To account for potential stock-related differences in condition of the experimental chum salmon (of unknown stocks), WBEC was determined for additional field-caught fish of known stocks.
We used graphical analyses to compare the WBEC and %MC for each experimental group to the norms (one standard deviation about the mean) derived from the entire SECM field data set (1997-2008) from June and July (n=1257; WBEC: 993.
Initial WBEC was significantly higher in June than in July (1081.
In contrast to WBEC, %MC of juvenile chum salmon increased over time in both experimental groups (Fig.
Hatchery stock group did not affect the WBEC or %MC of the July-caught juvenile chum salmon.
We did not directly measure lipid and protein, but the decline in WBEC that we observed between days zero and 10 and between days 20 and 45 in June could reflect similar declines in these nutrient measures.
In our study, chum salmon in June exhibited a 40% decline in WBEC and a 9% increase in %MC after 45 days of starvation at an average temperature of ~9[degrees]C.
The chum salmon caught in June initially had approximately 11% higher WBEC and approximately 3% lower %MC than fish caught in July--differences that could be accounted for by both environmental and biological variables.
We accounted for potential size-related effects on WBEC and %MC by using length-weight regression analysis, which corrected for natural variation in fish size; however, the results may still be misleading because this regression did not account for differences in actual nutritional status or body composition, such as protein, lipid, and water content (Miglavs and Jobling, 1989; Edsall et al.
In our study, stocks of juvenile chum salmon sampled from the same habitat did not differ in WBEC or %MC, but size did differ significantly.
After about 10 days of starvation, WBEC was below the normal range, %MC was above the normal range, and CR shifted from positive to negative, in both months.