Javor et al.: Otolith morphometries and population structure of Sardmops sagax along the west coast of North America 
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Tabie 1 
Dates and regions for collections of Pacific sardine (Sardinops sagax) from north to south. The number of otoliths obtained 
per site is given in Figure 4. Areas with two region numbers (e.g., 2\3) were considered transitional regions. DFO=Fisheries 
and Oceans; SWFSC = Southwest Fisheries Science Center; NWFSC = Northwest Fisheries Science Center; CDFG = California 
Department of Fish and Game; CICIMAR=Centro Interdisciplinario de Ciencias Marinas; CICESE = Centro de Investigacion 
Cientifica y de Educacion Superior de Ensenada. 
Region no. and area 
Year 
Collections 
Provider 
1 Canada 
2003 
Vancouver I., 4 dates (adults) 
C. Hrabek, DFO 
2005 
Vancouver I., 1/28/05 area 24 (age 0) 
C. Hrabek, DFO 
2 Pacific Northwest 
2003 
Cruise FR0307 (3/03), 4 trawls 
SWFSC 
2003 
Cruise MF0313 (11/03), 6 trawls 
R. Emmett, NWFSC 
2004 
Cruise FR0403 (3/04), 3 trawls 
SWFSC 
2010 
Columbia River plume, 5/12 and 5/25 
R. Emmett, NWFSC 
2\3 Humboldt Bay 
1996 
Port samples, 3 dates 
CDFG 
3 Monterey 
1996-97 
Port samples, 8 dates 
CDFG 
2006-97 
Port samples, 21 dates 
CDFG 
2008 
Port samples, 4 dates 
CDFG 
3\4 Port Hueneme 
2007 
Port samples, 7 dates 
CDFG 
4 Los Angeles 
1995-2003 
Port samples, March-April (age 1) 
CDFG 
4 San Diego 
2003-09 
Bait receiver, monthly samples 
SWFSC 
5 Ensenada 
1991-92 
Port samples, spring and fall 
CDFG 
6 Bahia Magdalena 
2004 
Spring and fall, 4 dates 
R. Felix-Uraga, CICIMAR 
7 Gulf of California 
2006 
February and December 
Y. Rios, CICESE 
and southern California (Lo et al., 2005). However, sea 
surface temperatures are markedly different at the two 
areas. The average annual temperature range in Mon- 
terey Bay at Pacific Grove is 11.8°-14.5°C, whereas 20 
km south on the open coast, strong upwelling drives the 
temperatures lower (10°-13°C annual range; Breaker, 
2005). The mean annual temperature range at the 
Scripps Institution of Oceanography pier in La Jolla 
(San Diego) is 13.9°-20.0°C (www.nodc.noaa.gov/dsdt/ 
cwtg, accessed September 2010), whereas 23 km offshore 
from San Diego the temperatures are about 1°C warmer 
(www.calcofi.org, accessed September 2010). We also 
included sardine captured in 2007 near Port Hueneme 
(region 3\4), a landing in the Southern California Bight 
about midway between Monterey (region 3) and San 
Diego (region 4). Because regions 3 and 4 sardine reach 
a birthday during April, collections of cohorts during a 
calendar year are indicated as age 0—1, age 1-2, and age 
2-3. Each sample set included 19-25 fish per collection, 
and both left and right otoliths were used when possible. 
Statistical analysis 
For coast-wide comparisons, several statistical ap- 
proaches were used to ascertain patterns and regional 
characteristics of otoliths: principal components analysis 
(PCA), multivariate analysis of variance (MANOVA), and 
a method based on analysis of residuals described below. 
PCA was used initially to select the four most important 
otolith dimensions for the MANOVA and calculations of 
residuals. PCA and associated MANOVA statistics were 
applied only to age-1 otoliths (0.73-1.30 mg) because 
this age group was collected from all regions, whereas 
younger juveniles and older adults were not available 
from all areas. The coefficient 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 mea- 
surement among four variables. These selected measure- 
ments (length, area, perimeter, and weight) were then 
standardized (i.e., the correlation matrix rather than the 
covariance matrix) to be used in the MANOVA to test 
for possible differences in otolith dimensions with six 
orthogonal contrasts of individual regions or clusters of 
regions by using the Wilks’s lambda test of significance; 
Cl, regions 1-2 vs. 3-7; C2, region 1 vs. 2; C3, regions 
3-5 vs. 6-7; C4, regions 3 vs. 4-5; C5, region 4 vs. 5; and 
C6, region 6 vs. 7. PCA and MANOVA were conducted 
with S-Plus (TIBCO Software, Palo Alto, CA) or SAS 
(SAS Institute, San Diego, CA) software. 
In addition to MANOVA, we designed a method based 
on the residuals calculated from regression equations 
for measured otolith features in order to express mor- 
phometric data for comparisons with average data in 
simple models. Three regression equations with the 
use of the four most important dimensions determined 
by PCA (perimeter vs. area, perimeter vs. length, 
and weight vs. length) were derived from a data set 
of 2213 otoliths from all ages of sardine and all re- 
gions, whereas the MANOVA was performed for age-1 
fish only. By applying these equations to the observed 
measurements of each otolith, the expected average 
perimeter and weight were calculated from the otolith 
area or length. The differences between observed and 
