Bilateral Asymmetry in Salmon— -L andrum 
197 
TABLE 1 
Bilateral Variation in the Number of Lateral Line Scales 
% 
% 
MEAN 
SAMPLE SOURCE 
NUMBER 
ASYMMET- 
ASYMMETRICAL 
OF 
100 
(YEAR) 
SPECIES 
SEX 
EXAMINED 
RICAL 
TOWARD LEFT 
(L-R) 
(P) 
MV "Attn” 
sockeye 
male 
13 
69.2 
66.7 
0.307 
>50 
56°N, 173°W 
female 
38 
65.8 
56.0 
0.053 
>50 
(1957) 
total 
51 
66.6 
58.8 
0.118 
>50 
53°N, 165°W 
sockeye 
male 
32 
68.8 
50.0 
-0.031 
>50 
(1957) 
female 
19 
63.2 
33.3 
-0.579 
>50 
total 
51 
66.6 
42.8 
-0.235 
>50 
50°N, 170° W 
sockeye 
male 
11 
72.7 
37.5 
0 
— 
(1957) 
female 
24 
62.5 
66.5 
0.208 
>40 
total 
35 
65.7 
56.5 
0.142 
>50 
Okanogan River 
sockeye 
male 
11 
90.9 
50.0 
0 
— 
(1957) 
female 
13 
76.9 
50.0 
0.154 
>50 
total 
24 
83.3 
50.0 
0.083 
>50 
Japanese Fishery 
sockeye 
male 
61 
59.0 
41.6 
-0.197 
>10 
50°N, 168°E 
female 
54 
68.5 
43.2 
-0.241 
>10 
(1958) 
total 
115 
63.4 
42.4 
-0.217 
> 5 
51°N, 172°E 
sockeye 
male 
49 
75.6 
44.1 
-0.244 
>10 
(1958) 
female 
74 
62.2 
43.4 
-0.175 
>10 
total 
119 
67.2 
43.7 
-0.202 
>10 
Combined sockeye 
male 
173 
68.8 
46.2 
-0.116 
>10 
samples 
female 
222 
65.3 
47.6 
-0.126 
>10 
total 
395 
66.8 
47.0 
-0.122 
> 5 
MV "Pioneer” 
chum 
male 
41 
75.6 
41.9 
-0.341 
>10 
50°-53°M, 
female 
33 
72.7 
20.8 
-1.121 
< 1 
175°-180°W (1957) 
total 
74 
74.3 
32.7 
-0.689 
< 1 
MV "Paragon” 
chum 
male 
72 
76.3 
36.3 
-0.430 
< 5 
50°-60°N, 175°W 
female 
63 
84.1 
52.8 
0.111 
>50 
(1957) 
total 
135 
80.0 
44.4 
-0.178 
>10 
Hokkaido I. 
chum 
male 
109 
70.6 
25.9 
-0.670 
< 1 
(1958) 
female 
51 
72.5 
35.1 
-0.608 
< 2 
total 
160 
71.2 
28.9 
-0.650 
< 1 
Combined chum 
male 
222 
73.4 
32.5 
-0.532 
< 1 
samples 
female 
147 
77.6 
40.4 
-0.415 
< 2 
total 
369 
75.1 
35.7 
-0.485 
< 1 
showed significant differences in counts from 
opposite sides. Approximately 78% of the total 
female chum salmon samples exhibited asym- 
metrical development, while only 73% of the 
males were asymmetrical. However, the prob- 
ability levels for the mean differences between 
sides for both males and females were not sig- 
nificant. Scale counts from the combined total 
of 369 chum salmon indicated some asymmetri- 
cal development in 75% of the specimens. Of 
all the specimens with asymmetries, counts from 
the right sides exceeded the left in approxi- 
mately 64%. The over-all mean difference be- 
tween left and right side counts (-0.485) was 
significant at the 0.01 level. 
Bilateral Variation in Gill Rakers 
Gill raker counts from the first left and right 
branchial arches were collected from sockeye 
salmon taken at 10 locations (Table 2). Male 
and female groups varied similarly, with no sig- 
nificant values occurring in either category in 
the individual samples. Probability values for 
sexes combined were significant in samples from 
3 locations. Bilateral asymmetry occurred in 
approximately 63% of the total of 668 sock- 
