Kagley et al.: Residency, partial migration, and late egress of Oncorhynchus tshawytscha and O. kisutch 
551 
A B 
122.5 122.3°W 
Examples of movement by individual Chinook salmon (Oncorhynchus tshawytscha) 
classified as (A) transient and (B) resident. The solid black circle in each panel indi¬ 
cates the tagging location, and open circles indicate receivers with that detected fish. 
The transient Chinook salmon (fish 37), tagged in central Puget Sound, left through 
the Strait of Juan de Fuca, was detected on the southern coast of Washington, and 
then returned to the Strait of Juan de Fuca. The resident Chinook salmon (fish 11) 
was tagged in central Puget Sound and detected at 14 receivers within central Puget 
Sound. The lines in panel B indicate movement of fish 11 between receivers. 
surgically implanted acoustic tags (Hall et al., 2009; Re- 
chisky and Welch 5 ). The detected fish did not represent 
a different age-group and were assumed to be broadly 
representative of the tagged fish, however the move¬ 
ments and fate of the undetected fish were unknown. 
Interpretation of the detection data was further com¬ 
plicated by the uncertain origin of the individual fish, 
some of which may have originated outside Puget Sound. 
However, the transients did not leave Puget Sound syn¬ 
chronously, rather they departed at seemingly random 
times over much of the year. This variation in departure 
timing and the small size of fish suggests that individu¬ 
als tagged that subsequently left did not do so as part 
of a spawning migration to rivers outside Puget Sound, 
but more likely as part of feeding migrations. 
Chinook salmon in our study showed behavior simi¬ 
lar to that of Puget Sound coho salmon studied simi¬ 
larly by Rohde et al. (2013). Of the Chinook salmon 
tagged and detected, 30% were classified as transients, 
and of the coho salmon tagged and detected, 20% were 
classified as transients according to the same criteria. 
5 Rechisky, E. L., and D. W. Welch. 2010. Surgical implan¬ 
tation of acoustic tags: influence of tag loss and tag-induced 
mortality on free-ranging and hatchery-held spring Chinook 
salmon (Oncorhynchus tshawytscha ) smolts. In PNAMP 
Special Publication: Tagging, telemetry, and marking mea¬ 
sures for monitoring fish populations: a compendium of 
new and recent science for use in informing technique and 
decision modalities (K. S. Wolf and J. S. O’Neal, eds.), p. 
69-94. PNAMP Spec. Publ. 2010-002. Pacific Northwest 
Aquatic Monitoring Partnership, Duvall, WA. [Available 
from website] 
Both species left Puget Sound throughout the year, 
showing no clear modal season, and for neither species 
did residents and transients differ in size, wild-hatch¬ 
ery origin, or time of year when tagged. Moreover, in¬ 
dices of site use at common receiver sites (numbers of 
fish detected, days with detections) were significantly 
correlated between the two species. In addition, coho 
and Chinook salmon that remained in Puget Sound as 
residents seldom moved from the central basin where 
they were tagged. Receivers in south Puget Sound and 
Hood Canal detected only 1 and 2 tagged fish, respec¬ 
tively. Few detections occurred in the Whidbey Basin 
as well. These areas are not devoid of resident Chinook 
salmon (Chamberlin et al., 2011) or coho salmon (Ro¬ 
hde et al., 2014), but both species tend to remain in 
one basin unless they leave Puget Sound entirely. 
There were several significant differences between 
the movements of the 2 salmon species. Chinook salm¬ 
on were detected on fewer different receivers, suggest¬ 
ing less overall movement than that of coho salmon, 
and Chinook salmon were also detected more often 
than coho salmon at receivers onshore and in shallower 
water. In addition, Chinook salmon showed weak and 
inconsistent diel activity patterns. In contrast, coho 
salmon were most active at shallow, onshore sites at 
night and deep, offshore sites during the day and were 
most often detected onshore near dawn and offshore in 
the afternoon (Rohde et al., 2013). These differences 
are also consistent with the pronounced differences in 
depth distributions and diel vertical movement report¬ 
ed by Smith et al. (2015) for coho and Chinook salmon 
in Puget Sound. 
