Reese et al.: Distribution and estuarine interactions between wild and hatchery Oncorhynchus keta 
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Sites sampled by beach seine (triangles) and Kodiak trawl (squares) in inner 
and outer Taku Inlet, Alaska, from late April to late June, 2004-05, and nearby 
hatchery release sites (circles) for chum salmon ( Oncorhynchus keta) fry. Sam- 
pling began before the outmigration period for wild fry (late April to mid-June) 
and before hatchery releases of approximately 25 million “early” fry (released 
in early May at 1.9 g size) and 25 million “late” fry (released in late May at 3.9 
g size) each year. 
Background and study area 
The Taku River enters the ocean 20 km south of Juneau, 
Alaska. About 90% of its 16,000 km 2 watershed is located 
in a roadless wilderness in British Columbia, Canada. 
Taku Inlet is a narrow fjord, 3-6 km wide by 18 km long 
(Fig. 2). In addition to chum salmon, the Taku River 
supports stable runs of sockeye (O. nerka), Chinook 
(O. tshawytscha), coho (O. kisutch), and pink salmon 
(O. gorbuscha). Migration timing of chum salmon fry 
in the Taku River is adapted to decreases in salinity 
and increases in sea surface temperature that typically 
occur from April through June (Meehan and Siniff, 1962; 
Murphy et ah, 1997). 
Annual production of chum salmon released by DIPAC 
at Limestone Inlet and Gastineau Channel near Taku 
Inlet increased from <1 million fry in 1982 to ap- 
proximately 60 million fry in 1994 and production has 
generally remained above 40 million since then (Fig. 
1). DIPAC has also released 50-60 million thermally 
marked fry annually in northern Southeast Alaska 
at sites distant from Taku Inlet. During this study, 
26 million “early” fry were released May 7-17 at 1.9 g 
wet weight and 24 million “late” fry were released May 
22-June 3 at 3.9 g in the vicinity of Taku Inlet in 
each year. These groups were produced from the same 
summer brood stock derived from coastal streams near 
Juneau and differed only in the rearing duration and 
the size and date at release. 
Methods 
Field sampling 
Sampling was conducted from late April to late June, 
2004-05, thus covering the outmigration period for chum 
salmon in Taku Inlet (Meehan and Siniff, 1962; Murphy 
et al., 1997). We conducted two 48-hour cruises per week, 
in which littoral and neritic habitats were sampled with 
different gear and at different times of day. We sampled 
littoral habitat throughout the inlet where it was feasible 
to use a 37-m longx3-m deep beach seine (3-mm bunt 
mesh) (Mortensen et al., 2000; Johnson and Thedinga, 
