Evaluation of Anadromous
Fish Potential Within the
Mainstem Snake River,
Downstream of the Hells
Canyon Complex of
Reservoirs
Phil Groves
Editor
Technical Report
Appendix E.3.1-3
December 2001
Hells Canyon Complex
FERC No. 1971
Copyright © 2003 by Idaho Power Company
A Description of Pacific
Lamprey Life History,
Physical Habitat and Water
Quality Criteria, and Their
Current Status Downstream
of the Hells Canyon
Complex
Phillip A. Groves
Anadromous Fisheries Biologist
Phil A. Bates
Environmental Technician
James A. Chandler
Fisheries Section Supervisor
Technical Report
Appendix E.3.1-3
Evaluation of Anadromous
Fish Potential Within the
Mainstem Snake River,
Downstream of the
Hells Canyon Complex of
Reservoirs
Chapter 4
December 2001
Hells Canyon Complex
FERC No. 1971
Copyright © 2003 by Idaho Power Company
Idaho Power Company
Chapter 4: Pacific Lamprey Downstream of the HCC
TABLE OF CONTENTS
Table of Contents............................................................................................................................. i
List of Tables .................................................................................................................................. ii
List of Figures ................................................................................................................................. ii
Abstract ............................................................................................................................................1
1. Introduction.................................................................................................................................2
2. Distribution and Affecting Factors .............................................................................................2
3. Life History Characteristics ........................................................................................................3
4. Current Population Status ...........................................................................................................6
5. Summary and Conclusions .........................................................................................................8
6. Acknowledgments.......................................................................................................................9
7. Literature Cited ...........................................................................................................................9
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LIST OF TABLES
Table 1.
A list of known predators of Pacific lamprey (from Close et al. 1995).................13
Table 2.
Counts of migrating adult Pacific lamprey, comparing former counts with
1997 counts at Columbia and Snake River projects (from Close 2000)................13
LIST OF FIGURES
Figure 1.
Juvenile Pacific lamprey downstream migration timing from the Smolt
Monitoring Program. The single value off the vertical scale is the passage
of 60,000 lamprey through McNary Dam on May 29 (Figure 3 from
Moursund et al. 2000). ...........................................................................................15
Figure 2.
1999 season juvenile lamprey collection at John Day Dam, showing
migration peaks and their relationship to discharge (Figure A-2 from
Martinson et al. 2000). ...........................................................................................15
Figure 3.
Adult and juvenile lamprey counts at Bonneville Dam (from CPUD 2000).........16
Figure 4.
Adult lamprey counts at The Dalles Dam (from CPUD 2000)..............................17
Figure 5.
Adult and juvenile lamprey counts at John Day Dam (from CPUD 2000). ..........18
Figure 6.
Adult and juvenile lamprey counts at McNary Dam (from CPUD 2000). ............19
Figure 7.
Adult lamprey counts at Ice Harbor Dam (from CPUD 2000). .............................20
Figure 8.
Historical juvenile lamprey counts at John Day Dam, 1985−1999. Heavy
line between years 97 and 98 indicates switch from “single gatewell” to
“full bypass” sampling and the corresponding y-axis scale change
(Figure C-7 from Martinson et al. 2000). ..............................................................20
Figure 9.
Historical juvenile lamprey counts at Bonneville Dam, 1988−1999.
(Figure D-7 from Martinson et al. 2000). ..............................................................21
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Chapter 4: Pacific Lamprey Downstream of the HCC
ABSTRACT
Within this chapter, we summarize information about Pacific lamprey gathered from relevant
peer-reviewed literature and data regarding fish passage collected at Columbia and Snake river
hydroelectric projects. The information and data help us to describe the life history, distribution,
and habitat and water quality requirements of these fish. Historically, Pacific lamprey are
thought to have occurred throughout the Columbia and Snake river basins, mirroring ranges of
migrating salmon. As with other anadromous species, hydroelectric development on the
Columbia and Snake rivers has hindered upstream migration of adult lamprey. Pacific lamprey
are poor swimmers, and adults tend to have difficulty successfully migrating upstream through
hydroelectric fish passage facilities; in fact, fallback rates are very high (up to 50%). The
primary spawning and rearing habitats for Pacific lamprey are found in tributary streams, with
mainstem corridors used primarily during adult and juvenile migration periods. Pacific lamprey
tend to migrate upstream from late spring through late fall, overwinter, and then spawn in
tributary streams during the following spring. Water temperatures during spawning are generally
increasing from about 10 to 15 °C. Spawning has been observed in substrate consisting of fines
and gravel, at depths up to 4.0 m, and where water velocities are from 0.5 to 1.0 m/s. Pool
tailouts, riffles, and glides have all been identified as areas where spawning occurs. Ammocoetes
(larvae) spend 4 to 6 years burrowing into fine stream sediments and filter feeding on algae,
diatoms, and detritus. The juveniles are thought to prefer cool water (16.0 to 21.8 °C) but have
been collected when water temperatures were as high as 25 °C. Juvenile lamprey migrate
downstream after completing metamorphosis, or during its final stages, in late fall through
spring. While parasitic, Pacific lamprey are not associated with a specific host. And though
lamprey and salmon arose concurrently within the Columbia River Basin, lamprey are not
considered a significant source of predation on Pacific salmon. Passage and spawning data, used
for assessing trends in population status, are virtually nonexistent for Pacific lamprey. Neither
adult nor juvenile passage data have historically been collected specifically for Pacific lamprey.
What data have been collected are inconsistent.
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1. INTRODUCTION
Historically, Pacific lamprey (Lampetra tridentata) have been of little concern throughout the
Pacific Northwest region, and information about these primitive fish is scarce and difficult to
obtain. In this chapter, we describe the life history, distribution, and habitat and water quality
requirements of these fish, based on relevant peer-reviewed literature and fish passage data
collected at Columbia and Snake river hydroelectric projects. In essence, this chapter is a
synthesis of existing information.
Pacific lamprey are primitive anadromous fish indigenous to the Columbia and Snake river
basins. Historically, Pacific lamprey have been found along the North American coast as far
south as Baja California and as far north as the Bering Sea in Alaska (Wang 1986).
Lampetra tridentata is divided into two subspecies within Oregon, the anadromous Pacific
lamprey and the landlocked Goose Lake lamprey, which is listed as a species of special concern
(ODFW 1995). Two additional lamprey species, river lamprey (L. ayresi) and western brook
lamprey (L. richardsoni), also occur within the Columbia River Basin (Close et al. 1995). Recent
sightings of western brook lamprey have been documented on Cedar Creek (Stone et al. 2001), a
lower Columbia River tributary, and on the south fork of the Walla Walla River (Close and
Bronson 2001). However, no recent reports were found confirming the status of river lamprey.
As with Pacific lamprey, river and western brook lamprey are also anadromous forms, with the
Pacific and river lamprey exhibiting a parasitic life strategy (Close et al. 1995). Of these, only
Pacific lamprey have a native range that includes the Snake River (Scott and Crossman 1973).
Many factors that have affected populations of salmon species throughout the Pacific
Northwest have similarly affected Pacific lamprey. Hydroelectric projects have blocked access to
or altered habitat and probably disrupted passage, both upstream and downstream. Changes in
land-use practices have probably also affected habitat quality within spawning and rearing areas.
2. DISTRIBUTION AND AFFECTING FACTORS
Historically, Pacific lamprey have occurred throughout the Columbia and Snake river basins,
mirroring ranges of migrating salmon (Close et al. 1995). While two other lamprey species
inhabit the Columbia River Basin, no river or western brook lamprey were found in the
Snake River. Most historical accounts that mentioned the presence of lamprey failed to identify
species or give supporting evidence that additional species existed. However, at most upstream
sites, including those on the Snake River, the term “lamprey”—based on their life history and
our current state of knowledge—is widely accepted as referring to Pacific lamprey.
Pacific lamprey have historically been reported in the Snake River as far upstream as Lower
Salmon Falls (Gilbert and Evermann 1894). Bell (1959) documented the presence of lamprey as
by-catch while collecting chinook and steelhead juveniles immediately below Brownlee Dam in
1957 and 1958. However, as an example of how difficult it is to obtain records of lamprey, Bell
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Chapter 4: Pacific Lamprey Downstream of the HCC
(1957) did not mention or include data on lamprey while collecting all species of fish present
within the Snake River or its tributaries between the Mountain Sheep (river mile [RM] 194) and
Pleasant Valley Dam sites (RM 213). Tribal peoples harvested lamprey at traditional fishing
areas within the Snake River Basin, areas that included the Tucannon, Grande Ronde, and
Powder rivers (Close and Bronson 2001). Currently, the distribution of lamprey on the
Snake River extends upstream to Hells Canyon Dam (Close et al. 1995), the upstream barrier to
anadromous fishes. Recent investigations into lamprey populations in Snake River tributaries
show that low numbers of lamprey larvae remain in the Grande Ronde (Close and Bronson 2001)
and Clearwater river basins (Cochnauer and Claire 2000). Conversely, recent investigations into
the status of lamprey in the John Day Basin indicate “general reproductive and rearing success”
(Close and Bronson 2001), although current population numbers are largely unknown. The
overall trend in declining numbers of lamprey has been attributed to several causes, including
habitat loss, water pollution, ocean conditions, and dam passage (Close et al. 1995, CPUD 2000,
Cochnauer and Claire 2000, Close 2001).
As with other anadromous species, hydroelectric development on the Columbia and
Snake rivers hinders upstream migration of adult lamprey. Access to suitable habitat seems to
have a greater effect on regional distribution of the species than distance from the ocean
(Kan 1975). Recent research on upstream passage efficiency at Bonneville Dam suggests that
hydroelectric projects can significantly threaten migrating adult lamprey, with a passage success
rate of less than 50% (Close and Bronson 2001). Barriers, which are placed into fish ladders at
some Columbia River dams, may cause additional stress for adult migrating lamprey (Close et al.
1995).
3. LIFE HISTORY CHARACTERISTICS
Primary spawning and rearing habitats for Pacific lamprey (referred to simply as lamprey,
unless otherwise noted) are found in tributary streams (Kan 1975), with “limited use of mainstem
corridors except during adult and juvenile migration periods” (Moursund et al. 2000). Close et al.
(1995) found that lamprey begin their spawning migration into freshwater as early as March and
have completed their migration into streams by September. Pacific lamprey are widely described
as poor swimmers, averaging between 4.5 and 8.0 km per day during upstream migrations
(Beamish and Levings 1991, Kan 1975). During their migration, adult lamprey discontinue
feeding after entering freshwater and may shrink by as much as 20% before they spawn
(Beamish 1980).
Stone et al. (2001) found that adult lamprey entered Cedar Creek during June and September
2000. The National Marine Fisheries Service (NMFS) found that lamprey move upstream to
spawn from May to September in the Columbia River Basin (Bayer et al. 2001). Bayer et al.
(2001) reported from telemetry studies that most lamprey initiated overwinter holding by
mid-September 2000 and continued to mid-March 2001. All but one of their tagged lamprey
(n = 42) held in the lower John Day River at depths of 0.5 to 10.4 m (n = 35, median = 0.9), with
velocities from 0.02 to 1.22 m/s (n = 29, median = 0.37 m/s), before moving into spawning areas.
In the Columbia River system, most lamprey hide under stones and overwinter until the
following spring, after which they resume their spawning migrations (Scott and Crossman 1973).
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Bayer et al. (2001) found that overwintering lamprey in the John Day River displayed similar
cryptic behavior, hiding under boulders in riffle or glide habitats.
Spawning commences the following spring when temperatures reach between 10 and 15 °C.
Based on temperatures, lamprey can spawn as early as May along the Oregon coast or as late as
July in upper reaches (Close et al. 1995 and citations therein).
Adult lamprey spawning behavior includes building nests in sandy gravel (Scott and
Crossman 1973, Close et al. 1995 and citations therein), gravel in riffles (Page and Burr 1991),
or the tails of pools (Scott and Crossman 1973, Close et al. 1995). Water depth at nest sites is
typically less than 1.0 m (Wang 1986, Close et al. 1995), but nests have been observed in depths
up to 4.0 m (Close et al. 1995 and citations therein). Nests are typically constructed in lotic
environments where water velocities have been measured between 0.5 and 1.0 m/s (Pletcher
1963, Kan 1975). Pacific lamprey nests identified on Cedar Creek (n = 132) by Stone et al.
(2001) in April through July 2000 indicate that these fish use 50% pool tailouts, 33% riffles, and
12% glides at a mean depth of 0.4 m in fine and gravel substrate. After a pair constructs a
shallow nest, the male attaches to the female and fertilizes the eggs as they are emitted during an
estimated 12-hour spawning session (Scott and Crossman 1973). Nest building continues
throughout and between spawning acts. During this nest construction, the adhesive embryos are
covered with sand and pebbles (Scott and Crossman 1973, Close et al. 1995). Males may mate
with multiple females in different nests (Wang 1986 and citations therein).
Fecundity estimates vary, ranging from between 98,000 and 238,400 for lamprey in Oregon
(Close et al. 1995) to between 30,000 and 100,000, as reported by Simpson and Wallace (1982)
and Scott and Crossman (1973), and between 10,000 and 106,000 (Wang 1986). After spawning,
adult lamprey have been reported to die within 1 to 36 days (1 to 14 days, Scott and Crossman
1973; 3 to 36 days, Close et al. 1995).
Lamprey larvae hatch within two to three weeks (Scott and Crossman 1973, Close et al.
1995) and leave their natal substrate at approximately two or three weeks after hatching, drifting
downstream into slower pools and eddies (Close et al. 1995). The eyeless larvae (ammocoetes)
spend four to six years burrowing into fine stream sediments and pumping water through their
branchial chamber to filter feed on algae, diatoms, and detritus (Stone et al. 2001 and citations
therein).
During this life stage, ammocoetes seem to prefer fine sediment (mud or silt) located near the
river margins rather than coarser sediment located in deeper habitats (CPUD 2000). Ammocoetes
seem to prefer cooler water, but they have been collected when water temperatures were as high
as 25 °C in Idaho (Mallat 1983). Similarly, Holmes and Lin (1994) reported that larval sea
lamprey (Petromyzon marinus) preferred summer water temperatures ranging from 17.8 to
21.8 °C. Data from Close and Bronson (2001) also corroborate these temperature ranges. During
an extensive survey within the Columbia River Basin, they observed highest densities of larval
Pacific lamprey (12 to 32 individuals/m2) in streams where mean water temperatures were
recorded between 16.0 and 21.8 °C. Data concerning this species’ oxygen tolerance are relatively
scarce. Mallat (1983) reported that a low partial pressure of oxygen (7 to 10 mm Hg) at 15.5 °C
caused larval lamprey to die, whereas they tolerated concentrations from 18 to 20 mm Hg at the
same temperature.
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Chapter 4: Pacific Lamprey Downstream of the HCC
Transformation from an ammocoete to a juvenile (macropthalmia) is a multiphase process
that involves internal as well as external changes in the fish. These changes prepare it to
successfully osmoregulate in salt water (Close et al. 1995). The process generally occurs from
July through October, prior to a late fall to spring outmigration (CPUD 2000 and citations
therein). Major external changes during this alteration include the development of eyes and the
transformation of the hood into a disc-shaped mouth. Internal changes involve development of
the foregut and a unidirectional respiratory system, changes in blood proteins, and senescence of
the gallbladder and the bile duct (Close et al. 1995). During and after transforming to
macropthalmia, the species’ habitat preference shifts: juveniles prefer higher velocities and larger
substrate material (CPUD 2000 and citations therein).
Juvenile lamprey migrate downstream after completing their metamorphosis (Close et al.
1995) or during its final stages (Moursund et al. 2000) in late fall through spring. Moursund et al.
(2000) found that during sampling at John Day and McNary dams in 1998, lamprey outmigration
peaked on May 29 (Figure 1), with all lamprey collected showing signs of late metamorphosis.
Nonetheless, these lamprey may have been on course to complete metamorphosis before they
entered the saline estuary downstream of Bonneville Dam. This late May peak migration seems
to concur with results from fyke net sampling at the Wells and Rocky Reach dams in the middle
Columbia River (CPUD 2000). Likewise, incidental catch during 1999 monitoring efforts for
downstream migrating salmon and steelhead smolts at John Day Dam yielded three distinct
juvenile lamprey outmigration peaks: April 23, June 3 through 6, and a smaller one July 3
(Figure 2) (Martinson et al. 2000). Timing of downstream migrations tends to correlate with
spring freshets (Stone et al. 2001).
Juvenile migrants are relatively weak swimmers (Moursund et al. 2000) and tend to drift
downstream tail first rather than swim in the conventional sense (Close et al. 1995 and citations
therein, CPUD 2000). Developing juvenile and young adult lamprey initially leave the substrate
and migrate during the night hours (Close et al. 1995, Moursund et al. 2000) in the lower
portions of the water column, as seen in fyke net data from the Wells Dam investigations where
nets greater than 90 ft depth collected most lamprey (CPUD 2000). This behavior may help
decrease their susceptibility to predators (Moursund et al. 2000). As juveniles approach the
estuary, lamprey actively migrate in the daytime as well. Little information exists on time spent
in the estuary before the lamprey enter the ocean; however, it is at this time that lamprey become
parasitic feeders (Wang 1986). Variations in the spatial scale of rearing to estuary locations for
lamprey populations may account for the various estimates on time spent in the ocean, which
range from 1 to 3.5 years. Kan (1975) estimated that lamprey off the Oregon coast may spend
20 to 40 months in the ocean.
While in the ocean, lamprey may use a variety of habitats to support their new feeding
strategy. They have been found as far off the Oregon coast as 100 km and at depths of 800 m
(Kan 1975). Little is known of their migratory behavior while in the ocean. While at sea, they
may use olfaction, electroreception, and vision to locate prey (Close et al. 1995). As parasites,
they may need to be highly opportunistic (CPUD 2000), feeding on the blood and fluids of
various fish and marine mammals (Scott and Crossman 1973). To do so, they attach their
suctorial disc and disc teeth into the side or belly of the prey and then rasp through the scales or
skin with a toothed tongue (Scott and Crossman 1973). An anticoagulating agent that lamprey
produce while feeding keeps the blood and fluids of the prey flowing. Respiration for the
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lamprey again returns to a bidirectional effort across the gills to collect oxygen (Scott and
Crossman 1973).
While lamprey are not associated with a specific host, Beamish (1980) reported that walleye
pollock (Theragra chalcogramma) were the most common prey observed during his
investigations. When considering Pacific salmon runs, Scott and Crossman (1973) reported that
sockeye salmon (Oncorhynchus nerka) were more affected than pinks (O. gorbuscha). In the
Adams River, a tributary of the Fraser River, lamprey were thought to have killed 1.8% of a
sockeye salmon run either directly or indirectly, presumably because of the species’ reduced
fitness prior to their migration (Scott and Crossman 1973 and citations therein). While steelhead
returning to Hells Canyon Dam and spring chinook salmon returning to Rapid River (P. Abbott,
IPC, personal communication) have shown evidence of predation by lamprey, no clear estimates
exist of lamprey’s influence on those fishes’ spawning success. Potential for increased predation
on smolting salmon by juvenile lamprey is largely unknown. Although salmon stocks in the
Columbia River Basin arose concurrently with the presence of lamprey, lamprey are currently
not considered a significant source of predation on Pacific salmon (NMFS 2000).
Predation on various life stages of lamprey from fish, birds, and marine mammals is not
uncommon (Table 1). Juvenile and larval lamprey in the Snake River are preyed on by northern
pikeminnow (Ptychocheilus oregonensis) and channel catfish (Ictalurus punctatus) (Poe et al.
1991). Researchers have also found that wild salmon fry prey on lamprey eggs and larvae and
that hatchery salmon fry grow well when lamprey is added to their diet (Close et al. 1995 and
citations therein). When considering predation by marine mammals, Close et al. (1995)
suggested that adult lamprey’s behavior and caloric content may make them a more attractive
target than salmonids, thus reducing predation on the salmon. Investigations into the dietary
makeup of both seals and sea lions revealed that lamprey are the most common prey item
captured (Close et al. 1995 and citations therein). Likewise, an abundance of migrating larval
and juvenile lamprey may reduce predation on juvenile migrating salmon by predatory fishes and
birds (Close et al. 1995). This reduced predation is probably due to the slow numerical response
in predators exploiting a migrating population.
Humans have also historically preyed on lamprey. Native Americans harvested lamprey for
consumption or trade and either roasted or dried the meat before eating it. Fishermen in the
Snake, Columbia, and Fraser rivers commonly use lamprey as bait for white sturgeon.
Commercial harvest of lamprey for medicinal anticoagulants, teaching specimens, and food
continues today (Close et al. 1995). In 2001, the state of Oregon permitted commercial and
personal-use harvest of the lamprey population in the Willamette River but restricted commercial
harvest to 14,400 pounds (ODFW 2001).
4. CURRENT POPULATION STATUS
Collecting accurate lamprey numbers at lower Columbia and Snake River hydroelectric
projects has proven to be problematic for a number of reasons. In the past, fish-counting
techniques relied on personnel counting for 8 hours near the beginning and end of the salmon
runs and for 16 hours during peak periods (Close et al. 1995). Given that adult lamprey appear to
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Chapter 4: Pacific Lamprey Downstream of the HCC
be most active at night (Close et al. 1995, Moursund et al. 2000), counters probably
underestimated actual numbers. Under current fish-counting techniques, fish are counted for
24 hours or recorded by video during migration for later analysis (CPUD 2000). Still, counting
stations are designed for salmon enumeration (Close 2000), and lamprey can pass fish-counting
windows at hydroelectric projects undetected (Jackson et al. 1996). At Bonneville Dam, for
example, lamprey can move along the bottom of the counter undetected, skirt the counter by
passing behind the picketed leads at the crowder, or avoid detection by other means (Jackson
et al. 1996 and citations therein). Inconsistent data on adult lamprey passage have been collected
at all eight dams on the lower mainstem Columbia and Snake rivers, preventing direct
comparisons among run years (Jackson et al. 1996). Finally, Close (2000) determined that
lamprey display a high degree of fallback at the dams, particularly Bonneville Dam. Based on
data collected at the Washington shore-count station, for every Pacific lamprey observation, only
3% will result in a net upstream count (Close 2000).
Data collection on downstream juvenile migrations have also been subject to similar
problems. Most information found on juvenile numbers comes either from collection operations
for salmon smolts or from directed study (for example, electroshocking for ammocoetes or using
fyke nets) to assess current numbers.
Juvenile lamprey are commonly captured in downstream salmon smolt collection facilities,
indicating that the intake bypass screens probably intercept them. Because of their demersal
nature, a more significant number are routed through the turbines (Moursund et al. 2000). Recent
studies indicate that juveniles contacting fixed bar screens have a high probability of
impingement when velocities exceed 1.5 ft/s at the screen (Moursund et al. 2000). Moursund
et al. (2000) also investigated the role that turbine shear forces may have on downstream juvenile
lamprey survival and determined that these forces have little consequence to the juveniles.
Comparisons presented in Close (2000) between adult passage estimates collected in the
early 1960s with 1997 U.S. Army Corps of Engineer (COE) counts are presented in Table 2.
While data should be treated as conservative, trends clearly show significant reductions in 1997
counts. A closer look at the 1997 counts in Table 2 reveals that over 1,000 adults “disappeared”
at Lower Monumental and Little Goose dams and then reappeared at Lower Granite Dam, a
phenomenon that indicates the difficulty in counting and reporting at various projects. This last
factor is also true for Pacific salmon, but it is probably more common for lamprey.
Adult and juvenile passage data for Columbia River dams and the Ice Harbor Dam from
CPUD (2000)—which in turn used data from Close et al. (1995), Jackson et al. (1996, 1997),
Chelan Public Utility District (PUD), Douglas PUD, and the COE—are presented in Figures 3
through 7. For undetermined reasons, adult counts for all the projects appear to fall most sharply
in the late 1960s. At face value, juvenile counts appear to display infrequent but highly
successful recruitment. However, counting uncertainties make this assumption questionable.
Data inconsistencies prevent the formulation of any stock recruitment relationships over time.
Information that Martinson et al. (2000) presented includes collection data for downstream
migrating lamprey juveniles at John Day and Bonneville dams between 1985 and 1999.
However, we can only extrapolate trend data for their overall abundance among years at the
project because juvenile sampling is a by-product of salmon smolt collection efforts at mainstem
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dams and lamprey behave differently than salmon do. Regarding collections at John Day Dam,
Figure 8 illustrates a transition in sampling methodology between 1997 and 1998, switching
from “single gatewell” to “full bypass” sampling for downstream juvenile salmon. Changes in
collection design, while certainly more efficient (as shown on the second y-axis scale), make
comparisons with results for prior years difficult. Collections of macropthalmia at Bonneville
Dam between 1988 and 1999 show the continuing, widespread problem of highly variable counts
(Figure 9). We don’t know whether entrainment rates through turbines or spill varies among
projects (indicating that lamprey bypass the counters) or whether current counting techniques
reflect what is occurring biologically with lamprey.
5. SUMMARY AND CONCLUSIONS
Because Pacific lamprey are a parasitic fish and held little value as a sport or commercial
species to early Anglo-European settlers in the Northwest, these fish have either been
ecologically ignored or deliberately eradicated. This lack of concern has resulted in a limited
body of knowledge concerning Pacific lamprey’s ecology, life history, and historic and present
distribution or status. However, the small amount of reference materials and data that do exist
indicate the following:
1.
Of the various species of lamprey established within the Northwest, only the Pacific
lamprey (Lampetra tridentata) is found within the Snake River Basin.
2.
Historical distribution of Pacific lamprey throughout the Northwest was similar to
that of Pacific salmon. Specifically, within the Snake River Basin, these fish were
observed at least as far upstream as Lower Salmon Falls. Hells Canyon Dam is
currently the upstream terminus of migration within the Snake River.
3.
Pacific lamprey tend to migrate upstream from late spring through late fall,
overwinter, and then spawn in tributary streams during the following spring. Water
temperatures during spawning are generally increasing from about 10 to 15 °C.
This process is similar to what has been observed for steelhead.
4.
Physical habitat where spawning has been observed consists of fines and gravel
substrate, at depths up to 4.0 m with water velocities from 0.5 to 1.0 m/s. Pool
tailouts, riffles, and glides have all been identified as spawning areas; these habitats
are similar to steelhead habitat.
5.
Given their life history, Pacific lamprey probably used the mainstem Snake River
primarily as a migration corridor (as do steelhead, spring/summer chinook, and
sockeye salmon). There is no evidence that Pacific lamprey used or use the mainstem
Snake River for spawning or rearing.
6.
Pacific lampreys are poor swimmers; adults have difficulty successfully migrating
upstream through fish passage facilities associated with dams. Fallback rates are very
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Chapter 4: Pacific Lamprey Downstream of the HCC
high (up to 50%). Access to suitable habitat apparently has a greater effect on
regional distribution of the species than distance from the ocean.
7.
Ammocoetes spend 4 to 6 years burrowing into fine stream sediments and filter
feeding on algae, diatoms, and detritus. These juveniles seem to prefer cooler water
(16.0 to 21.8 °C) but have been collected when water temperatures were as high as
25 °C.
8.
Juvenile lamprey migrate downstream after completing metamorphosis, or during its
final stages, in late fall through spring. Little information exists on the time they
spend in the estuary before they enter the ocean; however, it is at this time that
lamprey become parasitic feeders.
9.
While parasitic, Pacific lamprey are not associated with a specific host. And though
lamprey and salmon arose concurrently within the Columbia River Basin, lampreys
are not considered significant predators on Pacific salmon.
10.
Passage and spawning data, used for assessing trends in population status, are
virtually nonexistent for Pacific lamprey. Neither adult nor juvenile passage data have
historically been collected specifically for Pacific lamprey. When these data were
collected, methods and resulting data have been inconsistent.
11.
Spawning surveys and juvenile density estimates have only recently been attempted
and only on a limited basis. The current baseline will be useful in the future; however,
data concerning the status and distribution of these fish within the Snake River Basin
are significantly lacking.
6. ACKNOWLEDGMENTS
This chapter would not have been possible without the assistance of Phil Bates. It is my
opinion that Pacific lamprey are the ignored “red-headed stepchild” of the Pacific Northwest and
do not receive the attention they deserve. These are a truly remarkable fish, cute and cuddly, that
continue to survive within a modified hydroelectric system against significant odds. Hooray for
lamprey!
7. LITERATURE CITED
Bayer, J. M., T. C. Robinson, and J. G. Seelye. 2001. Upstream migration of Pacific lampreys in
the John Day River: Behavior, timing and habitat use. 2000 Annual Report to the
Bonneville Power Administration, Contract 00AI26080, Project 2000–052, Portland, OR.
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Beamish, R. J. 1980. Adult biology of the river lamprey (Lampetra ayresi) and the Pacific
lamprey (Lampetra tridentata) from the Pacific coast of Canada. Canadian Journal of
Fisheries and Aquatic Sciences 37:1906–1923.
Beamish, R. J., and C. D. Levings. 1991. Abundance and freshwater migrations of the
anadromous parasitic lamprey, Lampetra tridentata, in a tributary of the Fraser River,
British Columbia. Canadian Journal of Fisheries and Aquatic Sciences 48:1250–1263.
Bell, R. J. 1957. Timing of runs of anadromous species of fish and resident fishery studies in the
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Idaho Department of Fish and Game, Boise, ID.
Bell, R. J. 1959. Time, size, and estimated numbers of seaward migrations of chinook salmon
and steelhead trout in the Brownlee–Oxbow section of the middle Snake River. Idaho
Department of Fish and Game. Vol. 6, Article 67, 33 p.
CPUD (Chelan County Public Utility District). 2000. A status of Pacific lamprey in the
mid-Columbia region. Rocky Reach Hydroelectric Project No. 2145. Chelan County
Public Utility District, Wenatchee, WA.
Close, D. A. 2001. Pacific lamprey research and restoration project. 1999 Annual Report to the
U.S. Department of Energy, Bonneville Power Administration, Contract 95BI39067,
Project 94-026, Portland, OR.
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Project 94-026, Portland, OR.
Close, D. A., and J. P. Bronson. 2001. Chapter 2: Distribution of larval Pacific lampreys
(Lampetra tridentata) in northeastern Oregon and southeastern Washington streams.
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1999 Annual Report to the Bonneville Power Administration, Contract 95BI39067,
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Jackson, A. D., D. R. Hatch, B. L. Parker, D. A. Close, M. S. Fitzpatrick, and H. Li. 1997.
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Portland, OR.
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Lampetra in Oregon. Ph.D. Thesis. Oregon State University, Corvallis, OR.
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Moscow, ID.
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Table 1.
Chapter 4: Pacific Lamprey Downstream of the HCC
A list of known predators of Pacific lamprey (from Close et al. 1995).
Common Name
Scientific Name
Life Stage Eaten
White sturgeon
Acipenser transmontanus
All life stages
Channel catfish
Ictalurus punctatus
Eggs and larvae
Minnows
Cyprinidae
Eggs and larvae
Logperch
Percina spp.
Eggs and larvae
Rainbow trout
Oncorhynchus mykiss
Eggs and larvae
Forster’s tern
Sterna fosteri
Ammocoetes
Western gull
Larus occidentalis
Ammocoetes
California gull
Larus californicus
Ammocoetes
Ringbill gull
Larus delawarensis
Ammocoetes
Northern pikeminnow
Ptychocheilus oregonensis
Juveniles
Sculpins
Cottus spp.
Juveniles
Sable fish
Anoplopoma fimbria
Adults
Spiny dogfish
Squalus scanthias
Adults
Sperm whale
Physeter catodon
Adults
Harbor seal
Phoca vitulina
Adults
California seal lion
Zalophus californianus
Adults
Steller sea lion
Eumetopias jubatus
Adults
Great blue heron
Ardea herodias
Adults
Table 2.
Counts of migrating adult Pacific lamprey, comparing former counts with
1997 counts at Columbia and Snake River projects (from Close 2000).
Dam
Former Counts
Bonneville
350,000 in early 1960s
22,830
The Dalles
300,000 in early 1960s
14,835
John Day
No data
14,845
McNary
25,000 in early 1960s
4,213
Ice Harbor
50,000 in early 1960s
1,454
Lower Monumental
No data
217
Little Goose
No data
245
Lower Granite
No data
1,274
Rock Island
No data
2,321
Rocky Reach
17,500 twice in 1960s
1,405
Wells
No data
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1997 Counts
773
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Chapter 4: Pacific Lamprey Downstream of the HCC
Figure 1.
Juvenile Pacific lamprey downstream migration timing from the Smolt
Monitoring Program. The single value off the vertical scale is the passage
of 60,000 lamprey through McNary Dam on May 29 (Figure 3 from
Moursund et al. 2000).
Figure 2.
1999 season juvenile lamprey collection at John Day Dam, showing
migration peaks and their relationship to discharge (Figure A-2 from
Martinson et al. 2000).
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Figure 3.
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Adult and juvenile lamprey counts at Bonneville Dam (from CPUD 2000).
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Figure 4.
Chapter 4: Pacific Lamprey Downstream of the HCC
Adult lamprey counts at The Dalles Dam (from CPUD 2000).
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Figure 5.
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Adult and juvenile lamprey counts at John Day Dam (from CPUD 2000).
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Figure 6.
Chapter 4: Pacific Lamprey Downstream of the HCC
Adult and juvenile lamprey counts at McNary Dam (from CPUD 2000).
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Figure 7.
Adult lamprey counts at Ice Harbor Dam (from CPUD 2000).
Figure 8.
Historical juvenile lamprey counts at John Day Dam, 1985−1999. Heavy
line between years 97 and 98 indicates switch from “single gatewell” to “full
bypass” sampling and the corresponding y-axis scale change (Figure C-7
from Martinson et al. 2000).
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Figure 9.
Chapter 4: Pacific Lamprey Downstream of the HCC
Historical juvenile lamprey counts at Bonneville Dam, 1988−1999.
(Figure D-7 from Martinson et al. 2000).
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