Yasumiishi et al.: Effect of population abundance and climate on 2 populations of Oncorhynchus keta 
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stage, combined and separate indices for chum and 
pink salmon abundance were calculated for WA and 
southern BC (SBC), northern BC (NBC), southern and 
northern British Columbia (BC), southeast Alaska and 
Yakutat (SE), SE to the Alaska Peninsula (AP) (SE— 
AP), BC through AP (BC-AP) and Asia (AS) owing to 
overlap in the distribution and diets of juvenile and 
adult pink and chum salmon (Fig. 1) (Orsi et al. 3 ; Davis 
et al. 4 , 2009). Chum salmon abundance indices were 
calculated by age (0.0, 0.1, 0.2, 0.3) to match each age 
during the growth period (SW1, SW2, SW3, SW4). For 
this study, SWla, SWlb, and SWlc were related to age 
0.0 pink and chum salmon abundances, SW2 was re- 
lated to age 0.1 pink and chum salmon abundances, 
SW3 was related to age 0.1 pink salmon and age 0.2 
chum salmon abundances, and SW4 was related to age 
0.1 pink salmon and age 0.3 chum salmon abundances. 
Three chum and pink salmon abundance indices were 
calculated for SW1 growth during age-0.0, the first 
year at sea. Maturing pink salmon were combined with 
the immature and maturing chum salmon because of 
spatial and dietary overlaps (Davis et al. 4 ). 
Each juvenile growth variable was related to three 
salmon abundance indices (chum salmon, pink salmon, 
and chum and pink salmon combined) from various re- 
gional groupings. For Fish Creek chum salmon, SWla 
was related to SE salmon abundance indices (3 indi- 
ces), SWlb was related to SE and BC-SE salmon abun- 
dance (6 indices), and SWlc was related to SE, BC-SE, 
SE-AP salmon abundance (9 indices). For Quilcene 
River chum salmon, SWla was related to SBC salmon 
abundance (3 indices), SWlb was related to BC and 
BC-SE salmon abundance (6 indices), and SWlc was 
related to SE, BC-SE, SE-AP salmon abundance (9 in- 
dices). For the immature and maturing stages, chum 
salmon growth was related to two salmon abundance 
indices (chum salmon and chum and pink salmon com- 
bined) from various regional groupings. For Fish creek 
chum salmon, SW2, SW3, and SW4 were related to SE, 
BC-SE, SE-AP, BC-AP, BC-AS, and AS (12 indices). 
For Quilcene River chum salmon, SW2, SW3, and SW4 
were related to BC, BC-SE, SE-AP, BC-AP, BC-AS, 
and AS (12 indices). 
Age composition for chum salmon in Alaska and 
Asia was assumed to be well characterized by the time 
series of age composition from the Fish Creek stock, 
whereas the age composition for the BC stocks was as- 
sumed to be characterized by age composition from the 
Quilcene River stock. 
3 Orsi, J., A. Wertheimer, M. Sturdevant, E. Fergusson, and B. 
Wing. 2009. Insights from a 12-year biophysical time series 
of juvenile Pacific Salmon in southeast Alaska: the Southeast 
Alaska Coastal Monitoring Project (SECM). NOAA Alaska 
Fisheries Science Center AFSC Q. Res. Rep., 8 p. [Available 
at website.] 
4 Davis, N. D., K. W. Myers, and Y. Ishida. 1998. Bering Sea 
salmon diet overlap in fall 2002 and potential for interac- 
tions among salmon. North Pacific Anadromous Fish Com- 
mission (NPAFC) Doc. 779, 30 p. 
Marine mortality rates were calculated from fry to 
maturity. Marine mortality rates were approximately 
97% for chum and pink salmon (Kaeriyama, 1998). Ap- 
proximately 70% of the total mortality occurs within 
the first 40 days at sea (Parker, 1968) and pink salmon 
experience a mortality of 2-4% (we used 3%) mortality 
per day for the first 40 days and 0.4-0.8%/d (we used 
0.6%/d) thereafter (Parker, 1968). These daily mortality 
rates were used to develop a survival rate schedule by 
life stage for pink and chum salmon. The products of 
the daily survival rates were used to expand returns to 
reflect abundance during the middle of each life stage 
in our study. 
Climate indices 
The six climate indices used in this study were mean 
late spring (May-June) wind speed (m/s), mean fall 
(Sept-Oct) wind speed (m/s), deepest winter (Dec-Feb) 
mixed layer depth (m), spring transition index (day of 
year), mean summer/fall (July-Oct) SST (°C), and the 
winter (Dec-Feb) Pacific Decadal Oscillation (PDO) 
index. 
Wind speed index Surface wind speed data were ac- 
cessed from the website of the NOAA Fisheries South- 
west Fisheries Science Center’s Environmental Re- 
search Division (website, accessed Sept 2009). Indices 
were derived from data sets of atmospheric pressure 
fields at 6-hour intervals from the Fleet Numerical Me- 
teorology and Oceanography Center. The spring wind 
(WS) index was calculated as the values for April 16 or 
17 at Dixon Entrance off southern SE Alaska (56.5°N, 
134. 5°W). The fall wind (WF) index was calculated as 
the average of the September and October monthly 
wind index values at the surface east of Kodiak Island 
(58.5°N, 150. 0°W). 
Mixed layer depth index A mixed layer depth (MLD) 
index for winter was available for the mouth of Res- 
urrection Bay (60°N, 149°W) in the northern GOA 
(Sarkar, 2007). The Freeland et al. (1997) algorithm 
was used to calculate the deepest winter MLD (m). 
Spring upwelling transition index The spring transition 
index (STI) represents the timing (day of year) of the 
transition from downwelling to upwelling off the coast 
of WA and OR (Logerwell et al., 2003). The STI values 
ranged from 48 in 1985 to 161 in 1993. The transition 
occurs between March and June. 
Upwelling magnitude index The monthly magnitude of 
upwelling (m 3 s _1 100 nr 1 of coastline) off WA was ac- 
cessed from NOAA’s Pacific Fisheries Environmental 
Laboratory website (website, accessed Sept 2008). The 
location of the upwelling index (UI) was 23 nautical 
miles (nmi) south and 13 nmi west of Cape Flattery 
at the tip of the Olympic peninsula off the WA coast 
(125°W and 48°N). A spring UI was calculated as the 
sum of the May and June indices. 
