433 
Spatial and temporal distribution and 
the potential for estuarine interactions 
between wild and hatchery chum salmon 
( Oncorhynchus keta ) in Taku Inlet, Alaska 
Car8 Reese (contact author) 12 
Nicola Hillgruber 2 
Molly Sturdevant 3 
Alex Wertheimer 3 
William Smoker 2 
Rick Focht 4 
Email address for contact author: carl.reese@alaska.gov 
1 Alaska Department of Environmental Conservation 
410 Willoughby Avenue 
Juneau, Alaska 99801 
2 School of Fisheries and Ocean Sciences 
University of Alaska Fairbanks 
17101 Point Lena Loop Road 
Juneau, Alaska 99801 
3 Auke Bay Laboratories 
Alaska Fisheries Science Center 
National Marine Fisheries Service 
17109 Point Lena Loop Road 
Juneau, Alaska 99801 
4 Douglas Island Pink and Chum, Inc 
2697 Channel Drive 
Juneau, Alaska 99801 
Abstract — We investigated estuarine 
spatial and temporal overlap of wild 
and marked hatchery chum salmon 
( Oncorhynchus keta) fry; the latter 
included two distinct size groups 
released near the Taku River estu- 
ary (Taku Inlet) in Southeast Alaska 
(early May releases of ~ 1.9 g and late 
May releases of ~ 3.9 g wet weight). 
Our objectives were to compare abun- 
dance, body size, and condition of wild 
chum salmon fry and hatchery chum 
salmon fry raised under early and 
late rearing strategies in different 
habitats of Taku Inlet and to docu- 
ment environmental factors that could 
potentially explain the distribution, 
size, and abundance of these chum 
salmon fry. We used a sampling 
design stratified into inner and outer 
inlet and neritic and littoral habitats. 
Hatchery fry were rare in the inner 
estuary in both years but outnum- 
bered wild fry 20:1 in the outer estu- 
ary. Hatchery fry were significantly 
larger than wild fry in both littoral 
and neritic samples. Abundances of 
wild and hatchery fry were positively 
correlated in the outer inlet, indicat- 
ing the formation of mixed schools 
of hatchery and wild fry. Spatial 
and temporal overlap was greatest 
between wild and early hatchery fry 
in the outer inlet in both habitats. 
The early hatchery release coincided 
with peak abundances of wild fry in 
the outer inlet, and the distribution 
of wild and early hatchery fry over- 
lapped for about three weeks. Our 
results demonstrate that the timing 
of release of hatchery fry may affect 
interactions with wild fry. 
Manuscript submitted 16 December 2008. 
Manuscript accepted 22 June 2009. 
Fish. Bull. 107:433-450 (2009). 
The views and opinions expressed 
or implied in this article are those 
of the author and do not necessarily 
reflect the position of the National 
Marine Fisheries Service, NOAA. 
Salmonids have been reared and 
released from hatcheries since the 
nineteenth century (Olla et al., 1998) 
and enhancement facilities now exist 
worldwide (e.g., Mahnken et al., 1998; 
Kaeriyama, 1999; Zaporohzets and 
Zaporohzets, 2004). Many authors 
have expressed concern that large- 
scale salmonid hatcheries may dimin- 
ish fitness and productivity of wild 
populations (Hilborn and Eggers, 2000; 
Einum and Fleming, 2001; Zaporo- 
zhets and Zaporozhets, 2004; Araki 
et al., 2007). Others have shown that 
hatchery releases support the recovery 
of declining populations (Heard et al., 
1995; Brannon et al., 2004) and can 
enhance fisheries without impacting 
wild stocks (e.g., Bachen and Linley, 
1995; Heard et al., 1995; Wertheimer, 
1997). Hatchery salmonids can impact 
wild fish in a number of ways, such 
as through spawning interactions, 
genetic interactions, inducing over- 
harvesting, and by trophic or behav- 
ioral interactions during estuarine 
and oceanic life-history phases (Lev- 
ings et al., 1986; Bigler et al., 1996; 
Olla et al., 1998). Hatchery salmonids 
can also impact wild fry populations 
by either attracting predators that 
selectively eat smaller wild fry (Har- 
greaves and LeBrasseur 1986; Wert- 
heimer and Thrower, 2007; Duffy and 
Beauchamp, 2008) or hatchery sal- 
monids can benefit wild populations 
by buffering wild fry from predators 
(Willette et al., 2001; Briscoe et al., 
2005). The potential for hatchery fish 
to affect wild fish increases with the 
degree of spatial and temporal over- 
lap between fishes of similar life-his- 
tory stages. Hatcheries often employ 
different rearing and release strate- 
gies to reduce these impacts, such as 
releasing fry away from streams that 
produce wild fish (Bachen and Linley, 
1995; Heard et al., 1995) or releasing 
