 

 

 

2.11. Growth data for fish in the October 28, 1966 sample
2 mi. south of Epoufette.
. Average
Age Year Calc. T.L. (mm.) at age. T.L.
Group Class No. 1 2 3 at Capture
II 1964 26 168.6 304.0 410.2
III 1963 48 186.0 316.1 422.6 491.3
'1 .2 3
Av. Calc. T.L. (mm.) 179.9 311.8 422.6
AV. calc. T.L. (inc) 7o;08 12028 16060
Av. increment (mm.) 179.9 131.9 110.8
Av. increment (in.) .7408 5.20 4.32
Rel. growth (%0 100.00 73.32 35.54
2.12. Growth-data for fish in the October 8, 1965 sample
1 mi. east of'Seul Choix Point.
. Average
Age Year Calc. T.L. (mm.) at age. T.L.
Group Class No. l 2 at Capture
II 1963 43 187.95 338.51 413.65
1 2
Av. calc. T.L. (mm.) 187.95 338.51
Av. calc. T.L. (in.) 7.40 13.33
Av. increment (mm.) 187.95 150.56
Av. increment (in.) 7.40 5.93

Rel. Growth (96) 100. 00 80.14

 

Growth-data for fish in the Octdber 8,

west of Seul Choileoint.

1965 sample

 

 

 

 

Calc. T.L. (mm.) at age: Average
Age Year T.L.
Group Class No. 1 2 3 at Capture
II 1963 76 210.0 375.3 454.5
III 1962 1 193.0 373.0 482.0 538.0
1 .2 .3
Av. Calc. T.L. (mm.) 209.8 375.3 482.0
Av. Calc. T.L. (in.) 8.26 14.78 18.98
Av. increment (mm.) 209.8 165.5 106.7
Av. increment (in.) 8.26 6.52 4.20
Rel. Growth (%) 100.00 78.93 28.42

 

 

 

 

 

2.14. Growth data for fish in the June 1, 1966 sample
1/4 mi. west of Seul Choix Point.
Calc. T.L. (mm.) at age: Average
Age Year 1T.L.
Group Class No. 1 2 3 at Capture
I 1964 6 208.7 366.2
II 1963 10 207.7 348.7 452.6
III 1963* 1 226.0 373.0 460.0 478.0
1 2
Av. Calc. T.L. (mm.) 208.1 .348.7 --
Av. Calc. T.L. (in.) 8.19 13.73 --
Av. increment (mm.) 208.1 140.6
Av. increment (in.) 8.19 <5.54 --
Rel. Growth (%0 100.00 67.58 --

 

*Considered in this year class on basis of amount of
growth achieved since 3rd annulus (as explained in
text). (NOt included in growth-rate calculations.)

91

 

 

 

 

 

2.15. Growth data for fish in the October 26, 1966 sample
1 mi. SW of Port Inland (pound nets).
Calc. T.L. (mm.) at age: Average
Age Year T.L.
Group Class No. 1 2 3 at Capture
I 1965 13 204.2 323.8
II 1964 40 198.6 343.9 440.9
III 1963 40 189.0 331.9 437.8 499.7
1 2 ~3
Av. Calc. T.L. (mm.) 195.3 .337.9 437.8
Av. Calc. T.L. (in.) 7.69 13.30 17.24
Av. increment (mm.) 195.3 142.6 99.9
Av. increment (in.) 7.69 5.61 3.94
Rel. Growth 0%) 100.00 73.02 29.56

 

 

 

 

 

2.16. Growth data for fish in the October 26, 1966 sample
1 mi. SW of Port Inland (trap nets).
Calc. T. L. (mm.) at each age: Average
Age Year .T.L.
Group Class No. 1 2 3 4 at Cap.
II 1964 16 195.7 .348.1 451.9
III 1963 29 181.4 327.7 444.1 511.5
IV 1962 3 158.3 306.0 431.0 499.7 554.7
1 2 3 4
Av. Calc. T.L. (mm.) 184.7 333.1 442.9 499.7
Av. Calc. T.L. (in.) 7.27 13.11 17.44 19.67
Av. increment (mm.) 184.7 148.4 109.8 56.8
Av. increment (in.) 7.27 5.84 4.33 2.23
Rel. Growth (%) 100.00 80.35 32.96 12.82

 

2.17.

92

1 mi. SE Port Inland.

W

eroth data for fish in the October 26,

 

1966 sample

 

 

Calc. T.L. (mm.) at age: Average
Age Year T.L.
Group Class No. l 2 3 4 at Cap.
II 1964 58 195.6 339.7 442.4
III 1963 82 185.6 324.1 434.5 498.0
IV 1962 4 170.3 298.3 424.5 482.3 523.8
1 2 3 4

Av. Calc. T.L. (mm.) 189.2 329.7 434.0 482.3
Av. Calc. T.L. (in.) 7.45 12.98 17.09 18.99
Av. increment (mm.) 189.2 140.5 104.3 48.3
Av. increment (in.) 7.45 5.53 4.11 1.90
Rel. Growth (%) 100.00 74.26 31.63 11.13

 

 

 

 

2.18. Growth data for fish in the February, 1966 sample
from.Little Bay de Noc.
W
Calc. T.L. (mm.) at age: Average
Age Year T.L.
Group Class No. l 2 at Capture
I 1964 21 211.9 358.4
II 1963 1 204.0 385.0 480.0
1 2
Av. Calc. T.L. (mm.) 211.5 385.0
'Av. Calc. T.L. (in.) 8.33 15.16
‘Av. increment (mm.) 211.5 1173.5
'Av. increment (in.) 8.33 6.83
Rel. Growth (%) 100.00 81.99

 

93

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2.19 Growth data for fish in the October 25, 1966 sample
from "Blacksnake Hump,” Big Bay de Noc.
Calc. T.L. (mm.) at age: Average
Age Year T.L.
Group Class No. 1 2 3 at Capture
(II 1964 56 198.2 352.7 447.7
III 1963 5 205.6 375.8 453.6 »507.0
1 2 3
Av. Calc. T.L. (mm.) 198.8 354.6 453.6
Av. Calc. T.L. (in.) 7.83 13.96 17.86
Av. increment (mm.) 198.8 155.8 99.00
Av. increment (in.) 7.83 6.13 3.90
Rel. Growth (76) 100.00 78.4 27.91
2.20 Growth data for fish in the October 25, 1966 sample
3 mi. NW of Fairport in Big Bay de Noc.
Calc. T.L. (mm.) at age: Average
Age Year T.L.
Group Class No. 1 2 3 at Cap.
II 1964 130 201.9 359.0 450.2
III 1963 6 188.8 367.0 474.0 538.5
1 2 3
Av. Calc. T.L. (mm.) 201.3 359.4 474.0
Av. Calc. T.L. (in.) 7.93 14.15 18.66
Av. increment (mm.) 201.3 158.1 114.6
Av. increment (in.) 7.93 6.22 4.51
Rel. Growth (76) 100.00 78.53 31.88

 

94

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2.21 Growth data for fish in the July 13, 1966 sample
1/2 mi. NE of North Fox Island.
Calc. T.L. (mm.) at each age: Average
Age Year T.L.
Group Class No. 1 2 3 4 5 6 7 at Cap.
V 1961 1 150 247 332 395 418 437
VII 1959 l 131 198 248 313 347 380 398 411
2.22 Growth data for fish in the July 15, 1966 sample
1/2 mi. SSE of Whiskey Island.
CaIc.2T.fl.3(mm.).at1each:age:w2Average
Age' Year T.L.
Group Class No. 1 2 3 at Capture
II 1964 l 201 352 386
III 1963 l 160 301 406 450
2-23. Growth data for fish in the July 16, 1966 sample
from Sand Bay, Beaver Island.
Calc. T.L. (mm.) at age: Average
Age Year T.L.
Group Class No. l g 2 ; 3 4 5 at Capture
IV 1962 1 197 3255 432 504 551
V 1961 2 199.5 358.5 466 526 565 594.5

 

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