Pacific lamprey ammocoetes have no eyes, teeth, or swimming ability. After 4-7 years, they enter metamorphosis, or macropthalmia. In addition to developing eyes and teeth, their fins become more defined, and their heads and naso-pineal organs enlarge. ("Oregon Lampreys: Natural History, Status, and Analysis of Management Issues", 2002; Close, et al., 2002)
Pacific lampreys spend 3-7 years as larvae before entering macropthalmia, or metamorphosis, from July to November. During macropthalmia, Pacific lampreys grow into their free-swimming, parasitic adult form over the course of several months. Sometime between fall and spring, when macropthalmia has been completed, they begin their migration to the Pacific Ocean. Pacific lampreys spend 1-3 years in their marine life stage before returning to freshwater between February and June. They remain in freshwater habitat for approximately one year before spawning and die 3-36 days after reproduction. (Close, et al., 2002; Streif, 2007)
Pacific lampreys construct their nests, called redds, by moving small stones with their mouthparts. A male and female cooperate to build a redd. The redd may be anywhere from 29-80 cm long and 30-85 cm wide, and is usually located 24-99 cm below the water’s surface. Individual Pacific lampreys will usually construct multiple redds. After spawning, adults have no involvement with their eggs or larvae. (Mayfield, et al., 2014; Streif, 2007)
Pacific lamprey ammocoetes often cluster together at high densities. Until metamorphosis, they are unable to swim. However, they can detach from the stream bed and drift downstream, usually when the current is at high velocity. Larger ammocoetes typically drift during fall, and smaller ammocoetes typically drift during spring. In freshwater habitats, Pacific lampreys are generally nocturnal. Adults are solitary outside of spawning season. During spawning season, either the male or the female may initiate courtship by rubbing up and down a potential mate's body. ("Oregon Lampreys: Natural History, Status, and Analysis of Management Issues", 2002; Stone and Barndt, 2005)
Pacific lampreys rely most heavily on their olfactory and visual systems. Adults navigate to their spawning grounds by following the trail of pheromones released by ammocoetes. (Braun, 1996; Yun, et al., 2011)
During their larval stage, Pacific lampreys are filter feeders, consuming algae and detritus. Adults are parasitic, latching onto prey with their oral discs and consuming their blood and other bodily fluids. They feed on salmonids and a variety of other fishes, as well as several species of whale. ("Oregon Lampreys: Natural History, Status, and Analysis of Management Issues", 2002; Close, et al., 2002)
Ammocoetes stay hidden from predators by sheltering under substrate and only emerging at night. As they grow, they develop tougher skin that makes them less palatable. Adult cryptic coloration- dark on their dorsal side, light on their ventral side- disguises them from predators. (Close, et al., 2002; McPhail, 2007; "Oregon Lampreys: Natural History, Status, and Analysis of Management Issues", 2002)
Pacific lamprey are prey for many species of fish, birds, and mammals. Eggs that overflow the nest are eaten by fish. Ammocoetes are particularly vulnerable to predators when emerging from their burrows and when dislodged by runoff. Adult Pacific lamprey are heavily preyed upon during the migration to their spawning grounds. After spawning, their carcasses also provide food for many species. (Close, et al., 2002)
The burrowing of Pacific lamprey ammocoetes aerates the streambed and softens the substrate. Ammocoetes may digest less than half of the food they consume, excreting the rest as fine particles that can be consumed by aquatic insects and other species. Pacific lampreys are higher in fats and calories than salmon, making them a valuable food source. Steller sea lions, Eumetopias jubatus, harbor seals, Phoca vitulina, and California sea lions, Zalophus californianus, have been found to consume more Pacific lamprey than salmon when both are available. This suggests Pacific lampreys may reduce the impact of predation on salmon. They supply high-calorie meals for many additional species, and their decomposing bodies provide nutrients to the freshwater and riparian ecosystems in which they spawn. (Close, et al., 2002; Roffe and Mate, 1984; Shirakawa, et al., 2012)
Pacific lampreys were historically a major food source for indigenous peoples of the Pacific Northwest. Oil harvested from Pacific lampreys was used as food, hair conditioner, and treatment for ear aches. Pacific lampreys still hold great cultural and religious significance to many native peoples, and are harvested on special occasions. During the 1800's, Pacific lampreys were used to feed livestock and farmed fish. By potentially acting as a buffer between salmon and their natural predators, Pacific lampreys may increase the available harvest for fishermen. The anticoagulants in their saliva have made them a subject of medical research. ("Oregon Lampreys: Natural History, Status, and Analysis of Management Issues", 2002; Close, et al., 2002)
While Pacific lampreys may kill their hosts on rare occasions, there is no evidence that they have a significant negative impact on salmon populations. Pacific lampreys are often viewed negatively because they are mistakenly associated with sea lampreys, a pest species in the Great Lakes region. Unlike sea lampreys, which are an invasive species in the Great Lakes, Pacific lampreys are native to northwestern America and play an important role in its ecosystems. (Close, et al., 2002)
Dams and other artificial barriers have restricted Pacific lampreys' access to large portions of their freshwater range, contributing to their decline in river systems such as the upper Columbia Basin. Pacific lampreys are not strong swimmers and are unable to jump. These traits make it difficult for them to use the conventional fish ladders that help other fishes traverse dams. Dams with gratings appear to be especially difficult, since they impede Pacific lampreys' climbing ability. Adding rough surfaces to fish ladders could make climbing easier and increase the number of Pacific lampreys that cross the dams successfully. Although lampreys generally have a high tolerance for pollutants, chemical spills in river systems can kill large numbers of lampreys. Lamprey ammocoetes are especially vulnerable to pollution, since the sediments they inhabit can easily accumulate chemicals. Dredging also threatens ammocoetes. Among river lampreys (a close relative of Pacific lampreys), less than a third survived a dredging event. Pacific lamprey adults rely on the pheromones released by ammocoetes to find their way to their spawning grounds. If the ammocoete population near a spawning ground decreases enough, adults will not be able to locate the habitat and will disappear entirely from that area. Scientists are attempting to create synthetic versions of these pheromones, which could be used to guide Pacific lampreys to suitable spawning habitat. ("Oregon Lampreys: Natural History, Status, and Analysis of Management Issues", 2002; Yun, et al., 2011)
Sophie("Zosia") Lynch (author), Colorado State University, Peter Leipzig (editor), Colorado State University, Tanya Dewey (editor), University of Michigan-Ann Arbor.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
uses smells or other chemicals to communicate
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
an animal that mainly eats decomposed plants and/or animals
particles of organic material from dead and decomposing organisms. Detritus is the result of the activity of decomposers (organisms that decompose organic material).
a substance used for the diagnosis, cure, mitigation, treatment, or prevention of disease
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
fertilization takes place outside the female's body
union of egg and spermatozoan
a method of feeding where small food particles are filtered from the surrounding water by various mechanisms. Used mainly by aquatic invertebrates, especially plankton, but also by baleen whales.
A substance that provides both nutrients and energy to a living thing.
mainly lives in water that is not salty.
An animal that eats mainly plants or parts of plants.
A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.
makes seasonal movements between breeding and wintering grounds
having the capacity to move from one place to another.
specialized for swimming
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
an organism that obtains nutrients from other organisms in a harmful way that doesn't cause immediate death
An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).
chemicals released into air or water that are detected by and responded to by other animals of the same species
an animal that mainly eats fish
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
mainly lives in oceans, seas, or other bodies of salt water.
breeding is confined to a particular season
offspring are all produced in a single group (litter, clutch, etc.), after which the parent usually dies. Semelparous organisms often only live through a single season/year (or other periodic change in conditions) but may live for many seasons. In both cases reproduction occurs as a single investment of energy in offspring, with no future chance for investment in reproduction.
reproduction that includes combining the genetic contribution of two individuals, a male and a female
digs and breaks up soil so air and water can get in
uses touch to communicate
uses sight to communicate
Oregon Department of Fish and Wildlife. Oregon Lampreys: Natural History, Status, and Analysis of Management Issues. 635000. Portland, Oregon: Fish Division, Oregon Department of Fish and Wildlife. 2002.
Amiotte, L. 2013. ""Pacific Lamprey- Lampetra Tridentata"" (On-line). Washington State Department of Natural Resources. Accessed February 22, 2018 at http://file.dnr.wa.gov/publications/em_fs13_018.pdf.
Braun, C. 1996. The Sensory Biology of the Jawless Fishes: a Phylogenetic Assessment. Brain Behavior and Evolution, Volume 48, Issue 5: 262-276.
Clemens, B., L. Wyss, R. McCoun, I. Courter, L. Schwabe, C. Peery, C. Schreck, E. Spice, M. Docker. 2017. Temporal genetic population structure and interannual variation in migration behavior of Pacific Lamprey, Entosphenus tridentatus. Hydrobiologia: The International Journal of Aquatic Sciences, Vol. 794, Issue 1: 223-240.
Clemens, B., S. van de Wetering, S. Sower, C. Schreck. 2013. Maturation characteristics and life-history strategies of the Pacific lamprey, Entosphenus tridentatus. Canadian Journal of Zoology, Vol. 91, Issue 11: 775-788.
Close, D., M. Fitzpatrick, H. Li. 2002. The Ecological and Cultural Importance of a Species at Risk of Extinction, Pacific Lamprey. North American Journal of Fisheries Management, Vol. 27, Issue 7: 19-25.
Mayfield, M., L. Schultz, L. Wyss, B. Clemens, C. Schreck. 2014. Spawning Patterns of Pacific Lamprey in Tributaries to the Willamette River, Oregon. Transactions of the American Fisheries Society, Vol. 143, Issue 6: 1544-1554.
McPhail, J. 2007. The Freshwater Fishes of British Columbia. Edmonton, Alberta: University of Alberta.
Morrow, J. 1980. The Freshwater Fishes of Alaska. Anchorage, Alaska: Alaska Northwest Publishing Company.
Murasakas, J., A. Orlov, K. Siwicke. 2013. Relationships between the Abundance of Pacific Lamprey in the Columbia River and their Common Hosts in the Marine Environment. Transactions of the American Fisheries Society, Vol. 142, Issue 1: 143-155.
Roffe, T., B. Mate. 1984. Abundances and Feeding Habits of Pinnipeds in the Rogue River, Oregon. Journal of Wildlife Management, Volume 48, Issue 4: 1262-1274.
Shirakawa, H., A. Goto, S. Yanai. 2012. Lamprey larvae as ecosystem engineers: Physical and geochemical impact on the streambed by their burrowing behavior. Hydrobiologia: The International Journal of Aquatic Sciences, Vol. 701, Issue 1: 313-322.
Stone, J. 2006. Observations on Nest Characteristics, Spawning Habitat, and Spawning Behavior of Pacific and Western Brook Lamprey in a Washington Stream. Northwest Naturalist, Volume 87, Issue 3: 225-232.
Stone, J., S. Barndt. 2005. Spatial Distribution and Habitat Use of Pacific Lamprey (Lampetra tridentata) Ammocoetes in a Western Washington Stream. Journal of Freshwater Ecology, Vol. 20, Issue 1: 171-185.
Streif, B. 2007. "Pacific Lamprey- Lampetra tridentata" (On-line). U.S. Fish and Wildlife Service. Accessed February 08, 2018 at https://www.fws.gov/pacificlamprey/Documents/Fact%20Sheets/111407%20PL%20Fact%20Sheet.pdf.
Yun, S., A. Wildbill, A. Dittman, S. Corbett, W. Li, D. Close. 2011. Identification of putative migratory pheromones from Pacific lamprey(Lampetra tridentata). Canadian Journal of Fisheries and Aquatic Sciences, Vol. 68, Issue 12: 2194-2203.