Development of Passage Structures for Adult Pacific Lamprey at Bonneville Dam, 2009-2010

Mary L. Moser, Darren A. Ogden, Howard T. Pennington,†

Matthew L. Keefer,‡ and Christopher C. Caudill‡

Report of research by

Northwest Fisheries Science Center, National Marine Fisheries Service National Oceanic and Atmospheric Administration 2725 Montlake Boulevard East, Seattle, WA 98112

†Pacific States Marine Fisheries Commission

45 S. E. 82nd Drive, Suite 100, Gladstone, OR 97027-2522

‡Idaho Cooperative Fish and Wildlife Research Unit, U.S. Geological Survey, University of Idaho, Moscow, ID 83843

for

Portland District U.S. Army Corps of Engineers

P.O. Box 2946, Portland OR 97020 Contract E96950021

March 2012

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EXECUTIVE SUMMARY In 2009-2010, we continued a multi-year study to evaluate and improve adult Pacific lamprey passage at Bonneville Dam with the following objectives: 1) Evaluate use of the existing lamprey passage structures (LPSs) installed in the

Washington-shore and Bradford Island auxiliary water supply channels

2) Design, fabricate, and install a new lamprey passage structure at the Cascades Island Fishway entrance, and monitor lamprey use of this new structure

3) Monitor lamprey use of the collector at the Washington Shore fishway entrance

4) Monitor lamprey entrance into the top of the Cascades Island fishway To achieve the monitoring objectives, we used two approaches. First, we counted individual lamprey passage in the new and existing structures. For these counts, we used lamprey-activated counters in the Washington Shore and Bradford Island AWS structures and terminal trap boxes in the Cascades Island and the Washington-shore fishway structures. Second, we marked lamprey with passive integrated transponder (PIT) tags and monitored their movements within the LPSs. In 2009, we tagged 369 adult lamprey with a PIT tag (PIT-only) and 299 with both a half-duplex PIT-tag and radio transmitter (double-tagged). In 2010 we tagged 19 PIT-only and 312 double-tagged fish. Low returns of adult Pacific lamprey limited sample sizes in both years, with 2010 returns the lowest on record. Antennas to detect PIT tags were integrated into all of the lamprey passage structures, and an antenna was also operated at the top of the Cascades Island fishway to identify lamprey passage routes and rates of movement.

In 2010, we raised the picketed lead at the entrance to the Washington-shore AWS channel by 3.8 cm, and this increased lamprey access to the passage structure. In contrast, collection efficiency stayed the same or decreased slightly at the LPS in the Bradford Island AWS, where no changes were made to improve access. At the Bradford Island AWS, LPS passage efficiency was 100%. At the Washington-shore AWS, LPS passage efficiency was 71% in 2009 and 86% in 2010. This may have been due to the accumulation of algae on exposed ramps at this LPS. As a result, these ramps were cleaned and covered to reduce future algal growth.

A new lamprey passage structure was completely operational at the Cascades Island fishway by 25 May 2009. This LPS featured the greatest overall length (> 92 m) and elevation gain (27 m) tested thus far, allowing lamprey to ascend from the tailwater

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level to a position above the forebay. The new structure was used by 208 lamprey in 2009 and 48 lamprey in 2010. No PIT-tagged lamprey volitionally entered the structure in either year. However, 6 PIT-tagged lamprey placed in the upper LPS successfully ascended to the top of the structure. Video monitoring in 2009 indicated that lamprey had difficulty on steep ramps during high flow treatments; consequently, we operated the structure with a lower flow in 2010. The Washington Shore entrance collector was operated in both 2009 and 2010, but the number of lamprey using this structure decreased sharply relative to 2007 and 2008. This may have been a consequence of recent changes in operations designed to reduce velocity emanating from the Washington Shore ladder north downstream entrance (NDE) at night, making it less likely for lamprey to accumulate near this entrance. We continued to monitor lamprey use of the Cascades Island fishway flow control section upstream from the upstream migrant transportation (UMT) channel in 2009 and 2010. PIT-tagged lamprey were detected at lower frequencies than in previous years (7% of PIT-only and 3% of double-tagged fish in 2009 and 2% of double-tagged fish in 2010). This was likely due to either lower overall sample sizes of tagged fish in 2009 and 2010, or the effects of modifications to the Cascades Island fishway entrance made in 2009.

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CONTENTS EXECUTIVE SUMMARY ............................................................................................... iii INTRODUCTION .............................................................................................................. 1 OBJECTIVE 1: Evaluate Lamprey Passage Structures in the Washington Shore and

Bradford Island Auxiliary Water Supply Channels ..................................................... 5 Structure Design and Modifications ....................................................................... 5 Evaluations Based on Counts................................................................................ 10

Methods..................................................................................................... 10 Results ....................................................................................................... 11

Evaluations Based on Monitoring of Tagged Lamprey ........................................ 13 Methods..................................................................................................... 13 Results ....................................................................................................... 15

Bradford Island AWS Channel LPS ............................................. 15 Washington Shore AWS Channel LPS ......................................... 16

Discussion ............................................................................................................. 17 OBJECTIVE 2: Evalute a New Lamprey Passage Structure at the Cascades Island

Fishway Entrance ....................................................................................................... 19 Structure Design and Installation .......................................................................... 19 Evaluations of Lamprey Use ................................................................................. 24

Trap Box Counts, Video Observation, and Flow Experiments ................ 24 Monitoring of Tagged Lamprey ................................................................ 25

Discussion ............................................................................................................. 26 OBJECTIVE 3: Monitor use of a Lamprey Collector at the Washington Shore Fishway

Entrance ..................................................................................................................... 29 Methods................................................................................................................. 29 Results ................................................................................................................... 30

Trap Box Collections ................................................................................ 30 Evaluations Based on Monitoring of Tagged Lamprey ............................ 30

Discussion ............................................................................................................. 31 OBJECTIVE 4: Monitor Lamprey Entrance into the Cascades Island Upper

Fishway/Flow Control Area ...................................................................................... 33 Methods................................................................................................................. 33 Results ................................................................................................................... 34 Discussion ............................................................................................................. 35

ACKNOWLEDGMENTS ................................................................................................ 36 REFERENCES ................................................................................................................. 37

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INTRODUCTION In the Columbia River Basin and worldwide, providing fish passage at dams is critical to preserving the distribution and fitness of migratory species (Lucas and Baras 2001; Roscoe and Hinch 2010). However, passage aids at many dams target only the species that support commercial or recreational fisheries (e.g., salmonids and alosids). There is increasing recognition of the need to provide passage for a broader component of the aquatic community, including fish and invertebrates incapable of using traditional fishway designs (Fievet 2000; Jansen et al. 2000; Stuart et al. 2008; Thiem et al. 2012). Ideally, passage facilities would accommodate as many species and life stages as possible in order to preserve historical metapopulation and population structures, as well as the continuity of species clines (Gollmann et al. 1998; Agostinho et al. 2007). Making fishways accessible to a variety of species requires knowledge of their swimming performance and behavior (Northcote 1998). To acquire such knowledge, laboratory investigations and testing of prototypes are often used to determine swim performance limits (Mallen-Cooper 1992; Haro et al. 2004; Pratt et al. 2009; Keefer et al. 2011). In some cases, existing fishways can be retrofitted to accommodate weak swimmers (Yasuda et al. 2004; Stuart et al. 2008), very large fish (Stuart and Berghuis 2002; Parsley et al. 2007), or fish with unique passage behaviors (Barry and Kynard 1986; Moser et al. 2000). In other cases, completely separate fishway systems are required (Whitfield and Kolenosky 1978; Schwalme et al. 1985; Clay 1995; Fievet 2000; Baker and Boubee 2006; Barrett and Mallen-Cooper 2006). Development of both modifications and separate fishway systems has been the challenge in providing passage routes for imperiled adult Pacific lamprey Lampetra tridentata (Gairdner) in the northwestern United States (Moser et al. 2011). To reach historic spawning areas in the Columbia River basin, anadromous adult Pacific lamprey must pass up to nine hydroelectric dams on the mainstem rivers and numerous low-elevation structures on tributary streams. Lamprey consistently exhibit poor rates of passage at traditional fishways (Moser et al. 2002; Keefer et al. 2009, 2010), and counts of upstream migrants at Bonneville Dam have dropped by 50% or more in the last several decades, reaching record lows in recent years (USACE 2008; Keefer et al. 2011). Calls to improve dam passage success have become increasingly urgent, as these fish are important to both the riverine ecosystem and to Native Americans in the region, for whom lamprey are a cultural necessity (Close et al. 2002; Keefer et al. 2011). Providing safe dam-passage routes for lamprey is challenging. However, improving dam passage was identified by the U.S. Fish and Wildlife Service Lamprey Technical

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Workgroup as one of the highest priorities for Pacific lamprey recovery in the Columbia and Snake Rivers (CRBLTW 2005). Consequently, developing a robust “toolbox” of lamprey-friendly fishway designs is critical to the success of both new passage structures and the addition of structures to existing fishways. After entering the Columbia River, adult Pacific lamprey encounter Bonneville Dam, the first mainstem hydropower dam at river kilometer 235 (Figure 1). Here they have difficulty entering fishways, and those that successfully enter are often obstructed or delayed near the upper areas of the fishways (Moser et al. 2002; Johnson et al. 2009b). In these areas, serpentine weirs present an obstacle to upstream movement. Lamprey routinely aggregate in auxiliary water supply channels (AWS channels), which are adjacent to the tops of these fishways (Moser et al. 2005). Lamprey enter AWS channels through connecting diffuser gratings or via picketed leads downstream from count stations. There is no readily passable outlet from AWS channels to the dam forebay. Radiotelemetry results have indicated that lamprey reside in AWS channels for 4 d on average, and then typically move back downstream (Moser et al. 2005). In 2002 we began development of the first lamprey-specific fishway from the Bradford Island AWS channel into the forebay at Bonneville Dam Powerhouse 1 (Figure 1c).

To design fishways specifically for adult lamprey, we collected information about historic lamprey distribution and capture methods through conversations with tribal elders. We also gleaned data from studies of sea lamprey Petromyzon marinus in the Laurentian Great Lakes (R. McDonald, Great Lakes Fisheries Commission, personal communication). Using this information, we developed prototype passage structures, in concert with laboratory testing of specific design elements, over a 5-year period (Reinhardt et al. 2008; Keefer et al. 2010, 2011; Kemp et al. 2009, 2010, 2011; Moser et al. 2011). The success of the prototype lamprey passage structure (LPS) in the AWS channel of the Bradford Island fishway prompted further development. We installed a prototype fishway entrance collector at the Washington shore fishway in 2005 (Moser et al. 2008) and a second full LPS at the Washington-shore AWS channel in 2007 (Moser et al. 2011). While the LPS in the Washington-shore AWS channel was used regularly by lamprey, its collection efficiency was not as high as that of the Bradford Island structure. In addition, the entrance collector at the Washington shore fishway had low collection efficiency relative to the collectors in both AWS channels.

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Figure 1. Schematic drawing showing configuration of Bonneville Dam with

approximate locations of the fishways at (a) Washington shore, (b) Cascades Island, and (c) Bradford Island. Black dots show Hamilton Island and Tanner Creek release sites used for tagged lamprey in 2009 and 2010 (black dots).

In 2009-2010 our objectives were to: 1) Evaluate lamprey use of the existing lamprey passage structures installed in the

Washington shore and Bradford Island auxiliary water supply channels

2) Design, fabricate, and install a new lamprey passage structure at the Cascades Island fishway entrance and monitor lamprey use of this new structure

3) Monitor lamprey use of the collector at the Washington shore fishway entrance

4) Monitor lamprey entrance into the Cascades Island upper fishway/flow control area

To achieve the monitoring objectives, we used two approaches. First, we assessed the use of existing structures based on counts of lamprey as they passed through each LPS exit. Lamprey-activated counters were used at LPSs in the Washington Shore and Bradford Island AWS channels, and a terminal trap box was used to count lamprey at the Cascades Island and the Washington-shore ladder entrance collectors.

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Second, we tagged migrating adult Pacific lamprey with passive integrated transponder (PIT) tags and released them downstream from the dam. We recorded passage events for these fish using PIT-tag monitors installed at the LPS exits and at other locations within the LPSs. We calculated LPS collection efficiency, passage efficiency, and passage rate at each structure using detections of PIT-tagged lamprey.

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OBJECTIVE 1: Evaluate Lamprey Passage Structures in the Washington Shore and Bradford Island Auxiliary Water Supply Channels

Structure Design and Modifications The LPS at the top of the Bradford Island fishway is positioned at the upstream end of the AWS channel (Figure 2). Overall horizontal distance of this LPS is approximately 35.6 m, and elevation gain is 7.9 m (Figure 3). Figure 2. Schematic drawing of the Bradford Island fishway system at Bonneville Dam

with locations of the auxiliary water Supply LPS (AWS LPS) and count window.

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To enter the LPS, lamprey ascend one of two collector ramps in the AWS channel, and from either ramp must pass a PIT-tag monitor (PIT 1 or PIT 2) before entering Rest Box 1 (Figure 3). Lamprey then ascend a short ramp with a broad-crested weir to enter Rest Box 2, a large rest box. From there they ascend another short ramp, passing another PIT-tag monitor (PIT 3) to enter Rest Box 3. They then traverse a shallow ramp and a 20.3-cm wide horizontal tube to Rest Box 4 (Figure 3). At the entrance to each rest box, we inserted a 20.3-cm wide plastic-mesh cone to prevent lamprey from passing back down the LPS. The mesh cone forced lamprey to exit the rest box in an upstream direction. Columbia River water was supplied to the top of the Bradford Island LPS via a 10.2-cm-diameter PVC pipe fed by two 3-hp submersible pumps in the forebay. Flow was regulated by pumping water into an upwelling box at the top of the LPS. This design stimulated lamprey to move onto the exit slide, even though water was passing down the slide. Pumps were operated to maintain a depth of 3 cm on the ramps and approximately 10 cm in the closed tubes. Figure 3. Top view of the Bradford Island LPS with locations of half-duplex PIT-tag

detection antennas (PIT 1-4) indicated. Further detail on the dimensions and schematics of this LPS were reported by Moser et al. (2009).

PIT 2PIT 1

Rest Box 1PIT 3

PIT 4

Rest Box 2Large Rest

Box

Rest Box 3

PIT 2PIT 1

Rest Box 1PIT 3

PIT 4

Rest Box 2Large Rest

Box

Rest Box 3

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To monitor passage of PIT-tagged lamprey, the LPS was constructed with a series of four half-duplex PIT-tag detection antennas and transceivers (Figure 3). Antennas were integrated into the LPS using a rectangular PVC sleeve, which was inserted seamlessly into the chutes leading to Rest Boxes 1, 2, and 4. The PVC prevented the aluminum from attenuating the PIT signal. Each loop antenna was 10-G multistrand wire wrapped around the PVC insert, and each insert had an outer aluminum housing, which shielded the antenna. Each antenna was connected to a transceiver, which recorded the time and date of each detection. Transceivers were synchronized by wiring them together. In 2007 we designed, fabricated, and installed a second LPS in the AWS channel near the top of the Washington Shore fishway (Figure 4). While this second LPS was in many respects similar to the Bradford Island LPS, it incorporated some unique features. Similar to the Bradford Island LPS, the Washington shore LPS was fabricated of aluminum, with 51-cm wide ramps that terminated in rest boxes. Figure 4. Plan view showing locations of lamprey passage/collection structures at the

AWS and fishway entrance areas of the Washington Shore fishway.

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6.3 m

2.9 mUpwelling Box

Rest Box 1

Upwelling Box

Rest Box 2

Rest Box 2

Rest Box 1

Rest Box 3

Rest Box 3

Side View

Top View

Upwelling Box

Rest Box 1

Upwelling Box

Rest Box 2

Rest Box 2

Rest Box 1

Rest Box 3

Rest Box 3

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Top View

14.3 m

The crest at the top of each ramp was the same width as the ramp (51-cm). Hence, the mesh cones directing lamprey into each rest box were wider (51-cm) at the base than the cones used at Bradford Island rest boxes (20.3-cm) and had a larger opening at their terminus. Ramp grades in the Washington Shore and Bradford Island AWS LPSs were similar (45°), as were the water-supply systems and lamprey counters at the exit slide. The LPS in the Washington Shore AWS featured a “switchback” design to allow greater elevation gain in a smaller area (Figure 5). The overall length of the Washington Shore AWS LPS was approximately 19 m, with an elevation gain of 9.1 m (Figure 5). Figure 5. Top and side views of the Washington Shore AWS LPS. The shaded arrows

on the top view indicate the direction of water flow on the switchback ramps. Black boxes on the side view indicate the position of half-duplex PIT antennas.

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In 2009, the picketed lead at the entrance to the Washington Shore AWS channel (Figure 4) was operated as in previous years, with pickets extending nearly to the bottom of the channel and restricting lamprey access. In early May 2010, this picketed lead was modified by installing a 2.5-cm metal spacer at the bottom of each picket frame (Figure 6). These spacers were installed when the fishway channel was full of water; therefore, it was not possible to measure the resulting space underneath the pickets. Instead the space was measured during winter 2010-2011, when the fishway was de-watered. The distance from the AWS floor to the bottom of the pickets was found to be approximately 3.8-cm (Figure 6).

Figure 6. Upper right photo shows de-watered Washington Shore picketed lead looking downstream from inside the AWS channel. Shaded arrows indicate the locations where 2.5-cm metal spacers (inset at top right) were installed. Lower left photo shows pickets raised approximately 3.8-cm above the AWS channel floor.

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Evaluations Based on Counts Methods In 2009, both the Bradford Island and Washington Shore AWS LPSs were operated from 26 May to 2 November. During this period there were several gaps in the LPS count record due to power outages at Bradford Island (10-12, 20-22, and 27-30 July) and at the Washington Shore (20-22 and 27-30 July). Thus, the lamprey count at AWS structures was underestimated in 2009. To address this problem, a new type of event logger (Comet S7841) with an internal battery pack was installed at each AWS LPS exit slide in 2010. No outages were experienced during operation of either AWS LPS in 2010 (Bradford Island 4 June-25 October; Washington Shore 8 June-25 October). In 2010, during the first night of operation of the Washington Shore AWS LPS a plastic mesh liner on the exit slide failed and fell to the end of the exit slide, blocking lamprey egress. During that night, 28 lamprey died in the exit tube; 27 of these fish were used for proximate analysis by the University of Idaho. The remaining 20 live fish were released into the forebay, and the structure was shut down for repairs. To address this problem, a section was cut out of the exit slide to allow for visual inspection, and a mesh cover was secured over the cutout (Figure 7). A corresponding slot on the underside of the slide was cut out and covered with mesh to prevent lamprey from attaching to the slide during their exit. The mesh liner at the Bradford Island AWS LPS exit slide (located inside the PVC pipe) was also checked at that time. This incident highlighted the need for regular inspections of both the exterior and interior of the LPS to ensure safe lamprey passage.

Figure 7. Modified exit slide in the LPS at the Washington Shore fishway AWS channel. An opening with a mesh cover was made in the PVC exit tube to allow visual inspection of the LPS terminus.

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Results At the exit of the LPS in the Bradford Island AWS channel, 3,302 lamprey were counted in 2009 and 1,933 in 2010. In both years, the number of lamprey counted at the exit was higher than the number counted during the day (0500-2100) at the count window in the adjacent fishway (Figure 8). Figure 8. Number of lamprey counted at the Bradford Island count station (shaded areas)

and at the AWS LPS exit slide (closed diamonds) during the periods of LPS counter operation in 2009 (top panel) and 2010 (bottom panel).

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The number of lamprey counted at the Washigton Shore AWS LPS in 2009 was 1,199 and the number counted in 2010 was 2,961. The proportion of lamprey using this LPS relative to the number counted at the adjacent count window was higher in 2010 than in 2009 (Figure 9). Figure 9. Number of lamprey counted at the Washington Shore count station (shaded

areas) and at the AWS LPS exit slide (closed diamonds) during the periods of LPS counter operation in 2009 (top panel) and 2010 (bottom panel).

We estimated collection efficiency in both AWS LPSs by estimating total lamprey abundance at the top of each ladder. This was done by tripling the count station counts at each ladder in each year. This extrapolation was necessary because the count-station counts were made only during the day, while approximately two-thirds of

Washington-shore Fishway

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WA AWS LPSn= 1,199

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n= 3,381

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migrating lamprey typically pass count stations at night (Moser and Close 2003). Estimates of abundance were then divided by the AWS LPS count in each year for each ladder (Table 1). These estimates indicated that over the two study years, collection efficiency decreased at Bradford Island (50 to 39%) but increased at Washington Shore (10 to 29%). Table 1. Lamprey abundance estimates (visual daytime counts × 3), LPS counts, and

collection efficiency (LPS count/abundance) at each structure in 2004–2008. Bradford Island Washington Shore

Abundance

n LPS count

n (%) Abundance

n LPS count

n (%) 2004 35,913 7,490 (21) 2005 30,771 9,242 (30) 2006 44,586 14,975 (34) 2007 19,420 7,387 (38) 22,551 2,517 (11) 2008 15,903 6,441 (40) 16,125 1,985 (12) 2009 6,597 3,302 (50) 11,886 1,199 (10) 2010 4,959 1,933 (39) 10,143 2,961 (29)

Evaluations Based on Monitoring of Tagged Lamprey Methods Lamprey were collected for tagging at the adult fish facility (AFF) and in the Washington Shore entrance collector in both 2009 and 2010. We collected lamprey for PIT-tagging with traps set at the Washington Shore fishway. Lamprey were also collected from the Washington Shore entrance collector (described below) and from two portable traps and two traps at weirs of the Bonneville Dam AFF fishway. Traps were deployed each night from approximately 2100 to 0700 PST. Each morning, trapped lamprey were transferred to a holding tank with running Columbia River water. After anaesthetizing the lamprey using 60-ppm eugenol, we measured weight (nearest g), total length (nearest 0.5 cm), and girth (nearest 0.1 cm) at the insertion of the anterior dorsal fin (nearest mm) of each fish. We then made a 4-mm incision just off the ventral midline at a location even with the insertion of the anterior dorsal fin. A sterilized half-duplex PIT tag (3 × 32 mm) was inserted into the body cavity. Fish were allowed to recover for at least 1 h prior to release approximately 3 km downstream from Bonneville Dam at the Hamilton Island boat ramp on the Washington shore (Figure 1).

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In both years, lamprey implanted with a radio transmitter also received a PIT tag (see Johnson et al. 2009b for radio-tagging methodology). For these fish, a larger incision was made, and the PIT tag was inserted first. A catheter was then passed through the body wall approximately 5 cm posterior to the incision, and the radio antenna was threaded through the catheter. The catheter was then pulled through the body wall, and the radio tag was inserted so that it rested anterior to the PIT tag. The incision was closed with simple, interupted sutures, and fish were allowed to recover for at least 1 h prior to release. These fish were released at both the Hamilton Island boat ramp and across the river at Tanner Creek (rkm 232.5) in approximately equal proportions (Figure 1). In 2009, 369 lamprey were tagged with only a PIT tag (PIT-only) and 299 were tagged with both a PIT and radio transmitter (double-tagged, Johnson et al. in press). The PIT-only fish were tagged between 1 June and 2 September 2009 (mean date 22 June) and released at the Hamilton Island boat ramp. Mean length of these fish was 65 cm (range 40-76 cm). Double-tagged fish were tagged between 1 June and 24 August (mean date 5 July) and released at both the Hamilton Island boat ramp and at Tanner Creek. Mean length of double-tagged fish was 67 cm (range 56-79 cm). Double-tagged fish were larger on average because a minimum girth of 9 cm was required for radio-tagging. In 2010, we tagged 19 PIT-only fish because lamprey abundance was at a record low that year. Thus, there were not enough study animals to attain study objectives. Six of the 19 PIT-only fish (mean length 66 cm) were released directly into Rest Box 3 of the Cascades Island LPS collector (to allow assessment of passage through the upper section of this structure (see Objective 2). The remaining 13 were released downstream from Bonneville Dam at Hamilton Island (mean length 62 cm). We tagged 312 lamprey with both an HD-PIT tag and a radio transmitter. Double-tagged fish were released at both the Hamilton Island boat ramp and at Tanner Creek. The mean length of the double-tagged fish was 67 cm (range 55-77 cm).

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Results Bradford Island AWS Channel LPS—Of the 369 PIT-only fish released downstream from Bonneville Dam in 2009, 26 (7.0%) were detected at the Bradford Island AWS LPS. In contrast, 10 (3.2%) of the double-tagged fish were detected at this structure in 2009 (Table 2). At the Bradford Island LPS in 2010, none of the 13 PIT-only fish were detected, and 10 of the 312 double-tagged fish were detected (3.2% of that release group). One fish tagged in 2009 was also detected in this structure on 13 June 2010. Table 2. Number of PIT-tagged fish detected in the LPSs in the Bradford Island and

Washington Shore auxiliary water supply (AWS) channels. These values as a percentage of PIT-tagged fish released downstream from Bonneville Dam are given in parenthesis.

Lamprey dections n (%) Location of LPS 2007 2008 2009 2010 Bradford Island AWS PIT only 31 (4) 55 (9) 26 (7) 0 Double tag -- 14 (5) 10 (3) 10 (3) Washington Shore AWS PIT only 26 (3) 16 (3) 10 (3) 5 (38) Double tag -- 0 17 (5) 5 (2) In 2009, all PIT-tagged fish detected at the top of a collector ramp were subsequently detected at the exit slide (i.e., passage efficiency through the Bradford Island AWS LPS was 100%). Median passage time from a collector to the exit slide was 0.75 h for both the PIT-only (range 0.43-1.4 h) and double-tagged group (range 0.51-2.1 h). Similarly, in 2010 all fish detected in the Bradford Island AWS LPS were detected at the exit slide (i.e., passage efficiency was 100%). For the 5 fish detected at the top of the collector ramps in 2010, median passage time through the structure was 0.61 h (range 0.52-1.4 h). PIT-tagged fish were also detected using the Bradford Island fishway exit, either in addition to or instead of the LPS. In 2009, 63 PIT-tagged fish were detected at the fishway exit but were not detected in the LPS. Of the 36 fish detected in the LPS during 2009, 5 (14%) were subsequently detected at the fishway exit; only 1 of these was subsequently detected at upstream dams. In 2010, 47 (14%) of the PIT-tagged fish detected at the fishway exit were not detected at the LPS. Of the 11 lamprey that used the LPS, one (9%) was subsequently detected at the Bradford Island fishway exit, and this fish was not detected at an upstream dam.

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In each year, some lamprey that exited the LPS or Bradford Island fishway exit were later detected at upstream PIT-tag monitoring sites. In 2009, 18 (50%) of the fish that used the LPS were detected at upstream sites; in 2010, 7 (64%) were detected at upstream sites. In comparison, of the fish detected exiting the Bradford Island fishway without using the LPS, 80% (2009) and 57% (2010) were detected at upstream sites. Washington Shore AWS Channel LPS—Of the 369 PIT-only fish released downstream from Bonneville Dam in 2009, 10 (2.7%) were detected at the Washington Shore AWS LPS. Five double-tagged fish (1.6%) were also detected using this structure in 2009 (Table 2). In addition, 2 PIT-tagged fish that we released downstream from Bonneville Dam in 2008 were detected in this LPS during 2009 (one PIT-only and one double-tagged). These fish overwintered and passed the Washington Shore LPS on 9 and 26 June 2009. In 2010, 5 (38.5%) of the 13 PIT-only fish and 17 of the double-tagged fish (5.4% of that release group) were detected at the Washington Shore AWS LPS. In 2009, 3 of the 11 PIT-only fish detected at the first HD-PIT antenna were not detected at the exit slide (i.e., passage efficiency through the Washington Shore AWS LPS was 75%). Similarly, 4 (67%) of the 6 double-tagged fish were detected at the exit slide. Median travel time from the first antenna to the exit slide was 0.41 h range (0.37 to 1.6 h) for PIT-only fish and 0.47 h (range 0.36 to 0.75 h) for double-tagged fish. In 2010, all of the 13 PIT-only fish detected in the Washington Shore AWS LPS were also detected at the exit slide (i.e., passage efficiency was 100%). However, only 6 of the 17 (35%) double-tagged fish detected in the LPS were also detected at the exit slide. These fish were most likely missed by monitors at the exit slide, as 14 (82%) of them were subsequently detected at the Washington Shore fishway exit. Median passage time from the first antenna to the exit slide was 0.41 h (range 0.38-0.58 h) for PIT-only fish and 0.44 h (range 0.36-0.62 h) for double-tagged fish. The Washington Shore LPS empties into the Washington Shore fishway downstream from the fishway exit. In both years, PIT-tagged fish that had not been detected in the LPS were detected at the Washington Shore fishway exit. In 2009, 128 PIT-tagged fish that did not used the LPS were detected at this fishway exit. Of the 17 fish that used the LPS in 2009, 14 (82%) were detected at the fishway exit; of the remaining 3 fish, none were detected at upstream dams. In 2010, 56 lamprey (17%) were detected at the Washington Shore fishway exit but were not detected in the LPS. Of the 21 lamprey detected in the Washington Shore LPS, 3 were not detected at the fishway exit, but 2 of these were detected at upstream dams; thus at least 2 fish were missed by the detector at the Washington Shore fishway exit. The remaining 18 fish were all detected at the fishway exit after using the LPS.

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Lamprey detected at the Washington Shore fishway exit were often detected at PIT-tag monitoring sites upstream. In 2009, 3 (18%) fish that used the Washington Shore LPS were detected at upstream sites, while 53 (41%) fish detected using only the traditional fishway exit were detected at upstream sites. In 2010, 7 lamprey that used the LPS (33%), were detected at upstream locations, while 17 (30%) of the 56 fish detected exiting the fishway without using the LPS were detected at upstream sites.

Discussion Our objective was to evaluate lamprey use of the existing LPSs at the Washington-shore and Bradford Island Auxiliary Water Supply (AWS) channels. This was done using both conventional counting methodologies and HD-PIT detections. As was the case in previous years of AWS LPS operation (Moser et al. 2011), significant numbers of lamprey were counted using these methods relative to the numbers counted during the day at the two count windows. In addition, HD-PIT detections indicated that the LPSs in both AWS channels continue to play an important role in lamprey passage at Bonneville Dam. However, data from both years also indicate that improvements could be made to further increase lamprey use of these structures. By raising the picketed lead at the Washington-shore AWS in 2010, lamprey access to the AWS channel was improved, and we saw an immediate increase in LPS use. This translated to an overall increase in lamprey passage efficiency at Bonneville Dam in 2010 (Clabough et al. 2011). Further efforts to improve lamprey access to the AWS channels at both fishways should result in additional improvements in overall lamprey passage. As in previous years, lamprey typically required less than 1 h to negotiate each AWS LPS. In both years, passage efficiency through the Bradford Island LPS was 100%, while passage efficiency at the Washington Shore LPS was lower. We speculated that heavy accumulation of algae on the open ramps of this LPS might have resulted in the low (71%) passage efficiency seen in 2009 (Figure 10). These ramps were cleaned in winter 2009, and all exposed ramps were covered. Nevertheless, in 2010, we again documented lower passage efficiency of double-tagged fish; however, this appeared to be due in part to missed detections rather than passage failures. Detections at the fishway exit indicated an overall passage efficiency at the Washington Shore AWS LPS of at least 86% in 2010.

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This result highlighted the need for regular LPS inspections and rapid attention to even seemingly minor repairs. In 2010, a malfunction in the mesh lining of the Washington Shore LPS exit tube resulted in lamprey mortality. This malfunction was not corrected immediately because the mesh was not readily visible and was consequently difficult to examine during brief, daily inspections of the structure. This was remedied by cutting a section from the exit slide to permit visual examination of the interior mesh lining (Figure 7). A similar modification should be made at the Bradford Island LPS exit slide. While lamprey exhibited high passage efficiency at the Bradford Island LPS, some fish in each year fell back downstream and re-entered the fishway. The Bradford Island LPS exit slide drops lamprey into the forebay from a height of more than 3 m, and as a result of this long drop, fish are likely disoriented when they hit the water. The exit slide could be improved by extending

Figure 10. Open ramps of LPS in the Washington Shore AWS showing thick mat of algae on exposed ramps. This potential obstruction to lamprey attachment was cleaned in winter 2009, and exposed ramps were covered to prevent future algal development.

it to a position further away from the Bradford Island fishway exit. In addition, reducing the distance from the LPS terminus to the water surface could reduce the potential for disorientation or physical injury. By allowing lamprey to quickly re-orient after exiting the structure, their vulnerability to predation could also be reduced. Further study is needed to determine whether predators key in on lamprey near this LPS exit. Ultimately, improvements to lamprey passage that occur when an LPS is provided should translate to improved lamprey fitness and greater reproductive potential. In 2009, lamprey that used the AWS structures were detected at upstream dams at a lower rate than fish detected only at traditional fishway exits. This result was similar to those from previous years of LPS operation (Moser et al. 2011), and could mean that lamprey using an LPS did not migrate upstream as successfully as those using traditional passage routes. However, in 2010 this trend was reversed: lamprey using the AWS structures had higher upstream detection rates than those detected only at the fishway exits. It is not clear why this change occurred, and further research is needed to confirm that lamprey using an LPS have the same (or better) reproductive potential as those migrating via fishways.

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OBJECTIVE 2: Evaluate a New Lamprey Passage Structure at the Cascades Island Fishway Entrance

Structure Design and Installation In 2009, a new collector-type LPS was installed at the entrance of the Cascades Island fishway in conjunction with other modifications to improve lamprey access. These other modifications included installation of a variable-width weir at the fishway entrance and a field of velocity-disrupting bollards on the fishway floor immediately inside the entrance (Figure 11). Bollards were positioned to guide lamprey toward the entrance to the LPS collector, which was located inside the fishway along its north wall. This position for the LPS entrance was selected to minimize potential impacts to salmonids, which enter the fishway and move along the south fishway wall. The bollard field and LPS entrance were immediately downstream from a series of inset diffusers (Figure 11). Figure 11. Cascades Island fishway entrance (from inside the entrance looking

downstream) before (left panel) and after (right panel) installation of bollards to slow flow and improve passage for lamprey.

The entrance collector for the Cascades Island LPS was designed to provide lamprey with a passage route from inside the fishway entrance to a position above the forebay on the Bonneville Dam deck (the structure terminates at the +85 deck near the FV5-4 fish valve). Consequently, this was the longest LPS (92.4 m) with the greatest elevation gain (27 m) of any that have been built thus far (Figure 12). At present, lamprey using this structure must be collected in a trap at its terminus and released to the forebay. However, in the future this structure can be extended to allow lamprey egress into the area above the dam.

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5 m

Rest Box 1

Rest Box 4

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Figure 12. Upper panel shows top view with location of PIT monitors in new Cascades

Island LPS collector. Lower panel shows plan view with rest boxes. The Cascades Island structure was composed of a series of ramps, which were wetted to a depth of approximately 3 cm and interspersed with horizontal flumes and rest boxes (Figure 12). The first ramp extended 13.79 m upward at an angle of 58.6° from the fishway floor to Rest Box 1, which was 11.28 m above the ramp entrance. This ramp was fabricated of 0.63-cm aluminum and was supported at 1.8-m intervals by aluminum brackets attached to the fishway wall with wedge anchors (1.3- × 14.0-cm stainless steel). To improve lamprey collection, the ramp was flared to a width of 1.22 m where it contacted the fishway floor and then narrowed to a width of 0.61 m over its first 0.61 m (Figure 13). At a point 6.7 m up the ramp (normally above the water line), the ramp gradually narrowed to a width of 0.51 m to allow space for flanges, which were needed to connect subsequent ramp sections (3.66-m-long; Figure 13). After narrowing, the ramp continued upward 7.50 m and emptied into Rest Box 1 via a plastic mesh cone (Rest Box1 measured 1.22 × 0.61 × 0.76 m). Because it was not accessible from the deck, this rest box was equipped with a remote drain valve which could be opened to purge lamprey when the structure was shut down.

FLOW

FLOW

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Figure 13. Photo at left shows lower section of Cascades Island collector ramp, which

narrows from 0.61 m to 0.51 m above the water line. A guide rail and camera housing were installed in winter 2010 to allow remote deployment of an underwater camera and infrared lighting array (note orange cable harness connected to camera and lights secured within the housing). Photo at right shows base of the collector ramp during installation in the 2009 in-water work period. The ramp flared at its base to a width of 1.22 m (4 ft) and narrowed quickly to a width of 0.61 m (2 ft) (shown at top right).

The second ramp was the same width and depth as the first, and started at the base of Rest Box 1, angling upward in the opposite direction (west) at 39° (Figure 14). This ramp crested at a 0.9-m horizontal section, from which lamprey entered Rest Box 2. This rest box had the same design and dimensions as Rest Box 1, including a remote drain valve. From Rest Box 2, lamprey exited in the opposite direction (east) through a second 0.9-m horizontal section and up a 39° ramp to a 4.27-m horizontal flume at elevation 17 m (Figure 14). This flume was the same width and depth as the ramps, but made an abrupt (90°) turn, terminating after 10.67 m at Rest Box 3 (located on the south wall of the Cascades Island fishway, Figure 12). Immediately before entering Rest Box 3, lamprey passed through a PIT-detection antenna (Figures 12 and 14).

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5 m

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Figure 14. Detail of the lower Cascades Island LPS collector to Rest Box 3. Blocked

arrow indicates location of the PIT antenna immediately downstream from Rest Box 3.

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The design of Rest Boxes 3-6 was the same as for Rest Boxes 1 and 2, but Rest Boxes 3-6 were accessible from the deck and featured a hinged lid to allow inspection of the contents. They could also be drained manually and did not require remotely operated valves. These rest boxes were separated by a series of ramps (0.15 m deep × 0.51 m wide) and short horizontal sections (Figure 15). All ramps had a 45° angle except the ramp between Rest Box 4 and 5, which had a 30° angle (Figure 15). When lamprey had ascended to above the +85 deck level (elevation 27 m), they continued through a horizontal aluminum flume (0.15 m deep × 0.2 m wide × 25 m long) before passing through a PIT antenna and into a terminal trap box (Figure 15). The trap box was hoisted to allow transfer of lamprey to an insulated aluminum tank (capacity > 2 m3). Lamprey collected in this tank were enumerated prior to release upstream from Bonneville Dam at the boat ramp at Stevenson, WA. Columbia River water was supplied to the top of the LPS and into the trap box via a 10.2-cm diameter PVC pipe from two, 3-hp submersible pumps. In 2009, both pumps were operated to create a high flow condition, and this treatment was tested against a low flow condition, where only one pump was operated. In 2010, only the low flow condition was used, and this treatment maintained a depth of approximately 3 cm on the ramps and approximately 10 cm in the terminal flume. Because it was necessary to monitor the trap each day, the Cascades Island LPS collector was not operated on weekends or on holidays. To de-water the structure, lamprey were manually removed from the terminal trap box and from Rest Boxes 3-6 and enumerated. Pumps were then shut down, and any lamprey in Rest Boxes 1 or 2 were evacuated by activating the remotely operated valves. Lamprey removed in this way were enumerated as they dropped into the fishway.

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Evaluations of Lamprey Use Trap Box Counts, Video Observation, and Flow Experiments The Cascades Island entrance collector was completely installed and operational on 26 May 2009. It was operated on weekdays from 26 May to 3 September 2009. During this period, 106 lamprey were captured in the terminal trap box of the LPS (Figure 15). These 106 lamprey represented 2.6% of the daytime lamprey count from both count windows at Bonneville Dam on the days of trap operation in 2009. A power outage on 27 July resulted in three lamprey mortalities in the structure. Figure 15. Detail of the upper Cascades Island LPS collector from Rest Box 3 to the

terminal trap. Block arrows indicate the PIT antennas located immediately downstream from Rest Box 3 and immediately downstream from the trap.

5 m

22.5 m

5.0 m

25.0 m

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Trap

5 m

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Alternating flow treatments were conducted from 5 July to 27 August. During these treatments, 88 lamprey were captured in the Cascades Island LPS Collector (65 during the low-flow treatment and 23 during the high-flow treatment). A two-tailed t-test was used to compare flow treatments, and results indicated that the number of lamprey collected during the low-flow treatment was significantly higher than the number collected during the high-flow treatment (t = 2.65, df = 18, P = 0.016). Daytime video observations of lamprey climbing up the lowest collector ramp were made during 11-27 August 2009. Of the resulting 147 h of video, 132 h were analyzed. A total of 15 lamprey were observed climbing the open section of this ramp, and 9 of these (60%) fell back downstream at the point where the ramp narrowed (Figure 13). All of these fallbacks occurred on days when the ramp was operated with the high-flow treatment (i.e., both pumps turned on). In 2010, the Cascades Island collector was operated on weekdays from 31 May to 10 September; operation was interrupted during 7-14 June, after a winch at the terminal trap box failed. During operations in 2010, 48 non-tagged lamprey were collected in the terminal trap box; these 48 represented 1.4% of the daytime lamprey count at both Bonneville Dam count windows on the days of trap operation. During 13-14 July 2010, daytime underwater video observations were made at the point of contact between the lamprey collector ramp and fishway floor. While visibility was very low, 18 lamprey were observed as they approached the ramp and 5 (28%) were observed on the ramp. Monitoring of Tagged Lamprey Tagged lamprey used to evaluate the new LPS in the Cascades Island fishway were the same fish collected for tagging as described in Objective 1. In 2009, there were 369 PIT-only and 299 double-tagged lampry (tagged with both a radio transceiver and PIT tag). In 2010, there were 19 PIT-only lamprey and 312 double-tagged lamprey. In both years, most tagged lamprey were released at both the Hamilton Island boat ramp and at Tanner Creek, as described above for Objective 1. However, in 2010 6 of the PIT-only fish were released directly into Rest Box 3 (Figure 12) to evaluate lamprey use of the upper part of the LPS. In 2009, no PIT-tagged lamprey were detected in the Cascades Island LPS entrance collector, although 68 were detected at the fishway entrance. In 2010, 48 PIT-tagged lamprey were detected at the Cascades Island fishway entrance, but none were detected in the entrance collector.

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We placed PIT-tagged lamprey into Rest Box 3 of the LPS (Figure 12) in 2010 to evaluate passage success and passage time. The 6 PIT-only fish released into Rest Box 3 successfully ascended to the terminal trap and were subsequently released upstream at the Stevenson Boat Ramp; 2 of these fish were later detected at The Dalles Dam. On 2 August 2010, a double-tagged fish was re-captured at the AFF and was also released into Rest Box 3. It was detected at the upper HD-PIT detector, but did not enter the terminal trap. This lamprey was subsequently detected at the Cascades Island fishway entrance on 3 August, and at the Cascades Island LPS collector on 13 August, but again fell back downstream and was not detected thereafter. While the exact time to pass from Rest Box 3 to the upper HD-PIT antenna is unknown, we were able to establish that 5 of the 7 fish released at Rest Box 3 in 2010 ascended on the same day that they were released (probably after nightfall). For these fish, the median time from release at around noon to detection at the upper HD-PIT antenna was 11.2 h (range 9.8-12.1 h). The 2 lamprey released at Rest Box 3 on 8 September took more than 24 h to reach the upper HD-PIT antenna (median = 40.0 h, range 32.8-47.3 h), and were found in the trap on the morning of 10 September 2010

Discussion Our objective was to install a new LPS at the Cascades Island Fishway entrance and monitor lamprey use of this new structure. This installation was completed prior to the adult lamprey migration period of 2009, and evaluations in 2009 and 2010 were informative but disappointing. In both years, fewer lamprey used the structure than anticipated, and we conducted in-season testing to identify obstacles to lamprey use of this LPS, which is the longest and steepest designed to date. In particular, we were interested in identifying whether the relatively low use of the structure was related to the entrance location (i.e., poor collection rate) or inadequate conditions within the structure (i.e., poor passage success through the structure). Both video observations and PIT-tag detections indicated that lamprey collection efficiency at this structure was poor. Of individuals viewed approaching the bottom of the LPS collector ramp on a single day, only 28% appeared to attach to the ramp. In addition, none of the 116 PIT-tagged lamprey detected entering the Cascades Island fishway in 2009 and 2010 were subsequently detected in the collector. While it is possible that these fish entered the collector ramp and did not make it as far upstream as the first PIT detector (Figure 12), it is also plausible that few adult lamprey encountered the LPS ramp because the bollard field failed to guide lamprey laterally to the north

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fishway wall. Direct observations of lamprey at the fishway and LPS entrances using DIDSON acoustic cameras or other imaging systems are needed to evaluate lamprey behaviors on such a small spatial scale. Video observations and flow manipulation experiments also helped to identify problem areas encountered by lamprey after entering the new LPS. Above-water video observations indicated that lamprey had difficulty ascending the exposed portion of the first collector ramp. In particular, lamprey fell back at a position where the ramp narrowed (a design feature to allow space along the wall for flanges that connect the ramp sections, Figure 13). In this constricted area, lamprey would encounter an increase in water volume flowing over the ramp surface. We tested the effects of flow manipulation by conducting an evaluation of lamprey captures under the original flow (both pumps operating) and low flow (one pump operating) in 2009. Results indicated that significantly more lamprey used the structure during the low-flow treatment. This operational change was implemented in 2010, but thereafter even fewer lamprey were collected in the terminal trap box relative to those enumerated at count windows during the days of Cascades Island LPS operation. To examine lamprey passage success through the upper part of the structure, seven PIT-tagged lamprey were introduced into the structure at the lowest rest box accessible from land (Rest Box 3, Figure 12; sample sizes were limited by available study animals). Results from this test were informative. Most fish ascended the LPS the first night, and passage success to the upper PIT antenna was 100% (Figure 12). However, one fish (17%) detected at the upper antenna did not enter the terminal trap (a distance of only a few meters more). It is possible that the lamprey avoided the juncture between the LPS and the trap box, or that it was repelled by lamprey already in the box. Further study is needed to confirm whether this will be a recurrent problem, and this result highlights the need to provide volitional egress from the structure. Lamprey that did not enter the Cascades Island trap box fell back downstream through all of the rest boxes, in spite of the fact that each box was equipped with a mesh cone to prevent downstream movement. Further evaluation and testing is needed to determine whether lamprey regularly fall back through the LPS after ascending to this point. Small changes to the cone design could potentially help to retain lamprey in the rest boxes. In both years of operation, lamprey were regularly found in the rest boxes of the Cascades Island LPS when it was de-watered for the weekend. This result contrasted sharply with findings in the AWS structures, where lamprey were rarely seen occupying a rest box. It is likely that the length of the ramps and the cumulative effects of climbing

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may cause lamprey to spend more time resting in the Cascades Island structure relative to the less-taxing LPSs of the AWS channels. While relatively few lamprey successfully found and ascended the LPS (n = 154 in 2 years), negotiating this type of structure is clearly within the realm of lamprey swimming performance and climbing ability. The Cascades Island LPS is over three times higher and nearly three times longer than any previous structure tested (Moser et al. 2011). It also features the longest and steepest collector ramp (60°), and the greatest number of transitions and direction changes. The fact that lamprey were capable of ascending this full-scale LPS indicates that with some modifications, structures of this kind could be used to facilitate lamprey passage from a dam tailrace to its forebay.

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OBJECTIVE 3: Monitor use of a Lamprey Collector at the Washington Shore Fishway Entrance

Methods

A lamprey collector and trap box were installed at the north downstream entrance (NDE) of the Washington shore fishway in August 2005 (Figure 16). This location was chosen based on radiotelemetry studies, which indicated that lamprey entrance efficiency was consistently low at this location (Moser et al. 2005; Johnson et al. 2009a). This collector consists of a transition structure leading to an open ramp (0.51- × 12.6-m; Figure 16). After climbing the 45° open ramp, lamprey entered a closed chute (0.15- × 0.20-m) equipped with a PIT-tag monitor (same PVC/antenna construction as in the AWS LPS), which terminated at a trap box (0.6- × 0.6- × 0.9-m; Figure 16). The trap box was accessed daily via a caged ladder, and any lamprey present were retrieved by hoisting the trap box with an electric winch and boom. Lamprey in the trap were enumerated, measured, tagged, and released downstream from Bonneville Dam (see Objective 1). In both years, velocity at the Washington Shore fishway north

Figure 16. Schematic drawing illustrating dimensions of the entrance collector installed at the Washington Shore downstream north entrance.

downstream entrance was reduced from approximately 2.4 to 1.2 m s-1 during approximately 2200-0400 PDT. In 2009, this low-velocity treatment was applied on randomly selected nights (see Johnson et al. in press), while in 2010 it was applied each night throughout the lamprey migration season. In both years, flow at the fishway entrance was periodically reduced to near zero at night for maintenance operations (see details in Johnson et al. in press).

Top View

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Results Trap Box Collections In 2009, the Washington Shore fishway entrance collector was operated from 1 June to 28 September. During this period, only 71 lamprey were collected in the trap box at the terminus of the collector. In comparison, 992 lamprey were trapped in the Adult Fish Facility (AFF) fishway (946 in weir traps, 42 in portable traps, and 4 in the AFF flume). Thus, the Washington Shore entrance collector contributed approximately 6.7% of the total lamprey trapped at the Washington Shore fishway in 2009.

In 2010, the Washington Shore fishway entrance collector was started on 31 May but was shut down on 2 June due to high tailwater elevations. It was started again on 1 July and operated until 11 September. During this period only 14 lamprey were captured. In comparison, trapping at the AFF (31 May-11 September) yielded 353 lamprey (316 in weir traps, 33 in portable traps, and 4 in the AFF

Figure 17. Lamprey collected on 23 July 2010 in the AFF weir trap. This fish was hooked through the gill pore and still carried a lure and wire leader. The hook was removed, but the fish died as a result of this injury.

flume). A lamprey with a lure in its gill chamber was collected on 23 July and died as a result of this injury (Figure 17).

Evaluations Based on Monitoring of Tagged Lamprey Tagged lamprey used to evaluate the Washington Shore fishway entrance collector were the same fish collected for tagging as described in Objective 1. In 2009, 369 PIT-only and 299 double-tagged lampry (tagged with both a radio transceiver and PIT tag) were released below Bonneville Dam. In 2010, 19 PIT-only lamprey and 312 double-tagged lamprey were released. In both years, most lamprey were released at both the Hamilton Island boat ramp and Tanner Creek, as described above for Objective 1.

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Of the PIT-only lamprey released downstream from Bonneville Dam, only 2 (0.5%) were detected in the Washington Shore entrance collector in 2009, and none were detected there in 2010. Both of the fish detected in 2009 entered the structure during nighttime, with the first entering at 0035 PDT on 19 June and the second at 0205 on 26 June. On the night of 18-19 June, flow in the fishway was shut down for maintenance from 2223 to 0404, resulting in no flow at the fishway entrance. Between 2200 on 25 June and 0400 on 26 June, fishway velocity was reduced (1.2 m s-1) relative to normal daytime operations (2.4 m s-1). The lamprey detected on June 19 was released only 13 h prior to detection in the structure. This fish apparently did not enter the terminal trap box and was detected 23 h later inside the Washington Shore fishway. It then ascended to the fishway exit and was last detected there on 20 June at 0500. Similarly, the lamprey detected in the entrance structure on 26 June was there only 15 h after its release, but this fish also did not enter the trap box. It was subsequently detected at the Washington Shore fishway exit on 4 July and passed upstream from McNary Dam on 22 August 2009.

Discussion Our objective was to assess the efficacy of a lamprey collector positioned outside the north downstream entrance to the Washington Shore fishway. The fishway entrances at Bonneville Dam have historically created a bottleneck to adult lamprey passage (Moser et al. 2002, 2005; Johnson et al. 2009a). An efficient collector positioned outside a main fishway entrance could help lamprey to bypass this troublesome area and improve overall dam passage. In 2009 and 2010, the number of lamprey trapped in the Washington Shore fishway entrance structure was far lower than in 2007 and 2008, when the structure had collected 41 and 36% of all lamprey trapped at the Washington Shore fishway (Moser et al. 2010). The contribution of lamprey trapped in this structure fell to less than 7% in 2009 and reached an all-time low of less than 4% in 2010. PIT-tag detections also indicated reduced lamprey use of the Washington Shore ladder entrance collector relative to earlier years. In 2007 and 2008, respective proportions of lamprey detected in this structure were 2 and 3% for PIT-only lamprey and 1 and 5% for double-tagged lamprey. Detection rates decreased in 2010 to 0.5% for PIT-only fish in 2009 and 0% for all tagged fish. Why did lamprey use of this structure fall off so dramatically? One hypothesis is that the implementation of reduced velocities near the fishway entrance at night has

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successfully reduced the number of lamprey that accumulate there. Johnson et al. (in press) documented an increase in entrance efficiency of lamprey during velocity-reduction tests. Thus, by improving the ability of lamprey to enter the fishway, the need for lamprey to use the collector was reduced, with fewer lamprey potentially available to the collector. A second hypothesis is that lamprey were discouraged from using the structure due to improper maintenance. Because the structure was in place year-round during 2009 and 2010, there was no opportunity to inspect it for damage. After the lamprey migration periods of 2007 and 2008, the structure was lifted, examined, and lowered back into place prior to the next lamprey run. In both 2009 and 2010, the structure was not lifted due to changes in U.S. Army Corps of Engineers safety requirements. Consequently, changes to the submerged portion of the ramp, increased vibration, or debris may have hindered lamprey use of the structure. In 2009, lamprey were observed as they climbed the exposed portion of the ramp and encountered a raised silicon seal. Even this small anomaly was enough to reduce their ability to ascend the ramp. The seal was repaired immediately, but it is possible that other problems of this kind were not identified due to the reduced level of inspection this structure received. A third hypothesis is that lamprey successfully ascended the structure but did not enter the trap at its terminus. In 2009, neither of the PIT-tagged lamprey detected using the structure were collected in the trap, even though they were detected less than 1 m away from the trap (Figure 16). This behavior was also observed in PIT-tagged fish detected in the Cascades Island fishway LPS. Further investigation is needed to determine why lamprey exhibited this behavior. A final and most likely hypothesis is that decreased use of the Washington Shore fishway collector resulted from a combination of reduced lamprey run size, reduced nighttime velocities at the fishway entrance, and lack of maintenance. We plan to install a new type of lamprey entrance structure in winter 2012-2013, and the Washington Shore entrance collector is slated for removal prior to that installation. However, lessons learned during the relatively short lifespan of this structure should be considered for new LPS designs and locations.

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OBJECTIVE 4: Monitor Lamprey Entrance into the Cascades Island Upper Fishway

Methods To assess lamprey use of the upper Cascades Island fishway, we installed a PIT-tag antenna and detector immediately upstream from the picket lead at the downstream end of the flow-control section near the upstream migrant transportation (UMT) channel (Figure 18). The 10-G multistrand wire loop antenna was encased in a rectangular PVC frame (12.8- × 0.9-m). The frame spanned the fishway channel that led to an obsolete count station section. The frame was clamped to the existing walkway hand rail to support it in a position approximately 15 cm from the bottom of the channel. The read range of this antenna was very limited (5 cm), so only lamprey that were traveling very close to the bottom or sides of the channel could be detected. Lamprey used for these evaluations were the same fish described in Objective 1 (369 PIT-only and 299 double-tagged fish in 2009 and 19 PIT-only and 312 double-tagged fish in 2010). In both years, tagged lamprey were released at either the Hamilton Island boat ramp or at Tanner Creek (except that 6 PIT-only fish were released directly into Rest Box 3 of the new Cascades Island LPS in 2010). Figure 18. Location of the HD-PIT antenna at the picket lead near the upstream migrant

transportation channel (UMT) at the top of the obsolete Cascades Island fishway.

Spillway

B - Branch fishway Cascades Island fishway

UMT

Flow

HD-PIT antenna

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We compared numbers of PIT-tagged lamprey detected in the upper Cascades Island fishway to numbers detected at the Washington-shore and Cascades Island entrance collectors and in the LPSs in the Bradford Island and Washington Shore AWS channels. We also compared detections in this area to detections at other locations at Bonneville Dam and detections at other lower Columbia and Snake River dams (see Keefer et al. 2009). In addition to determining passage behavior and routes, these detection data allowed us to compute travel time from release to first detection at each location.

Results In 2009, 27 of the 369 PIT-only fish (7%) were detected at the upper Cascades Island fishway antenna (in the flow control area above the upstream migrant transportation (UMT) channel junction). In addition, 10 double-tagged lamprey released in 2009 and 1 PIT-only lamprey released in 2008 were detected at this site. Median travel time from release in 2009 to detection at the upper Cascades Island fishway was 9.6 d (range 1.3-38.8 d; n = 37). This travel time was similar to that observed in 2007 and 2008 (median 10.9 and 8.6 d, respectively). Most fish detected in the upper fishway in 2009 had also been detected at the Cascades Island fishway entrance (n = 28, 76%). For these 28 fish, median travel time from the fishway entrance to the upper fishway/flow control area was 1.9 d (range 0.1-22.0 d). Of the lamprey detected in the Cascades Island upper fishway during 2009, 16 (43%) were detected at the Washington Shore fishway exit, and 4 were detected at the Washington Shore AWS LPS (11%). Six of these fish were subsequently detected at upriver dams. In 2010, 7 double-tagged fish were detected in the upper Cascades Island fishway (2.2% of the double-tagged population released that year). Median travel time from release to detection in the upper fishway was 12.5 d (range 5.4-37.6 d). Only 3 of these 7 fish were also detected at the Cascades Island fishway entrance (43%), and median travel time from the fishway entrance to the upper fishway was 6.3 d (range 5.1-7.0 d). Of all 7 lamprey detected in Cascades Island upper fishway in 2010, 1 was detected at the Washington Shore fishway exit (14%); this fish was subsequently detected at upriver dams.

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Discussion Our objective was to determine lamprey use of the obsolete fishway exit at the top of the Cascades Island fishway. Visual observations during fishway maintenance have indicated that lamprey regularly enter this area and may become trapped (T. Mackey, USACE, personal communication). Moreover, in 2006-2008, detections of PIT-tagged fish at the picketed lead downstream from the Cascades Island count window indicated that 6-8% of the lamprey released downstream from Bonneville Dam found their way into the top of this fishway. Due to the improvements made to the Cascades Island fishway entrance prior to the adult lamprey migration of 2009, we expected a relative increase in the percentage of lamprey entering the flow control area at the top of this fishway. In fact, the percentage of fish detected in this area was lower in both 2009 (7% of PIT-only and 3% of double-tagged fish) and 2010 (2% of double-tagged fish) than in 2007 and 2008 (8% in both years). In addition, a lower percentage of fish detected using this fishway were later detected at upriver dams in both 2009 (16%) and 2010 (14%) than in either 2007 (36%) or 2008 (32%). These data suggest that changes to the Cascades Island entrance may have improved entrance success, but that this entrance success did not translate to overall improvements in passage. For example, a higher percentage of fish detected at the Cascades Island fishway entrance were subsequently detected at the upper fishway antenna in 2009 (76%) than in 2010 (43%). Moreover, travel time from the fishway entrance to the upper fishway increased from 1.9 d in 2009 to 6.3 d in 2010. Some of these interannual changes may be attributed to changes across study years in both sample size and in the tags used to monitor fish. In 2007 and 2008 we had large samples of PIT-only fish (> 600 individuals each year). In 2009 the number of PIT-only fish was reduced to 369, and the balance were double-tagged. Because of a record-low run of adult lamprey in 2010, we released only a handful of PIT-only fish and only 312 double-tagged fish. Thus, comparison among years was made difficult by the large variations in sample size and in the proportion of double-tagged fish. Nevertheless, it was clear that the 2009 modifications to the fishway entrance at Cascades Island did not result in greater passage success to the upper fishway. In addition, there is some indication that the problem area in this fishway may have shifted upstream. Future studies should incorporate as many PIT-only fish in the sample as possible to allow valid comparisons with previous years and the opportunity to fully assess all passage routes at Bonneville Dam.

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ACKNOWLEDGMENTS Sam McCormick and Hilary Griffin helped with lamprey collection and tagging and with maintenance of the HD-PIT detection system. The design, fabrication, and installation of the LPS structures would not have been possible without the exceptional skills and efforts of Jim Simonson, Jeff Moser, and Bill Wassard of the NOAA Fisheries Pasco Research Station. We also thank Galen Wolf, Louis Tullos, Ron Marr, of the Pasco Station and the rigging crew at Bonneville Dam for help with equipment installations. Sean Tackley, David Clugston, Jon Rerecich, Tammy Mackey, Robert Stansell, and John Dalen of the U.S. Army Corps of Engineers provided assistance on many fronts throughout the project. Administrative assistance at NOAA Fisheries was provided by Doug Dey, Paula McAteer and Tom Ruehle. Mike Jepson and Tami Clabough (University of Idaho) provided administrative and database support. We thank JoAnne Butzerin (NOAA Fisheries) for editing this report. Funding for this work was provided by the U.S. Army Corps of Engineers, Portland District.

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