480 
Fishery Bulletin 107(4) 
to season could be detected. During the winter of 
2006, Pacific herring were sampled in January {n- 68, 
mean weight=111.26 g, SD = 41.00), February (n=70, 
mean weight=8.98 g, SD = 1.86), March (n = 68, mean 
weight=35.92 g, SD = 56.37), and April (n= 23, mean 
weight=166.14 g, SD = 36.30) from Sitka Sound, AK. 
Fish were collected by cast net. Impedance was mea- 
sured within 12 hours of capture and fish were held 
on ice or snow between capture and measuring. After 
measuring, a subset of the fish (January n= 20, March 
n= 14, April n = 18) was sent to the Auke Bay Labo- 
ratory, Juneau, AK, for bomb calorimetry. A linear 
mixed-effects (LME) model was used to test for dif- 
ferences in phase angles between months. 
Phase angle and water balance in postmortem fish 
Adult pink salmon were measured to characterize 
changes in phase angle in postmortem fish to better 
understand how changes in cell integrity influence 
phase angle. Three adult pink salmon (520 mm-550 
mm) were individually killed and connected to the 
Quantum-II and placed in a standard ice chest with- 
out ice and held at <11°C. The Quantum-II was set 
to record impedance every five minutes for five days. 
A temperature data logger placed inside the ice chest 
recorded temperature every five minutes. Each fish 
was removed from the ice chest 4-5 days later and 
impedance measures and temperature data were 
downloaded for analysis. Changes in phase angle of 
postmortem fish over time were analyzed by regres- 
sion analysis. Significance tests were done on each 
fish to test for nonzero slopes by using a standardized 
major axis (SMA) test and by reporting the Bartlett- 
corrected likelihood ratio test (LR) for differences in 
the slopes between the different fish. 
Results 
Temperature and time 
Phase angles measured on dead fish depended on tem- 
perature and decreased as temperatures increased 
(Fig. 1A). Slopes of phase angles (-0.19) were not 
different among fish (LR=5.87, P=0.05). There was 
an interaction between fish and phase angle (F 2 46 - 
20.92, P=0.01). Time did not affect phase angles in 
fish that were placed on ice for up to 12 hours. Phase 
angles measured in groups of dead fish placed on ice 
were not significantly different between times of less 
than 12 hours, (LME t 30 30 <2, P>0.08) (Fig. IB). At 
12 hours, there was a significant effect of time on 
phase angle (LME t 30 30 >5, P<0.05). 
Laboratory studies 1-3 
In each of the laboratory studies, phase angle decreased 
in fasted fish and not in fed fish. In the brook trout 
experiment there was a significant interaction in phase 
Figure 1 
(A) Repeated measures of phase angles for three adult 
pink salmon (Oncorhynchus gorbuscha) that were brought 
from 8°C to freezing. Time required for freezing was <1 
hour. Each of the three symbols and their corresponding 
line represents one of the three fish. (B) Phase angles of 
group means for juvenile coho salmon (n = 6 per group) 
that were killed and placed on ice. Every 3 hours, a group 
was measured for impedance, and the phase angle means 
per group were calculated. Notches extend to ±1.58 inter- 
quartile ran ge/Vn and represent roughly 95% confidence 
intervals, horns indicate that the interval is larger than 
the interquartile range (as seen in the bottom half of each 
of the boxplots). 
I 
1 
angle between feeding group and time (ANOVA, P<0.05, 
df=8). The interaction resulted in a temporal change in 
phase angle among the fasted fish — a change that was 
not observed among fed fish. Phase angles in the fasted 
brook trout in weeks 3-9 were significantly lower than 
