62 
PACIFIC SCIENCE, Vol. XVII, January 1963 
TABLE 5 
Vertebral Counts for Gillichthys mirabilis 
(Key: x, mean; s, one standard deviation.) 
NO. 
OF VERTEBRAE 
STATISTICAL PARAMETERS 
AREA 
YEAR 
31 
32 
33 
n 
X 
±s 
Pacific Coast 
San Francisco 
1955 
3 
13 
3 
19 
32.00 
0.577 
Pta. Abreojos 
1948 
2 
14 
1 
16 
31.88 
0.341 
Gulf of California 
Bahia Cholla 
1949 
- 
29 
1 
30 
32.03 
0.182 
San Felipe 
1955 
- 
39 
1 
40 
32.03 
0.157 
Est. Soldado 
1952 
- 
30 
- 
30 
32.00 
0 
Salton Sea 
1955 
1 
23 
6 
30 
32.17 
0.461 
of fin ray counts may change, the relationships 
between them are relatively unaffected. 
The divergence of means between the year 
class samples from Bahia Cholla is greater than 
that recorded in the Salton Sea material. The 
mean number of rays for each fin, except the 
first dorsal, is higher in the "cold” year than in 
the "normal” year fish. The differences are sig- 
nificant at the 5% critical level. The outstand- 
ing deviation is in the mean of the second dorsal 
fin which is higher by one full ray. 
The relationship between the counts of the 
fin rays also is different in the 1949, or "cold” 
year class from Bahia Cholla. This results from 
the disproportionate increase of the soft dorsal 
fin count, which exceeds the anal fin by 1.7 rays. 
In most populations, as in the 1954 collection 
from Bahia Cholla, the average number of rays 
in the second dorsal fin surpasses that in the 
anal by only about one ray (0.8 to 1.3). 
The fin index also reflects the change in the 
relationship between the fin counts. It is higher 
by 4% in the 1949 sample, probably due to 
the unusual rise in the number of dorsal fin rays. 
Although the average number of fin rays and 
their interactions may change from year to year, 
the variance of each fin remains the same. F- 
tests were performed using the maximum and 
minimum variance of each fin within the year 
classes of each population; all F-ratios were 
below the 5% level of significance. 
The direction of the annual variation in fin 
counts is of particular importance to conclusions 
drawn later. In each instance when a year class 
deviates to a noticeable degree, the direction of 
the changes are the same for all fins with seg- 
mented rays. Increases in the dorsal and anal fin 
counts, as just shown, are paralleled by an in- 
crease in the number of pectoral fin rays; i. e., 
they are positively correlated. Within any one 
year class, however, there is no correlation what- 
soever between the number of segmented rays 
in median fins and in the pectoral fins (Table 
7 ) . The pectoral fin counts are the same, on 
the average, whether a fish has many or few 
median fin rays, when from the same year class. 
The bilateral asymmetry of the number of 
pectoral fin rays fluctuates between samples of 
year classes from the Salton Sea and from Bahia 
Cholla. Both the amount and the direction of 
the asymmetry vary (Table 4). The total asym- 
metry is maximal in the Salton Sea sample for 
1955 and in the Bahia Cholla collection taken 
in 1949. 
The head and jaw length and the anal fin 
heights are about the same in the three year 
classes collected from the Salton Sea. When the 
three groups are tested together, the differences 
are significant (Table 2), although the com- 
parison of anal fin heights for all three samples 
just exceeds the 5% level of significance. If 
only the 1954 and 1955 samples are compared, 
the differences no longer are significant (Table 
3). The size ranges of the 1954 and 1955 sam- 
ples nearly coincide, while that from the 1953 
year class contains larger fish. The inclusion in 
