Nearshore Habitat Use by Juvenile Chinook Salmon in Lentic ...

(ANOVA, F = 5.6, df = 2,3, P = 0.098). However, 46% of all the Chinook salmon were present
in the open sections and 65% of those within sections with structure (OHV/SWD and SWD)
were located in the open, away from the structure.
During the late time period (May 2–16), seven daytime and four nighttime snorkel
surveys were conducted. There was no significant difference in Chinook salmon abundance
between shoreline types during either the daytime (Figure 42; ANOVA, F = 0.02, df = 2,3, P =
0.98) or nighttime (ANOVA, F = 6.0, df = 2,3, P = 0.089). Unlike the early time period, few
Chinook salmon used OHV during the daytime of the late time period. On average, only 7.2% of
the Chinook salmon within the OHV/SWD sections were most closely associated with the OHV
while 30.2% were associated with the SWD and 62.6% were in the open on the periphery of the
structure. During the early time period, only 17% more Chinook salmon were observed at night
than during the day; however, twice as many were observed at night as during the day during the
late time period. This suggests that either snorkelers were less able to observe the Chinook
salmon during the day of the late time period or many of the Chinook salmon were further
offshore during the day of the late time period and not close to snorkelers.
# of Chinook
# of Chinook
160 March 24 - April 9
120
80
40
0
100
80
60
40
20
0
OHV/SWD
OHV/SWD
May 2 -16
SWD
Open
SWD
Open
Day, n = 10
Night, n = 3
Day, n = 7
Night, n = 4
FIGURE 42.—Mean number (±range) of juvenile Chinook salmon observed in three habitat types during an early
and late time period, Gene Coulon Park , south Lake Washington (2003). Bars represent the mean of two replicates.
n = the number of snorkel surveys used to calculate the mean number observed for each replicate. OHV =
overhanging vegetation; SWD = small woody debris.
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