550 
Fishery Bulletin 115(4) 
Offshore-deep receivers 
NS 
Chinook presence 
Onshore-deep receivers 
NS 
Chinook movement 
Figure 4 
Circular histograms showing the diel patterns of presence (top) and move¬ 
ment (bottom) of Chinook salmon (Oncorhynchus tshawytscha ) at offshore- 
deep (>1 km from shore and >95 m deep), onshore-deep (<1 km from shore 
and >95 m deep), and onshore-shallow (<1 km from shore and <95 m 
deep) receivers in Puget Sound, Washington. The Rvalue indicates signifi¬ 
cance from a Rayleigh test of uniformity (NS=not significant). The arrow 
on the significant plot indicates the mean time vector with length rho, a 
measure of the concentration of data. 
Onshore-shallow receivers 
P = 0.047 
detected only Chinook salmon, and 51 receivers detected 
only coho salmon. Chinook salmon were detected on 104 
receivers and coho salmon on 125 receivers. The species 
detected (both, Chinook salmon only, coho salmon only) 
varied with receiver type (offshore-deep, onshore-deep, 
onshore-shallow: x 2 =21.88, df=4, P<0.01). The receiv¬ 
ers that detected only Chinook salmon were mostly 
onshore-shallow receivers (70%), followed by onshore- 
deep receivers (23%), and offshore-deep receivers (7%) 
whereas the receivers that detected only coho salmon 
were mostly offshore-deep (45%), followed by onshore- 
shallow (33%), and onshore-deep (22%). The receivers 
that detected both species were more evenly distrib¬ 
uted (38% offshore-deep, 35% onshore-deep, and 27% 
onshore-shallow). The 44 receivers within Puget Sound 
that detected both Chinook and coho salmon showed 
positive correlations with the numbers of individual 
fish (coefficient of correlation [r]=0.47, P<0.01) and days 
with detections (r=0.54, P<0.01). 
Discussion 
All the Chinook salmon tagged in this study were cate¬ 
gorized initially as residents because they were still in 
Puget Sound late in their first or in their second year 
in salt water. Had all of them remained within Puget 
Sound, we would have inferred a clear distinction be¬ 
tween these resident fish and the typical migrants 
that leave Puget Sound after a few months to feed in 
the coastal or open ocean waters until they return to 
spawn. However, 30% of the tagged fish later left Puget 
Sound, and so were termed transients. If they had been 
caught in fisheries along the coast, there is no way to 
know that they had spent significant time in Puget 
Sound. Indeed, some fish were tracked out to the coast 
and then back into Puget Sound, further illustrating 
the flexibility of residency and coastal migrations. 
There was no effect of size, origin (hatchery or wild), 
tagging location, or tagging season on whether a fish 
remained resident or became a transient, although the 
small sample sizes limited our effort to detect effects. 
For example, we included only fish with a minimum of 
6 d of detection data (sufficient to detect possible de¬ 
parture). The Chinook salmon detected for more than 
6 d after tagging were larger than those omitted for 
lack of ample detection data. This observation is con¬ 
sistent with size-selective natural mortality or an effect 
of handling, although 2 laboratory studies found little 
or no size effects on survival for Chinook salmon with 
