Martinson et al.: Growth and survival of Oncorhynchus nerka 
491 
2000). Marks were made along the reference line at the 
center of the scale focus, between the last freshwater 
circulus and the first marine circulus, at the outer edge 
of the first marine annulus, at the outer edge of the 
second marine annulus, and the outer edge of the scale. 
Scales were measured to the nearest 0.0001 mm. 
Growth indices 
Four growth rates in body length were estimated from 
the scale measurements. Body length at the time of 
entry into saltwater (FW) was estimated as the dis- 
tance from the focus to the end of the last freshwa- 
ter annulus or the end of the plus growth. First-year 
marine (Ml) scale growth was estimated as the dis- 
tance from the center of the space between the last 
freshwater and first marine circulus to the outer edge 
of the first marine annulus. Second marine-year scale 
growth (M2) was estimated as the distance from the 
outer edge of the first marine annulus and the outer 
edge of the second marine annulus. Third marine- 
year (M3) scale growth was estimated as the distance 
from the outer edge of the second marine annulus to 
the outer edge of the scale. Means were calculated for 
each growth variable by brood year. Growth along the 
radius of the scale was assumed to be proportional to 
the growth in length of the fish, where the distance 
from each annulus on the scale provides an estimate of 
the total annual increase in body length for each year 
at sea (Dahl, 1909). 
Climate and oceanic indices 
Five climatic and oceanic indices (C-0 indices) were used 
in the analysis. Three coastal indices of the northern 
GOA included sea-surface temperature (SST), precipita- 
tion (PREC), and the Upwelling Index (UI). Two North 
Pacific Ocean wide indices were used: the Atmospheric 
Forcing Index (AFI) and the Northern Oscillation Index 
(NOI). Because of the shorter time series of the coastal 
indices, we used two periods for the correlation analysis 
(1922-2000 and 1951-2000). 
Sea-surface temperature Sea-surface temperature 
(SST) was represented by the Reynolds reconstructed 
sea surface temperatures in waters off the continen- 
tal shelf at a point 150 nmi south of the west end of 
Kodiak Island (55°N, 155°W), the general direction of 
migration of juvenile salmon. Data were accessed from 
the NOAA Pacific Fisheries Environmental Labora- 
tory (PFEL), National Marine Fisheries Service, at the 
Southwest Fisheries Science Center, Pacific Grove, Cali- 
fornia (http://www.pfeg.noaa.gov, accessed June 2004). 
An average annual spring SST index was estimated as 
the average monthly (Mar-May) temperature (°C) for 
years from 1951 to 2000 (n = 50 years). 
Precipitation Precipitation (PREC) amounts (cm) near 
Kodiak, Alaska, were accessed from the NOAA Western 
Regional Climate Center homepage (http://www.wrcc. 
dri.edu, accessed June 2004). Daily records taken at the 
Kodiak Naval Air Station were available for the years 
1951 to 1969 (n=19 years), data taken at the National 
Weather Service Office on the U.S. Coast Guard Kodiak 
Base were available for the years 1970 to 1972 (n = 3 
years), and data from the the Kodiak Airport were 
available for the years 1973 to 2000 (n - 28 years). The 
PREC index was calculated as the cumulative winter 
and spring precipitation amounts from December 1 
through May 31. 
Upwelling Index The coastal upwelling index (UI) 
east of Kodiak Island (60°N, 149°W) from 1951 to 2000 
(n = 50 years) were obtained from the PFEL homep- 
age (http://www.pfeg.noaa.gov, accessed June 2004). 
Upwelling indices to the east were correlated with 
the one used in our study. The UI values (m 3 /s/100 m 
coastline) were derived from wind stress and resulting 
mass transport of the surface water from subsurface 
layers. Mass transport was determined by the wind 
stress divided by the Coriolis parameter (a function 
of the rotation and latitude of the earth). Positive UI 
values indicated upwelling and negative UI values 
indicated downwelling. Cumulative winter and spring 
coastal upwelling east of Kodiak Island were calcu- 
lated as the sums of monthly values from December 1 
to March 31. 
Atmospheric Forcing Index The Atmospheric Forcing 
Index (AFI) was accessed from the Fisheries and Oceans 
of Canada fisheries climatology webpage (http://www. 
pac.dfo-mpo.gc.ca/sci/sa-mfpd/climate/clm_indx_afi. 
htm, accessed June 2004). The AFI values are the 
standardized scores of the first principle component of 
the winter (December through March) Aleutian Low 
Pressure Index, the Pacific Decadal Oscillation Index, 
and the Pacific Circulation Index (McFarlane et al., 
2000). We used AFI winter values from 1922 to 2000 
(n= 79 years). 
Northern Oscillation Index The Northern Oscillation 
Index (NOI) values were obtained from the PFEL homep- 
age (http://www.pfeg.noaa.gov, accessed June 2004). The 
NOI is calculated as the difference between the monthly 
sea level pressure anomaly at the North Pacific High 
and the monthly sea level pressure anomaly at Darwin, 
Australia. The NOI was calculated as the average of the 
December through February from 1949 through 2000 
(n = 52 years). 
Survival index 
Direct estimates of marine survival of Karluk sockeye 
were not available; therefore indirect survival estimates 
were obtained from residuals of the stock-recruitment 
curve (Ricker, 1975). Stock size was estimated as the 
escapement counts of sockeye made at the Karluk weir 
from 1924 to 1996 (n-12 years), and recruitment was 
estimated as the number of offspring from the spawn- 
ing population that returned from the ocean to the 
