direct and indirect effects of barriers to migration – pacific lamprey at mcnary …...
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Technical Report 2008-7
IDAHO COOPERATIVE FISH AND WILDLIFE RESEARCH UNIT
DIRECT AND INDIRECT EFFECTS OF BARRIERS TO MIGRATION – PACIFIC LAMPREY AT McNARY AND ICE HARBOR DAMS IN THE COLUMBIA RIVER
BASIN
A Report for Project ADS-P-00-8
by
D. L. Cummings, W. R. Daigle, C. A. Peery U.S. Geological Survey, Idaho Cooperative Fish and Wildlife Research Unit
Department of Fish and Wildlife Resources University of Idaho, Moscow, ID 83844-1141
and
M.L. Moser Northwest Fisheries Science Center, NOAA Fisheries
2725 Montlake Blvd. East, Seattle, WA 98112
for U.S. Army Corps of Engineers
Walla Walla District
2008
Cooperators
Preface
Pacific lampreys are native anadromous fishes of the Pacific Northwest. But unlike Pacific salmonids, lampreys have historically received limited attention by managers and researchers. Like all long distance migrants, Pacific lamprey must negotiate numerous challenges to achieve reproductive success and population sustainability. In the 1990’s, the US Army Corps of Engineers began funding investigations on adult lamprey behavior and passage at federally-operated hydropower dams on the lower Columbia River. These initial studies demonstrated low lamprey passage success at Bonneville Dam and other lower Columbia River dams. Further studies were conducted to determine specific mechanisms for poor passage and the development of structures and operations to improve adult lamprey passage at these lower river projects. We initiated evaluations of adult lamprey passage at McNary and Ice Harbor dams during 2005 and 2006.
This and related publications from the University of Idaho, Fish Ecology Research Lab can be found at www.cnr.uidaho.edu/uiferl/
Acknowledgements
We would like to thank our colleagues at the University of Idaho Fish Ecology Research Lab whose assistance made this study possible, especially Travis Dick, Ken Tolotti, Mike Jepson and Dan Joosten. Brian Burke and Kinsey Frick at NOAA Fisheries, Northwest Fisheries Science Center developed and maintained the telemetry database. Darren Ogden, Jim Simonson, and Jeff Moser, of the National Marine Fisheries Service Pasco, WA, Research Station helped design and construction of the fish traps used for this study. This work was funded by the U.S. Army Corps of Engineers Walla Walla District Office, Study Code ADS-P-00-8, and U.S.G.S Research Work Orders 485, 520, 630, and 631.
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Table of Contents
Table of Contents ........................................................................................................................... i List of Figures ii List of Tables iii Abstract iv Introduction ................................................................................................................................... 1 Methods ........................................................................................................................................ 4
Study Area ........................................................................................................................ 4
Trapping Procedure .......................................................................................................... 7
HD PIT Tagging Procedures ............................................................................................. 9
Radio Tagging Procedure ................................................................................................. 9
Tracking Procedure ......................................................................................................... 10
Dam Passage Characterization ...................................................................................... 10
Potential Problem Passage Areas .................................................................................. 10
Results ........................................................................................................................................ 12
Trapping and Tagging ..................................................................................................... 12
Potential Problem Passage Areas .................................................................................. 16
Disease Diagnosis .......................................................................................................... 18
Proximate Analysis .......................................................................................................... 19
Discussion ................................................................................................................................... 22
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List of Figures
Figure 1. Life history of Pacific lamprey (Lampetra tridentata) ..................................................... 2 Figure 2. Columbia River Basin with the location of hydropower dams. McNary and Ice Harbor
dams are the primary locations for this research. (Northwest Power and Conservation Council, http://www.nwcouncil.org/dams/print.asp ................................................................ 2
List of Tables
Table 1. Summary of adult Pacific lamprey radio-tagged at Bonneville Dam from 2000 to 2002. 3 Table 2: Pathogens for which Pacific lamprey were screened at the USFWS Idaho Fish Health
Center ................................................................................................................................. 11 Table 3. Passage efficiency by fishway section at McNary and Ice Harbor Dams in 2005 and
2006. Transition pool is from inside of entrance up to tailwater elevation in ladder. Top of the ladder is from top of transition pool to ladder exit. ........................................................ 19
Table 4. Proximate analysis data for the portion of each Pacific lamprey that was not freeze dried. ................................................................................................................................... 21
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Abstract
Barriers to migration, such as dams, roads, and areas of deforestation, can have both direct (mortality and migration delay) and indirect (increase in disease susceptibility, decrease in genetic variability, and increase in predation) effects on anadromous fish. This study focused on passage performance for adult Pacific lamprey (Lampetra tridentata) at McNary and Ice Harbor dams. During the 2005 and 2006 migration season (summer and early fall), 120 adult lamprey were collected at McNary Dam on the Columbia River and equipped with a half-duplex passive integrated transducer (HD PIT) tag and a coded radio transmitter, and an additional 70 fish received only a HD PIT tag to assess passage success and behavior at this stage of their migration. Of the radio-tagged fish released 1 km below McNary and Ice Harbor dams, 48.8% (39/80) and 55.0% (22/40), respectively, returned to the dam and were detected outside of a fishway entrance. At McNary Dam, 61.5% (24/39) of the fish that approached an entrance eventually passed the dam and at Ice Harbor Dam, 59.1% (13/22) passed. Median dam passage times for the radio-tagged lamprey were 2.1 and 2.3 days at McNary and Ice Harbor dams, respectively. Individual lamprey movements through the fish ladders showed that potential problem areas for adult lamprey at McNary and Ice Harbor dams included fishway entrances, the top of transition pools, and areas associated with diffuser grating.
During the 2006 season, 29 adult Pacific lamprey were collected at Bonneville and McNary dams and were assayed for the presence of known fish pathogens and then processed for proximate analysis. In the disease analysis, Aeromonas hydrophila was the only pathogen identified, found in 6 of the 29 lamprey inspected. Proximate analysis of the crude fat content showed that adult Pacific lamprey collected at Bonneville Dam had a mean lipid content of 91 g versus 59 g at McNary Dam, representing a 35% decline in lipid reserves over a distance of 235 km.
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Introduction
Anthropogenic activities can modify the life history processes of aquatic species at multiple levels. Freshwater systems are especially vulnerable to habitat alterations because of multiple demands placed on water and river basins (Minns et al. 1996). For example, migratory species are significantly affected if barriers occur within migrational routes. Dams can represent both direct and indirect effects on fish migrations and have been cited as one of several factors associated with the decline of many fish populations in the Pacific Northwest (e.g. NRC 1996; Northcote 1998). While efforts to address passage and survival of salmonids in freshwater systems have been extensive, relatively little work has focused on other anadromous species, including Pacific lamprey Lampesterus tridentata. Recently, researchers have examined the behavior, swimming performance, and factors that affect passage success of adult lamprey in the lower Columbia River (Daigle et al. 2005; Mesa e al. 2003; Moser et al. 2002a; Moser et al. 2002b; Ocker et al. 2001). In this study, we initiated an evaluation of adult Pacific lamprey passage at these two upstream hydroelectric dams.
Like salmon, Pacific lampreys are anadromous and must negotiate the Columbia River
twice during their life span (Figure 1). Mature adults begin their inland migration to freshwater spawning streams between May and August. In the Columbia River Basin, Pacific lamprey must pass up to nine hydroelectric dams and their associated reservoirs to reach historical spawning areas in the upper basin (Figure 2). Spawning typically occurs between April and July of the following spring, requiring lamprey to overwinter within the system. Even though fossil records suggests that Pacific lamprey have persisted for more than 450 million years (Schwab and Collin 2005, Bond 1996), recent modifications to the Columbia Basin, including impoundment by dams, have significantly altered conditions experienced by lamprey, to their apparent detriment.
Since the construction of Bonneville Dam in 1937, Pacific lamprey counts at dams have
decreased dramatically throughout the basin (Figure 3), prompting the first studies of lamprey migrations during the mid-1990’s. From 1997 to 2003, radiotelemetry studies, funded through the USACE, were used to evaluate lamprey passage in the lower Columbia River, focusing at Bonneville Dam (Moser et al. 2002; 2003; 2004; 2005). Results indicated Pacific lamprey did not readily pass dams and poor passage could represent a critical limitation on system productivity (Close et al. 1995; Moser et al. 2002). Specifically, Moser et al. (2002; 2003; 2004; 2005) found that fishway entrances, collection/transition areas, count stations, diffuser gratings, and serpentine weirs impeded adult Pacific lamprey dam passage at Bonneville, The Dalles, and John Day dams. Passage efficiencies at these three dams averaged 47%, 74%, and 48% respectively from 2000 through 2002, while the median passage time ranged from 1.3 days to 11.0 days (Table 1). The reason for poor lamprey performance at dams is related to their swimming abilities. The designs of fishways at these dams were based on the swimming ability of anadromous salmonids (e.g. Clay 1995). Unfortunately, swimming ability of lamprey differs significantly from that of salmonids. Primarily, lampreys have a limited ability to swim against high water velocities compared to salmonids. Critical swimming speed for adult Pacific lamprey is 0.85 m/s (Mesa et al. 2003), while velocities at fishway entrances can exceed 2.0 m/s (Clay 1995). When the water velocities exceed their swimming speed, adult Pacific lamprey will attach to a nonporous surface with their suctorical disc. Once attached, the lamprey is then able to move forward in short increments, reattaching in between, until it is through high velocity areas. Thus, any constriction such as sharp corners, vertical walls and lips, and diffuser gratings in areas with high water velocities can delay or block lamprey movements.
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Figure 3. Comparison of the historical counts of returning adult Pacific lamprey at
Bonneville and McNary dams. (adapted from US Army Corp of Engineers Annual Fish Passage Reports, 1969, 1995 to 2003, and Columbia Basin Research, http://www.cbr.washington.edu/dart/dart.html).
Table 1. Summary of adult Pacific lamprey radio-tagged at Bonneville Dam from 2000 to
2002. 2000a 2001b 2002c
Number Tagged 349 298 201 Passage Efficiency Bonneville 47% 46% 48% The Dalles 82% 73% 66% John Day 55% 53% 35% Median Passage Time Bonneville 4.4 days 11.0 days 9.0 days The Dalles 2.1 days 2.1 days 4.0 days John Day 2.5 days 1.3 days 4.2 days
there are still many aspects of the Pacific lamprey’s life history that are not understood, such as what diseases loads they may carry as returning adults, and what impacts translocation may have on local lamprey production and other aquatic fauna. Another portion of the Pacific lamprey’s biology that is unknown is the amount of energy that an adult Pacific lamprey uses as it migrates through the entrained river and if this may be a limiting factor in lamprey productivity,
0
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especially for upstream populations. An added concern is the belief that lampreys do not home to natal streams, based on sea lamprey research in the Great Lakes. Instead, there is evidence that adult lamprey are attracted by pheromones released by ammocoetes in spawning streams, an indication these streams have suitable habitat to survive (Bergstedt 1995). If true, areas with declining populations, will emit less pheromones; therefore, less adults return to the area. Currently, it is unknown what factors influence adult Pacific lamprey passage success at McNary and Ice Harbor dams and how mitigation actions, such as translocating lamprey, affect the species. This study focused on determining adult Pacific lamprey dam passage characteristics at McNary and Ice Harbor dams. In 2004, NOAA Fisheries and the University of Idaho also began testing the use of half-duplex passive integrated transponders (HD PIT) tags as a means to monitor lamprey at dams and potentially other locations (Figure 4). If effective, HD PIT would provide a less costly means to evaluate lamprey passage at dams, and potentially other locations, that would not interfere with salmon monitoring programs.
Figure 4. Comparison of half-duplex PIT tag (left) used in this study and full-duplex PRI
tag (right) generally used to monitor salmonids. (Penny for scale) (Image: Oregon RFID, http://www.oregonrfid.com/tags/index/html)
Methods Study Area Adult Pacific lamprey were captured in the Oregon-shore fishway and tagged at the Juvenile Fish Facility of McNary Dam, Columbia River kilometer (river kilometer [rkm] 469.8). Half-duplex PIT tagged and radio-tagged lamprey were released approximately one kilometer downstream from McNary and Ice Harbor (rkm 537.7) dams (Figures 5, 6, and 7). McNary Dam is the fourth dam adult Pacific lamprey encounter as they migrate up the Columbia River. Ice Harbor Dam is the first dam they must pass after entering the Snake River (Figure 2). McNary and Ice Harbor dams both have fishways on the north and south-shores. Each fishway has a major entrance at the downstream end, as well as access to the south fish ladder via orifice entrances along the powerhouse. Once inside a fishway, fish encounter a transition pool, the weired ladder, which includes a counting facility at some point, and then they
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Figure 5. Study area at McNary Dam. Radio receiver sites are marked by circles with the number of antennas at each site. Half-duplex receiver sites are marked by squares with the number of antennas. Release sites are shown by lightning bolts. The lamprey trap is the 4-sided star.
Figure 6. Study area at Ice Harbor Dam North. Radio receiver sites are marked by circles with the number of antennas at each site. Half duplex receiver sites are marked by squares with the number of antennas at each site. The release site was on the north-shore 1 km downstream.
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Figure7. Study area at south-shore ladder of Ice Harbor Dam. Radio receiver sites are marked by circles with number of antennas at each site. Half duplex receiver sites are marked by squares with the number of antennas at each site. The release site on the south-shore was 1 km downstream.
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can exit into the forebay. Transition pools are areas where there are variable water flows, velocities, and temperatures as water is added from the tailrace. Both dams have fish ladders that are made up of overflow weirs with diffuser grating between alternate weir sections (Figure 8). Fish may swim over either side where water flows over the top of the weir or they can swim through two orifices near the floor of the ladder. Each dam also has a navigation lock, spillway, and powerhouse (Figure 5).
Movements of tagged lamprey at both dams were monitored using an array of fixed-site radiotelemetry receivers (Lotek Engineering Inc., Newmarket, Ontario, Canada) and half-duplex PIT tag detectors (Figures 5, 6, and 7). Combined with the receivers were Yagi antennas and Digital Spectrum Processors to monitor lamprey in near the fishways. Half-duplex readers and antennas were assembled from components from Texas Instruments and Oregon RFID. Readers were placed in fishways in transition pool areas and at tops of ladders. Fish used for pathogen screening and energy condition analyses were collected from the Adult Fish Facility (AFF) on the north-shore of Bonneville Dam and from the Juvenile Fish Facility on the south-shore of McNary Dam. Trapping, Tagging, and Tracking
Coded radio transmitters were used to document the movements of Pacific lamprey in reservoirs above and below dams and through fishways at the dams on the Columbia and lower Snake Rivers. Half-duplex PIT tags were also used to monitor Pacific lamprey movements through the fish ladders of McNary and Ice Harbor dams where half-duplex receivers were located (Figures 5, 6, and 7). Radio tags were also used to monitor Pacific lamprey movements upstream and downstream of the dams using portable radio receivers. Trapping Procedure
Adult Pacific lamprey were trapped in the Oregon-shore fish ladder at McNary Dam using a 0.9 m × 0.7 m × 1.2 m metal trap (Figure 9). The trap was lowered into the ladder at approximately 2000 hrs each day. The trap was positioned so that front lip sat on top of the overflow weir (Figure 10). In this position, lamprey traveling along the wall or over the weir were able to move up a ramp into the trap where they remained until being inventoried the next morning at approximately 0700 hrs. Trapping at night increased the efficiency of catching lamprey as they are primarily nocturnal in their behavior at dams. This also decreased chances of interfering with salmonid passage. Adult Pacific lamprey were also collected with dipnets from the south-shore fish ladder at McNary Dam, at a location approximately six weirs upstream from the trap on the opposite side of the ladder.
In the morning following collection, all lamprey were anesthetized with 60 ppm eugenol,
the active ingredient in clove oil. Measurement of length (nearest mm), weight (nearest g), and girth (nearest mm), notes on condition, tissue sample collection, and half-duplex PIT tagging were all conducted while under anesthesia. The scale used to weigh lamprey in 2006 was unavailable for a three week period resulting in fewer lamprey weights that year. A radio transmitter representing less than 1% of their body weight was surgically implanted following Moser et al. (2002b) tagging guidelines. Transmitters were either 4.5 g or 2.1 g (air weight) and were individually coded to allow identification of individual fish. The 4.5 gram transmitter was model NTC-6-2 (Lotek Wireless). This coded radio tag had a length of 30.1 mm, diameter of 9.1 mm, burst rate of 5 seconds, and expected battery life of 235 days. The smaller transmitter, model NTC-4-2L, was 18.3 mm in length, 8.3 mm in diameter, and had an expected battery life of 87 days with a 5 second burst rate.
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Figure 9. Frontal view of lamprey trap. Adult Pacific lamprey can enter via the front ramp or along the side into the collection well.
Figure 8. Dewatered overflow weirs that are typical of McNary and Ice Harbor dams.
The pools between weirs here diffuser grating in the floor of the ladder.
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Figure 10. Lamprey trap lowered into the south-shore fishway at McNary Dam
HD PIT Tagging Procedures Half-duplex (HD) PIT tags were 23 mm long, 3 mm in diameter, and had a weight of 0.6 g (Figure 4). The HD PIT tags and surgical tools were sanitized in chlorhexaderm. After anesthetizing the lamprey in eugenol and recording morphometric measurements, a 3-mm incision was made just left of the ventral midline directly below the anterior-most portion of the first dorsal fin and the HD PIT tag was inserted. Adult lamprey receiving only an HD PIT tag were then allowed to recover in a flow through tank for at least two hours before transportation and release. Radio Tagging Procedure In both 2005 and 2006, 60 coded radio transmitters were surgically implanted ventrally in the intraperitoneal cavity of adult Pacific lamprey. Following five to eight minutes of anesthesia, a lamprey was moved into a 12 cm diameter polyvinyl chloride (PVC) pipe with a sealed T-end. A portion of the pipe was cut away to allow access to the ventral surface for the surgery. The head and gills were submerged in a 60 ppm concentration of eugenol anesthetic throughout the surgery. An incision approximately three centimeters long was made at the same location as described for HD PIT tag implantation. A catheter was then placed inside the body cavity, and pushed through the musculature and skin approximately five centimeters posterior to the incision. A HD PIT tag was inserted as previously described. Next, a radio tag antenna was guided through the catheter, and the transmitter was inserted into the fish. Two or three simple interrupted vicryl sutures were made to close the incision. In 2005, 20 Lotek Wireless NTC-6-1 Nanotags and 40 NTC-4-2L Nanotags were used. In 2006, NTC-4-2L Nanotags were implanted in all 60 lamprey due to the smaller size of the transmitter, which allowed use of a larger size
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range of Pacific lamprey. The adult lamprey receiving both HD PIT tag and coded radio tag were allowed to recover in a tank with flowing Columbia River water for at least two hours. After tagging and recovery, fish were released in the tailrace of either McNary or Ice Harbor dams, about 1 km downstream from the dam. Tracking Procedure As tagged Pacific lamprey moved through McNary and Ice Harbor dams and the surrounding river, their behavior was recorded on fixed site radio receivers and half-duplex detectors that were downloaded weekly. Also, at various times throughout the year, Pacific lamprey with radio tags were tracked with a portable radio receiver from a boat or truck. The data were electronically transferred to the NOAA Fisheries office in Seattle, WA for initial processing. Each data file was loaded into an Oracle database and processed through initial screens that removed obvious errors and records produced from electronic background noise. The screened data were then transferred to the University of Idaho for coding. Coding involved inspection of all records for each adult lamprey at a given dam and assigning a code to records that defined a specific behavior for that individual fish (e.g., first passage of the tailrace receiver, entrance or exit from a fishway). The University of Idaho has developed an automated program to interpret behaviors/records at dams using Visual Basic.NET (Version 7.0). The data were run through the automated program and then all records that were assigned a code were reviewed for appropriateness and accuracy. A final database was then assembled by inserting records from tributary receivers and records from mobile tracking surveys. These data were then used to identify and summarize complete migration histories of the radio-tagged adult Pacific lamprey. Dam Passage Characterization To evaluate the success of Pacific lamprey dam passage at McNary and Ice Harbor dams, the percentage of lamprey that subsequently approached their respective dam after release, and the percentage of these lamprey that entered a fishway and passed the dam were calculated. Median dam passage times (the time from the first approach to a fishway entrance to the last record at a fishway exit) were calculated using both PIT tag and radio tag information. Potential Problem Passage Areas
To identify problem passage areas for adult Pacific lamprey, the most upstream position of each lamprey that did not pass a dam was located. These locations were evaluated in relation to the structural components present in each fishway.
To determine if sections of the fish ladders may hinder adult lamprey dam passage, the proportion of lamprey that passed each section of the fish ladder (entrance, transition pool, and top of the fish ladder) was calculated by determining the number of individual lamprey that approached a fishway section, and dividing that number into the number of exits from that section. Passage efficiency was thus defined for each fish ladder section at each dam. Disease Diagnosis
Twenty adult Pacific lamprey were collected from the Bonneville Dam Adult Fish Facility on 1 August, 2006. An additional nine adult lamprey were collected from the McNary Dam Juvenile Fish Facility between 28 July and 16 August, 2006. Those lamprey were transported live to the USFWS Idaho Fish Health Center. There, they were initially weighed and underwent
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BacteriaRenibacterium salmoninarumFlavobacterium psychrophilumYersinia ruckeriAeromonas salmonicidaAeromonas hydrophila
VirusesInfectious Hematopetic Necrosis VirusInfectious Pancreatic Necrosis VirusLarge Mouth Bass VirusOnchorhynchus masou VirusSrping Viremia of Carp VirusViral Hemorrhagic Septicemia Virus
ParasitesMyxobolus cerebralis Ceratomyxa shastaBothriocephalus acheilognathi
Table 2: Pathogens for which Pacific lamprey were screened at the USFWS Idaho Fish Health Center
screening for five bacteria, six viruses, and three parasites that are typical in salmonid pathogen screening (Table 2). Pathogen culture and identification followed procedures as described in the American Fisheries Society Blue Book (Thoeson 1994). Samples from the kidney, brain, spleen, and intestinal tract were streaked on brain-heart infusion agar (BHIA), tryptone yeast extract with salts (TYES) agar, or tryptic soy agar (TSA), and were allowed to incubate at 20 to 25°C for 24 to 48 hours. Colony growths on the agars were then identified using AFS Blue Book flow charts (Thoeson 1994). An enzyme-linked immune sorbent assay (ELISA) was conducted to screen for Renibacterium salmoninarum, as this pathogen fails to grow on a TSA plate at 20°C even after two weeks (Thoeson 1994). Samples from the kidney, spleen, and gill filaments were homogenized and inoculated with either an epithelial cell line (EPC) or Chinook salmon embryo line (CHSE) to identify viral pathogens. After inoculation, the cell cultures were incubated at 15°C. A pepsin trypsin digest (PTD) was used to dissolve cartilage and look for spores of Myxobolus cerebralis in the brain. General observations were conducted under a microscope to look for evidence of Ceratomyxa shasta and Bothriocephalus acheilognathi, a Pseudophyllidean tapeworm. When pathogen screening was complete, each lamprey was individually weighed again and frozen. Proximate Analysis After completion of pathogen screening at the USFWS Idaho Fish Health Center, the 29 Pacific lampreys were sent to the Washington State University Wildlife Habitat Laboratory for proximate analysis. At the laboratory, approximately one third of each lamprey was freeze dried, while the remaining two-thirds was left in a natural state. For each of the two forms of lamprey tissue (freeze dried and non-freeze dried) the percentages of crude fat and total ash were measured. To derive the crude fat, an ether extract was processed using methods from Official
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Methods of Analysis (1965) where hot ether was continually passed through the lamprey tissue sample dissolving lipids on each pass. The volatilized ether was then separated from the lipids in a cellulose thimble by evaporation, and the remaining lipid was measured. To derive the total ash content, a lamprey tissue sample was ignited to 500-600°C to burn off all organic matter, and the remaining ash was weighed. A Students t-test (Ott and Longnecker 2001) was conducted to test for differences, in crude fat percentage between lamprey collected at Bonneville and McNary dams and between males and females at each dam. The condition factor used with proximate analysis was calculated from lamprey weight and length measurements using the formula: K = (Wg) / L3
cm (Wedemeyer 2001). A Students t-test (Ott and Longnecker 2001) was used to determine if there was a difference between lamprey condition at Bonneville and McNary dams. Separate tests were performed for male and female lamprey at each dam.
Results
Trapping and Tagging
In 2005, a total of 102 adult Pacific lamprey were collected and tagged from 8 July to 17 September and 88 Pacific lamprey were collected and tagged in 2006 from 22 June to 19 September. The lamprey trap in the south-shore fishway of McNary Dam was operated nightly from 8 July to 17 September in 2005, and from 22 June to 19 September in 2006. In 2005, the trap was fished for 681 hours and we captured a total of 54 lamprey (0.08 lamprey/hour). In 2006, the trap fished for 715 hours and captured 50 lamprey (0.07 lamprey/hour). An additional 31 and 6 lamprey were collected from the Juvenile Fish Facility in 2005 and 2006, respectively. Also, 17 and 32 lamprey were dip-netted out of the south-shore fishway of McNary Dam in 2005 and 2006, respectively. In 2005, adult lamprey collected at McNary Dam ranged from 270 to 638 g in weight (mean = 439 g). In 2006, the mean weight of the collected lamprey was slightly higher at 452 g, (range = 292 to 596 g) (Figure 11). Total length ranges of lamprey were similar between 2005 and 2006: 55.0-76.5 cm in 2005 and 54.5-76.0 cm in 2006 (Figure 12). The mean total length in 2005 and 2005 was 67.0 cm and 66.0 cm, respectively. The girth of the tagged lamprey also was consistent between years, ranging from 8.5 to 12.5 cm in 2005 and from 9.0 to 12.4 cm in 2006 (Figure 13). In both years the lamprey had a mean girth of 11.0 cm.
Of the 102 lamprey collected and tagged in 2005, 31 were identified as females, 37 as males, and 34 could not be sexed (sex was rarely determined for HD PIT-tagged only lamprey because the incision was too small to see the gonad). In 2006, 32 of 88 lamprey collected were females, 25 were males, and the sex of the remaining 31 fish was undetermined. Mean times in anesthesia (total surgery time) for double-tagged lamprey were 11:51 minutes in 2005 and 11:47 minutes in 2006. Mean weight, length, and girth for the double-tagged lamprey was 461 g, 67.0 cm, and 11.0 cm, respectively. The mean total surgery time for HD PIT-tagged only lamprey was 7:34 min in 2005 and 7:18 min in 2006. The mean weight of these fish was 426 g, length was 66.0 cm, and girth was 11.0 cm for both years. A total of 80 double-tagged adult lamprey were released in the tailrace of McNary Dam over the two years, with 20 released at both the North and South-shore release sites each year. Of the 52 HD PIT-tagged only lamprey released at McNary Dam, 15 were released at each site below McNary Dam in 2005, and 11 in
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Figure 11. Frequency distribution of adult Pacific lamprey weights for fish collected and tagged at McNary Dam in 2005 and 2006.
02468
1012141618
250-275
301-325
351-375
401-425
451-475
501-525
551-575
601-625
Weight (g)
Num
ber
2005, n=1022006, n=45
Figure 12. Frequency distribution of adult Pacific lamprey lengths for fish collected and tagged at McNary Dam in 2005 and 2006.
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54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76
Total Length (cm)
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Figure 13. Frequency distribution of adult Pacific lamprey girth for fish collected and tagged at McNary Dam in 2005 and 2006.
0
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8.5-8.9 9.0-9.4 9.5-9.9 10.0-10.4
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Girth (g)
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2006. At Ice Harbor Dam, 40 double-tagged lamprey were released over the 2005 and 2006 field seasons, with 10 lamprey released at both the North and South-shore release sites each year (Figures 6 and 7). In 2005, 9 HD PIT-tagged only lamprey were released at the North-shore release site below Ice Harbor Dam (Figure 6), and three were released at the South-shore release site (Figure 7). In 2006, three HD PIT-tagged only lamprey were released at each site.
Forebay water temperatures at McNary Dam ranged from 18.9 to 21.6 °C, with a mean
of 20.4 °C during the lamprey run in 2005, and 15.9 to 21.4 °C, with a mean of 21.0 °C in 2006. At Ice Harbor Dam, water temperatures in the forebay ranged from 19.0 to 22.0 °C, with a mean of 20.7 °C in 2005, and 15.9 to 21.4 °C, with a mean of 21.0 °C in 2006. Water temperatures peaked at McNary Dam on 11 August 2005, and 26 July 2006. At Ice Harbor Dam, maximum water temperatures occurred on 13 August, 2005, and 30 July 2006. During the tagging operation, water was spilled at both McNary and Ice Harbor dams until 1 September of each year. From 8 July 2005 to 31 August 2005, the percent spill at McNary Dam ranged from 52 to 74%, with a mean of 65%. For the same period at Ice Harbor Dam, the percent spill ranged from 33 to 73%, with a mean spill of 58%. From 22 June, 2006 to 31 August, 2006, the percent spill at McNary Dam ranged from 39-61%, with a mean of 49%. The percent spill at Ice Harbor Dam ranged from 30-78%, with a mean spill of 59% for the same time period in 2006 (CRDART 2007). Dam Passage Characterization
Adult Pacific lamprey dam passage was characterized in terms of the percent of released lamprey that re-approached a dam, the percent of those lamprey that successfully
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passed the dam via a fishway, the median passage time from the first approach to a fishway to the exit, and the median passage time from the entrance into a fishway to the exit. There was no significant difference between years at either dam for these four measures (Students t-test; P-values = 0.9608 and 0.0509 at McNary and Ice Harbor dams, respectively).
Of the 40 radio-tagged adult lamprey released below McNary Dam in 2005, 21 (53%) re-
approached the dam. Of those 21 lamprey, 13 (62%) successfully passed McNary Dam (Figure 14). There was no evidence of a tag size effect: 14 of the 27 (52%) lamprey with small radio transmitters re-approached McNary Dam and seven of 13 (54%) lamprey with the large radio transmitters re-approached the dam in 2005. The 2006 results at McNary Dam were similar: 18 of 40 (45%) radio-tagged lamprey released below McNary Dam re-approached. Passage efficiency was 61%: 11 of 18 lamprey that re-approached the dam successfully negotiated the fishways and passed the dam (Figure 14). Combining the 2005 and 2006 data at McNary Dam produced an overall passage efficiency of 62% for fish that approached the dam (Figure 14).
At McNary Dam, with 2005 and 2006 data combined, individual lamprey made from one to seven approaches at fishway entrances, with a median of 1.5 approaches. Thirty-six radio-tagged adult lamprey re-approached McNary Dam in 2005 and 2006 at a fishway entrance. Of these, 17 first approached the north-shore ladder, and 19 first approached the south-shore ladder. A comparison between the release site (north or south-shore) and the fishway that the radio-tagged lamprey first approached suggested that the side of the river where lamprey were released below the dam did not affect whether they first approached the north or south fishway entrance at the dam (P = 0.75). Overall, 47% (17/ 36) of the adult lamprey first approached the fishway on the same shore as they were released, while 53% (19/ 36) approached the fishway on the opposite shore. Of the 36 lamprey that approached McNary Dam, 32 (89%) entered a fishway, with 10 (31%) entering the north-shore entrance and 22 (69%) entering the south-shore entrance. At the top of the fishways, four lamprey exited via the north-shore exit and 14 exited via the south-shore exit.
Figure 14 Passage efficiency at McNary Dam for 2005 and 2006.
53%45%
62% 61%
49%
62%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
% of lamprey thatapproached in
2005
% of lamprey thatapproached in
2006
% of approachedlamprey that
passed in 2005
% of approachedlamprey that
passed in 2006
% of lamprey thatapproached in2005 and 2006
combined
% of lamprey thatpassged in 2005
and 2006combined
16
Pacific lamprey made their first approach to McNary Dam fishway in a median time of 6.6 days (range = 0.2-37.6 d). In 2005, 74% (34 of 46) of all approaches to McNary Dam occurred while water was being spilled. This approach rate was 83% (20/24) in 2006, and 77% (54/70) for both years combined. The median McNary Dam passage time, from the first approach to a fishway to the last exit at the top of the fish ladder, was 2.1 days (range = 0.3-18.9 d). The median time from first entry to a fishway entrance until the last detection at the top of a ladder was 0.9 d (range = 0.2-18.9 d).
Lamprey passage at Ice Harbor Dam varied more between years. In 2005, nine of the 20
(45%) radio-tagged adult lamprey released below Ice Harbor Dam approached the dam. Of these, three successfully passed Ice Harbor Dam via the fishway, resulting in a 33% passage efficiency (Figure 15). The passage efficiency was 77% in 2006 when 13 of 20 (65%) radio-tagged adult lamprey released below Ice Harbor Dam approached, and 10 of those 13 successfully passed the fishways. The 2005 and 2006 combined passage efficiency for Ice Harbor Dam was 59% (Figure 15).
At Ice Harbor Dam, with 2005 and 2006 data combined, individual lamprey approached
fishways a median of three times (range 1-21) before either successfully passing the dam or migrating downstream. Twenty-three radio-tagged adult lamprey approached Ice Harbor Dam in 2005 and 2006 at a fishway entrance. Of these 23, four first approached the north-shore fish ladder, while 19 first approached the south-shore ladder. A Students t-test revealed that the side of the river that the lamprey were released from below Ice Harbor Dam did not affect whether they first approached the north or south fishway entrance at the dam (P = 0.45). Overall, 52% (11/21) adult lamprey first approached the fishway on the same shore as they were released, while 48% (11/21) approached the fishway on the opposite shore. Of the 23 radio-tagged adult lamprey that approached Ice Harbor Dam, 20 entered a fishway: four (20%) at the north-shore entrance and 16 (80%) at the south-shore entrance. At the top of the fishways, six lamprey exited from the north-shore exit, and seven exited the south-shore exit.
Pacific lamprey made their first approach to a fishway at Ice Harbor Dam in a median of
2.6 d (range = 0.5-26.4 d) after release. In 2005, 88% (35/40) of lamprey approached Ice Harbor Dam. The approach rate was 74% (66/89) in 2006, and 78% (101/129) for both years combined. All lamprey approached the dam during periods of spill. The median time from the first approach to a fishway to the exit from the top of a ladder was 2.3 d (range = 0.3-24.2 d) with both years combined. Median time from when lamprey first entered a fishway to the time they were detected exiting the top of a ladder was 0.4 d (range = 0.2-9.8 d).
Of the 15 lamprey that did not pass McNary Dam in 2005 and 2006, four were last
detected outside of the fishway at the north-shore entrance, one was last detected outside of the fishway at the south-shore entrance. Four lampreys entered the north-shore fishway and one entered the south-shore entrance, but fell back out of the entrance shortly thereafter. Five lampreys successfully passed through most of the fishway. However, they were not recorded at the top of the south-shore fishway and were not detected again (Figure 16). Potential Problem Passage Areas Potential problem passage areas for adult lamprey were similar at Ice Harbor Dam in 2005 and 2006. Of the ten lamprey that approached Ice Harbor Dam, but did not pass, two were last recorded outside of the south-shore fishway entrance and one was last recorded outside of the entrance to the north-shore fishway. One entered the north-shore fishway and soon fell back out of the entrance. Another lamprey entered the north-shore fishway and was
17
Figure 15 Passage efficiency at Ice Harbor Dam for 2005 and 2006.
45%
65%
33%
77%
55%59%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
% of lamprey thatapproached in
2005
% of lamprey thatapproached in
2006
% of approachedlamprey that
passed in 2005
% of approachedlamprey that
passed in 2006
% of lamprey thatapproached in
2005 and 2006combined
% of lamprey thatpassged in 2005
and 2006combined
One other lamprey approached all of the ladder entrances, but never entered.
Spillway
Fore ba y
Powerhouse
N ladder exit
S ladder exit
A1A2A4
A3A4
A1 A2A
A
A5
A4
A5
A3
A1
A3
A
Juvenilechannel
A
A
A1
A2
497.8 rkm
A1 A2 A3
A A2 A3
Flow
Figure 16. The most upstream or last known location of radio-tagged adult Pacific lamprey migrating through McNary Dam in 2005 and 2006. Each star indicates and individual lamprey.
18
e
A 1
A 2A 2
A 1
A I H
B I H
A 6
A 3 9 I H A 2
Flow
later found dead under diffuser grating. Five entered the south-shore fishway and were detected passing to the top of the transition pool and then turned back and exited the fishway via the entrance (Figure 17).
Figure 17. The most upstream or last known location of radio-tagged adult Pacific lamprey migrating through Ice Harbor Dam in 2005 and 2006. Each star indicates an individual lamprey.
At McNary Dam, the 2005 and 2006 combined passage efficiency through the entrances, transition pools, and tops of ladders was 57%, 80%, and 100% respectively (Table 3). The passage efficiency for the fishway sections was generally lower at Ice Harbor Dam with a combined entrance efficiency of 29%, transition pool efficiency of 47%, and 100% passage at the top of the fishway (Table 3, Figure 18).
Disease Diagnosis
The Idaho Fish Health Center performed disease screenings for 20 lamprey collected at Bonneville Dam and nine collected at McNary Dam. The pathogen Aeromonas hydrophila was present in four of the lamprey collected at Bonneville Dam and two of those collected at McNary Dam. Using a TYES plate, the Idaho Fish Health Center also found that two lamprey collected from Bonneville Dam had a bacteria similar to Flavobacterium psychrophilum, the causative agent of cold water disease. However agglutination and PCR techniques were negative for cold water disease and the bacteria was unidentified. All viral and parasitic analyses were negative for pathogens.
19
Table 3. Passage efficiency by fishway section at McNary and Ice Harbor Dams in 2005 and 2006. Transition pool is from inside of entrance up to tailwater elevation in ladder. Top of the ladder is from top of transition pool to ladder exit.
# Appr. # Exit Efficiency# Appr. # ExitEfficiency# Appr. # ExitEfficiency2005 46 22 47.8% 18 17 94.4% 15 15 100%2006 24 18 75.0% 17 11 64.7% 5 5 100%Combined 70 40 57.1% 35 28 80.0% 20 20 100%
# Appr. # Exit Efficiency# Appr. # ExitEfficiency# Appr. # ExitEfficiency2005 40 14 35.0% 14 3 21.4% 3 3 100%2006 89 23 25.8% 20 13 65.0% 12 12 100%Combined 129 37 28.7% 34 16 47.1% 15 15 100%
Entrance Transition Pool Top of Fishway
McNary Dam
Ice Harbor Dam
Top of FishwayTransition PoolEntrance
Figure 18. Pacific lamprey passage efficiency at McNary and Ice Harbor dam fishway
sections in 2005 and 2006, shown separately and with both years combined.
Proximate Analysis The percent of crude fat in adult lamprey collected at Bonneville Dam ranged from 13.6 to 24.8%, with a mean of 18.5% (SD = 3.2%) (Figure 19; Table 4).The lamprey collected at McNary Dam had a range of crude fat content from 8.6 to 17.9%, with mean of 14.0% (SD = 2.8%) (Table 4). This difference was significant (Student t-test P = 0.0013). At Bonneville Dam,
0%
20%
40%
60%
80%
100%
Entrance Transition Pool Top of Ladder
Pass
age
Effi
cien
cy b
y Fi
shw
ay S
ectio
n
McNary 2005McNary 2006Ice Harbor 2005Ice Habor 2006McNary CombinedIce Harbor Combined
20
Figure 19. Comparison of mean fat content between male and female adult Pacific lamprey collected at McNary and Bonneville Dams in 2006.
18
14
18 19
16
9
0
2
4
6
8
10
12
14
16
18
20
Bonneville McNary BON Male BON Fem MCN Male MCN Fem
Mea
n %
Fat
Con
tent
the lipid content ranged from 57 to 143 g, with a mean of 91 g (for fish with mean weight and length of 483 g and 67 cm, respectively). The lipid content of lamprey collected at McNary Dam ranged from 30 to 84 g, with a mean of 59 g (mean weight and length of 418 g and 65 cm, respectively). From these data, one could infer a 35% decrease in mean lipid content of lamprey between Bonneville Dam and McNary dams. There was no difference in lipid content for males and females at Bonneville Dam (P = 0.83), but at McNary Dam, mean crude fat percentage was 16.3% for males and 9.1% for females (P = 0.02).
The condition factor for lamprey collected at Bonneville Dam ranged from 1.44 to 1.68, with a mean of 1.60 (SD = 0.74). The lamprey collected at McNary Dam had a range in condition factor from 1.43 to 1.53, with a mean of 1.50 (SD = 0.33). There was a significant difference between lamprey collected at Bonneville and McNary dams (Student t-test P = 0.0006). However, there was no difference in the condition factor of male and female lamprey (P = 0.52 and 0.54, respectively) at either dam.
21
Table 4. Proximate analysis data for the portion of each Pacific lamprey that was not freeze dried.
Gender
%
Moisture
% Total Ash
% Crude
Fat
Calculated % Crude Protein
Weight (g)
Length (cm)
Lipid Content
(g)Female 63.34 0.80 21.83 14.03 605 74 132.07Male 66.45 0.72 18.07 14.76 465 65.75 84.03Male 62.21 0.69 22.23 14.87 684 78 152.05Male 65.38 0.83 19.82 13.97 390 61.5 77.30Male 68.46 0.80 14.39 16.35 395 62 56.84
Female 65.57 0.84 18.51 15.08 470 66 87.00Male 63.12 0.64 18.99 17.25 660 77 125.33Male 59.55 0.72 24.81 14.92 575 72 142.66Male 59.78 0.68 23.86 15.68 505 68 120.49Male 67.53 0.81 17.00 14.66 445 64.75 75.65
Female 64.37 0.83 20.13 14.67 595 73 119.77Male 68.60 0.90 15.32 15.18 500 67.75 76.60Male 70.87 0.64 15.63 12.86 390 61.75 60.96Male 67.71 0.83 15.56 15.90 375 61 58.35
Female 63.14 0.69 19.26 16.91 545 70.5 104.97Male 69.67 0.67 14.61 15.05 395 62 57.71
Female 70.05 0.78 13.63 15.54 400 62.25 54.52Male 65.20 0.69 18.35 15.76 410 62.75 75.24
Female 68.60 0.82 16.42 14.16 315 57.5 51.72Female 63.91 0.82 20.99 14.28 535 70 112.30Mean 65.68 0.76 18.47 15.09 482.70 66.88 91.28
Gender
%
Moisture
% Total Ash
% Crude
Fat
Calculated % Crude Protein
Weight (g)
Length (cm)
Lipid Content
(g)Male 67.83 0.71 17.88 13.58 470 68.25 84.04Male 69.90 0.71 15.09 14.30 410 64.75 61.87
Female 72.66 0.63 11.08 15.63 320 59.5 35.46Male 68.84 0.95 15.95 14.26 440 66.5 70.18
Female 70.08 1.58 12.57 15.77 385 63.25 48.39Female 67.27 0.66 14.06 18.01 535 72 75.22Female 67.31 0.80 14.61 17.28 495 69.75 72.32Male 66.67 0.84 16.29 16.20 360 61.75 58.64
Female 72.32 0.76 8.57 18.35 345 61 29.57Mean 69.21 0.85 14.01 15.93 417.78 65.19 59.52
McNary Dam Lamprey
Bonneville Dam Lamprey
22
Discussion
The overall passage efficiencies of 61.5% and 59.1% at McNary and Ice Harbor dams respectively, indicated that adult lamprey did not readily pass these two structures. Pacific lamprey passage at McNary and Ice Harbor dams in 2005 and 2006 was similar to the passage efficiencies at lower Columbia River dams in previous studies (Table 1). In contrast, the salmonid passage in fish ladders at these dams has been highly successful. In 2004 and 2005 combined, 98% of the spring and summer Chinook salmon that approached McNary Dam successfully passed the fishways and dam. For the same two years, the passage efficiency for Chinook salmon at Ice Harbor was 97% (University of Idaho, unpublished data). Not only was passage relatively reduced for adult lamprey, but it also took them longer to pass the dams compared to salmonids. The median passage time from the first approach until exit into the forebay for adult lamprey was more than 2.0 d at McNary and Ice Harbor dams. Comparable median passage times for Chinook salmon were approximately nine hours at McNary Dam and five hours at Ice Harbor Dam.
Lamprey passage times for McNary and Ice Harbor dams were similar or shorter than those observed during previous studies at lower Columbia River dams. At Bonneville Dam in 2000 and 2001, Pacific lamprey had median passage times of 4.4 and 11.0 days (Moser et al. 2002b, 2003), or two to five times longer than those at McNary and Ice Harbor dams in 2005 and 2006. At The Dalles Dam, lamprey had a median passage time of 2.1 days in both 2000 and 2001 (Moser et al. 2002b, 2003), while Chinook salmon passed the dam with a median time of 0.6 days in both years (Keefer et al. 2004). The dam with the greatest median passage time for summer Chinook salmon from 1996 through 2001 was John Day Dam, where median passage times were 1.3 and 1.4 days in 2000 and 2001 (Keefer et al. 2004). These same years, lamprey successfully passed John Day Dam in 2.5 and 1.3 days, some of the faster passage times reported for lamprey in the lower Columbia River (Moser et al. 2002b, 2003).
The median time it took for a lamprey to be detected at McNary and Ice Harbor dams after release in 2005 and 2006 combined was similar to findings at other lower Columbia River dams. From 1997 to 2002, Moser et al. (2005) reported median lamprey approach times to Bonneville Dam ranging from 4.0 to 7.8 days. Therefore, the median time from release to approach of 6.6 and 2.6 days for McNary and Ice Harbor dams, respectively, were within the range at Bonneville Dam. However, in those same years, Moser et al. (2005) reported 87 to 96% of all lamprey released below Bonneville Dam later detected at the dam. Findings at McNary and Ice Harbor dam in 2005 and 2006 were considerably lower with only 49% and 55% of the lamprey being detected at McNary and Ice Harbor dams, respectively.
Water temperature, tag effects, or migration stage may have influenced the percent of
lamprey that approached either McNary or Ice Harbor dams. Water temperatures during most of the lamprey migration at McNary and Ice Harbor dams in 2005 and 2006 were greater than 19°C. Ocker et al. (2001) found that water temperature greater than 19.5°C was associated with lower lamprey migration success. Close et al. (2003) reported that swimming performance of lamprey was not affected after one and seven days following implantation of a 7.4 g transmitter. Implantation of a 3.4 g transmitter was considered equivalent to the act of handling the fish. However, Mesa et al. (2003) found that lamprey tagged with a 3.6 g dummy transmitter had a significantly lower mean critical swimming speed than lamprey without transmitters. The smallest transmitters used by both Close et al. (2003) and Mesa et al. (2003) were larger than most (100 of 120) of the transmitters implanted into lamprey at McNary and Ice Harbor dams. Also, we did not find a difference in performance of lamprey that received large and small transmitters in 2005. Therefore, we expect that tagging and handling effects would be less than
23
those reported by Mesa et al. (2003). Close et al. (2003) conducted their study between 12-13°C, while Mesa et al. (2003) held their fish in 15°C water. These temperatures were markedly cooler than those lamprey experienced in 2005 and 2006 at McNary and Ice Harbor dams. Furthermore, this study handled lamprey at McNary Dam, where lamprey are smaller and further into their migration, potentially affecting either condition or migration motivation. The combination of condition of fish, water temperatures, migration motivation would likely have influenced the proportion that returned to and passed the two projects.
Although some lamprey were collected at McNary Dam and released at Ice Harbor Dam
in 2005 and 2006, there seemed to have been no negative affects due to transportation. The overall percent of lamprey that approached Ice Harbor Dam after release was greater than the percent that approached McNary Dam. Also, the median time from release until detection was less at Ice Harbor Dam in both years. Finally, the overall passage efficiency at Ice Harbor Dam was not considerably different from the overall passage efficiency at McNary Dam. Although the eventual destination (if any) for the tagged fish was unknown, the successful transportation of these fish and their resumption of migration may indicate that Pacific lamprey do not home to specific natal sites but may instead use environmental or other cues to find suitable spawning habitat.
Sample sizes were smaller than anticipated for this study because of the decreasing
number of adult Pacific lamprey that migrate to McNary Dam. Additionally, the single trap can only potentially collect a fraction of the total lamprey present at McNary Dam. This trap operates at an overflow weir along one wall of the 9.1 m (Downing and Prentice, 2003) fishway. Thus, there were many alternate routes available for lamprey migrants that could bypass collection in the trap. For future studies we would recommend that a second trap be placed on the opposite side of the same weir and thus potentially double the number of lamprey encountering a trap.
Median lamprey passage times varied between the two study years. This was largely due to the differences in the amount of time it took for individual lamprey to enter a fishway after making their initial approach, which in turn may have been related to the relatively small sample sizes. The variable entry times and repeated entry attempts indicate that lamprey have difficulty finding and entering fishways at these dams. Structural or operational changes to the entrances may be needed to improve lamprey passage success. For example, lower entrance velocities at night is currently being tested at Bonneville Dam. If effective, such an operational change could be tested at McNary and Ice Harbor dams. Also, rounded entrance bulkheads appear to make entrances easier at the spillway entrances at Bonneville Dam (Moser et al. 2002).
At McNary Dam, the greatest limitation to lamprey passage appeared to be at fishway
entrances and sections of the ladder up to the top of transition pools. Ten of the 15 lamprey that did not successfully pass the dam either did not enter a fishway entrance or moved to just inside the entrance and then fell back. Problem passage areas within the fishways of McNary and Ice Harbor dams were similar to those found at Bonneville, The Dalles, and John Day dams. After fish successfully entered a fishway, one factor that may have increased passage efficiency compared to downstream dams may have been the absence of serpentine weirs in the fish ladders of McNary and Ice Harbor dams (see Moser et al. 2002b).
The entrances to the fishways have high water velocities and gate slots, which create
90-degree corners lamprey must pass (Figure 20). Due to high water velocities, lamprey must use their suctorial disk to assist in their migration by attaching to the side of the entrance and hopping along the wall or floor. However, once they reach the gate slots, they may have difficultly hopping or swimming around the 90-degree corners into the slot and could be swept
24
out of the fishway. The entrances also had the lowest passage efficiency of the three fish ladder sections at McNary Dam in both years, with just over half of the lamprey that approached the entrance making it through to the next section of the fishway. Modifying entrances to eliminate bulkhead slots to create smooth surface entrance routes may improve entry success here.
Figure 20. Ice Harbor Dam fishway entrance. Black arrows indicate two gate slots with 90 degree angles. At McNary Dam, lamprey approached both the north and south-shore at equal rates in both years; however, more successfully entered a fishway and passed the dam at the south-shore fish ladder. At Ice Harbor Dam, lamprey approached and successfully entered the south-shore fishway at a much higher rate than the north-shore fishway. However, lamprey successfully passed the dam at equal rates via the north- and south-shore fishways. This indicates that lamprey in the south-shore fishway may have encountered obstacles to their continued migration through the fishways, and exited the fish ladder back at the entrance.
Five lamprey that were considered unsuccessful migrants at McNary Dam passed the transition pool and almost reached the top of the fish ladder (Figure 16). It is possible that these lamprey did actually pass McNary Dam but were not detected by the final radio telemetry or PIT tag antennas at fishway exits. There were two other lamprey that were not detected by the radiotelemetry antennas in these same areas, but were detected by the PIT tag antennas; therefore, they were classified as successful migrants. If these five lamprey successfully exited the fishway at the top of the fish ladder, the passage efficiencies calculated for McNary Dam would increase to 74.4%. These lamprey may also have exited the fishway at the top of the ladder via other routes. There are numerous openings in the side of the fishway that could allow lamprey to exit to the forebay of the dam. Therefore, the current passage efficiency of 61.5%
25
should be considered a minimum estimate at McNary Dam1. The five missing lamprey were not detected again anywhere in the fishway or elsewhere and it is likely they did not survive passage at the dam.
Entrances at Ice Harbor Dam presented problems for lamprey migration evidenced by a
passage efficiency of only 29%, the lowest combined passage efficiency of all studied fishway sections. The entrances at Ice Harbor Dam had the highest number of approaches even though there were only one-third the number of lamprey released at the dam. As described for McNary Dam, high water velocities and squared corners likely prevented lamprey from negotiating the entrance bulkheads.
Five lamprey were unable to successfully pass through the south fish ladder at Ice Harbor Dam (Figure 17). Those lamprey entered the fishway and began to pass through the transition pool but then fell back either to the entrance section or completely out of the fishway. This is the section of the fishway that includes the top of the transition pool. We believe that most salmon migrate through this section along the bottom of the fishway, using the underwater orifices to pass weirs (e.g. Naughton et al. 2007). Adult lamprey may have difficulty moving through this segment of the fishway due to diffuser grating in alternating weir sections, which prevents them from attaching to the floor, a requirement for passing though orifices (Daigle et al. 2005). In tests conducted in an experimental fishway, covering diffusers with a metal plate for a distance 12 inches just upstream from orifices was sufficient to allow lamprey to pass weirs and pools with diffusers (Daigle et al. 2005).
Of the 29 adult lamprey collected at Bonneville and McNary dams, one bacterial pathogen, A. hydrophila, was identified, and another was detected. A. hydrophila is a pathogen commonly found in salmonids and other fish species (Plumb 1999). Under non-stressful conditions, effects of the pathogen can be minor. However, when fish must navigate through water temperatures at their upper tolerance levels, mortality can increase (Thoeson 1994; Plumb 1999). For example, salmon and steelhead mortality due to A. hydrophila increased from 0% to 64 - 100% when water temperatures increased from 9.4 to 18°C (Plumb 1999). Run timing for Pacific lamprey at McNary Dam coincides with the warmest water temperatures of the year (e.g. Figure 21) and, although this may have been the historical condition, we know water temperatures in the Columbia River have trended upward since development of the hydrosystem. This suggests that temperature should be further investigated as a factor influencing migration success and escapement to the Snake River.
Collecting lamprey at McNary Dam was difficult due to the low number of lamprey that
reached that dam. Further disease research should be conducted before conclusive results can determine what pathogens lamprey may carry during their inland migration. Other agencies have successfully isolated R. salmoninarum and A. salmonicida from lamprey in the Columbia River Basin (Aaron Jackson, Confederated Tribes of the Umatilla Indian Reservation, pers. comm.; Mary Moser, Northwest Fisheries Science Center, pers. comm.). With the growing list of pathogens found in sea lamprey, it is possible that Pacific lamprey may be carriers of the same pathogens. If numbers of lamprey reaching upstream locations remains low, there will be continued efforts by agencies to translocate adult Pacific lamprey. It is important to know and understand the pathogens that lamprey are carrying, as they may be detrimental to other species.
1 Additional monitoring in 2007 indicates fish were using an alternate route to pass the dam at this point in the south ladder at McNary Dam.
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26
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27
300350400450500550600650700
55 60 65 70 75 80Length (cm)
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Bonneville Dam
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Figure 22. Length-weight relationship of Pacific lamprey collected at Bonneville and
McNary Dams in 2006 and submitted for proximate analysis.
successful in passing lamprey from the auxiliary water supply (AWS) channel into the forebay of the dam (Moser et al. 2006). The AWS channel is an area where lamprey congregate and their upstream migration is obstructed. Although the LPS structure has increased lamprey passage at Bonneville Dam, no locations have been found within fishways at McNary or Ice Harbor dams where similar structures could be implemented (that is, ‘dead end’ channels where lamprey may congregate and thus eventually find and then use a LPS structure). Other lamprey passage strategies currently being explored by UI and NOAA personnel, such as decreased water velocities as night when the majority of lamprey migrate, covering gate slots, and decreasing the number of weir sections that contain diffuser grating may improve adult lamprey dam passage at McNary and Ice Harbor dams.
28
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