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Fishery Bulletin 117(3) 
Figure 1 
Map of the 5 regions of the California Current System 
where Pacific sardine (Sardinops sagax) were sampled 
from 2005 through 2008 for analyses of parasite commu¬ 
nities. The regions are Vancouver Island, British Columbia 
(BC), Canada, Washington and Oregon (WA-OR), North¬ 
ern California (NorCA), Central California (CenCA), and 
Southern California (SoCA). Boxes outlined with a black 
line represent areas within each region in which opportu¬ 
nistic samples were taken. 
Although not all Pacific sardine were aged, we esti¬ 
mated ages to vary from 0 to 10 years, on the basis of 
Hill et al. (2010) and by using a relationship between age 
and SL (Javor 4 ). A subset of the Pacific sardine caught off 
California during this period was aged. The median age 
of this subset ranged from 2 years in 2005 and 2006 to 
3 years and 4 years in 2007 and 2008 (Dorval et al., 2015). 
4 Javor, B. 2008. Personal commun. Southwest Fish. Sci. Cent., 
Natl. Mar. Fish. Serv., 8901 La Jolla Shores Dr., La Jolla, 
CA 92037. 
However, analyses did not focus on fish age because it 
was not possible to age all individual Pacific sardine in 
our study. 
During 2007 and 2008, 168 northern anchovy 
(98.0-143.0 mm SL) were collected to serve as non- 
migratory sample controls. In June-July 2007, 20 north¬ 
ern anchovy (104-125 mm SL) were collected off Grays 
Harbor, Washington (47.00°N), and 97 fish (100-143 mm 
SL) were captured off Willapa Bay, Washington (46.67°N). 
In June 2008, 51 northern anchovy (98-142 mm SL) were 
collected off Point Hueneme, California (34.15°N). 
Each fish was thawed in the laboratory, weighed to the 
nearest 0.1 g, and measured (as SL in millimeters). To 
account for shrinkage due to freezing, lengths of thawed 
Pacific sardine were adjusted by using the following 
regression (Lo et al., 2007): 
Fresh SL = 2.89 + 1.0286 ( Thawed SL). 
No length regression formula was available for the north¬ 
ern anchovy to estimate fresh SL; therefore, SL values are 
reported from fish that were frozen and then thawed. 
Parasite recovery 
Standard necropsy procedures were followed to examine 
fish for parasites (Arthur and Albert, 1994; Baldwin and 
Goater, 2003), with the body cavity and external surface of 
the viscera examined for parasites during removal of the 
stomach and intestine. Gills were examined only in Pacific 
sardine caught in 2005 because only one unknown mono- 
genean was recovered from gills examined in 2005. Eyes 
were also not examined because no parasites were recov¬ 
ered from the eyes of Pacific sardine by us in a previous 
study; nor were they reported in other studies in the CCS 
(Love and Moser, 1983). When possible, recovered para¬ 
sites were identified morphologically to species by using 
dissection and compound microscopes; then they were pre¬ 
served in 95% ethanol. Most parasites were identified to 
species, but those in poor condition were classified only 
to phylum or class. Because we found no difference in geo¬ 
graphic distributions among 5 anisakid nematode taxa 
from a subset of these Pacific sardine in a previous study 
(Baldwin et al., 2011), all anisakids (identified genetically 
or morphologically) were combined into one category for 
this study and referred to herein as Anisakis spp. 
Statistical analyses 
We divide the study area of the CCS into 5 regions to 
best define where fish were sampled: 1) Vancouver Island 
(hereafter, referred to as British Columbia (from 52.0°N 
to 48.3°N), 2) Washington and Oregon (48.3°N to 42.0°N), 
3) Northern California (from the Oregon-California bor¬ 
der at 42.0°N to 38.0°N), 4) Central California (38.0°N to 
35.0°N), and 5) Southern California (south of 35.0°N to 
32.0°N) (Fig. 1). We describe the parasite communities as 
defined by Bush et al. (1997) by using parasite prevalence 
(the percentage of infected fish) and mean intensity (the 
number of individual parasites per infected fish). 
