378 
Fishery Bulletin 109(4) 
Table 5 
Comparison of Steller sea lion (Eumetopias jubatus ) diet composition by site, after controlling for collection year and month. 
Sample size ( n ) and individual number of prey types (D) are given for each diet; pooled number of unique prey types (D ), cor- 
relation coefficient ( r M ), and permutation-based P-value (based on 9999 replications) are given for each comparison. * Indicates 
significance at the a=0.002 level (based on Bonferroni adjustment of a=0.05 for 26 multiple comparisons). 
Year 
Month 
Diet 1 
Diet 2 
D e 
Mantel test 
Site 
tl 
D 
Site 
n 
D 
r M 
P value 
1990 
July 
Orford Reef 
41 
6 
Rogue Reef 
43 
16 
17 
0.079 
0.0002* 
2002 
July 
Rogue Reef 
33 
27 
St. George Reef 
33 
13 
28 
0.075 
0.0023 
2004 
July 
Rogue Reef 
33 
20 
St. George Reef 
33 
21 
25 
0.096 
0.0008* 
Pacific hake 
Salmon species 
Skate species 
Pacific lamprey 
Unidentified clupeid 
Rockfish species 
Northern anchovy 
Cephalopod combined 
Unidentified fish 
© Pacific herring 
Q. 
.S' Pacific staghorn sculpin 
aT Pacific sardine 
?• Pacific sand lance 
c 
| Smelt species 
^ Three spine stickleback 
Sculpin species 
Jack mackerel 
Irish lord species 
Shrimps 
Eulachon 
Northern lampfish 
Capelin 
Pacific cod 
Arrowtooth flounder 
Atka mackerel 
Walleye pollock 
0 20 40 60 80 100 
Percent (%) frequency of occurrence 
Figure 3 
Percent frequency of occurrence (FO) of primary prey reported for Steller sea lions (Eumetopias juba- 
tus') in Alaska (n = 6 studies) and northern California and Oregon (this study). FO summary for Trites 
et al. (2007b) and Merrick et al. (1997) was calculated by the authors of the present study. Scientific 
names for prey types can be found in Table 1. 
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t* X V A • 
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9 « 
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Symbol 
Region 
Years 
□ 
WAK 
1990-93 
O 
WAK 
1990-98 
* 
Gulf AK 
1975-78 
X 
Gulf, AK 
1999-05 
A 
SE AK 
2001-04 
V 
SE AK 
1993-99 
• 
NCA/OR 
1986-07 
n Source 
338 Merrick et al. (1997) 
3762 Sinclair and Zeppelin (2002) 
250 Pitcher (1981) 
2760 McKenzie and Wynne (2008) 
787 Womble and Sigler (2006) 
1494 Trites et al. (2007b) 
1416 This study 
samples. For example, scat that we collected on rook- 
eries (i.e., Rogue Reef, Orford Reef, St. George Reef) 
during the summer breeding season primarily reflect 
adult female diet because males often fast during the 
breeding season and juveniles are not generally present 
at rookery sites. 
The Steller sea lion recovery plan (NMFS, 2008) 
notes that although several factors affecting the endan- 
gered WDPS also affect the threatened EDPS, those 
threats do not appear to be affecting the sustained 
growth or recovery of the EDPS. It is noted in the 
plan, however, that concerns regarding climate change, 
