Javor et al.: Otolith morphometries and population structure of Sardmops sagax along the west coast of North America 
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sons for the significant differences between neighboring 
regions that share spawning or oceanographic features 
(contrasts 2, 5, and 6) were not apparent. Small sample 
sizes may have biased some of the results. Age 0-1 
otoliths from the northernmost areas were not well 
represented: n = 30 from Canada (region 1), all from a 
single collection date; and n- 20 from the Pacific North- 
west (region 2). However, sample size might not explain 
why southern California and Ensenada (regions 4 and 
5) otoliths were significantly different, and why Bahia 
Magdalena and Gulf of California (regions 6 and 7) 
were dissimilar. 
We initially conducted PCA of over 1100 otoliths 
by aggregating all ages in a region, from juveniles to 
adults, which resulted in size-biased, significant dif- 
ferences within and between regions (data not shown). 
Otoliths from regions 1 and 2, the only areas with 
large adults in the collections, differed from all other 
regions. This response derived from the overall shape 
differences between young and older otoliths (Fig. 2). In 
order to compare otoliths of all sizes in collections that 
had different distributions of sizes, another approach 
was required. 
Perimeter-weight profiles (PWPs) The regression lines 
between pairs of otolith features for sardine of all ages 
and regions were linear (perimeter vs. length) or curvi- 
linear (perimeter vs. area, and weight vs. length) (Fig. 
3). The regression equations used for calculating PWPs 
and their correlation coefficient (R 2 ) values for these 
features are as follows: 
Perimeter (based on area) = 
-0.2250 area 2 + 3.1559 area + 1.9071, R 2 = 0.968 (4) 
Perimeter (based on length) = 
2.6808 length + 0.118, R 2 = 0.975 (5) 
Table 2 
Summary of principal components (comp) analyses of 
age-1 sardine ( Sardinops sagax) otolith measurements 
based on the four most important features of length, area, 
perimeter, and weight. One otolith was examined per fish. 
The numbers of otoliths per region are as follows: region 
1 (30), region 2 (20), region 3 (86), region 4 (280), region 5 
(87), region 6 (36), region 7 (150), total (689). 
Importance of components 
Comp 
1 
Comp 
2 
Comp 
3 
Comp 
4 
Standard deviation 
1.86 
0.59 
0.32 
0.29 
Proportion of variance 
0.864 
0.088 
0.026 
0.022 
Cumulative proportion 
0.864 
0.953 
0.978 
1.000 
Eigenvalues 
3.46 
0.35 
0.10 
0.08 
Coefficients 
Length 
0.514 
-0.229 
0.732 
0.384 
Area 
0.520 
-0.850 
Perimeter 
0.496 
-0.540 
-0.639 
0.233 
Weight 
0.468 
0.810 
-0.220 
0.276 
Weight (based on length) = 
(length 2 - 2429 ) x (0.1054), 
R 2 = 0.966, for otoliths <3 mm (6) 
Weight (based on length) = 
0.2709 length 2 - 0.605 length + 0.6084, 
7? 2 =0.947, for otoliths >3 mm (7) 
PWPs showed several distinct regional and age patterns, 
particularly between northern California (regions 2\3 
and 3, Humboldt Bay and Monterey) and regions 5-7 
Table 3 
Data from a coast-wide survey of the four most important Pacific sardine ( Sardinops sagax ) otolith dimensions (length, area, 
perimeter, and weight) determined by principal component analysis and multivariate analysis of variance to test the hypothesis 
of no overall region effects and in each of the six orthogonal contrasts of individual regions and clusters of regions. The coef- 
ficient of the characteristic vector of the product of contrast sum-of-square cross-product (SSCP) matrix (H) and the inverse of 
the error SSCP matrix (E) were used to determine the influential measurement among the four variables. The results include 
characteristic roots and vectors of E-1H. Significance ( PR>F ) was <0.0001 for no region effect and all contrasted regions. 
Denom. = denominator. 
Characteristic vector 
Wilks’s Standardized measurements 
Contrasted regions 
Hypothesis: no effect 
lambda 
value 
F 
value 
No. of 
df 
Denom. 
df 
Characteristic 
root 
Percent 
Length 
Area 
Perimeter 
Weight 
No region effect 
0.61 
15.13 
24 
2370 
0.359 
64.15 
0.010 
-0.003 
0.055 
-0.032 
1: 1-2 vs. 3-7 
0.94 
10.02 
4 
679 
0.071 
100 
0.010 
-0.074 
0.081 
0.010 
2: 1 vs. 2 
0.92 
14.61 
4 
679 
0.059 
100 
-0.010 
0.057 
0.019 
-0.033 
3: 3-5 vs. 6-7 
0.90 
19.86 
4 
679 
0.042 
100 
-0.170 
-0.007 
0.042 
0.025 
4: 3 vs. 4-5 
0.93 
12.06 
4 
679 
0.116 
100 
0.001 
0.042 
0.029 
-0.044 
5: 4 vs. 5 
0.90 
19.74 
4 
679 
0.086 
100 
0.011 
-0.011 
0.019 
-0.026 
6: 6 vs. 7 
0.96 
7.16 
4 
679 
0.117 
100 
-0.026 
0.039 
-0.055 
0.045 
