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

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Discussion Johns Creek.— Results from Johns Creek indicated that Chinook salmon extensively use this nonnatal tributary from year to year. Several nonnatal tributaries of Lake Washington and Lake Sammamish were surveyed in 2002 and the number of Chinook salmon found in Johns Creek was higher than all the other tributaries combined. Johns Creek appears to be an ideal nonnatal tributary because it has a low gradient, is a small- to medium-sized stream, and is close to the natal system, the Cedar River. Preliminary results from Lake Quinault in 2004 indicate there are also several nonnatal streams that are used by juvenile Chinook salmon. We plan to conduct additional surveys of these streams in 2005 to identify important factors that influence their use of these streams. In the lower part of the Fraser River, British Columbia, juvenile Chinook salmon used nonnatal tributaries that had low gradients and had no fish barriers such as waterfalls, culverts, bridge footings, or flood control gates (Murray and Rosenau 1989). The use of the lower reaches of nonnatal tributaries by juvenile Chinook salmon has also been documented in the upper Fraser River system in British Columbia (Scrivener et al. 1994), the Taku River system in Alaska (Murphy et al. 1989) and the Umpqua River system in Oregon (Scarnecchia and Roper 2000). Based on the habitat use patterns of Johns Creek, a suitable stream for juvenile Chinook salmon should have a wide variety of habitat features, which would take into account the change in habitat use of Chinook salmon as they grow. Shallow, slow water habitats (< 0.35-m depth) or glides were used extensively in February and early March. We also observed small Chinook salmon in pocket water of riffles, thus using cobbles and small boulders in riffles might provide additional rearing habitat. After late March, Chinook salmon were usually in deeper pools but we did not observe them in pools greater than 0.9 m depth. Throughout the study period, juvenile Chinook salmon appeared to often use overhead cover. The density of Chinook salmon in the convergence pool was considerably lower than in the upstream reach. Low density in the convergence pool may be due to a combination of suboptimal habitat conditions and presence of other fish species. Much of the convergence pool had riprap banks and there was little woody debris and little riparian vegetation to provide overhanging cover. Potential predators of Chinook salmon, such as largemouth bass, smallmouth bass, large trout, and prickly sculpin, were commonly observed in the convergence pool, thus Chinook salmon may avoid this area. Besides predators, the convergence pool also had large numbers of potential competitors (juvenile peamouth, juvenile sunfish, threespine stickleback, and prickly sculpin), which could reduce the food available for Chinook salmon. In the upstream reach, few other fish species were present and the habitat conditions appeared to be better than the convergence pool. Culvert Creek.— Although few Chinook salmon were present at Culvert Creek, it does provide evidence that small creeks or seeps could be potential Chinook salmon rearing habitat. The number observed at Culvert Creek in 2004 was higher than the number observed in 2002 in much larger tributaries such as May Creek (Tabor et al. 2004b). Use of these small tributaries has not been well documented; however, in the Nooksack River system, Chinook salmon fry were frequently caught in several spring seeps and small tributaries but not along the river edge 65
(P. Castle, WDFW, unpublished data). Use of these small tributaries in Lake Washington is probably most beneficial for newly emerged fry. These tributaries would provide shallow water habitat and large predatory fish would most likely be absent. As they grow and move into deeper habitats their use of these small tributaries would be greatly reduced. The number of juvenile Chinook salmon in Culvert Creek may actually be high considering the poor condition of the habitat. The creek could be significantly improved if it was daylighted and riparian vegetation was planted. Additionally, the creek delta was adjacent to riprap and the abundance of predatory fishes (bass and large sculpin) appeared to be much higher than at other tributary deltas. Any stream restoration project would probably also need to include removing the riprap. If the creek was restored, perhaps it could support as many as 50 juvenile Chinook salmon (based on densities observed in Johns Creek). 66
Page 1 and 2:
U.S. Fish and IU.S. Wildlife FishSe
Page 3 and 4:
SUMMARY In 2003 and 2004, we contin
Page 5 and 6:
An overhanging vegetation/small woo
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Table of Contents Page SUMMARY ....
Page 9 and 10:
List of Figures Figure Page FIGURE
Page 11 and 12:
FIGURE 37.—Water column depth (m)
Page 13 and 14:
The major tributary to Lake Washing
Page 15 and 16:
Fry emerge from their redds from Ja
Page 17 and 18:
FIGURE 2.—Location of index sites
Page 19 and 20:
most dates (Figure 4). Unlike 2002,
Page 21 and 22:
Chinook/m 2 1 0.8 0.6 0.4 0.2 0 Wes
Page 23 and 24:
0.3 Mercer Island Chinook/m 2 0.2 0
Page 25 and 26: particularly valuable. Shoreline im
Page 27 and 28: FIGURE 8.—Map of south Lake Washi
Page 29 and 30: FIGURE 10—Map of south Lake Washi
Page 31 and 32: # of marked Chinook 40 30 20 10 0 A
Page 33 and 34: CHAPTER 3. RESTORATION SITES Introd
Page 35 and 36: Beer Sheva Park.—At Beer Sheva Pa
Page 37 and 38: Results Seward Park, 2003.—In 200
Page 39 and 40: 4 3.5 Chinook/100 m 3 2.5 2 1.5 1 0
Page 41 and 42: Martha Washington Park, 2003.—In
Page 43 and 44: 120 Chinook/100 m 100 80 60 40 20 s
Page 45 and 46: snorkeling and scuba diving were co
Page 47 and 48: Water column depth (m) . 0.80 0.60
Page 49 and 50: CHAPTER 5. FEEDING AT TRIBUTARY MOU
Page 51 and 52: FIGURE 28.—Location of four south
Page 53 and 54: FIGURE 29.—Photos of sites used t
Page 55 and 56: sampling. At night, Chinook salmon
Page 57 and 58: TABLE 5.—Diet overlap indices (C)
Page 59 and 60: TABLE 7.—Diet overlap indices (C)
Page 61 and 62: TABLE 10.—Diet composition of juv
Page 63 and 64: The lack of a large difference betw
Page 65 and 66: CHAPTER 6. USE OF NONNATAL TRIBUTAR
Page 67 and 68: shallow to snorkel were surveyed th
Page 69 and 70: Number of Chinook ff 700 600 500 40
Page 71 and 72: column depth used by Chinook salmon
Page 73 and 74: Chinook / m . 5 4 3 2 1 2003 - upst
Page 75: TABLE 13.—Diet overlap index (C)
Page 79 and 80: FIGURE 41.—Placement of Scotch br
Page 81 and 82: FIGURE 43.—Photo of a group of ju
Page 83 and 84: CHAPTER 8. LAKE QUINAULT SURVEYS In
Page 85 and 86: FIGURE 45.—Photos of large woody
Page 87 and 88: Similar to April surveys, the nears
Page 89 and 90: Chinook / 100m . 500 400 300 200 10
Page 91 and 92: Tabor and Wurtsbaugh (1991) conclud
Page 93 and 94: FIGURE 48.—Location of south Lake
Page 95 and 96: FIGURE 49.—Conducting visual obse
Page 97 and 98: FIGURE 52.—Photo of a group of ju
Page 99 and 100: ACKNOWLEDGMENTS We wish to thank He
Page 101 and 102: workshop, Shoreline, Washington, No
Page 103 and 104: Paron, D.G., and E. Nelson. 2001. S
Page 105 and 106: Werner, E.E., and D.J. Hall. 1988.
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