Biology, Management, and Conservation of Lampreys in North America

<em>Abstract</em>.—There are 11 lamprey species in Canada: Vancouver lamprey <em>Entosphenus macrostomus</em> (formerly <em>Lampetra macrostoma</em>), Pacific lamprey <em>Entosphenus tridentatus</em> (formerly <em>Lampetra tridentata</em>), chestnut lamprey <em>Ichthyomyzon castaneus</em>, northern brook lamprey <em>Ichthyomyzon fossor</em>, silver lamprey <em>Ichthtyomyzon unicuspis</em>, river lamprey <em>Lampetra ayresii</em>, western brook lamprey <em>Lampetra richardsoni</em>, Alaskan brook lamprey <em>Lethenteron alaskense</em>, American brook lamprey <em>Lethenteron appendix</em> (formerly <em>Lampetra appendix</em>), Arctic lamprey <em>Lethenteron camtschaticum</em> (formerly <em>Lampetra camtschatica</em>), and sea lamprey <em>Petromyzon marinus</em>. <em>Entosphenus</em> and <em>Lethenteron</em> were previously synonymized with <em>Lampetra</em>, but Nelson (2006) recognized these as three distinct genera. Conservation status has been assessed in only five species and in two of these (western brook lamprey and chestnut lamprey), only for portions of their Canadian population. The 2007 Committee on the Status of Endangered Wildlife in Canada list indicates that the enigmatic population of western brook lamprey in Morrison Creek, British Columbia, is endangered; the Vancouver lamprey in British Columbia is threatened; the chestnut lamprey in Saskatchewan and Manitoba is special concern; the northern brook lamprey in Manitoba, Ontario, and Quebec is of special concern in the latter two provinces and data deficient in the former; and the Alaskan brook lamprey in the Northwest Territories is data deficient. The threats to the four species at risk were collectively related to habitat degradation and loss, sensitivity to a catastrophic event, and sensitivity to lampricide used to control the invasive sea lamprey in the Great Lakes basin. Despite much lamprey work being conducted in the past decade, there still remain a number of knowledge gaps. These gaps include unequivocal evidence as to whether parasitic and nonparasitic members of a paired species should be considered distinct species and information on the distribution and population sizes and trends of the native lamprey species.

Biology, Management, and Conservation of Lampreys in North America

<em>Abstract.</em>—Pacific lampreys <em>Entosphenus tridentatus </em>(formerly <em>Lampetra tridentata</em>) and western brook lampreys <em>L. richardsoni</em> are observed in many coastal Oregon basins; however, few data are available to adequately describe their distribution and spawning habitat associations. To document landscape-scale distribution and habitat use of spawning adult lampreys, we conducted biweekly redd surveys at 62 randomly selected sites in Smith River (Umpqua basin, Oregon). Characteristics of lamprey habitat were measured at the redd, habitat unit, and reach scales to quantify available and occupied habitat. Pacific lampreys were found primarily in wider, low-elevation streams, whereas western brook lampreys were more widespread but concentrated in headwater and low-order streams. At the unit scale, unit type and dominant substrate were weakly correlated to presence of spawning lampreys. Both species spawned in gravel rich habitats, predominantly pool tail-outs and low gradient riffles. This study infers habitat associations and broad-scale distribution within a coastal basin to assist in the design of monitoring strategies and population assessments at a regional scale.

Biology, Management, and Conservation of Lampreys in North America

<em>Abstract</em>.—Reported predators of lamprey include a variety of fishes, amphibians, reptiles, birds, and mammals, and predation on lamprey is known in both marine and freshwater habitats. Although lampreys are not typically prominent in the reported diets of predators, it does not follow that predation is not an important source of lamprey mortality. Concentrations of migrating and spawning lampreys may be especially vulnerable. Assemblages of predators on lampreys have changed through human activities such as stocking and harvest of fishes. In southeastern Minnesota, for example, most of the 1,145 km in 139 streams that currently are managed for trout now support brown trout <em>Salmo trutta</em>, an exotic species that has been reported to prey on several species of lamprey. Prior to its establishment, relatively few fish in these streams would have been capable of feeding on large ammocoetes or adult lampreys.

Biology, Management, and Conservation of Lampreys in North America

<em>Abstract</em>.—The systematics of lampreys was investigated using complete mitochondrial cytochrome <em>b</em> sequences from all genera and nearly all recognized species. The families Geotriidae and Petromyzontidae are monophyletic, but the family Mordaciidae was resolved as two divergent lineages at the base of the tree. Within Petromyzontidae, the nonparasitic <em>Lethenteron</em> sp. S and <em>Okkelbergia aepyptera</em> were recognized as distinct lineages, <em>Lethenteron morii</em> and <em>Lampetra zanandreai</em> were moved to new genera, a sister species relationship was recovered between <em>Caspiomyzon wagneri </em>and <em>Eudontomyzon hellenicus</em>, and a clade was recovered inclusive of <em>Entosphenus hubbsi</em> and western North American <em>Lampetra </em>(<em>L. ayresii </em>and <em>L. richardsoni</em>). The placement of <em>E. hellenicus</em> as the sister species to <em>C. wagneri </em>reduces the number of genera comprised entirely of parasitic species to two, <em>Geotria</em> and <em>Petromyzon</em>. The recognition of distinct lineages for <em>O. aepyptera</em> and <em>Lethenteron</em> sp. S recognizes, for the first time, lineages comprised entirely of nonparasitic species. Apart from the results mentioned above, monophyly was supported for the multispecific genera <em>Entosphenus</em>, <em>Eudontomyzon</em>, <em>Ichthyomyzon</em>, <em>Lampetra</em> (restricted to European species), and <em>Lethenteron</em>. Intergeneric relationships within Petromyzontidae were poorly resolved, but separate clades inclusive of <em>Entosphenus</em> and <em>Tetrapleurodon</em> (subfamily Entospheninae) and one comprised of <em>Eudontomyzon</em>, <em>Lampetra</em>, and <em>Okkelbergia</em> were recovered.

Biology, Management, and Conservation of Lampreys in North America

<em>Abstract</em>.—Lampreys are among the least studied group of fishes in California. At least seven species inhabit freshwater habitats within the state, including the Kern brook lamprey <em>Lampetra hubbsi</em>, a California endemic. Four species are micropredators on fish, Pacific lamprey <em>Entosphenus tridentatus</em> (formerly <em>L. tridentata</em>), river lamprey <em>L. ayresii</em>, Klamath lamprey <em>E. similis</em> (formerly <em>L. similis</em>) and Goose Lake lamprey <em>Entosphenus</em> sp. The remaining three species are nonfeeding as adults and are presumed to have many populations isolated from one another. Pacific lamprey and river lamprey are anadromous and may have increased diversity through multiple runs. A systematic analysis of the limited information available indicates that, with the possible exception of the Pit-Klamath brook lamprey <em>E. lethophagus</em> (formerly <em>L. lethophaga</em>), all species are either declining, in low numbers, or in isolated populations. Causes of the declines are multiple and species-specific, but in general, alteration of watersheds by humans, resulting in increased siltation, temperatures and pollution, as well as other habitat changes are the principal causes. Protecting lampreys has the benefit of protecting stream ecosystems throughout the state because of the wide historic presence of lampreys and because ammocoetes require clean, cool water and relatively complex habitat, including stable backwaters.

Biology, Management, and Conservation of Lampreys in North America

<em>Abstract</em>.—In-season homing of Pacific lampreys <em>Lampetra tridentata </em>was investigated using radiotelemetry in the lower Columbia River from 1998 through 1999. A total of 50 Pacific lampreys were captured: 25 at Willamette Falls (river kilometer [rkm] 45 on the Willamette River, a tributary to the Columbia River, with its confluence at rkm 163) and 25 at Bonneville Dam (rkm 238 on the Columbia River). Each fish was fitted with a radio transmitter, transported, and released in the Columbia River approximately 26 km downstream from the confluence of the Willamette River. Movement of the radio-tagged Pacific lampreys was monitored for several months using mobile and fixed receiver stations to observe rates of homing towards the site of original capture. Results indicated that the lampreys exhibited nonsignificant in-season homing fidelity (<em>p</em> = 0.622) based on the null expectation that one-half of the total recoveries would home and the other half would stray. Final location classifications were 17 homed, 20 strayed, and 13 undetermined. The undetermined classification included individuals that were not detected upstream of the confluence of the Willamette River or in other Columbia River tributaries. Final location classifications were not influenced by fish length (<em>p</em> = 0.594). Although considered weak swimmers, Pacific lampreys were capable of traveling at velocities near 2.5 km/h and sustaining that activity for at least 24 h.

Biology, Management, and Conservation of Lampreys in North America

<em>Abstract</em>.—Low-head barriers against invasive sea lampreys <em>Petromyzon marinus</em> in the Great Lakes are designed to maintain a minimum crest height of 30 cm and have a lip on the crest to prevent them from climbing over the barrier. We tested the ability of migratory-phase sea lampreys to scale inclined ramps with shallow (0.7–5 cm) water depth. We predicted that sea lampreys would jump the barrier and that their ability to attach would increase passage success. A recirculating flume and ramp with a vertical height of 10–30 cm and an inclination between 308 and 608 were used to evaluate lamprey climbing ability. Lampreys trying to scale the ramp were monitored by passive integrated transponder tag readers and low-light video cameras. No lampreys were observed jumping out of the water to scale a barrier. Independent of ramp angle, no fish passed over a 30-cm ramp. Lampreys often attached themselves to the ramp, but without a gain of vertical height between repeated attempts. The success rate at lower ramp heights varied between 0% (15 cm height, 308 angle) and 63% (10 cm height, 608 angle). Only ramps shorter than half the body length of the lampreys could be surmounted. Apparently, the lampreys had to have their dorso-ventral fins fully submerged in the downstream pool to create enough propulsion to scale a ramp in burst-swimming mode. An analysis of 1,300 passage attempts in a field-validation experiment showed a greater apparent motivation to move up a ramp but reconfirmed our laboratory findings on passage technique and maximum performance. We conclude that sea lamprey barrier height could be further reduced and that an overhanging lip is not necessary as sea lampreys neither climb nor jump over barriers. A ramp with a shallow inclination and moderate vertical height and water flow is a new design suggestion for a barrier that blocks sea lampreys and may allow other fish species to pass.

Biology, Management, and Conservation of Lampreys in North America

<em>Abstract</em>.—Both juvenile and adult anadromous lampreys encounter a variety of obstacles to passage during migration. Hydropower dams can delay or obstruct adults, and turbine entrainment or screen impingement can injure or kill juveniles. Lampreys also face less dramatic obstacles such as culverts, irrigation diversion dams and screens, weirs, and other low-elevation structures. The extent to which most structures affect juvenile and adult movements is not known. However, recent research on lamprey swimming performance and migration behavior has provided new insight into the physical and performance factors that may limit lamprey movements. We drew from both field and laboratory studies to review lamprey swimming performance and migration behavior and the effects of water velocity, attachment sites, light, and temperature on lamprey movements. Based on this review, we identified the following as primary research needs for all lamprey life stages: determination of cues lampreys use to orient during migration, documentation of lamprey endurance limits, and evaluation of energy expenditure during migration and its effects on lamprey fitness.

Biology, Management, and Conservation of Lampreys in North America

<em>Abstract</em>.—This chapter summarizes reproduction and the latest findings on reproductive endocrinology in one of the only two living representatives of the most ancient lineage of vertebrates, agnathans. Modern vertebrates are classified into two major groups, the gnathostomes (jawed vertebrates) and the agnathans (jawless vertebrates). The agnathans are classified into two groups, myxinoids (hagfishes) and petromyzonids (lampreys), while the gnathostomes constitute all the other living vertebrates, including the bony and cartilaginous fishes and the tetrapods. During the past two decades, there have been rapid advances in our knowledge of the structure and function of reproductive hormones in lamprey. Lampreys are the earliest evolved vertebrates for which there are demonstrated functional roles for two (possibly three) gonadotropin-releasing hormones (GnRHs) that act via the hypothalamic-pituitary-gonadal axis controlling reproductive processes. From our structural and functional studies, we have determined the primary amino acid and cDNA sequences of two forms of GnRH, lamprey GnRH-I and -III, one GnRH receptor, and one gonadotropin-beta (GTH-b) hormone. Since 2006, with the availability of the lamprey genome, we have identified an additional GnRH isoform (lamprey GnRH-II) and two glycoprotein hormone receptors (one gonadotropic-like and one thyrotropic-like). The high conservation of these hormones and their receptors throughout vertebrate species makes the lamprey model highly appropriate for examining the neuroendocrine system. Here, we present a summary on our current knowledge of reproductive endocrinology in these basal vertebrates.