Javor et a!.: Otolith morphometries and population structure of Sardmops sagax along the west coast of North America 
411 
Table 5 
General linear model (GLM) for year (fij) and location (fi 2 ) interactions effects of region 3 and 4 sardine ( Sardmops sagax) otolith 
measurements for each perimeter-weight profile (PWP) factor: perimeter based on area, perimeter based on length, and weight 
based on length. Because the interaction term (fi 3 ) was significant, GLM was performed for both 2006 and 2007 for the three 
PWP factors. Significance: *=P< 0.05, **=P<0.005, ***=P< 0.001. 
Coefficient 
Standard 
estimate 
error 
2 -value 
P 
Significance 
Perimeter based on area, coefficients 
(Intercept) 
-0.9163 
0.1479 
-6.195 
5.82xlO -10 
*** 
Location (/3J 
0.6286 
0.1874 
3.354 
7.97xl0- 4 
*** 
Year (/3. 2 ) 
-0.4773 
0.2006 
-2.380 
0.0173 
* 
Location:year (j3 3 ) 
0.8760 
0.2513 
3.486 
4.91xl0 -4 
Perimeter based on length, coefficients 
(Intercept) 
-1.0515 
0.1525 
-6.894 
5.42xl0 -12 
*** 
Location 
0.8035 
0.1909 
4.209 
2.57xl0- 5 
*** 
Year 
-0.2702 
0.2021 
-1.337 
0.1813 
Location:year 
0.7360 
0.2526 
2.914 
0.00357 
** 
Weight based on length 
(Intercept) 
0.1791 
0.1993 
0.899 
0.3763 
Location 
0.0164 
0.2620 
0.063 
0.9506 
Year 
0.4879 
0.2617 
1.864 
0.0724 
Location :year 
-0.4265 
0.3450 
-1.236 
0.2263 
Weight based on length after excluding interaction 
term 
(Intercept) 
0.3226 
0.1650 
1.956 
0.0599 
Location 
-0.2305 
0.1718 
-1.342 
0.1897 
Year 
0.2427 
0.1722 
1.410 
0.1690 
2006 Perimeter based on area, coefficients 
(Intercept) 
-0.9163 
0.1479 
-6.195 
5.82xlO- 10 
*** 
Location 
0.6286 
0.1874 
3.354 
7.97xl0- 4 
*** 
2007 Perimeter based on area, coefficients 
(Intercept) 
-1.3936 
0.1355 
-10.286 
2.00xl0 -16 
*** 
Location 
1.5046 
0.1674 
8.988 
2.00 xl0“ 16 
*** 
2006 Perimeter based on length, coefficients 
(Intercept) 
-1.0515 
0.1525 
-6.894 
5.42xl0- 12 
*** 
Location 
0.8035 
0.1909 
4.209 
2.57xl0“ 5 
*** 
2007 Perimeter based on length, coefficients 
(Intercept) 
-1.3218 
0.1326 
-9.965 
2.00xl0“ 16 
*** 
Location 
1.5395 
0.1654 
9.310 
2.00xl0- 16 
*** 
southern stocks (where large adults are rarely cap- 
tured). These dissimilarities are likely due to age differ- 
ences. Within the size-class defined to comprise mostly 
age-1 otoliths, the dimensional relationships spanned a 
smaller range, but they could have biased the results if 
all regions did not have a similar distribution of otolith 
sizes. The results may have also been biased by the 
relatively small number of age-1 representatives from 
regions 1 and 2. Any statistical analysis is most reliable 
when sample sizes are large and balanced (Osborne and 
Costello, 2004). 
The predictability of dimensions of an average sardine 
otolith of any length or area was the premise for devel- 
oping the PWP method to compare sets of otoliths as an 
alternative approach for analyzing the data. PWPs gave 
a picture of regional signatures and temporal trends 
within and between year classes. Juvenile otoliths from 
northern California (and in 2010, the Pacific North- 
west) showed a regional signature as predominantly 
heavy and smooth, whereas juvenile otoliths from their 
southernmost distribution were predominantly light and 
lobate. Multiyear surveys showed trends in age-specific 
profiles for Monterey otoliths. 
The PWP method, which permitted the comparison 
of individual otolith features, revealed unique profiles 
among Mexican sardine. Region 5 otoliths appeared to 
have weight characteristics of the more southerly region 
6 and 7 populations and perimeter characteristics of 
region 4 southern California sardine. Migratory move- 
ments that could account for the uniformity of region 6 
