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Fishery Bulletin 109(4) 
A Perimeter based on area 
June Dec June Dec 
B Perimeter based on length 
C Otolith weight based on length 
Figure 5 
Perimeter-weight profiles (PWPs) of late age-0 and 
age-1 Pacific sardine ( Sardinops sagax) otoliths from 
Monterey (region 3), San Diego (region 4), and Port 
Hueneme (region 3\4), 2006-07. (A) Perimeter based 
on area. (B) Perimeter based on length. (C) Weight 
based on length. The dashed line at 50% PWP repre- 
sents the population average (i.e., 50% of the residuals 
lie above the regression line) as determined by the 
regression equations. 
data in Figure 6. The ageiyear interaction term was not 
significant for perimeter (both P/L and P/A); therefore 
no further GLM was performed (Table 6). The age ef- 
fect was significant for perimeter (both P/A and P/L); 
the year effect was significant for only P/A and not for 
P/L. For the GLM of W/L, the age and year interaction 
term was significant. 
2006 2007 2008 1996 1997 2006 2007 2008 2008 
age 0 age 0 age 0 age lage lege lage lage 1- age 2- 
2 2 2 2 2 3 
Figure 6 
Multiyear comparisons of perimeter-weight profiles (PWPs) 
of Pacific sardine (Sardinops sagax ) otoliths from Mon- 
terey (region 3). (A) Profiles by collection year and age 
(number of otoliths indicated). The dashed line at 50% 
PWP represents the population average (i.e., 50% of the 
residuals lie above the regression line) as determined by 
the regression equations. The number of otoliths is indi- 
cated above each set. (B) Averages by age: age-0 (mean of 
3 years) and ages 1-2 (mean of 5 years). Each collection 
was normalized to 100 otoliths to remove year-based bias. 
Error bars are ±95% confidence intervals. 
Discussion 
PCA and PWP methods of comparison 
We compared otolith characteristics from a large collec- 
tion of Pacific sardine sampled from most of their North 
American range, which was divided into seven regions 
between Canada and the Gulf of California. Regional 
similarities and differences determined with MANOVA 
and perimeter-weight profile comparisons did not agree 
consistently with each other. 
One of the inherent problems with this kind of survey 
is that sardine otoliths elongate asymmetrically as they 
grow. Including all sizes of otoliths in any statistical 
analysis resulted in significant differences between 
northern stocks (where large adult sardine are com- 
mercially captured and few juveniles were found) and 
