546 
Fishery Bulletin 11 5(4) 
Map of the study area showing the locations in Puget Sound, Wash¬ 
ington, where Chinook salmon (Oncorhynchus tshawytscha) were 
caught and tagged (shaded rectanglar area) during 2006-2008 and 
the locations of active stationary receivers. The major basins in 
Puget Sound are outlined by dotted lines. 
Study fish were transferred from the seine into a 
live well with aerated flowthrough seawater at ambient 
temperature (10-12°C) and salinity. Compressed air 
was pumped into the tank and dissolved oxygen levels 
were periodically checked. Fish with visible distress 
or with scale losses greater than 10% were excluded 
from being tagged. Weights (measured in grams) and 
lengths (measured in millimeters) were recorded for se¬ 
lected animals before tagging. Fish were transferred to 
a small cooler with 65 mg/L tricaine methanesulfonate 
and anesthetized to a point that induced loss of equilib¬ 
rium but still allowed opercular movement. Each fish 
was checked for an adipose fin clip and codedwire tag, 
either of which would indicate hatchery origin. The fish 
was then transferred to a surgical table of closedcell 
foam shaped to allow the fish to be positioned on its 
dorsum. A supply of water infused with anesthetia was 
fed by gravity through a tube and deliv¬ 
ered to the gills. 
An individually coded V9 (i.e., one of 
the following: V9-1L at 24 mm, V9-2L at 
29 mm, and V9-6L at 21 mm in length) 
acoustic transmitter (VEMCO, 4 Bedford, 
Nova Scotia, Canada) was inserted into the 
peritoneal cavity through a small incision 
(15-20 mm) just off center of the linea alba 
of the abdomen and anterior to the pelvic 
fins. Tag-to-body-weight ratio did not ex¬ 
ceed 2%, well below that recommended by 
Hall et al. (2009) to minimize tag effects. 
All tags had a power output of 145 dB, a 
variable ping rate, and a projected battery 
life of 79-537 d. The incision was closed 
by using absorbable surgical thread (coat¬ 
ed Vicryl 60; Ethicon, Somerville, NJ) and 
sutured with a tapered RB-1 needle and 
using 2 surgeon knots. Including time un¬ 
der anesthesia, each fish was handled for 
an average of 6 min of which the surgery 
took approximately 2 min. After surgery 
the fish were placed in a recovery tank 
until they were upright and swimming in¬ 
dependently (ca. 15 min); they were then 
released near the capture site. 
Data collection 
Since 2004, hydroacoustic tags have been 
extensively used in Puget Sound, the 
Strait of Georgia, and nearby water bod¬ 
ies to study movements of many fish spe¬ 
cies (Melnychuk et al., 2007; Welch et al., 
2009; Moore et al., 2010; Hayes et al., 
2011; Andrews and Quinn, 2012). Receiv¬ 
ers were deployed in Puget Sound and 
maintained by several investigative teams 
(Hood Canal=119 receivers, Admiralty In- 
let=61, central Puget Sound=271, Whidbey 
Basin=140 and south Puget Sound-50; 
Fig. 1). These studies also coincided with 
the Pacific Ocean Shelf Tracking Project, an interna¬ 
tional monitoring effort using the same technology to 
deploy arrays of receivers along the continental shelf 
from California to Alaska. Combined, these individual 
and arrayed receivers provided the means to detect fish 
migrating to the Pacific Ocean via the Strait of Juan de 
Fuca and Johnstone Strait, British Columbia, Canada, 
as well as fish moving within the San Juan Islands 
(Fig. 1; Arostegui et al., 2017). Combined, there were 
over 800 active receivers within the Salish Sea and an 
additional 55 along the Washington State coast (includ¬ 
ing the Willapa Bay subarray; Reichisky et al., 2013) 
in the Pacific Ocean during the study. The amount of 
4 Mention of trade names or commercial companies is for iden¬ 
tification purposes only and does not imply endorsement by 
the National Marine Fisheries Service, NOAA. 
