Pacific Lamprey Research Articles

Occupancy and Detection of Larval Pacific Lampreys and Lampetra spp. in a Large River: the Lower Willamette River

AbstractPacific lampreys Entosphenus tridentatus (formerly Lampetra tridentata) are declining in the Columbia River basin, and the use of large, main‐stem river habitats by larvae of this species is unknown. We used a deepwater electrofisher to explore occupancy, detection, and habitat use of larval Pacific lampreys and larval Lampetra spp. in the lower Willamette River, Oregon. We used a generalized random tessellation stratified approach to select sampling quadrats (30 × 30 m) in a random, spatially balanced order. Pacific lampreys, Lampetra spp., and unidentified lampreys were found in the Willamette River; larvae were detected in all areas except the Multnomah Channel. We calculated reach‐ and quadrat‐specific detection probabilities and the amount of sampling effort required for 80% confidence that larval lampreys were in fact absent when they were not detected. Lampreys were detected in a variety of areas (although relatively low numbers were collected), including shallow, nearshore areas; midchannel areas (depth up to 16 m); and anthropogenically affected areas. Detection probabilities (i.e., in occupied areas) were 0.07 (reach) and 0.23 (quadrat). The sampling effort required for 80% confidence that lampreys were absent when undetected was 20 quadrats (in the lower Willamette River reach) and 6 subquadrats (within a quadrat). Differences in lamprey detection by depth were not observed. A variety of sizes was collected (20–144 mm total length), indicating the likely occurrence of multiple ages of larvae. Our study identifies how the occurrence of larval Pacific lampreys can be quantified with statistical rigor in a large river (i.e., larger than fourth order [1:100,000 scale]). The effect of channel management activities on larval lampreys should be considered in efforts to conserve these important species.

Identification of putative migratory pheromones from Pacific lamprey (Lampetra tridentata)

Pacific lamprey, Lampetra tridentata , has declined precipitously throughout their range in the Columbia River basin of North America. Tribal Nations and Federal and State agencies are engaged in efforts to restore these fish. Understanding whether Pacific lamprey emit and detect migratory pheromones is particularly important for these restoration efforts. Using behavioural assays, we demonstrated that migratory adult Pacific lamprey are attracted to odors emanating from their larval conspecifics. We then identified putative pheromones released by larval Pacific lamprey. Chemical analysis of the conditioned water from larval lamprey using liquid chromatography – mass spectrometry (LC–MS) revealed that the Pacific lamprey can release petromyzonamine disulfate (PADS), petromyzosterol disulfate (PSDS), and petromyzonol sulfate (PZS). Electro-olfactogram studies further demonstrated that adult Pacific lamprey can smell those bile acid compounds. Our data strongly indicate that the Pacific lamprey employ a chemical communication system mediated by a mixture of bile acids, as evidenced by pheromonal functions of the bile acid compounds in guiding migratory adult sea lamprey to the spawning streams. Comprehensive understanding of the chemical communications involved in lamprey migratory behavior may lead to improved scientific approaches for restoration efforts.

Surgical wound healing in radio-tagged adult Pacific lamprey Entosphenus tridentatus held on different substrata

Radio-tagged adult Pacific lamprey Entosphenus tridentatus held in a raceway with Plexiglas-lined walls and bottom healed more slowly and retained sutures longer than fish held in an all-concrete raceway or one with Plexiglas walls and a cobble-lined bottom. On all substrata, healing depended on when sutures were lost, and fish that lost their sutures in <14 days post-surgery healed faster than those that kept sutures longer. Long-term suture retention led to tissue trauma, infection and poor survival.

Effect of the western pearlshell mussel Margaritifera falcata on Pacific lamprey Lampetra tridentata and ecosystem processes

Suspension feeders concentrate organic material from the water column and enhance deposition to the surrounding benthos. On the South Fork of the Eel River (Mendocino, California) two suspension feeders, the freshwater mussel Margaritifera falcata and Pacific lamprey larvae Lampetra tridentata, co‐occur in areas with low flow velocities and boundary sheer stresses. We investigated mussel/lamprey larvae interactions, and their impacts on nutrient and organic matter cycling, in flow‐through enclosures placed where lamprey larvae and mussels naturally occurred. Over the 80‐day study, lamprey larvae grew faster in the presence of mussels and in food addition treatments. Our results suggest that lamprey larvae benefit from native mussels, and that lamprey populations and organic matter retention in rivers may decrease with the rapid decline of native freshwater mussels.

Numerical analysis of a unique mode of locomotion: vertical climbing by Pacific lamprey

Pacific lampreys are capable of climbing vertical wetted surfaces through a two-phase (bending and stretching) locomotion mode using the oral disc for adherence. We investigate the physical mechanism and performance of this process by using a continuous beam model. Two mechanisms, one akin to the jumping process and the other related to the fast stretching of the body, have been identified. This locomotion mode may inspire biomimetic designs of anguilliform swimming devices capable of overcoming steep obstacles. By using a genetic algorithm simulation we identify the combination of kinematic parameters corresponding to optimal efficiency (defined as the gravitational potential energy gained in each climbing step divided by the energy spent to activate the motion). These parameters are similar to laboratory observations of lamprey motion, suggesting that this type of locomotion has been optimized for maximum efficiency through evolution.

Short Communication Characterization of 12 microsatellite loci for the Pacific lamprey, Entosphenus tridentatus (Petromyzontidae), and cross-amplification in five other lamprey species

The Pacific lamprey (Entosphenus tridentatus) is an anadromous fish that is of conservation concern in North America and Asia. Data on Pacific lamprey population structure are scarce and conflicting, impeding conservation efforts. We optimized 12 polymorphic microsatellite loci for the Pacific lamprey. Three to 13 alleles per locus were observed in a sample of 51 fish collected from the West Fork Illinois River, Oregon. Observed heterozygosity ranged from 0.235 to 0.902 and expected heterozygosity ranged from 0.214 to 0.750. Cross-species amplification produced 8 to 12 polymorphic loci in four other Entosphenus species and in the western brook lamprey (Lampetra richardsoni). Two loci appear to be diagnostic for distinguishing Entosphenus from Lampetra. These markers will be valuable for evaluating population structure and making conservation decisions for E. tridentatus and other lamprey species.

Similarities, Differences, and Unknowns in Biology and Management of Three Parasitic Lampreys of North America

AbstractSea lampreys, Petromyzon marinus, are invasive to the Laurentian Great Lakes where they have decimated native fishes. Great Lakes sea lampreys have been subjected to control measures for several decades, and the drive to control them has led to major advances in understanding their biology and in informing management. In contrast, anadromous sea and Pacific (Entosphenus tridentatus) lampreys have co‐evolved with their oceanic prey. Both of these anadromous lampreys are in decline, and a limited amount of information on their biology has stymied conservation. The tendency has been to make biological inferences about anadromous lampreys based on the Great Lakes sea lamprey without justifiable evidence. We identify areas in which key information is missing for the juvenile (parasitic feeding) phase and adult freshwater spawning migrations, and compare and contrast information for these lampreys. Our comparisons reveal major differences, some intriguing similarities, and key unknowns that will require empirical testing.

Development of Pacific lamprey fishways at a hydropower dam

Abstract Traditional fishways do not accommodate the passage needs of all migrating species. In the north-western United States, structures designed to aid adult Pacific lamprey, Lampetra tridentata (Gairdner), passage are critically needed. The structures described here were fabricated in modular units and installed at Bonneville Dam on the Columbia River (235 km). They featured a series of aluminium ramps interspersed with rest boxes that prevented lamprey from moving back downstream. The effects of various design changes and structure operation (water volume delivered) were assessed using lamprey counts and passive integrated transponder detections. Up to 40% of the lamprey entered the structures and 90–100% of these passed through to the exit. Lowering water volume pumped to the structures had little effect on lamprey performance, but passage improved when a 3.8-m-long, steep (40°) ramp was replaced with two, 1.4-m-long, 45° ramps. Pacific lamprey ascended the 8- to 9-m-high structures and entered the dam forebay in less than 1 h. The success of these prototypes was attributed to site selection and attention to lamprey-specific performance.

Behaviour of adult Pacific lamprey in near-field flow and fishway design experiments

Abstract An experimental fishway was used to examine adult Pacific lamprey, Lampetra tridentata (Gairdner), behaviour in a series of attraction and passage-performance tests. Among all experiments, lamprey oriented to the fishway floor and walls and were attracted to both ambient and concentrated flow. When confronted with high-velocity areas (vertical-slot and submerged-orifice weirs), many lamprey failed to pass upstream. However, lamprey were able to find and take advantage of low-velocity refuges when they were provided. Lamprey climbed shallow- and steep-angled ramps when attraction cues were sufficient and other passage routes were restricted. The combined results demonstrated the passage challenges that fishways designed and operated for salmonids present to non-salmonid species. They also highlight the importance of evaluating trade-offs between fishway attraction and passage efficiency. The experiments were integrated with tagging studies and development of lamprey-specific passage structures, a research combination that provided an effective template for fishway performance evaluations.

Traumatization of Kamchatka River Pacific salmon by lampreys

Salmon that enter the Kamchatka River are intensively traumatized by lamprey (from 12.0 to 74.0% in different years). An analysis of the frequency distribution of oral disk marks on salmon revealed two types of marks: (1) small (diameter 2.2 cm, of roundish form, located in the front in the lower third of body). The small marks (type I) are mainly left by the Kamchatka lamprey Lethenteron camtschaticum. The second type of trauma is inflicted by large individuals of the Pacific lamprey Enthosphenus tridentatus in the 2nd and 3rd year of marine life. The most typical traumatic injuries caused by lamprey to salmon are described. Injury data are provided for six species of salmon, namely, sockeye, pink, chum, coho, chinook, and char.

Passage and Behavior of Radio-Tagged Adult Pacific Lampreys (Entosphenus tridentatus) at the Willamette Falls Project, Oregon

Abstract Populations of Pacific lamprey (Entosphenus tridentatus) in the Columbia River basin have declined and passage problems at dams are a contributing factor. We used radio telemetry to monitor the passage of adult Pacific lampreys at the Willamette Falls Project (a hydroelectric dam integrated into a natural falls) on the Willamette River near Portland, Oregon. In 2005 and 2006, fish were captured at the Project, implanted with a radio tag, and released downstream. We tagged 136 lampreys in 2005 and 107 in 2006. Over 90% of the fish returned to the Project in 7 – 9 h and most were detected from 2000 – 2300 h. In 2005, 43 fish (34%) passed the dam via the fishway, with peak passage in August. No fish passed over the falls, but 13% ascended at least partway up the falls. In 2006, 24 fish (23%) passed the Project using the fishway, with most prior to 9 June when the powerhouse was off. Although 19 lampreys ascended the falls, only two passed via this route. The time for fish to pass through the fishway...

Records of Entosphenus tridentatus from the Naka River system, central Japan; physical characteristics of possible spawning redds and spawning behavior in the aquarium

Records of Entosphenus tridentatus from the Naka River system, central Japan; physical characteristics of possible spawning redds and spawning behavior in the aquarium

Swimming Performance of Larval Pacific Lamprey (Lampetra tridentata)

Abstract Laboratory experiments were conducted to measure the prolonged-sustained and burst swimming speeds of wild larval (ammocoete) Pacific lamprey (Lampetra tridentate). Prolonged-sustained speeds were measured using an annular variable speed swimming chamber and burst speeds were determined using a swimming raceway and digital video analysis. During prolonged-sustained swimming experiments, the mean length of time lamprey (72 – 143 mm TL) were able to swim in the chamber ranged from 43.0 min when exposed to a velocity of 10 cm/s, to 0.4 min when exposed to 50 cm/s. The burst swimming speeds of lamprey tended to increase as length increased from 107 to 150 mm TL, and ranged from 33.3 to 75.0 cm/s. Our estimates of the overall swimming performance of this life-stage are the first reported for this species, and can provide important information when developing approach velocities and infrastructure to improve lamprey passage while minimizing entrainment loss.

Testing Adult Pacific Lamprey Performance at Structural Challenges in Fishways

AbstractAdult Pacific lampreys Lampetra tridentata migrate through areas of difficult passage and high water velocity by attaching their oral discs to substrate and then releasing and bursting upstream. In fishways at dams, this burst‐and‐attach behavior can be ineffective, particularly where suitable attachment surfaces are unavailable. We used an experimental fishway to test performance of adult Pacific lampreys when confronted with a series of structural challenges. These included vertical steps near fishway weir orifices, squared versus rounded orifice entrances, and floor‐mounted metal grates. All experimental challenges simulated common existing structures in weir‐and‐orifice fishways at Columbia and Snake River dams. Most experiments were paired with field evaluations of radio‐tagged Pacific lampreys or video observations of untagged individuals in situ. Field and experimental results consistently indicated that the structural challenges reduced passage efficiency and lengthened passage times. Improving Pacific lamprey passage may be facilitated by removing or modifying vertical steps and other sharp‐edged corners and by providing adequate attachment surfaces. Such accommodations should be especially beneficial in areas with high water velocity. The findings demonstrate how fish morphology and behavior should be explicitly considered in the design or retrofitting of fish passage structures.

Characterization of ten microsatellite loci for western brook lamprey Lampetra richardsoni

We describe the isolation and development of ten polymorphic microsatellite loci for western brook lamprey (Lampetra richardsoni). Two to nine alleles were observed per locus in a sample of 35 fish. Gene diversity ranged from 0.000 to 0.792 in six populations. Cross-species amplification was successful as nine, seven and eight loci were polymorphic in Lampetra pacifica, Entosphenus hubbsi, and Entosphenus tridentatus, respectively. These markers will aid in evaluating the population structure of lamprey that are native to western North America.

Effects of Body Size and River Environment on the Upstream Migration of Adult Pacific Lampreys

AbstractDams in the Columbia River basin present significant obstacles to declining populations of anadromous Pacific lampreysLampetra tridentata. Mitigation efforts have focused on fine‐scale improvements in passage at individual dams, but there is an increasing need for basinwide estimates of survival and escapement. We developed a half‐duplex passive integrated transponder (PIT) tag monitoring array at five Columbia and Snake River dams to evaluate adult lamprey migrations. We tagged 3,598 lampreys over 3 years and calculated the rates of main‐stem escapement through 15 river reaches. From these data, we assessed the relative effects of lamprey size, river discharge, water temperature, and migration timing on upstream passage. The results indicated high attrition as lampreys progressed upstream. In each year, about one‐half of the fish passed one dam, 28–33% passed two dams, 17–19% passed three dams, 4–5% passed four dams, and about 1% passed the first dam on the Snake River (five dams and &gt;300 km upstream from their release sites). In most reaches, upstream passage was strongly size dependent, the largest lampreys being two to four times more likely to pass than the smallest fish. Lamprey size was more predictive of passage than were the river discharge, temperature, or migration timing variables. These findings suggest that adult Pacific lamprey migration is affected by physiological constraints and that effective mitigation for the difficult passage conditions at dams should include size‐related considerations.

Detection and Longevity of Uncured and Cured Visible Implant Elastomer Tags in Larval Pacific Lampreys

AbstractStudies of the biology, ecology, and status of the Pacific lamprey Lampetra tridentata may require effective means of tagging larval Pacific lampreys. However, few assessments of the methods suitable for tagging larval Pacific lampreys have been conducted. We evaluated the performance of visible implant elastomer (VIE) tags in larval Pacific lampreys, specifically testing the effects of elastomer treatment (uncured versus cured VIE) and inspection light source (ambient light versus blue light‐emitting diode [LED] flashlight) on tag detection in 40 larvae. Through day 251 after tagging, tag detection was 100% for both uncured and cured VIE tags observed under ambient light and blue LED light. Longevity of uncured VIE tags was assessed in a second cohort of 32 VIE‐tagged larval Pacific lampreys over a 2‐year captive rearing period. Percent VIE tag detection was 91% for red tags, 90% for orange tags, and 64% for green tags through day 699 after tagging. This study affirms that both uncured and cured VIE tags can be effectively used to tag larval Pacific lampreys. Tagging with uncured VIE is a convenient and economical alternative to cured VIE tagging, particularly when tagging over protracted periods or small sample sizes.

Annual sex steroid and other physiological profiles of Pacific lampreys ( Entosphenus tridentatus)

We documented changes in plasma levels of estradiol 17-β (E2), progesterone (P), 15α-hydroxytestosterone (15α-T), thyroxine (T4), triiodothyronine (T3), protein, triglycerides (TGs), and glucose in adult Pacific lampreys ( Entosphenus tridentatus) held in the laboratory in two different years. Levels of E2 in both sexes ranged from 0.5 to 2 ng/mL from September to March, peaked in late April (2–4 ng/mL), and decreased in May, with levels higher in males than in females. Levels of P were low from September through April, but then increased substantially during May (2–4 ng/mL), with levels again highest in males. Levels of 15α-T in males were around 0.75 ng/mL through the winter before exceeding 1 ng/mL in April and decreasing thereafter, whereas females showed a gradual increase from 0.25 ng/mL in November to 0.5 ng/mL in April before decreasing. Thyroxine concentrations differed between fish in each year, with most having levels ranging from 0.75 to 2.5 ng/mL in the fall and winter, and only fish in 2003 showing distinct peaks (3–4 ng/mL) in early April or May. Plasma T3 was undetectable from November through mid-March before surging dramatically in April (ca. 150 ng/mL) and decreasing thereafter. Levels of protein, TGs, and glucose decreased or were stable during the fall and winter with TGs and glucose surging in late April to early May for some fish. Our study is the first to document long-term physiological changes in Pacific lampreys during overwintering and sexual maturation and increases our understanding of the life history of this unique fish.

Do summer temperatures trigger spring maturation in Pacific lamprey, Entosphenus tridentatus?

Abstract – Pacific lamprey, Entosphenus tridentatus, return to streams and use somatic energy to fuel maturation. Body size decreases, the lamprey mature, spawn, and then die. We predicted that warm, summer temperatures (&gt;20 °C) would accentuate shrinkage in body size, and expedite sexual maturation and subsequent death. We compared fish reared in the laboratory at diel fluctuating temperatures of 20–24 °C (mean = 21.8 °C) with fish reared at cooler temperatures (13.6 °C). The results confirmed our predictions. Lamprey from the warm water group showed significantly greater proportional decreases in body weight following the summer temperature treatments than fish from the cool water group. A greater proportion of warm water fish sexually matured (100%) and died (97%) the following spring than cool water fish (53% sexually mature, 61% died). Females tended to mature and die earlier than males, most obviously in the warm water group.

Variability in migration timing of adult Pacific lamprey (Lampetra tridentata) in the Columbia River, U.S.A.

We examined the effects of river environment on the timing of spawning migrations by anadromous Pacific lamprey, Lampetra tridentata, in the Columbia River (U.S.A.). In a 41-year time series of adult lamprey counts, migration timing was earliest in warm, low-discharge years and latest in cold, high-flow years. Threshold temperatures associated with run timing were similar throughout the dataset despite significant impoundment-related warming, suggesting that temperature-dependent migration cues have been temporally stable. Within each year, migration rates of PIT-tagged lampreys were positively correlated with temperature and negatively correlated with discharge through multiple river reaches, offering additional evidence for environmental control of upstream movement. Both visual count and PIT-tag data indicated that there may be population-based differences in migration timing within the aggregate Columbia River lamprey run. These life history and behavioral results have potentially far-reaching implications for management of lamprey species.