250 
Fishery Bulletin 107(2) 
Table 4 
Hierarchical gene-diversity analysis of 27 populations of chum salmon ( Oncorhynchus keta) within 13 regions for 14 microsatel- 
lite loci. Regions had a Pacific Rim distribution, and the time difference between the earliest and latest samples included for 
specific populations ranged from 1 to 21 years. Ratio is the sum of the variance components of among populations within regions 
and among regions divided by the variance component among years within populations. * P<0.05 ** P<0.01. 
Locus 
Within 
populations 
Among years 
within populations 
Among populations 
within regions 
Among 
regions 
Ratio 
Oke3 
0.9204 
0.0004 
0.0056** 
0.0736** 
198.0 
OkilOO 
0.9673 
0.0008 
0.0070** 
0.0249** 
39.9 
Ots3 
0.9254 
0.0018* 
0.0044** 
0.0685** 
40.5 
Oki2 
0.9625 
0.0065** 
0.0044* 
0.0266** 
4.8 
OmylOll 
0.9783 
0.0016 
0.0013 
0.0187** 
12.5 
Onel04 
0.9783 
0.0004 
0.0030** 
0.0183** 
53.3 
Otsl03 
0.9837 
0.0007 
0.0029** 
0.0126** 
22.1 
Ssa419 
0.9785 
0.0018* 
0.0054** 
0.0143** 
10.9 
OnelOl 
0.9635 
0.0015 
0.0088** 
0.0262** 
23.3 
Omml070 
0.9918 
0.0011 
0.0031** 
0.0040* 
6.5 
Onell4 
0.9881 
0.0009 
0.0042** 
0.0068* 
12.2 
Onel02 
0.9941 
0.0008 
0.0018 
0.0033* 
6.4 
OtsG68 
0.9854 
0.0015 
0.0036** 
0.0095** 
8.7 
Onelll 
0.9727 
0.0016* 
0.0030 
0.0227** 
16.1 
Total 
0.9722 
0.0015 
0.0041** 
0.0222** 
17.5 
among regions, among populations within regions, 
and among years within populations. Within popula- 
tions, the time difference between the earliest and 
latest samples included in the analysis ranged from 21 
years (1986-2007) for Disappearance Creek (Southeast 
Alaska), 18 years (1986-2004) for Lagoon Creek (Queen 
Charlotte Islands), 16 years (1989-2005) for Nekite 
River in Smith Inlet, 15 years (1988-2003) for Gisasa 
River (Lower Yukon River), down to 1-3 year differences 
for populations in a number of regions. For 13 regions 
ranging from west Kamchatka to the Fraser River, the 
amount of variation within populations ranged from 
92% ( Oke3 ) to 99% (Omml070), with the average for an 
individual locus 97% (Table 4). Variation among the 13 
regions included in the analysis accounted for 2.2% of 
total observed variation. Variation among populations 
within regions accounted for 0.4% of observed variation, 
with differences among regions over five times greater 
than differences among populations within regions. The 
variation among sampling years within populations was 
the smallest source of variation observed, accounting 
for 0.2% of all variation. Differentiation among regions 
and populations within regions was approximately 18 
times greater than that of annual variation within 
populations. For the time intervals surveyed in our 
study, annual variation in microsatellite allele frequen- 
cies was relatively minor compared with differences 
among populations within regions and among regions 
on a geographically diverse scale of distribution of the 
populations analyzed. 
Population structure 
Significant genetic differentiation was observed among 
chum salmon populations sampled in the different 
geographic regions surveyed. The F ST value over all 
populations and loci was 0.033, with individual locus 
values ranging from 0.009 ( Omm 1070 ) to 0.104 ( Oke3 ) 
(Table 2). Chum salmon from Japan and the Yukon 
River were among the most distinct regional groups of 
stocks included in the survey (Table 5). Greatest genetic 
differentiation (greatest difference in F ST values) was 
observed in comparisons between Japanese, Russian, 
western Alaskan, and Yukon River chum salmon com- 
pared with those in other regions in North America to 
the south and east. In Asia, chum salmon from Japan 
were generally distinct from those in Russia. In North 
America, significant regional differentiation was gen- 
erally observed, with chum salmon in more northern 
regions distinct from those in more southern regions. 
Two major lineages of chum salmon populations were 
identified in the cluster analysis. The first lineage in- 
cluded all populations sampled from Korea, Japan, 
Russia, the Mackenzie River, Kotzebue Sound, Norton 
Sound, the Yukon River, and northern and central Bris- 
tol Bay. Populations from southern Bristol Bay were 
intermediate between the two major lineages, and all 
populations from the Alaska Peninsula south and east 
to Washington State were identified as the second ma- 
jor lineage (Fig. 2). Within the first lineage, all Asian 
populations were distinct from all North American 
