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

TABLE 13.—Diet overlap index (C) and diet breadth index (B) of juvenile Chinook salmon from Johns Creek and
Lake Washington, 2003. Lake Washington Chinook salmon were collected in the north part of Gene Coulon Park,
approximately 1 km from Johns Creek. Diet overlap index numbers in bold indicate a significant difference in diet
(C < 0.6). Diet breadth index values can range from 1 (no diet breadth) to infinity. Values less than 2 indicate little
diet breadth.
Diet overlap index (C ) Diet breadth index (B )
Date Johns Cr. and lake shore Johns Cr. lake shore
February 21 0.70 1.98 1.02
March 20 0.21 3.39 1.25
April 22 0.29 5.03 1.05
May 30 0.62 1.71 3.17
Culvert Creek.—A total of only five Chinook salmon were observed in Culvert Creek
(inside the culvert); however, the amount of available habitat was relatively small. The few
Chinook salmon observed inside the culvert were located close to the downstream end of the
culvert (mouth of the creek), presumably because light levels at the mouth were higher and more
conducive for foraging. Few other fish were observed inside the culvert. Out of four surveys,
only one sockeye salmon fry, one small trout, and three sculpin were observed. No Chinook
salmon were ever observed on the creek delta. Instead other fish, such as largemouth bass,
prickly sculpin, pumpkinseed (Lepomis gibbosus), and small trout, were usually present. Few
Chinook salmon were observed along the riprap transect. On three of the four surveys, large
adult bass (either largemouth bass or smallmouth bass M. dolomieu) were present. Other fish
observed included trout, pumpkinseed, and large prickly sculpin. The highest abundance of
Chinook salmon (#/m) was observed along the gravel beach transect (Figure 40). Except for
some small sculpin, few other fish were observed along this transect.
Chinook / m .
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
M March A April M May
Gravel shoreline
Creek (inside culvert)
Riprap shoreline
FIGURE 40.—Abundance (number per m) of juvenile Chinook salmon in Culvert Creek (inside culvert) and at
two nearby shoreline transects in Lake Washington, 2004.
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