Reese et al.: Distribution and estuarine interactions between wild and hatchery Oncorhynchus keta 
437 
for late hatchery fry between habitat types because no 
late hatchery fry were caught in the inner inlet. For all 
these analyses, fork length was In-transformed because 
some of the frequency distributions were not normally 
distributed. 
Distribution, size, and condition of wild chum 
salmon fry in relation to temperature, salinity, 
and chum salmon abundance 
Because of the small sample size of wild chum salmon 
in neritic trawls, analyses of the distribution and size 
of wild chum salmon were conducted only with data 
from littoral habitat. Correlation analysis and stepwise 
multiple regressions were used for fry in littoral habitat 
to determine the relationships of wild fry abundance, 
weight, and condition factor (defined below), with sea 
surface temperature, salinity, time (date), and total 
chum salmon abundance. Sea surface temperature and 
salinity were included in analyses because the behavior 
and distribution of outmigrating salmon fry in estuar- 
ies often reflects evolutionary adaptations to hydro- 
graphic conditions in the estuary (reviewed by Salo, 
1991; Murphy et al., 1997). To account for morphological 
changes that occur with ontogeny, condition factor was 
calculated as the residual of the regression of In weight 
versus In fork length (Jakob et al., 1996). Data from sets 
made before the release of hatchery fry were excluded 
from the analysis in order to address our goal of deter- 
mining if wild fish distribute themselves differently in 
the presence of hatchery-released fish. Separate analyses 
were conducted for each year, by location, and habitat. 
A forward-backward stepwise regression was used with 
an alpha of 0.10 to include variables in the equation and 
an alpha of 0.10 to exclude the significance of p, by using 
the following equation: 
Wild abundance = P H hatchery abundance + 
p T SST + p s salinity + p d date + £, (1) 
where abundance = In (catch + 1); 
SST = sea surface temperature; and 
date = day of the year. 
We added 1 to all catches because zeros would become 
undefined upon transformation. The same approach was 
used to relate weight of wild fry to wild fry abundance, 
hatchery fry abundance, sea surface temperature, and 
salinity. The stepwise regression used the following 
equation: 
Weight of wild fry = 
Pw wild abundance + p H hatchery abundance (2) 
+ f T SST + f s salinity + p d date + e, 
where Weight - In weight (g). 
Finally, we analyzed the relationship between condi- 
tion factor of wild fry and wild abundance, hatchery 
abundance, sea surface temperature, and salinity using 
the same techniques. The stepwise multiple regression 
equation used to analyze condition factors of individual 
wild fry was the following: 
Condition factor = wild abundance + 
P H hatchery abundance + P T SST + (3) 
p s salinity + P d date + e. 
No colinearity was found in these models (Sokal and 
Rohlf, 1995). 
Results 
Spatial and temporal distribution of relative abundance 
Littoral habitat Hatchery fry were most abundant in 
littoral habitat in the week following the early hatchery 
releases in both years, on 10 May 2004 and on 17 May 
2005 (Fig. 3, A and B). Both hatchery and wild fry were 
generally less abundant in 2004 than in 2005. During 
both years, hatchery chum salmon represented over 95% 
of the catch in the outer inlet, but in the inner inlet 
represented only 11% in 2004 and 1% in 2005 (Fig. 4). 
Abundance of wild and early hatchery chum salmon 
fry in littoral habitat declined within two weeks in late 
May in both the inner and outer inlet. Abundance of late 
hatchery fry declined within one week of their release 
in late May, but unlike early hatchery chum salmon, 
late hatchery fry were never caught by beach seine in 
the inner inlet. 
The greatest spatial and temporal overlap among 
chum salmon fry in littoral habitat occurred between 
wild and early hatchery fry in the outer inlet. Little 
potential existed for wild and early hatchery chum 
salmon fry to interact in inner Taku Inlet because 
hatchery fry were rare in this location. Similarly, little 
chance existed for wild and late hatchery fry to inter- 
act because the latter were not observed in the inner 
inlet and migrated from the outer inlet within one 
week of their release. The early hatchery release co- 
incided with peak abundance of wild fry in the outer 
inlet and the distribution of these stocks overlapped 
for about 3 weeks. Wild chum salmon were present in 
littoral habitat from the beginning of sampling on 19 
April through 21 June in both years. Abundance of 
wild chum salmon fry peaked in the inner inlet during 
the week of 17 May 2004 and the week of 3 May 2005 
(Fig. 3A). Abundance of wild chum salmon fry peaked 
in the outer inlet in the week of 17 May 2004 and 10 
May 2005 (Fig. 3B). 
Neritic habitat Hatchery fry were most abundant in 
neritic habitat in the outer inlet during the weeks of 
17-31 May. Both hatchery and wild fry were generally 
less abundant in 2004 than in 2005. By location, hatch- 
ery chum salmon represented over 98% of the catch in 
the outer inlet during both years, whereas in the inner 
inlet they represented 93% in 2004 and 24% in 2005 
(Fig. 4). Most of the hatchery chum salmon from neritic 
