Fishery bulletin of the Fish and Wildlife Service - NOAA

1
2
3
4 .
1
2
3
4
Age of seaward migrants
marked
Total
> See p. 284.
Age of seaward migrants
marked
Total
FISHERY BULLETIN OP THE FISH AND WILDLIFE SERVICE
Calculated
num her of
each age
marked
TABLE 35.—Data for the second 1930 marking experiment.
237
14,923
fl,554
25, 000
Calculated
number of
each age
marked
Age of fish
returning
from 1930
migration
4i
í ? ъ&г
6i
7i
S,
& 7«
6<
7j
Calculated
number of
each age
group examined
130
2,078
3,212
1,252
67, 451
32,251
8,669
72, 392
1,769
325
1,146
190 675
Number of
marked fish
of each age
group found
6
150
97
>2
37
345
13
16
666
Percentage
occurrence
of marked
flsb in fish
examined
0.479
.222
.301
.427
.477
.735
1.396
Calculated
number of
fish of each
age group
returning
804
18,664
38,624
8,764
714, 745
268,334
48,829
802,844
21,838
1,507
8,835
1, 633 788
TABLE 36.—Data for the third 1930 marking experiment
46
2,956
1,939
59
5,000
Age of fish
returning
from 1930
migration
a
4i
í 42
-5s
Oj
54
64
ll
\ 75
Calculated
number of
each age
group examined
130
2,078
3,212
1,252
67, 451
32, 251
8,669
72,392
1,769
325
1,146
190, 676
Number of
marked fish
of each age
group found
1
31
148
50 1
2
107
Percentage
occurrence
of marked
fish in fish
examined
0.080
.046
.043
.092
.069
.057
.175
Calculated
number of
fish of each
age group
returning
804
18,664
38,624
8,764
714, 745
268, 334
48,829
502, 844
21, 838
1,507
8,835
1, 633, 788
Calculated
number of
marked fish
returning
42
1, «87
808
230
2,399
161
123
5 350
Calculated
number of
marked fish
returning
7
329
115
45
347
12
16
870
Percentage
return
at various
ages
0.3
10.6
5.4
2.4
25.1
1.7
41.6
Percentage
re turn
at various
ages
0.2
11.1
3.9
2.3
17.9
.6
25.4
285
Total percentage
return
\ 0.0
/
1 16.3
[• 29.2
Total per
centage
return
} 0.0
In the third experiment, 5,000 seaward migrants were marked by amputating the
adipose and right pectoral fins, 107 of these were recovered, and a calculated total of
870 marked fish returned (17.4 percent).
The data for the first and second experiments are considered more reliable than
those of the third, because more fish were marked and more fish recovered, and because
there is the possibility that an unusual mortality occurred among the fish of the
third experiment. Some of the seaward migrants, marked by removal of the adipose
and right pectoral fins appeared to have a slight "list" and appeared to be maintaining
balance with difficulty.
Grouping the data for the first and second experiments, 50,000 were marked,
1,297 were recovered, and a calculated total of 10,495 marked fish returned (21.0
percent). The return from the marked 2-, 3-, 4-, and 5-year seaward migrants was
2.4, 16.6, 28.0, and 32.0 percent, respectively.
15. 2
20.8
26.4