MlGRATiON. AGE Mil“! GROWTH OF RAMBOW TROUT
FARR {N BLACK RIVER. MICHEGAN

Thesis for the Degree of M. S.
MICHIGAN STATE UNWERSETY
THOMAS M. STAUFFER
1968

 

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ABSTRACT

MIGRATION, AGE AND GROWTH OF RAINBOW TROUT
PARR IN BLACK RIVER, MICHIGAN

By Thomas M. Stauffer

Juvenile rainbow trout (parr) examined for the study were collected
in the Black River, Mackinac County, with an alternating-current electric
shocker in 1952 to 1958 and by a_weir with a downstream trap in 1951 to
1959. The shocker was employed each autumn in the river upstream from
the weir location to sample the age structure and growth of parr before
migration. Most of the data used in the study came from a weir that was
used to sample the annual downstream migration of parr. The weir was
located about 3/4 mile upstream from the mouth of the river and was down-
stream from rainbow trout spawning areas.

Annulus formation by rainbow trout parr in the Black River
occurred between october and April-May. Most parr probably began growing
in April or shortly before. The body-scale relationship was best expressed
by a linear regression: L (inches) - 0.16 + .08268 (mm x107). The relation-
ship between length (mm) and.weight (grams) was a curvilinear regression
where w - .00001384 LL04“.

Growth of rainbow trout parr for the first 3 years of life was
about 3 inches per year. During their first growing season, parr of the
1949 to 1951 year classes grew slower than those of the 1956 to 1958 year
classes. Within a migratory season, faster growing parr of age I migrated

sooner than those that grew slower. ‘As an annual average, parr in the

Thomas M. Stauffer

upper river in the autumn were 68% age 0, 29% age I and 32 age II.
Variations in age composition were related to year class strength. Average
lengths in inches were 2.9 for age 0, 6.4 for age I and 9.3 for age II.
Pew parr were of legal size (7.0 inches). As an annual average, parr in
the downstream migration were 642 age I, 34% age II and 2% age III. For
a given migratory season, age composition varied according to year class.
strength. Lengths of downstream migrants averaged 4.4 inches (age I), h.
7.1 inches (age 11) and 8.9 inches (age III). Most migration occurred
between May 21 and June 30 during hours of darkness or reduced light.
‘Within a migratory season, older parr migrated first. Most migration
occurred at water temperatures of 48-58° F.

The number of age-0 fish in the upper river during the autumn

was correlated with the number of subsequent downstream migrants.

MIGRATION, AGE AND GROWTH OF RAINBOW TROUT

PARR IN BLACK RIVER, MICHIGAN

By

.8\
Thomas M) Stauffer

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

1968

ACKNOWLEDGMENTS

I wish to express my appreciation for the assistance indicated
below. Messrs. Albert Vincent, Martin Hansen and Wilbert Wagner helped
collect the field data. Wilbert Wagner read the 1958 to 1959 fish scales‘
and tabulated data. Doris Greenleaf compiled much of the data and she
and Clarence Taube reviewed the manuscript in respect to grammar and form.
Statistical advice was given by Drs. Donald Mayne, James McFadden,
William Cooper and Mr. William Schaaf. Drs. Eugene Roelofs and William
Cooper critically reviewed the manuscript.

The thesis was written, in part, under Michigan Dingell-Johnson

projects F-l8-R—l, F—lB-R-Z, F-27-R-1 to F-27-R-4, F-3l-R-l and F—31-R-5-2.

ii

TABLE OF CONTENTS

ACKNOWLEDGMENTS . . . . . . . . . .
LIST OF TABLES . . . . . . . . . .
LIST OF FIGURES . . . . . . . . . .
INTRODUCTION . . . . . . . . . . .
METHODS . . . . . . . . . . . . . .

Collection of Data . . . . . . .

Validity of Weir Samples . . . .

Age and Growth Determination . .
. ANNULUS FORMATION . . . . . . . . .
BODY LENGTH-SCALE LENGTH REGRESSION
LENGTH-WEIGHT RELATIONSHIP . . . .
GROWTH RATES . . . . . . . . . . .

PARR IN UPSTREAM AREAS . . . . . .

Age . . . . . . . . . . . . . . .
Size 0 O O O O O O O O O O O O O

DOWNSTREAM MIGRATION . . . . . . .
Age of Parr . . . . . . . . . . .

Size Of Part 0 O O O O O O O O 0
Time of Downstream Migration . .

Water Temperature and Downstream Migration

BACK-CALCULATION

RELATIONSHIP OF UPSTREAM PARR TO DOWNSTREAM MIGRANTS . .

CON Claus IONS O O O O O O O O O O O O O O O O O O O O O O O

LITEMURE CITED 0 O O O O O O O O O O O O 0 O O I O O 0

iii

Page
ii

iv

(”NW

10
ll
l4
16
21

21
21

24
24
27
29
35
38

4O

Table

1.

2.

3.

4.

5.

7.

8.

9.

LIST OF TABLES
Page

Inclusive dates of collection and numbers
of rainbow trout examined, Black River,
1951 to 1959 O O O O O O O O O O O O O O O O O O O O 5

Back-calculated increment in length (inches)
of parr caught in the weir, 1951 to 1952 and
1958 to 1959 O O O O O O O O O C O O C O O O O O O O 17

Average back-calculated lengths (inches) of
downstream migrating parr, age I to III,
1951, 1952, 1958 and 1959 o o o o o o o o o o o o o 19

Numbers and percentages of age O-II parr
collected in September-November 1952 to
1958 with an A. C. shocker . . . . . . . . . . . . . 22

Numbers and percentages of ages I-III parr
caught migrating downstream, 1951 to 1959 . . . . . 25

Average empirical lengths in inches of
downstream migrating parr in the year classes
1949 to 1958 O O O O O O O O O O O O O O O O O O O O 28

Percentages of parr migrating downstream by
time periods, 1951 to 1959 . . . . . . o . . . . . . 30

Percentages of parr caught in the weir
during three daily periods, 1951 to 1959 . . . . . . 33

Numbers of parr in the 1951 to 1958 year

classes caught in the upper river and in
the weir, 1951 to 1959 . . . . . . . . . . . . . . . .36

iv

Figure

1.-

2.

3.

LIST OF FIGURES

Black River, Mackinac County, showing

collection sites . . . . . . . . . . . . . . . . .

Body-scale regression of downstreamdmigrating
parr in Black River, Michigan, 1951, 1952, 1958

and 1959 O O O O O O O O O O C O O O O O O O O O O

Lengthsweight relation of downstream-migrating
rainbow trout parr, Black River, Mackinac County,
1951-52, 1958-59. Dots represent empirical

data. The line is calculated . . . . . . . . . .

Average percentages of age-groups I, II and
III parr migrating downstream in different

time periods, 1951-59

'Page

12

15

32

INTRODUCTION

Young rainbow trout (Sglmg’gairdneri) inhabit many tributaries
of the Great Lakes. At the age of 1 to 3 years, they usually migrate into
one of the big lakes where they grow rapidly. After they attain sexual
maturity, they return to streams to spawn at an average size of about
5 pounds, and thereby provide an important sport fishery.

Knowledge of the juvenile stage of the rainbow trout's life
history is very limited. To expand this knowledge, as well as that on
the later stages in the life of this fish, a study was made from 1951 to
1959 on the Black River, a tributary of Lake Michigan. The principal
concerns in this thesis are the age, growth and the migration patterns
of young rainbow trout (parr) before and during their initial migration
into the Great Lakes. Aspects of adult life will be reported at a later
date. .

The Black River is located in Mackinac County, about 40 miles
west of the Straits of Mackinac, in the Upper Peninsula. During the study,
it was an excellent rainbow trout stream. It also had heavy spawning runs
from-Lake Michigan of sea lampreys (Pgtromyzon marinus), white suckers
(Catostomus commersoni), longnose suckers (Catostomus catostomus) and
smelt (Osmerus mordax). Moderate to large resident populations of brown
trout (§_a_l_m_o_ M): slimy sculpins (Cottus cognatus) and American brook
lampreys (Lampetra lamottei). A small resident population of brook

trout (Salvglinus fontinalis) was also present. The middle reaches of the

river contained gravel which was utilized for spawning by most of these

species. The water was dark brown and generally clear. The average '
flow 3 miles upstream from the mouth was 33.4 cubic feet per second; the
seasonal variation was from 12 to 154 cfs. In the lower 3 miles, two
tributaries added about 15 to 20 cfs. The drainage area was 28 square

miles. Summer water temperatures seldom exceeded 65° F.

METHODS

Collection g_f_ M

Rainbow trout parr examined for the study were collected with
an alternating-current electric shocker and a weir. The locations of
the collection sites are shown in Figure 1, dates and numbers of fish
collected, in Table 1..

The shocker was employed to sample the age structure of rainbow
trout upstream from the weir-locations. The following areas were not
sampled because populations were judged as low or nil: (1) upstream from
the railroad bridge, where the mainstream flows through a swamp and.where
low gradient makes it unlikely that there was suitable spawning habitat
for rainbow trout; (2) the three tributaries above Station 3 where spawn-
ing could have occurred but in which reproduction could hardly have been
significant because of the small size of the streams (rainbow trout were
not found in two collections on Spring Creek); and (3) the upper portions
of Peters and O'Neil creeks, which lacked gravel for spawning use. Further,
it does not seem likely that any of these areas could have had very many
parr that migrated from downstream areas. Northcote's study'(1962) of
streams with temperatures similar to those of Black River showed there
was little upstream movement by rainbow trout of ages 0 and I.

The areas that were judged to contain most of the juvenile
papulation were the mainstream of the river from the 1951 weir site to
the railroad and the extreme lower portions of Peters and O'Neil creeks.
The mainstream contained many juvenile fish and offered ample spawning
habitat for the adult rainbows that entered the Black River. The juveniles

in the lower portions of Peters and O'Neil creeks presumably came from the

 

 

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mainstream. Five stations in the area inhabited by the majority of the
juvenile papulation were sampled in September-November 1952 to 1958 with
the alternating-current shocker. Three of the stations were in.the main-
stream. Stations 1 and 2 had high juvenile densities and Station 3 was
in an area of low density. The three stations contained proportionately
more rapids and riffle areas than did the juvenile population area as a
whole. Hence, larger fish in deeper water may have been undersampled.
The remaining two stations were in Peters and O'Neil creeks where the
juvenile papulation was light to medium. About 8 hours were spent collect-
ing each year And 2,300 feet (400-700 feet per station) of stream were
sampled. The area sampled at each station was the same every year.
Rainbow trout less than 3.5 inches long were measured (total length) and
those longer than 3.4 inches were measured, weighed, and scale sampled.
All fish were returned alive to the stream.

Most of the data used in this study came from part caught in
the downstream trap of a weir located 4 miles (1951) or 3/4 mile (1952
to 1959) upstream from the mouth of the river. The location of the weir
was downstream from rainbow trout spawning areas in the mainstream except
in 1951, when about 100 yards of stream suitable for spawning was below
the weir. The weir consisted of a hardware cloth fence (k-inch mesh)
stretched diagonally across the river on a sheet piling foundation with
a downstream trap at the lower end and an upstream trafie’at the upper end.
Usually, the weir was operated from May to July (see Table 1 for exact
dates). The traps were visited daily at 8:30 a.m., 5:00 p.m. and 10:30 p.m.

Parr caught in the traps were either tagged or fin-clipped to determine

 

\b‘As little upstream migration Of parr occurred, it is not discussed

in this thesis.

subsequent migration. All were measured and many were also weighed and
scale sampled. Parr were then passed over the weir in the direction

they were traveling.

Validitylg§_Weir Samples
A Wolf trap (Wolf, 1951), with k-inch mesh, was installed

at a sea lamprey barrier dam (Stauffer, 1964) some 400 yards downstream
from the weir. The Wolf trap caught about 172 of the parr migrating
downstream when operated during major downstream migrations in 1954 to
1957. It was intended to provide data on speed of downstream migration
of fish marked at the weir. However, the trap also caught many rainbow
trout (47% of the total catch) that were unmarked.

Since all downstream migrants may not have been caught at
the weir, the representativeness of the weir sample was questionable.
However, a method of checking its validity was available in the Wolf
trap catch. Both unmarked and marked fish.were caught by the Wolf trap.
I assumed that the catch of unmarked fish in the Wolf trap was representa-
tive of the downstream migration and unbiased in respect to length.k If °
the average lengths of these two groups were similar, then the weir catch
could be assumed to be representative of the downstream migration. The
average lengths of unmarked and marked age-I fish for each year (tabulated

below) were tested for differences by Student.£ tests (Li, 1964).

 

Average lengths in inches,

 

 

 

 

Year number offfish in parentheses .5 P
Unnamed Marked

1954 4.37 (62) 4.42 (41) 0.502 >0.50

1955 4.37. (88) 4.65, (152) 4.017 .40.01

1956 4.33 (166) 4.42 (232) 1.538 ‘70.10

1957 4.63 (25) 4.60 (24) . 0.172 >0.80

8
The.£ tests revealed no significant differences in lengths of marked and
unmarked fish except in 1955 when marked fish were significantly longer.
Excluding parr under 3.9 inches (see below), the weir catch seemed to be
representative of the total migration except for the small difference in
average length during 1955.

In sampling the downstream migration with the weir, escapement
of small trout through the krinch mesh may have introduced a bias. To
determine the length of the fish that might escape, three groups of rainbow
trout were confined to the upper end of a hatchery trough by a k-inch mesh
screen. Periodically trout in the lower half of the trough were counted
to determine escapement. Rainbow trout 3.9 inches and over were retained,
but all trout 3.4 inches or less escaped. In the range of 3.5-3.8 inches,
some trout were retained and some were not. Thus, if parr under 3.9
inches migrated downstream at the Black River, at least some would have

escaped.

.533 and Growth Determination~

Scales were taken from an area between the insertion of the dorsal
fin and the lateral line. Scales‘were impressed on clear plastic sheeting
with a small roller press. Ages of fish collected from the weir in 1951,
1952, 1958 and 1959 were determined by scale analysis. The anterior scale
radii and annuli were measured for subsequent growth determination. From
1953 to 1957, age determinations of fish caught in the weir were made from
scale analysis and length-frequency distributions, but scale measurements
were not made. Inspection of the 1951 and 1952 length frequencies of part
showed that the modes of the age/groups were well defined, but with some
overlap. Thus, from 1952 through 1957, part in the overlapping lengths

‘were scale sampled and the rest were only measured. Parr caught with

the shocker that were under 3.5 inches were age 0 as indicated by their
distinct length-frequency distribution. Parr over 3.5 inches were aged
by scale analysis. A

Scales from the 1951 and 1952 downstream run of parr were read
by two persons. The 982 agreement in the determinations demonstrated the
distinctness of the annuli. The locations of the annuli were usually
determined by crowded circuli. The annuli were prominent, and little
difficulty was experienced in interpreting the scales. False annuli

and other checks were generally absent.

ANNULUS FORMATION

Most annulus formation occurred sometime between the autumn
(shocker) collecting and April-May (weir) collecting periods. The small
amount of growth beyond the last annulus on parr caught in April or May
suggested that in most instanCes growth began shortly before the fish
were caught. A few parr, mostly in ages II and III, had not formed their

annulus by early May. Parr with an unformed annulus were not taken after

May.

10

BODY LENGTH-SCALE LENGTH REGRESSION AND
BACKsCALCULATION

The body-scale regression was computed from parr in the 1951,
1952, 1958 and 1959 downstream migrations. The fish were mostly of ages
I and II and were 3.5 to 9.0 inches long. The relationship was best
described by a linear regression (L - a‘+ bS) where L is body length in
inches, 8 is anterior scale radius in mm (x107) and a and b are constants.
The fish from each year's collections were divided into k-inch length
groups. The average body length and corresponding average scale length
of each of these groups (49) were then used to compute the regression
of body length on scale length. Each of the 4 years was represented by
12 to 13 groups, each containing at least five fish. The calculated
regression, L - 0.16 + .08268, and 95% confidence limits are shown in f
Figure 2.

Body lengths at various ages were calculated according to
"procedure B" as outlined by Whitney and Carlander (1956). This procedure
reduces the variations due to deviation of fish length from the "normal"
body7scale relationship and differences in size of scales from individual
fish. For example, if the observed length of a fish is longer than
expected for the size scale observed, then fish length at annulus forma-
tion should also be proportionately longer than indicated by annuli
measurements. To adjust annuli measurements proportionately to the
observed body length, the body length that corresponds to the observed
scale length was calculated. The ratio of observed to calculated body
length is then multiplied by annuli measurements. This adjusted value
is then substituted in the regression formula to obtain back-calculated

lengths.
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Validity of the regression and back-calculation was substantiated
by the following evidence. First, empirical lengths of parr at the end .
of their first and second growing seasons were similar to back-calculated
lengths from the same year classes caught the following spring and early

summer as demonstrated below.

 

Age and year class,
numbers of fish ingparentheses

 

 

 

 

Source of lengths 0-I I-II
1957 1958 1956 1957
Empirical (fall) 3.3 (17) 3.0 (129) 6.0 (9) 7.3 (16)

Calculated (follow- 3.2 (185) 3.1 (564) 6.2 (148) 6.7 (42)
- ing spring) A .

“Second, calculated lengths of the age groups (see Table 3) were usually
in agreement with empirical lengths of fish caught at the end of the
growing season (see Table 4). Finally, other workers found similar

lengths (see discussion of growth).

LENGTH-WEIGHT RELATIONSHIP

The length-weight relationship was best expressed by the equation
for a general parabola, W - an as described by Beckman (1948).. To derive
the relationship, the weight (grams) of parr between 86 and 224 mm caught
in the weir in 1951, 1952, 1958 and 1959 were grouped by 2.5 mm length
intervals. Average length and weight of each group was then used to
calculate the relationship. Expressed in logarithmic terms, the relation-
ship was log W (g) - -5.1425 + 3.0426 log L (mm). The calculated line.

(E (g) - .00001384 L (mm)3'042€] and empirical data are given in Figure 3.
There was excellent agreement between the calculated line and the empirical
data (only alternate groups plotted), demonstrating that the line accurately

represented the lengthdweight relationship.

-14

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GROWTH RATES

Annual increment in length was determined from empirical data
(shocker collections) and back-calculated lengths (1951, 1952, 1958 and
1959 weir catches). Parr, at the end of the first, second and third growing
seasons, were available from shocker collections in 1952 to 1958. Mean
increments were 2.9, 3.5 and 2.9 inches in successive growing seasons.
Mean increments from back-calculated lengths of fish in ages I, II and III
were 3.0, 3.5 and 2.9 inches in successive growing seasons (Table 2).
Growth increments on the Black River were similar to those found by other
investigators. Edward Schultz (personal communication) determined annual
increment for rainbow trout from September collections on many Michigan
streams. It was assumed that the annual growth was nearly complete. He
reported increments of 3.4 inches for the first growing season and 3.5‘
inches for the second. Shetter and Hazzard (1939) collected young rainbow
trout in September on the Little Manistee and Pine rivers, Michigan.
Increment during the first growing season was 3.3 inches for both streams
and on the Pine River it was 2.6 inches the second season. Rainbow trout
parr in Michigan streams grew at a rate of approximately 3 inches per year.

There may have been a difference among years in growth rate of
Black River parr. Back-calculated lengths indicated that part of ages I
and II of the year classes 1949 to 1951 (collected in 1951 and 1952) grew
slower (Table 2) during their first growing season than did the year
classes 1956 to 1958 (collected in 1958 and 1959). Conversely, the
average length of age-I parr caught in the weir suggested more rapid
growth for year classes 1950 to 1951 than for the 1956 to 1958 year classes

(see Table 6). These empirical lengths, however, include an unknown

16

1 7

TABLE 2

BACK-CALCULATED INCREMENT IN LENGTH (INCHES) OF PARR
CAUGHT IN THE WEIR, 1951 TO 1952 AND 1958 TO 1959

 

 

 

 

Year Incremente’from age
Age group collected 0 to I I to II II to III
I 1951 2.93 ‘ .... ....
1952 2.85 .... ....
1958 3.17 .... ....
’1959 3.08 .... ....
Unweighted average 3.00 .... ....‘
II 1951 2.64 3.22 ....
1952 2.51 3.72 ....
1958 2.79 3.37 ....
1959 2.98 3.68 ....
Unweighted average 2.73 3.50 ....
III 1951 2.08 2.93 3.07
1952 2.56 2.95 2.94 .
1958 2.28 3.05 3.11
1959 2.90 2.77 2.51
Unweighted average 2.45 2.92 2.91

 

‘efNumbers of fish used to compute increment are the same as in Table 3.

/
, 18

amount of growh in the second summer. Hence, there is reason to suspect
that the year classes 1949 to 1951 actually did grow slower during the first
growing season than did year classes 1956 to 1958.

There were differences in growth rate among age-I fish in respect
to time of migration within years. A trend toward decreasing size at
annulus I as the migration season progressed was indicated by the calculated
lengths at annulus I of age-I parr in 1952, 1958 and 1959 (Table 3). For
these years, the average calculated lengths of age-I parr in each time
period containing 14 or more fish were subjected to a nonparametric test «
for trend (Mann, 1945). (The 1951 data were too'few to be tested.)
Probabilities of a downward trend in average calculated lengths were:

.001 (1952), .235 (1958) and .028 (1959). A significant trend occurred

in 1952 and 1959. Considered on a yearly basis, the evidence for a
downward trend in size at annulus I is conflicting. However, probabilities
from the independent sets of data can be combined to give a single
probability based on all the observational evidence (see Snedecor, 1956,
pp. 216-217). Combination of the three P values gave a chi-square value
of 23.8628 (d.f. - 6). The combined data from the 3 years demonstrated
that there was a significant downward trend (P <(.001) in size at annulus

I as the migratory season progressed, showing that the faster growing

fish migrated earlier.

The average lengths at annuli I and II of age-II parr caught in
1951 were also tested for trend. There was no significant trend in size
at either annulus I or II (P .235 and .068, respectively). The data for

1952, 1958 and 1959 were too few to be tested.

' TABLE 3

AVERAGE BACK-CALCULATED LENGTHS (INCHES) 0F DOWNSTREAM MIGRATING
PARR, AGE 1 T0 111, 1951, 1952, 1958 AND 1959

 

Age when scale sampled
Year and I II III

 

 

 

 

 

103

date caught Annulus Annulus Annulus
”—1—— 116’ I 11 N6 I II III
1951
May 1-10 -. o 3.37 6.83 5 2.08 5.23 8.35 6
May 11-20 - 0 3.04 6.85 31 2.11 5.08 8.37 '15
. May 21-31 - 0 2.71 6.02 90 2.06 4.99 7.73 13
June 1-10 2.98 7 2.53 5.70 62 2.03 4.37 7.70 2
June 11-20 2.98 18 2.51 5.52' 70 3.20 6.94 8.66 1
June 21-30 2.89 15 2.56 5.82 82 1.60 4.55 8.44 2
July 1-10 3.00 5 2.62 5.83 29 2.42 4.27 7.54 1
Average and
total 2.93 45 2.64 5.86 369 2.08 5.01 8.08 40
1952
May 11-20 - 0 2.72 6.83 3 2.34 5.21 8.60 3
May 21-31 3.I3 49 2.65 6.52 61 2.63 5.62 8.51 14
June 1-10 3.02 82 2.48 6.13 25 2.54 5.46 8.18 2
June 11-20 2.89 148 1.98 5.47 8 - - - o A
June 21-30 2.84 111 2.24 4.41 2 - - - 0
July 1-10 2.70 65 2.04 5.79 3 - - - 0
July 11-20 2.70 45 - - o - - - 0
July 21-31 - 0 2.17 .5.80 1 - - - 0
Average and '
total 2.85 500 2.51 6.23 2.56 5.51 8.45 19

 

’ 20 :

TABLE 3-Continued

 

 

Age when scale sampled

Year and I II ‘ III
date caught Annulus Annulus

 

 

 

I W I 11 M9 . I II III 163/
1958
April 21-30 - 0 3.32 6.99 1 - - - 0
May 1-10 - 0 3.19 6.97 10 2.60 5.56 9.35 . 3
May 11-20 3.46 17 2.88 6.26 75 1.90 4.91 7.93 4
May 21-31 3.13 35 2.80 5.94 16 - - - 0
June 1-10 3.23 34 2.59 6.04 19 2.32 4.98 7.78 1
. June 11-20 3.08 23 2.67 5.98 8 - - - 0
June 21-30 3.19 14 2.52 5.48 3 - - - 0
July 1-10 3.14 58 2.47 5.60' 16 2.46 5.73 8.30 3
July 11-20 3.49 4 - - 0 - - - 0
Average and
total 3.17 185 2.79 6.16 148 2.28 5.33 8.44 11
1959 .
May 11-20 3.36 40 3.10 7.17 16 3.22 6.24 7.68 2
May 21-31 3.19 167 2.92 6.34 15 2.28 4.58 9.16 1
June 1-10 3.00 103 - ~ 0 - - - 0
June 11-20 3.11 75 3.12 7.47 1 - - - 0
June 21-30 3.01 119 2.80 6.49 5 - - - 0
July 1-10 2.97 56 2.96 6.12 5 - - - 0
July 11-20 2.80 4 - - o - - - 0
Average and
total 3.08 564 2.98 6.66 42 2.90 5.67 8.18 3

 

‘CVNumber of parr used to back—calculate average length at the annuli.

PARR IN UPSTREAM AREAS

Ass

Parr collected in the spawning areas with an A. C. shocker in
the autumns of 1952 to 1958 were of ages 0, I and II (Table 4). In all
years of collection except 1953, age-0 parr predominated in number, but
there were large fluctuations in age composition. Age-I parr were
considered less numerous and predominated only in 1953. Only a few age-II
fish were collected. By an unweighted average of the yearly collections,
681 of the parr were age 0, 292 were age I and 32 were age II. A chi-square
test (Siegel, 1956) was used to determine if there were differences in
the ratios of age-0 and-I parr between mainstream and tributary stations.
The numbers of age 0 and I for'all years of collection in mainstream and
tributary stations were used (in a 2 x 2 contingency table) for the test.
There was no significant difference in age composition (d.f. - 1,.X2 -
0.1333, P')0.80). In fact, the proportions of age 0 and I were almost
identical. 0n the other hand, all age-II fish came from mainstream
stations; small numbers precluded analysis.

The collections demonstrated that there was considerable variation
in year class strength. The 1952 and 1955 year classes outnumbered all the
others. They were numerous as age 0 and I parr in the stream (Table 4) and

were strongly represented in the downstream migration as age-I fish.

Size
In the autumn, the average lengths of parr at ages 0, I and II
were 2.9, 6.4 and 9.3 inches, respectively (Table 4). The average length

of age-0 fish was closely similar among year classes 1952 to 1956 and

21

TABLE 4
NUMBERS AND PERCENTAGES OF AGE O-II PARR COLLECTED
IN SEPTEMBER-NOVEMBER 1952 TO 1958 WITH AN
A. C. SHOCKER

(Average lengths in inches in parentheses)

 

 

 

 

 

 

Age
Year of 0 I II
capture Numr Percent- Num- Percent- Num- Percent-
ber age ber age ber ‘ age Total
1952 133 88 19 12 0 0 152
(2.8) (6.3)
1953 20 17 92 81 2 2 114
(2.8) (6.2) (8.9) .
1954 36 78 4 9 6 13 46
(2.9) (6.4) . (8.9)
1955 384 92 31 7 3 1 418
(2.8) (6.4) (8.9) .
1956 86 52 79 47 1 1 166
(2.8) (6.2) (9.9)
1957 17 65 9 35 0 0 26
(3.3) (6.0)
1958 128 86 16 11 5 3 149
(3.0) (7.3) (9.8)
Total numbers
and average
percentages 804 68 250 29 17 3 1,071

 

23

1958, but was greater in the 1957 year class. The same situation applied
to age-I fish of these year classes. Fish of the 1957 year class evidently
grew faster than those of the other years. The longer length of fish may
be associated with the relatively small numbers of the 1967 year class.

A paired.£ test (Li, 1964) was used to determine if there were
differences in length (growth) of age—0 fish in mainstream and tributaries.
There was no significant difference (d.f. - S, _t_ - 0.375, P)0.70) in
average lengths. The average lengths of fish in the samples tested are

shown in the table below.

 

Average lengths in inches,

 

Year numbers of fish in parentheses
Mainstream Tributaries
1952 2.3 (44) 3.0 (84).
1954 2.9 . (26) 2.9 (9) '
1955 2.7 (300) 2.9 (70)
1956 2.8 (60) 2.8 (26)
1957 3.4 (7) 3.2 (10)
1958 3.1 (103) 3.1 (15)

For age-I parr, gross inspection of the data revealed no large
difference in average lengths among stations. These data were not tested for
significance because of the small number of fish. The small sample of age—II
fish precluded even gross analysis.

All age-0 fish were sublegal, 242 of age I were legal size
(7.0 inches or longer), and all age-II fish were legal. There was little
difference in the percentage (range, 19-262) of legal-size fish among

the stations.

DOWNSTREAM MIGRATION

Age _i Parr

 

Fish in the downstream migration were composed of ages I-III
(Table 5). Considered on a yearly basis, age-I trout predominated in
1952 to 1953, 1955 to 1956 and 1959, when they composed 78-952 of the
migration. Ages I and II were almost equally represented in 1957 to
1958, and age II predominated (62-812 of the run) in 1951 and 1954. Age III
comprised only a small percentage (.(1 to 92) of the run each year.
Variation in the age composition of part in the annual migration seemed
related to year class strength which varied considerably. As mentioned
before, the catch with the A. C. shocker demonstrated that the 1952 and
1955 year classes were very strong, with a result that age-II fish were
strongly represented in the 1954 and 1957 downstream migrations. The 1949
and 1951 year classes also contributed relatively large numbers of age-II
migrants (in 1951 and 1953). However, the data were inadequate to determine
year class strength.

Considering the downstream migration by year class, most of
each class migrated downstream at age I. The ages at migration of the
1952 to 1957 year classes were similar; 63-872 migrated at age I, 12-362
at age II and 1% at age III. The 1950 and 1951 year classes were
characterized by unusually low percentages of age-I migrants. The unusually
low percentage of age-I migrants from the 1950 year class may be related
to the upstream location of the weir in 1951. The 1951 year class may
have had unusually good survival to age II, thus contributing a larger
number of fish migrating at that age. According to an unweighted average
for the year classes 1950 to 1957, 682 of the parr migrated at age I,
311 at age II and 12 at age III. There was no apparent association

between age of the migrants and population density.

91.

25

TABLE 5

NUMBERS AND PERCENTAGES OF AGES I-III PARR
CAUGHT MIGRATING DOWNSTREAM, 1951 TO 1959

 

 

 

 

 

 

Age
Year of I II III Total
capture Num- Percent- Num- Percent- Num- Percent- number
ber age her age her age caught
1951 45 10 369 81 40 9 454
1952 500 80 103 17 19 3 ' 622
1953 1,797 78 499 22 11 <1 2,307
1954 210 37 ‘ ‘ 355 62 ' 7 1 572
1955 531 80 119 18 14 2 664
1956 1,382 95 - 73 5 3 ' .41. 1,458
1957 359 50 354 50 . 3 < 1 ' _ 716
1958 185 54 148 43 11 3 . 344
1959 564 93 42 7 3 <1 609
Average
percentage
(unweighted) 64 34 2

 

26

Various investigators have determined the age at which parr leave
their stream of birth by analyzing growth patterns of scales of adult fish
which had returned to the river from lake or sea. Pautzke and Meigs (1941)
concluded that 732 of the rainbow trout parr left the stream at the age
of 2 years. Briggs (1953) stated: "K...most steelhead first spawn at the age
of 4 years, after having spent 2 years in the stream and 2 years in
salt water." Reynoldsz, in a study of adult rainbow trout that migrated
from Lake Michigan into the Platte River, reported that 1% left the stream
at the age of 1 year, 96% at 2 years and 32 at 3 years. Greeley (1933),
who made the same type of study on the Little Manistee River in Michigan,
found that 7.3% of the fish left the stream at the age of 1 year, 82.3%
at the age of 2 years, 9.42 in the third year and 12 in the fourth year.
These investigators agree that most rainbow trout parr migrate out of the
stream at or near the beginning of their third summer.

Shapovalov and Taft (1954) counted downstream migrants with a
weir on Waddell Creek, California. The downstream migration consisted of
fish of age 0 (402), I (402), II (192) and III (12). Their data and the
Black River data show a considerable number of age-0 and/or age-I migrants
which_was not revealed by inspection of adult scales (investigators cited
in preceding paragraph). Possible reasons for the inconsistency include:
(1) a higher mortality of younger fish when they reach the ocean or lake,
(2) younger fish are less likely to continue migration into the ocean or
lake and (3) fish migrating at age 0 and I were not detected by scale

analysis of returning adults.

 

2 .
Reynolds, Dexter B., Jr. 1947. summary of twenty months investigation

on the Platte River and adjacent waters, Benzie County, Michigan, with
special reference to the rainbow trout (Salmogairdnerii irideus).
74 pp. (Typewritten thesis; University of Michigan).

27

John Hale (personal communication) indicated that migration of age-0
parr occurred in Minnesota streams tributary to Lake Superior. I also observed
rainbow trout fry moving from the Little Huron River, Marquette County,
into Lake Superior. Such migration likely occurred on the Black River

because age-0 fish could easily pass through the k-inch mesh of the weir.

Size f Parr

 

 

The average length of migrating parr from the various year classes
ranged from 4.2 to 4.7 inches for age-I fish, from 7.0 to 7.6 inches for
age 11 and from 8.4 to 9.6 inches for age III (Table 6). There was no
noticeable association of size with year class strength. The size of fish .
in the strong year classes of 1952 and 1955 were similar to those in weaker
year classes. There did, however, appear to be a trend toward smaller age-I
fish among the 1950 to 1958 year classes (Table 6). A nonparametric test
for trend (Mann, 1945) showed that the trend was significant (P.<.001).
The reason for the decline in average size of age-I fish is unknown. A
trend was not apparent in older fish.

The average lengths of age-I and -II parr caught in the weir
increased as the season progressed. The average lengths (unweighted ‘
averages of combined yearly collections) of parr during successive 10-day'

periods in 1951 to 1959 are shown below.

 

Age May June July
1-10 11-20 21-31 1-10 11-20 21-30 1-10 11-20

 

I 4.3 4.2 4.0 4.3 4.5 4.6 4.9 5.1

II 7.0 7.2 7.1 7.0 7.2 7.3 7.8 7.8

These data were tested for trend (Mann, 1945). There was a significant
upward trend in average lengths (PI<.01) for both age-I and -II fish."

The trends doubtless reflect growth during the migration season.

AVERAGE EMPIRICAL LENGTHS IN INCHES OF DOWNSTREAM
MIGRATING PARR IN THE YEAR CLASSES 1949 TO 1958

28

TABLE 6

 

 

 

 

Age Year class Average
1949 1950 1951 1952 1953 1954 1955 1956 1957 1958

1 4.7 4.7 4.6 4.4 4.4 4.4 4.3 4.4 4.2 4.4

11 7.1 7.4 7.0 7.0 7.2 7.0 7.0 7.0 7.6 7.1

in 9.0 8.7 8.6 8.4 9.6 9.0 9.0 8.9 8.9

 

29

Practically all age-I fish were sublegal, about half of age II
were legal sized and all age III were legal. Thus, the fish in the
migrations are but lightly exploited by anglers in Michigan.

In Waddell Creek, California, Shapovalov and Taft (1954) found
that average total lengths [honverted from for lengths (Carlander, 19532)
of downstream migrants were 4.2 inches for age I and 7.2 for age II. In
the Alsea River, Oregon, downstream migrants averaged 6.0, 6.8 and 7.3
inches at ages I, II and III (Wagner, Wallace and Campbell, 1963). In-
the Black River, lengths of downstream migrants of these ages were 4.4,
7.1 and 8.9 1.21.... Fish in _the Black River and Waddell Creek were
approximately the same lengths. In the Alsea River, the length at" age II
was similar to that in the other studies, but lengths at ages I and III
were not. The cause of the difference is unknown, but may be related to

the stocking of rainbow trout in the Alsea River.

Time 2; Downstream Migration

The downstream migration of parr-began in April and extended to
the end of July (Table 7). Since few fish were caught at the beginning
and end of the collecting operations, it seems valid to assume that the
‘trapping covered practically the entire period of migration. Further, very
few parr were taken when the weir was operated in August (1950) and in
September-November (1952 to 1955). Most downstream migration occurred
from May 21 to June 30. In 8 of the 9 years of study, the percentages
of fish that were caught during May 21-June 30, as related to the total
catch for the year, were closely similar (77-912). In 1958, however,
the major migration began earlier and lasted longer; only 452 of the

migrants were caught during May 21-June 30.

30

 

 

 

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sen .. s «N n e on as m« 4 av omen
oa« .. .. m u an «A e« on N .. «men
mme.a .. m Na on. «N EN NA 3 a .. ones
see ... av a. o. e« AN e« e A a «we.
«NA .. A N e. as e« MN on .. .. ems”
Nom.« av. m as «a «n AN N N n .. anus
«Ne ._v N a. m. AN as o« a o .. «ms.
ems .. .. m «N on 83 MN on N .. ane-
amIaN oNIaa cans onua« oNIAH sand amna« oNIas o~I_ onuaN
N095: .3 3. 33. . .23. 0.5.. 05.... 0.5.. .50: he: .32 a» a4 0.25.30
Hmuoa 0u=ua00 mo ouoa mo ~00»

 

 

ans” as ”man .maonmm anus an

z<mmamz3on OZHH<MOHS.M&<Q mo mmu<azmommm

u mgn<a

31

Pautzke and Meigs (1941) reported that the probable peak of
downstream migration of immature rainbow trout in Washington occurred in
May. In the Alsea River in Oregon, Wagner, Wallace and Campbell (1963)
found that most of the downstream migration occurred between mid-April
and mid-May. 0n Waddell Creek, California, Shapovalov and Taft (1954)
observed the heaviest downstream migration (69% of the total) from April 1
to July 21, but some downstream migration occurred the year around.

In Black River, the period of migration was limited to not more than 4
months. .

There were differences among the three age groups in time of
migration. Figure 4 gives the average percentages of the annual runs
that migrated downstream in different time periods. Periods in which the
weir was not operated every year are not included. Although considerable
overlap occurred, there was a definite sequence among the age groups for
downstream migration. Age-III parr began to migrate first, followed by
ages II and I, respectively. Seventy-six percent of age III migration
occurred during May, 752 of age II during May 11-June 10 and 70% of age I
in June. As on the Black River, older part in Waddell Creek (Shapovalov
and Taft, 1954) migrated first.

The major portion of downstream migration occurred during times
of darkness or reduced light (Table 8). Observations indicated that catches
examined on‘night and morning visits to the trap consisted almost entirely
of fish which had entered the trap during darkness. Little downstream
movement was observed during daylight hours, except under conditions of
high and turbid water. There was little seasonal or annual variation in

the percentages of fish trapped in the different daily periods.

32

. MAY JUNE JULY
II—20 2I-3I. I-Io II-20 2I-30| I-I0

 

 

 

PERCENTAGE

AG E I
30 I;I;I;I;I;:;2;Z

20

.........................
0000000000000000000000000

.........................
.........................

IO

 

   

 

"'20 2l'3l I'IO
MAY JUNE JULY

 

   

I
q
1
1
1
I
I
1

  

 

 

II-2o 2I-30 Ho

30

20

'I0

Figure 4. --Average percentages of age-group's I, II and III parr
migrating downstream in different time periods, 1951-59.

TABLE 8

PERCENTAGES OF PARR CAUGHT IN THE WEIR DURING
THREE DAILY PERIODS, 1951 TO 1959

 

 

Time of capture

 

 

10:30 p.m.- 8:30 a.m.- 5:00 p.m.-
Year 8:30 a.m. 5:00 p.m. 10:30 p.m.
1951 37 9 A 54
1952 '35 5 60
1953 42 8 50
1954 38 13 49
1955 47 5 . 48
1956 40 6 54
1957 33 1 66
1958 32 4 64
1959 45 10 45

Unweighted
average 39 7 54

 

34

The hours of migration on the Black River are in agreement with
other studies. Gauley, Anas and Schlotterbeck (1958) studied downstream
movements of salmonids at Bonneville Dam on the Columbia River._ More
juvenile steelheads migrated at night than in daylight hours during 4 of 5
years. On Waddell Creek, Shapovalov and Taft (1954) report "...the bulk
of the fish move downstream during the night or at least in the early

morning or late evening."

331:3; Temperature .a_n_d Downstream Migration

Maximum-minimum‘water temperatures for the preceding 24 hours were
recorded each morning in 1951 and 1952. In 1953, three temperature readings
were made daily at visits to the weir. Appreciable migration began when
water temperatures approached 500 F. In all 3 years, most of the migration

was associated with water temperatures of 48-58° F.

RELATIONSHIP OF UPSTREAM PARR TO DOWNSTREAM MIGRANTS

_Ability to predict numbers of downstream migrants by sampling
young-of-the-year and age-I fish in the stream would be useful to fish
managers to help predict future runs of adults. However, to permit
predictions, a reasonably consistant ratio must exist between the numbers
of parr in the stream population and the numbers in subsequent migrations.
'To determine if such a relationship existed in Black River, numbers of
parr taken in upstream sampling were compared with numbers of fish of the
same year class in subsequent migrations. As the entire population was
' not sampled, it must be assumed that sampling efficiency in upstream areas
and at the weir was approximately constant from year to year. This
assumption seemed valid since areas of collection and effort were the same
each year. Further, it must be assumed that: (1) over-winter mortality
was relatively constant from year to year and (2) mortality was not density-
dependent. If these assumptions are valid, then the following positive
correlations should be present: (1) numbers of age-0 autumn fish with age-I
fish migrating downstream in the following year, (2) numbers of age-0 autumn
fish with age-II migrants of that year class and (3) numbers of age-I autumn
fish with age-II downstream migrants of the following year. .

Spearman rank correlation tests (Siegel, 1956) were used to
determine the relationship of the three groups of fish (Table 9). For age-0
autumn fish and age-I fish migrating downstream, there was a significant
relationship (P (r8 . .857) 21.05) . There was also a significant relation-
ship {P (rs - ,905).<,o$) between age-0 autumn fish and fish from the same

year class migrating downstream at age II. On the other hand, there was

35

TABLE 9

NUMBERS OF PARR IN THE 1951 TO 1958 YEAR CLASSES CAUGHT
IN THE UPPER RIVER AND IN THE WEIR, 1951 TO 1959

 

 

 

 

 

 

Age
0-1 I-II
Year Fall catch Spring-summer Fall catch Spring-summer
class at age 0 catch of age I at age I catch at age II
(upper river) (weir) (upper river) (weir)
1951 ..... ..... 19 499
1952 133 1,797 92 355
1953 20 210 4 119'
1954 36 531 , 31 73
1955 384 1,382 79 354
1956 86 359 9 148 '
1957 17 185 16 42

1958 188 564 ..... .....

 

I 37

no relationship between age-I autumn fish and age-II fish migrated down-
stream the following year (P (r5 - .429) >.10) .

The correlation between numbers of age-0 fish in the autumn with
the subsequent numbers of downstream migrants suggests that collections
of young-of-the-year in the upper river would be useful in predicting
relative sizes of subsequent downstream migrations. A better sampling
design in the upper river would probably also show a relationship between
age-I fish upstream and numbers migrating downstream as age II the following
year provided mortality was constant from year to year and was not

density-dependent.

CONCLUSIONS

1. Annulus formation by rainbow trout parr in the Black River
occurred between October and April-May. Most parr probably began growing
in April or shortly before.

2. The body-scale relationship was best expressed by a linear
regression: L (inches) - 0.16 + .0826S (mm x107).

3. The relationship between length (mm) and weight (grams) was a
curvilinear regression where W - .00001384 L3°0426.
4. Growth of rainbow trout parr for the first 3 years of life was

about 3 inches per year. During their first growing season, parr of the
1949 to 1951 year classes grew slower than those of the 1956 to 1958 year
classes. Within a migratory season, faster growing parr of age I migrated
sooner than those that grew slower. ‘

5. Parr in the upper river in the autumn were age 0 (682), I (292)
and II (3%). Variations occurred in age composition; these were related
to year class strength. Average lengths in inches were 2.9 for age 0,

6.4 for age I and 9.3 for age II. Few parr were of legal size (7.0 inches).

.6. Parr in the downstream migration were of ages I (68%), II (312)
and III (1%). Age composition varied among migratory seasons according
to year class strength. Lengths of downstream migrants averaged 4.4 inches
(age I), 7.1 inches (age II) and 8.9 inches (age III). Most migration
occurred between May 21 and June 30 during hours of darkness or
reduced light. Within a migration season, older parr migrated first.

Most migration occurred at water temperatures of 48-580 F.

38

39

7. The number of age-0 fish in the upper river during the autumn

was correlated with the number of subsequent downstream migrants.

LITERATURE CITED

Beckman, William C. 1948. The length-weight relationship, factors for
conversions between standard and total lengths, and coefficients
of condition for seven Michigan fishes. Trans. Amer. Fish.

Soc. 75 (1945): 237-256.

Briggs, John C. 1953. The behavior and reproduction of salmonid fishes
in a small coastal stream. Calif. Dep. Fish and Game, Fish.
Bull. 94, 62 p.

Carlander, Kenneth D. 1953. Handbook of freshwater fishery biology
with the first supplement. Wm. C. Brown Company, Dubuque,
Iowa, 429 p.

Gauley, Joseph E., Raymond E. Anas and Lewis C. Schlotterbeck. 1958.
Downstream movement of salmonids at Bonneville Dam. U. S..Fish
and Wildl. Serv., Spec. Sci. Rep., Fish. 236, 11 p.

Greeley, John R. 1933. The growth rate.of rainbow trout from Michigan
waters. Trans. Amer. Fish. Soc. 63: 361-378.

Li, Jerome C. R. 1964. Statistical inference. Edwards Brothers, Inc.,
Ann Arbor, Michigan. Vol. 1, 658 p.

Mann, H. B. 1945. Nonparametric tests against trend. Econometrics,
Vol. 13 (3).

Northcote, T. G. 1962. Migratory behaviour of juvenile rainbow trout,
Salmo gairdneri in outlet and inlet streams of Loon Lake,
British Columbia. J. Fish. Res. Ed. Can. 19: 201-270.

Pautzke, Clarence F., and Robert C. Meigs. 1941. Studies on the life
history of the Puget Sound steelhead trout (Salmoiggirdnerii),
Trans. Amer. Fish. Soc. 70 (1940): 209-220.

Siegel, Sidney. 1956. Nonparametric statistics for the behavioral
sciences. McGraw-Hill Book Company, Inc., New York. 312 p.

Shapovalov,-Leo and Alan C. Taft. 1954. The life histories of the
steelhead rainbow trout (Salmo gairdneri gairdneri) and silver
salmon (anorhynchus kisutch) with special reference to
Waddell Creek, California, and recommendations regarding
their management. Calif. Dep. Fish and Game, Fish. Bull. 98,
375 p.

40

41

Shetter, David S. and A. S. Hazzard. 1939. Species composition by age
groups and stability of fish populations in sections of three
Michigan.trout streams during the summer of 1937. Trans. Amer.
Fish. Soc. 68 (1938): 281-302.

Snedecor, George W. 1956. Statistical methods (5th ed.). The Iowa
State College Press, Ames, Iowa, 534 p.

Stauffer, Thomas M. 1964. An experimental sea lamprey barrier. Prog.
Pubs-Colts 26: 80-830

Wagner, Harry H., Richard L. Wallace and Homer J. Campbell. 1963. The
seaward migration and return of hatchery-reared steelhead
trout, Salmo gairdneri Richardson, in the Alsea River, Oregon.
Trans. Amer. Fish. Soc. 92: 202-210.

Whitney, Richard R. and Kenneth D. Carlander. 1956. Interpretation of
body-scale regression for computing body length of fish. Jour.
Wildl. Mgt. 20: 21-27.

WOIf, Phillip. 1951. A trap for the capture of fish and other organisms
moving downstream. Trans. Amer. Fish. Soc. 80 (1950): 41-45.

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