Javor et al.: Otolith morphometries and population structure of Sardinops sagax along the west coast of North America 
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2003 2005 2003 2003 - 2010 1996 1996 - 2006 - 2007 2006 - 2009 - 1991 - 2004 2006 
2004 1997 2007 2007 2010 1992 
Region and year 
Figure 4 
Regional perimeter-weight profiles (PWPs) of Pacific sardine ( Sardinops sagax) otoliths. 
All are age 1-2, except age-0 juveniles (designated by a j) and adults >age-2 (designated by 
an a). Regions 2, 3, and 4 were divided by collection years (designated by ' and by "). 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 numbers above 
the columns represent the number of otoliths collected. 
of the three PWP factors, compared for each otolith 
(n=2213), were largely similar across the seven geo- 
graphic areas. They were positive between the two 
ways of conducting perimeter calculations (0.682) and 
negative or neutral between perimeter (P/A and P/L) 
and weight calculations (-0.382 and 0.071) (data not 
shown). 
Northern vs. southern California sardine populations 
The PWP perimeters calculated from otolith area and 
length in monthly or semimonthly collections were 
significantly different for Monterey and San Diego 
(regions 3 and 4) sardine in 2006-07 (Fig. 5, A and B). 
Monterey otoliths tended to have smoother perimeters. 
Distinctions between predicted and observed otolith 
weights for the two sites were not apparent (Fig. 50. 
Fish standard lengths (SL) and condition factors were 
similar for the two sites as were the regressions for SL 
vs. otolith weight and SL vs. otolith length (data not 
shown). Because somatic and otolith growth rates were 
similar in the cohorts at the two locations, differences 
in otolith perimeters were likely due to environmental 
factors. 
The Port Hueneme (region 3\4) samples in 2007 had 
perimeter profiles more like those of San Diego otoliths 
with the area-based regression and widely ranging 
perimeter attributes similar to both Monterey Bay and 
San Diego otoliths with the length-based regression. 
There was no distinction between weight profiles for 
the three sites during the same time period. The most 
salient feature of the 13 Port Hueneme collections over 
a five-month period was their nonuniformity. 
A GLM with logistic link was used to examine the 
possible difference between PWPs for perimeter based 
on area (P/A), perimeter based on length (P/L), and 
weight based on length (W/L) between Monterey and 
San Diego (location effect) and between years 2006 and 
2007 (year effect) (Table 5). For both cases of perimeter 
(P/A and P/L), the interaction term ( yearxage ) was 
significant, and therefore two separate GLMs were per- 
formed to test for possible location effects, each for 2006 
and 2007. The location effect for each of the two years 
was significant (PcO.001) with the difference between 
locations being greater in 2007 than in 2006. For the 
GLM analysis of PWP for W/L, location and year effects 
were not significant. Thus, only PWP perimeters (P/A 
and P/L) were dissimilar between regions 3 and 4 for 
these two years. 
Fish age and collection year were factors for PWPs 
of sardine captured in Monterey. In a multi-year sur- 
vey, age-1 and older otoliths tended to be smoother 
and heavier than average, but year-to-year PWPs were 
somewhat inconsistent (Fig. 6). Age-0 otolith PWPs did 
not show a predictable pattern that resembled that of 
older fish. The GLM was used to test age effect (age 0 
and age 1-2) and year effect (2006 and 2007) for the 
three PWP factors P/L, P/A, and W/L of the region 3 
