224 
Fishery Bulletin 108(2) 
These studies, along with ours, support the idea that 
different stock groups of juvenile salmon may have 
similar WBEC in common habitats despite stock-specific 
size differences, and thus emphasize the importance of 
habitat quality on fish condition. These different results 
could also be related to ontogenetic changes in physiol- 
ogy (Hoar, 1998; Wuenschel et al., 2006). 
Because so little mortality occurred within each ex- 
perimental group, we conclude that juvenile salmon 
can survive for prolonged periods without food during 
the summer months, as has also been reported by Ste- 
fansson et al. (2009). Most of the mortalities occurred 
within the first eight days of the June experiment. As 
discussed previously, the June fish were younger and 
less robust (lower CR) and could have been more sus- 
ceptible to environmental stresses because of scale loss 
(Bouck and Smith, 1979) from net abrasion during cap- 
ture, for example. However, even though juvenile chum 
salmon were still alive after 45 days of starvation, many 
salmonids cannot recover physiologically after extended 
periods of starvation because of compromised seawater 
tolerance or impaired compensatory growth (Bilton and 
Robins, 1973; Ban et al., 1996; Stefansson et al., 2009); 
such recovery capabilities in juvenile chum salmon re- 
main unclear. 
The experimental WBEC, %MC, and CR differed from 
the long-term average of the SECM data sets during 
both months. After about 10 days of starvation, WBEC 
was below the normal range, %MC was above the nor- 
mal range, and CR shifted from positive to negative, 
in both months. More specifically, by day 20, the June 
fish had lost twice their WBEC and CR, and had gained 
four times %MC as the July fish. The WBEC of the 
June fish required only 3-7 days of starvation before 
dropping to the lower initial level of the July fish. 
Our study on the effects of starvation on field-caught 
juvenile chum salmon indicates that WBEC, %MC, and 
CR are more responsive measures than WW and FL to 
prolonged food deprivation in a controlled laboratory 
environment. Although starvation is an extreme case 
of limited food resources, clearly juvenile chum salmon 
can survive these conditions for extended periods, but 
may consequently be less tolerant of variable environ- 
mental conditions and more susceptible to other sources 
of mortality, such as predation. Future studies will 
focus on monitoring the seasonal response of juvenile 
salmon condition measures, such as WBEC, %MC, and 
CR, in different habitats at sea. 
Acknowledgments 
We thank the command and crew of the NOAA ship 
John N. Cobb for help in collecting samples. We thank D. 
Tersteeg and the staff at the Macaulay Hatchery otolith 
laboratory for decoding all of the otoliths used in this 
study. This manuscript was improved with suggestions 
from three anonymous reviewers. Finally, we thank A. 
Wertheimer and A. Moles for statistical and editorial 
help with this manuscript. 
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