Beacham et al.: Population structure of Oncorhynchus keta across the Pacific Rim 
251 
Table 5 
Mean pairwise F ST values averaged over 14 microsatellite loci from 15 regional groups of chum salmon ( Oncorhynchus keta) 
outlined in Table 3 that were sampled at 381 locations across the Pacific Rim. Comparisons were conducted between individual 
populations in each region. Values in bold are the diagonal, and are comparisons among populations within each region. F ST 
values are listed below the diagonal, with standard deviations above the diagonal. Some of the reporting regions listed in Table 
1 were combined as indicated in Table 3 in order to facilitate the analysis. RC is region code, and codes are as follows: 1) Japan, 
2) Russia, 3) Western Alaska, 4) Yukon River, 5) Central Alaska, 6) Southeast Alaska, 7) Queen Charlotte Islands, 8) Northern 
British Columbia, 9) Skeena River, 10) Central British Columbia, 11) Southern mainland British Columbia, 12) West coast Van- 
couver Island, 13) East coast Vancouver Island, 14) Fraser River, 15) Washington. 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
1 
0.019 
0.009 
0.014 
0.023 
0.015 
0.007 
0.008 
0.009 
0.009 
0.009 
0.008 
0.007 
0.008 
0.011 
0.011 
2 
0.026 
0.017 
0.013 
0.018 
0.016 
0.011 
0.010 
0.011 
0.012 
0.011 
0.011 
0.010 
0.010 
0.011 
0.014 
3 
0.028 
0.024 
0.012 
0.018 
0.018 
0.011 
0.011 
0.011 
0.012 
0.011 
0.009 
0.010 
0.011 
0.015 
0.013 
4 
0.053 
0.054 
0.031 
0.018 
0.020 
0.013 
0.014 
0.014 
0.019 
0.014 
0.015 
0.013 
0.017 
0.022 
0.016 
5 
0.042 
0.032 
0.037 
0.064 
0.027 
0.014 
0.016 
0.015 
0.019 
0.016 
0.014 
0.015 
0.013 
0.011 
0.015 
6 
0.042 
0.029 
0.035 
0.062 
0.024 
0.007 
0.006 
0.005 
0.016 
0.006 
0.007 
0.005 
0.011 
0.006 
0.009 
7 
0.050 
0.039 
0.043 
0.068 
0.034 
0.015 
0.012 
0.007 
0.017 
0.007 
0.007 
0.005 
0.014 
0.008 
0.010 
8 
0.044 
0.031 
0.037 
0.063 
0.026 
0.008 
0.015 
0.008 
0.017 
0.007 
0.009 
0.007 
0.013 
0.009 
0.012 
9 
0.053 
0.041 
0.046 
0.066 
0.035 
0.019 
0.025 
0.019 
0.014 
0.017 
0.014 
0.012 
0.017 
0.015 
0.017 
10 
0.043 
0.031 
0.037 
0.062 
0.030 
0.011 
0.014 
0.010 
0.020 
0.008 
0.007 
0.005 
0.013 
0.008 
0.009 
11 
0.046 
0.033 
0.040 
0.068 
0.039 
0.022 
0.025 
0.021 
0.030 
0.018 
0.014 
0.007 
0.019 
0.012 
0.012 
12 
0.044 
0.034 
0.038 
0.062 
0.038 
0.019 
0.018 
0.019 
0.026 
0.017 
0.016 
0.008 
0.016 
0.009 
0.010 
13 
0.043 
0.032 
0.034 
0.060 
0.039 
0.026 
0.031 
0.026 
0.035 
0.025 
0.019 
0.022 
0.022 
0.018 
0.011 
14 
0.041 
0.028 
0.035 
0.063 
0.037 
0.025 
0.030 
0.026 
0.033 
0.024 
0.018 
0.021 
0.020 
0.013 
0.015 
15 
0.051 
0.039 
0.047 
0.076 
0.045 
0.028 
0.033 
0.029 
0.035 
0.025 
0.022 
0.023 
0.028 
0.022 
0.022 
populations. Within the Asian portion of the lineage, 
Japanese, Korean, and Russian Primorye populations 
were distinct from other Asian populations. In the sec- 
ond lineage, populations from Washington and southern 
British Columbia were among the most distinct group 
of populations, along with populations from the Queen 
Charlotte Islands in northern British Columbia. 
Chum salmon spawning in tributaries of different 
major river drainages generally clustered together in 
the analysis. For example, Fraser River populations 
clustered together in 39% of dendrograms evaluated, 
Skeena River populations clustered together in 97% of 
dendrograms evaluated, and Taku River populations 
clustered together in 96% of dendrograms evaluated 
(Fig. 2). The one exception was the Yukon River, where 
lower river summer-run populations did not form dis- 
tinct clusters unique from neighboring populations in 
the Kuskokwim River and the Nushagak River. 
A very distinct regional cluster of populations was 
observed in the Asian populations, with Korean, Japa- 
nese, and populations from the Primorye region in Rus- 
sia clustering together in 100% of dendrograms evalu- 
ated. Within that cluster, populations from Primorye 
clustered together in 67% of dendrograms evaluated, 
indicative of genetic differentiation between popula- 
tions from that region and those in Japan and Korea. 
Within Japan, a general regional structuring of popula- 
tions was observed, with populations from the Pacific 
coast of Honshu Island forming a distinct group (92% 
of dendrograms evaluated), as did populations from the 
Nemuro Strait (89% of dendrograms) and the eastern 
Pacific coast of Hokkaido Island (50% of dendrograms). 
Within Russia, Magadan region populations clustered 
together in 41% of dendrograms evaluated, as did pop- 
ulations from the northern Sea of Okhotsk (100% of 
dendrograms). Although populations from east coast 
of Kamchatka and west coast of Kamchatka generally 
clustered as two distinct regional groups, the groupings 
were not strongly supported by the bootstrap analysis. 
Populations from northeast Russia were distinct from 
those in other regions, with the possible exception of the 
Utka River population from west Kamchatka. 
In North America, some level of regional structuring 
of populations was observed in both Kotzebue Sound 
and Norton Sound (Fig. 2). Within the Yukon River 
drainage, there was clear separation between sum- 
mer-run populations in the lower and mid- portions 
of the drainage and fall-run populations in the upper 
portion of the drainage. For the fall-run, populations 
in the White River in the Yukon Territory were quite 
distinct, clustering together in 100% of dendrograms 
evaluated. Similarly, fall-run populations in the Ta- 
nana River (upper portion of Yukon River drainage in 
Alaska) clustered together in 74% of the dendrograms 
evaluated, and summer-run populations in the Tanana 
River drainage clustered together in 96% of dendro- 
grams. Summer-run populations in the lower Yukon 
River drainage did not cluster exclusively with each 
