Yasumiishi et al.: Effect of population abundance and climate on 2 populations of Oncorhynchus keta 
205 
4CTN - 
30°N - 
20°N - 
12 Anadyr 
13 East Kamchatka 
14 West Kamchatka 
15 Okhotsk Coast 
16 Amur River 
17 Primorye 
18 Sakhalin and 
Kurile Islands 
19 Japan 
8 9 
1 Southern BC, WA 7 
2 Northern BC 
3 Southeast AK and Yakutat 
4 Prince William Sound 
5 Cook Inlet 
6 Kodiak 
7 South AK Peninsula 
8 North AK Peninsula 
9 Bristol Bay 
10 Arctic-Yukon-Kuskokwim 
q|V\ Fish Creek, 
0 \\ Alaska 
Gulf of Alaska 
Pacific Ocean 
Quilcene River,^ 
Washington 
250 500 1,000 Miles 
J I I I I I I I 
A 
_i_ 
180° 
170°W 
i 
160°W 
150°W 
i 
140°W 
i 
130°W 
Figure 1 
Map showing the regions used to estimate chum salmon (Oncorhynchus keta ) and pink salmon ( O . 
gorbuscha ) abundances (from Ruggerone et al. [2010]) and locations of Fish Creek, Alaska, where 
biological data were collected from 1972 to 2007, and Quilcene River, Washington, where biological 
data were collected from 1973 to 2007. 
of pink and chum salmon abundance and climate on 
stage-specific growth of these fish in those portions of 
the North Pacific Ocean that they occupy. The null hy- 
pothesis was that growth was not negatively related 
to an index of pink and chum salmon abundance and 
therefore chum salmon production was not limited by 
density-dependent growth in the North Pacific Ocean. 
The alternative hypothesis was that growth was nega- 
tively related to pink and chum salmon abundance — 
an indication that chum salmon production was lim- 
ited by density-dependent growth in the North Pacific 
Ocean. Our objectives were 1) to determine the exis- 
tence and magnitude of density-dependent growth, 2) 
to describe differences in density-dependent growth for 
chum salmon from WA and southern southeast Alaska, 
3) to evaluate the influence of pink and chum salmon 
abundances on chum salmon growth, 4) to evaluate the 
influence of local and regional abundances on growth, 
and 5) to determine the influence of climate on growth. 
Material and methods 
Data, sample size, and assumptions 
The National Marine Fisheries Service, Auke Bay Lab- 
oratories scientists collected biological data from sum- 
mer chum salmon in Fish Creek near Hyder, Alaska, 
from 1972 to 2007 and from fall chum salmon from the 
Quilcene River and U.S. Fish and Wildlife’s Quilcene 
National Fish Hatchery near Quilcene, WA, from 1973 
to 2007 (Fig. 1). Fish Creek chum salmon were sampled 
from mid- to late-August, the peak of the summer run. 
Quilcene River chum salmon were typically sampled 
during the first two weeks of December, the peak of the 
fall run. Although Fish Creek chum salmon returned to 
spawn earlier in the year, they were larger at maturity 
than Quilcene River chum salmon. 
Scales, body lengths, and sex data were collected 
from up to 300 chum salmon carcasses per year from 
both stocks. The aim was to obtain 50 samples for each 
sex and for the dominant age classes: age-0.2, age-0.3, 
and age0.4. Salmon ages were denoted with the decimal 
method (x.y), where x is the number of winters spent 
in freshwater after spending a winter in the gravel 
and y is the number of winters spent in the marine 
environment. For this study, we used only age0.3 male 
chum salmon to reduce variation in growth because of 
differences in growth between sexes and ages, and be- 
cause of data availability. Only age-0.3 chum salmon 
were sampled in some years and we have larger sam- 
ple sizes for males than females. We sampled during 
the peak of the spawning migration and the samples 
represented the dominant age class at that time. Typi- 
