Predator Fish Monitoring at Installed Large Wood ...

Predator Fish Monitoring at Installed Large Wood Structures – Sammamish River Habitat Enhancement Projects Redmond, Washington RMDX 0000-0047 Prepared for: City of Redmond Public Works Department Redmond, Washington 98073 Prepared by: David Evans and Associates, Inc. 415 118th Avenue Southeast Bellevue, Washington 98005 October 2007

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Predator Fish Monitoring October 2007 Sammamish River Habitat Enhancement Projects Page i

Table of Contents

1.0 Introduction............................................................................................................. 1

1.1 Study Area .......................................................................................................... 1 2.0 Methods................................................................................................................... 3 3.0 Results..................................................................................................................... 5 4.0 Conclusions............................................................................................................. 8 5.0 References............................................................................................................... 9

List of Tables Table 1. Date, time, and water temperature during snorkeling and angling surveys.......... 5 Table 2. Species captured and date of capture during angling surveys. ............................. 5 Table 3. Stomach contents of captured predatory fish........................................................ 6 Table 4. Date and number of each species observed during snorkel surveys within all

reaches.................................................................................................................. 6 Table 5. Number and percent of fish species associated with installed wood structures

within Reaches 2-4............................................................................................... 7 Figures Figure 1. Predator Study ..................................................................................................... 2 Figure 2. Predator Study ..................................................................................................... 4 List of Appendices Appendix A: Literature Review Appendix B: Photographs


Predator Fish Monitoring October 2007 Sammamish River Habitat Enhancement Projects Page ii

Abbreviations and Acronyms

cm centimeters

DEA David Evans and Associates, Inc.

HEP Habitat Enhancement Project

RWMP River Walk Master Plan

WDFW Washington Department of Fish and Wildlife

WRIA Water Resource Inventory Area


Predator Fish Monitoring October 2007 Sammamish River Habitat Enhancement Projects Page iii

Executive Summary

This report summarizes efforts to determine predation of juvenile salmon around installed large wood structures on a rehabilitated reach of the Sammamish River in Redmond, Washington. David Evans and Associates, Inc. biologists angled and snorkeled during May 2007 in the study area to accomplish the goals of this project. The goals of this project include:

Conduct a brief review of existing information relating to predator fish/juvenile salmon interactions.

Determine predation of juvenile salmon by fish within the study area.

Determine presence of juvenile salmon fish predators around installed wood structures.

Predators observed in the study area included northern pikeminnow (Ptychocheilus oregonensis), smallmouth bass (Micropterus dolomieui), cutthroat trout (Oncorhynchus clarki), rainbow trout (O. mykiss), and sculpin sp. (Cottus sp.). Cutthroat trout, rainbow trout, and sculpin sp. were all less than 200 millimeters long and likely did not prey on juvenile salmon. We did not find a large percentage of predators or juvenile salmon associating with installed large wood structures.

Northern pikeminnow and smallmouth bass were greater than 9.5 inches (24 centimeters) and were capable of eating juvenile salmon. However, we did not find any juvenile salmon in the stomach contents of 26 northern pike minnow and 2 smallmouth bass. Although northern pike minnow were abundant, their stomach contents were generally empty. All of the captured northern pikeminnow were gravid and were on a spawning migration.

Considering the results of this study and the fact that most of the juvenile salmon migrate past the study area before June (i.e. before water temperatures are high enough for increased predation), and that most of the juvenile salmon are greater than 3 inches (7.5 centimeters—a large enough size to avoid predation), it is likely predation in the study area during May is low and not influenced by installed wood structures.


Predator Fish Monitoring October 2007 Sammamish River Habitat Enhancement Projects Page 1

1.0 Introduction This report summarizes efforts to determine predation of juvenile salmon around installed large wood structures on a rehabilitated reach of the Sammamish River (Figure 1). The City of Redmond has implemented several Habitat Enhancement Projects (HEPs) as phases of the River Walk Master Plan (RWMP), resulting in rehabilitation of habitat in several reaches of the Sammamish River and adjacent uplands (Appendix A). During the permit approval process for the most recent HEP phase, questions arose regarding the benefits of installed large wood structures on a relatively warm, slow moving river system such as the Sammamish River.

Agency staff was concerned about the possibility that large wood structures may provide shelter for piscivorous fish which may prey on juvenile salmon migrating downstream. In response, the City of Redmond authorized David Evans and Associates, Inc. (DEA) to investigate predator use and predation of juvenile salmon in and around installed large wood structures. The goals of this project include the following:

Conduct a brief review of existing information relating to predator fish/juvenile salmon interactions (Appendix B).

Determine predation of juvenile salmon by predators within the study area.

Determine presence of juvenile salmon predators around installed wood structures.

We accomplished these goals by:

Angling near installed wood structures;

Snorkeling reaches with installed wood structures.

1.1 Study Area

The Sammamish River is part of Water Resource Inventory Area (WRIA) 8 located in Central Puget Sound (Figure 1). The Sammamish River connects Lake Sammamish with Lake Washington. It is a low gradient river with dense aquatic vegetation (Elodea sp. and Myriophylum sp.) in the spring and summer months.

In the summer, water temperatures regularly exceed 68 degrees Fahrenheit (20 degrees Celsius). The river is channelized, straightened, and lacks woody structures. Despite these habitat deficiencies, the Sammamish River and its major tributary, Bear Creek, support runs of wild anadromous salmonids, including Chinook salmon (Oncorhynchus tshawytscha), that are listed as threatened under the Endangered Species Act.



Figure 1. Predator Study

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There is also a hatchery located upstream of the study area on Issaquah Creek. This hatchery produces coho (O. kisutch) and Chinook salmon. Approximately 500,000 Coho salmon averaging 5 to 6 inches (12.7 to 15.2 centimeters [cm]) long and 2,000,000 Chinook salmon averaging 3 inches (7.6 cm) long are released each year.

2.0 Methods DEA biologists angled and snorkeled during the month of May in the study area to accomplish the goals of this project. The study area included the Sammamish River near river mile 11 (17.7 kilometer), near the bridge crossings of NE 85th Street and NE 90th Street (Figure 2).

We timed our snorkel events to coincide with the peak outmigration of juvenile Chinook salmon from Bear Creek. Bear Creek is approximately one kilometer upstream of the study area. Previous years of monitoring by Washington Department of Fish and Wildlife (WDFW) showed the peak outmigration of juvenile Chinook salmon occurred in May (WDFW 2005; WDFW 2006; WDFW 2007). Primary releases of Chinook juveniles from a hatchery on Issaquah Creek (also upstream) occur slightly later than the Bear Creek timing. In 2007, most of the hatchery releases occurred in late May and early June (personal communication with Issaquah Salmon Hatchery manager).

Angling included hook and line sampling in the evening and morning. Angling consisted of:

Two anglers spin casting lures in areas with good bank access (Reach 2 and 3);

Landing predators and euthanizing them for stomach content analysis;

Analyzing stomach content which included cutting out and opening the digestive tract from the esophagus to the anus;

Identifying stomach contents and storing in ethanol.

We snorkeled four 328-foot (100 meter) reaches. Reach 1 is downstream of any rehabilitated reaches in the RWMP and did not include any installed wood structures. Reaches 2, 3, and 4 are between the bridge crossings of NE 85th Street and NE 90th Street. Snorkel surveys included:

Four distinct 328 foot (100 meter) reaches;

Evening and night time periods;

Each survey conducted with a snorkeler in the water and one data recorder on the bank.



Figure 2. Predator Study

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The snorkeler identified each fish to species (except for sculpin) and whether it was associated with installed wood. This information was then relayed to the data recorder. Fish were associated with wood if they were within 2 feet of the installed wood. Each installed wood structure in each reach was also counted.

All work was permitted under a WDFW Scientific Collectors Permit # 06-337.

3.0 Results DEA biologists conducted three angling and four snorkel surveys (Table 1). Our angling surveys usually preceded the snorkel surveys (Appendix B); however, we did conduct one morning angling survey on May 18, 2007. Water temperatures ranged from 13 degrees Celsius on May 2, 2007, to almost 68 degrees Fahrenheit (20 degrees Celsius) on May 30, 2007.

Table 1. Date, time, and water temperature during snorkeling and angling surveys (angling surveys in italics).

Date Time (24h) Water Temp (Celsius)* 05/02/2007 18:00-21:00 55.8-57.5 (13.2-14.2) 05/15/2007 18:00-21:00 60.1-62.8 (15.6-17.1) 05/15/2007 21:40-00:00 62.8-64.0 (17.1-17.8) 05/18/2007 06:00-09:00 60.1-60.8 (15.6-16.0) 05/23/2007 19:00-21:15 60.3-61.2 (15.7-16.2) 05/23/2007 21:50-00:00 61.5-62.2 (16.4-16.8) 05/30/2007 21:30-23:50 66.0-67.6 (18.9-19.8)

* King County data from USGS gauge 12125200 approximately 2.5 miles (four kilometers) downstream of study area.

During the three angling surveys we captured 26 northern pikeminnow (Ptychocheilus oregonensis), two smallmouth bass (Micropterus dolomieui), and one cutthroat trout (Oncorhynchus clarki) (Table 2).

Table 2. Species captured and date of capture during angling surveys.

Species 5/15/2007 5/18/2007 5/23/2007 Total Average length inches (cm) Cutthroat trout 0 1 0 1 7.75 (20) Northern pikeminnow 5 12 9 26 11.3 (28.7) Smallmouth bass 0 2 0 2 11.5 (29.3) Total 5 15 9 29 -



No juvenile salmon were found in the stomach contents of any captured fish (Table 3). One smallmouth bass had a sculpin sp. in its gut. The majority (73 percent) of the stomach contents of the northern pikeminnow were empty.

Table 3. Stomach contents of captured predatory fish (number in table is the count of individual fish with a certain type of stomach content).

Species Empty Insects Crawfish Sculpin sp. Unidentifiable bile Algae Total Cutthroat trout 0 1 0 0 0 0 1 Northern pikeminnow 19 2 1 0 3 1 26 Smallmouth bass 0 0 0 1 1 0 2 Total 19 3 1 1 4 1 29 During the four snorkel surveys we observed approximately 1,640 individual fish of 13 different species (Table 4). Sculpin sp. were the most abundant, followed by Chinook salmon, three-spine stickleback (Gasterosteus aculeatus), and coho salmon.

Table 4. Date and number of each species observed during snorkel surveys within all reaches (potential predators in bold).

Date Total Species 5/2/2007 5/15/2007 5/23/2007 5/30/2007

Bluegill (Lepomis machrochirus) 0 7 6 0 13 Chinook salmon 3 100 81 59 243 Coho salmon 00 27 42 24 93 Crayfish (Pacifastacus sp.) 0 0 0 2 2 Cutthroat trout 0 11 20 11 42 Largescale sucker (Catostomas macrocheilus) 0 3 1 1 5 Northern pikeminnow 4 1 6 49 60 Peamouth (Mylocheilus caurinus) 0 10 0 0 10 Pumpkinseed (Lepomis gibbosus) 2 5 10 4 21 Rainbow trout (Oncorhynchus mykiss) 0 3 0 0 3 Salmon (Oncorhynchus sp.) 0 1 1 2 Sculpin (Cottus sp.) 6 314 336 220 876 Smallmouth bass 0 0 2 2 4 Three-spine stickleback (Gasterosteus aculeatus) 5 63 60 104 232 Yellow perch (Perca flavescens) 10 8 7 9 34 Total 30 552 572 486 1640



Approximately 11 percent of the observed fish were associated with installed wood (i.e. within 2 feet; Table 5). Reach 1 was eliminated from this analysis because it did not contain any installed wood structures. Reaches 2 to 4 contained at least one installed wood structure each. The majority of the snorkel survey area of each reach did not have installed wood structures.

Table 5. Number and percent of fish species associated with installed wood structures within Reaches 2-4.

Number Associated with Wood Species Yes No Total

Percent Associated with Wood

Bluegill 1 10 11 9% Chinook salmon 17 118 135 13% Coho salmon 3 29 32 9% Crayfish 0 1 1 0% Cutthroat trout 5 27 32 16% Largescale sucker 0 2 2 0% Northern pikeminnow 26 33 59 44% Peamouth 10 0 10 100% Pumpkinseed 0 17 17 0% Rainbow trout 0 2 2 0% Salmon 0 1 1 0% Sculpin 51 656 876 7% Smallmouth bass 1 2 3 33% Three-spine stickleback 8 89 97 8% Yellow perch 5 20 25 20% Total 128 1006 1134 11% All salmon species, bluegill, yellow perch, pumpkinseed, and smallmouth bass observed during snorkeling were less than 3.9 inches (10 cm) long. Cutthroat and rainbow trout were less than 7.8 inches (20 cm) long. Northern pikeminnow, peamouth, and large scale suckers were mostly adults over 5.9 inches (15 cm) long; however, a few juveniles of these species were observed.

Adult northern pikeminnow were mainly observed in the thalweg of the channel during snorkeling and congregated around the installed wood structure in Reach 2. This wood structure was mostly submerged, protruded into the channel, and created variable flows as well as depths.



4.0 Conclusions Several conclusions can be drawn from the results of this study.

Predators are present in the study area during salmon outmigration.

o Northern pikeminnow, smallmouth bass, cutthroat trout, rainbow trout, and sculpin were observed in the study area.

o Northern pikeminnow make annual migrations into the Sammamish River to feed or spawn (Brocksmith 1999). Several studies confirm changes in northern pikeminnow diet during salmon migrations (Shively et al. 1996; Collis et al. 1995).

Predators are of a sufficient size to prey on juvenile salmon.

o Northern pikeminnow and smallmouth bass averaged over 9 inches (22.9 cm), which is the size at which theses fish become mainly piscivorous. Sculpin and cutthroat were smaller than 9 inches (22.9 cm) and fish do not likely compose a major component of their diet.

Northern pikeminnow are the most abundant predator.

o Angling: N=26, Snorkeling: N=59.

Predation on juvenile salmon was low in the month of May.

o No salmon in stomach contents of captured fish.

Installed wood structures do not appear to attract salmon predators in the study area.

o Predators were randomly distributed in the study area and did not specifically associate with woody structures, with the exception of the structure in Reach 2 on the May 30 sampling event.

There may be several reasons for the observations made:

Water temperatures may play a role in the empty stomachs of predators.

o Water temperatures ranged from 55 degrees Fahrenheit (13 degrees Celsius) to 63 degrees Fahrenheit (17 degrees Celsius) in the study area when predatory fish were captured and their stomach contents examined. In a personal communication with Roger Tabor, United States Fish and Wildlife biologist, he observed increases in northern pikeminnow predation of juvenile salmon in Lake Washington in June over May when water temperatures are warmer.



Northern pikeminnow were spawning and food consumption was minimal.

o Spawning occurs from late May through July depending on water temperatures (Wydoski and Whitney 2003). Northern pikeminnow were gravid (i.e. gametes expelled from anus when pressure was applied to the body). The male to female sex ratio of northern pikeminnow was 87 percent. Males stage before females during the spawning period (Wydoski and Whitney 2003). A majority of northern pikeminnow had empty stomachs (73 percent).

In conclusion, predators of juvenile salmon do inhabit the study area during the juvenile Chinook and coho salmon outmigration. However, they do not specifically associate with installed woody structures and they do not appear to prey on juvenile Chinook or coho salmon.

Most of the juvenile Chinook salmon outmigration from Bear Creek (just upstream of the study area) occurs before June 1 (WDFW 2005; WDFW 2006; WDFW 2007). In 2007, 63 percent of the total Chinook migration occurred in May (personal communication with Kelly Kiyohara, WDFW). Considering the results of this study and the fact that most of the juvenile salmon migrate past the HEP project area before June, it is likely predation by northern pikeminnow and smallmouth bass is low and not influenced by installed wood structures.

5.0 References

Beauchamp, D.A. 1995. Riverine Predation on Sockeye Salmon Fry Migrating to Lake Washington. North American Journal of Fisheries Management: Vol. 15, No. 2 pp. 358–365.

Brocksmith, R. 1999. Abundance, feeding ecology, and behavior of a native piscivore Northern pikeminnow (Ptychocheilus oregonensis) in Lake Washington. M.S. Thesis, University of Washington, Seattle. 82 p., plus appendices.

Collis, K., R.E.Beaty, and B.R. Crain. 1995. Changes in Catch Rate and Diet of Northern Squawfish Associated with the Release of Hatchery-Reared Juvenile Salmonids in a Columbia River Reservoir. North American Journal of Fisheries Management: Vol. 15, No. 2 pp. 346–357.

DeVries, P. 2000. PIT tagging of Juvenile Salmon Smolts in the Lake Washington Basin: Year 2000 Pilot Study Results. U.S. Army Corps of Engineers, November 2000.

Fayram, A.H. and T.H. Sibley. 2000. Impact of Predation by Smallmouth Bass on Sockeye Salmon in Lake Washington, Washington. North American Journal of Fisheries Management: Vol. 20, No. 1 pp. 81–89.



Greater Lake Washington Technical Committee. 2001. Draft Reconnaissance Assessment- Habitat Factors that Contribute to the Decline of Salmonids- Greater Lake Washington Watershed Water Resource Inventory Area 8. Report prepared for the Greater Lake Washington Steering Committee. August 22.

Shively, R.S., T.P. Poe, and S.T. Sauter. 1996. Feeding Response by Northern Squawfish to a Hatchery Release of Juvenile Salmonids in the Clearwater River, Idaho. Transactions of the American Fisheries Society: Vol. 125, No. 2 pp. 230–236

Tabor, R. and B. Footen. 2000. Predation of juvenile salmon by littoral fishes in the Lake Washington - Lake Union Ship Canal, preliminary result, King County – Wastewater Treatment Division, November.

Washington Department of Fish and Wildlife. 2005. Evaluation of Downstream Migrant Salmon Production in 2004 from the Cedar River and Bear Creek. Dave Seiler, Greg Volkhardt, and Lindsey Fleischer. March.

———. 2006. Evaluation of Downstream Migrant Salmon Production in 2005 from the Cedar River and Bear Creek. Greg Volkhardt, Dave Seiler, Lindsey Fleischer, and Kelly Kiyohar. April.

———. 2007. Evaluation of Downstream Migrant Salmon Production in 2006 from the Cedar River and Bear Creek. Kelly Kiyohara and Greg Volkhardt. March.

Wydoski and Whitney. 2003. Inland Fishes of Washington. University of Washington Press.


Predator Fish Monitoring October 2007 Sammamish River Habitat Enhancement Projects Appendix A - 1

Appendix A: Literature Review



The predation of juvenile salmon by fishes in Lake Washington is well documented (Fayram and Sibley 2000; Tabor and Footen 2000; Brocksmith 1999; Beauchamp 1995). Predation was identified as a known factor of decline in the WRIA 8 Draft Reconnaissance Assessment (Greater Lake Washington Technical Committee 2001).

High predation areas include the narrow regions of the Ship Canal and the Locks. Predation rates on juvenile Chinook are highest in June, which corresponds to the peak outmigration period in Lake Union (Tabor and Footen 2000; DeVries 2000).

Results from a 1999 predator study in the Ship Canal area show that predation by bass and pikeminnows on Chinook are very high (Tabor and Footen 2000). Smolts per predator ranged from 0.4 for pikeminnows, to 0.3 for smallmouth bass, to 0.1 for largemouth bass (May through July). Chinook smolts represented approximately 50 percent of the 30 salmonids consumed by the predators and identified to the species level. Bass as small as 138 mm were found to eat smolts of ~90 mm in size. Pikeminnows tended to aggregate at key locations such as the outlet of the UW Hatchery and the point at the north end of Lake Union. Other species of fish that may also prey on outmigrating juveniles include yellow perch, prickly sculpin, rainbow trout, cutthroat trout, and river lamprey.

Several studies have shown feeding responses to hatchery releases of Chinook by Northern pikeminnow (Collis et al. 1995; Shively et al. 1996). Northern pikeminnow caught after salmonid releases had a significantly higher frequency of occurrence and mean number of juvenile salmonids in their diet compared with fish caught before releases. Northern pikeminnow can quickly exploit hatchery releases of juvenile salmonids away from release sites in the Columbia River basin.

The Issaquah Hatchery does release a large number of Chinook smolts in late May. It is unknown if northern pikeminnow aggregations in the Sammamish River are related to spawning or feeding. Additional studies to conduct would be to extend the sampling period into June and concentrate efforts at migration “pinch points” such as the weir in Marymoor Park.

We did not find any specific literature in regards to predation of juvenile salmon in the Sammamish River or in relation to installed wood structures. WDFW has captured juvenile salmon fish predators in their traps to monitor juvenile salmon outmigrations in Bear Creek a tributary of the Sammamish River (WDFW 2006). Catches of northern pikeminnow, smallmouth bass, and largemouth bass have been documented. The stomach contents of theses catches is unknown.



Brocksmith (1999) found evidence that the Sammamish River supports a spawning population of northern pikeminnow in the vicinity of Little Bear Creek. Fish tagged in Lake Washington were found in the Sammamish River in May. This supports the findings of the predation study DEA conducted in May of 2007. DEA biologists captured 26 northern pike minnow by hook and line and observed 59 adults during night time snorkeling events.


Predator Fish Monitoring October 2007 Sammamish River Habitat Enhancement Projects Appendix B - 1

Appendix B: Photographs

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Appendix B

Predator Fish Monitoring – Sammamish River Habitat Enhancement Projects

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2 Himalayan blackberry lined banks of Sammamish River in Reach 1.

1 Sammamish River and installed wood structures facing south from NE 90th Street bridge.

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Appendix B


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4 Reach 3 facing north.

3 Installed wood structure in Reach 2.

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6 Angling in Reach 2 on May 15.

5 Snorkeling in Reach 1 on May 2, 2007.

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8 Northern pikeminnow from Reach 2.

7 Smallmouth bass from Reach 2.

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