Fishery bulletin of the Fish and Wildlife Service - NOAA

286 SALMON OF THE KARLUK EIVER, ALASKA
EXPERIMENTS IN 1931
Two marking experiments were conducted in 1931 (tables 37 and 38). For easy
reference they have been designated first and second although they were simultaneous.
In the first experiment, 50,000 seaward migrants were marked by amputating the
adipose and both ventral fins, 1,549 of these fish were recovered, and a calculated total
of 11,790 fish returned (23.6 percent of the number marked). The return from the
2-, 3-, 4-, and 5-year marked fish was 54.8, 21.2, 34.5, and 40.8 percent, respectively.
• . In the second experiment, 5,000 seaward migrants were marked by amputating
the adipose and dorsal fin, 124 were recovered, and a calculated total of 1,016 fish
returned (20.3 percent), -The return from this experiment, although slightly lower,
agrees closely with results of the first experiment. Amputation of the entire dorsal
fin close to the base results in a large wound that may have a deleterious effect on the
fish. The results of the first experiment are believed to be more reliable than those
of the second.
Age of
seaward
migrants
marked
2 ' . -.
3
t..
í. . ..
2„
3..
4.
{
Total ..
Age of
seaward
migrants,
marked
Total -
Calculated
number of
each age
marked
84
8,141
80,000
Calculated
number of
each age
marked
9
4, 131
824
36
5,000
TABLE 37.—Data for the first 19S1 marking experiment
Age of fish
returning
from 1931
migration
4»
61
81
4s
61
6s
7i
64
64
7«
84
/ 7»
X 8t
Calculated
number of
each age
group
examined
788
5,947
49
1,166
86,623
136, 439
249
' 1,434
48, 318
10, 669
17
1,721
293, 418
Number of
marked
fish of
each
age group
found
2
4
4
345
863 58
246
5S
14
1,549
Percentage
occurrence
of marked
fish In fish
examined
0. 264
.067
.343
.398
.633
2.008
.558
.509
.544
.813
Calculated
number of
flshof
each age
group
returning
9,191
34,756
2,143
11, 616
966, 016
767,240
2,278
21, 291
481, 549
62, 249
1,016
18, 407
671
2, 358, 320
Calculated
number of
marked
flsh
returning
23
23
. 39
3, 845
4,857
48
119
2,349
339
TABLE 38.—Data for the second 1981 marking experiment
Age of fish
returning
from 1931
migration
4i
5s
6s
4s
5s
6s
7s
64
64
74
84
f 7,
í 81
Calculated
number of
each age
group
786
5,947
49
1,186
86, 623
. 136,439
249
1,434
48, 318
10,869
17
1,721
293, 418
Number of
marked
fish of
each of
age group
found
1
37
57
24 3
2
124
Percentage
occurrence
of marked
fish In fish
0.086
.043
:042
.050
.028
.116
Calculated
number of
Ssh of
each age
group
returning
9,191
34, 756 '
2,143
11,516
968,015
767, 240
2,278
21, 291
461, 549
62,240
1,016
18, 407
671
2, 358, 320
150
11,790
Calculated
number of
marked
fish
returning
10
415
322
231
17
21
1,016
Percentage
return at
various
ages
27.4
27.4
.i
9.3
11.7
.1
1.5
28.8
4.2
40.8
Percentage
return at
various
ages
0.2
10.0
7.8
28. 0
2.1
68.3
Total
percentage
return
64.8
34.5
•
í 40.8
Total
percentage
return
'0.0
18.0
30. 1
\ ,
> 58.3