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The sea lamprey's oval mouth contains concentric rings of sharp teeth, with a bony, rasping long tongue used to bore into its host.
Source: US EPA Great Lakes National Program Office.

The sea lamprey (Petromyzon marinus) is a parasitic lamprey (a kind of jawless fish) found on the Atlanticmarker coasts of Europe and North America, in the western Mediterranean Sea, and in the Great Lakesmarker. It is brown or gray on its back and white or gray on the underside and can grow to be up to 90 cm (35.5 in) long. Sea lampreys prey on a wide variety of fish. The lamprey uses its suction-cup like mouth to attach itself to the skin of a fish and rasps away tissue with its sharp probing tongue and teeth. Secretions in the lamprey's mouth prevent the victim's blood from clotting. Victims typically die from excessive blood loss or infection.

Life cycle

The life cycle of sea lampreys is anadromous, like that of salmon.The young are born in inland rivers, live in the ocean as adults, and return to the rivers to breed. Young emerge from the egg as larvae, blind and toothless, and live that way for 3 to 17 years, buried in mud and filter-feeding. Once they have grown to a certain length, they metamorphosize into their parasitic form, after which they migrate to the sea. Parasitic lampreys feed on the tissue and blood of teleost fish. After several years they become sexually mature and stop feeding. Sexually mature lampreys return to freshwater rivers and streams and spawn, after which they die.

Invasion of Great Lakes

Sea lampreys are considered a pest invasive species in the Great Lakes region. The species is native to the inland Finger Lakesmarker and Lake Champlainmarker in New York and Vermont. It is not clear whether it is native to Lake Ontariomarker, where it was first noticed in the 1830s, or whether it was introduced through the Erie Canal, which opened in 1825. It is thought that improvements to the Welland Canalmarker in 1919 allowed its spread from Lake Ontario to Lake Erie, and while it was never abundant in either lake, it soon spread to Lake Michiganmarker, Lake Huronmarker, and Lake Superiormarker, where it decimated indigenous fish population in the 1930s and 1940s. They have created a problem with their aggressive parasitism on key predator species and game fish, such as lake trout, lake whitefish, chub, and lake herring. Elimination of these predators allowed the alewife, another invasive species, to explode in population, having adverse effects on many native fish species. Control efforts, including electric current, chemical lampricides, and barriers, have met with varied success. The control programs are carried out under the Great Lakes Fisheries Commission, a joint Canada-US body, specifically by the agents of the GLFC, Fisheries and Oceans Canada, and the United States Fish and Wildlife Service.

Efforts at control

Genetic researchers have begun mapping the sea lamprey's genome in the hope of finding out more about evolution; scientists trying to eliminate the Great Lakes problem are co-ordinating with these genetic scientists, hoping to find out more about its immune system and fitting it into its place in the phylogenetic tree. Several scientists in this field work directly for Fisheries and Oceans Canada or the United States Fish and Wildlife Service. Researchers from Michigan State University have teamed up with others from the Universities of Minnesota, Guelph, Wisconsin, as well as many others in a massive research effort into newly synthesized pheromones. These are believed to have independent influences on the sea lamprey behavior. One pheromone serves a migratory function in that odor emitted from larva are thought to lure maturing adults into streams with suitable spawning habitat; the other, sex , is emitted from males and is capable of luring females long distances to very specific locations - even in complete darkness and even though many lampreys at this stage in their life have strongly degraded eyesight. These two pheromones are actually both several different compounds that are thought to elicit different behaviors that collectively influence the lamprey to exhibit migratory behaviors or spawning behaviors. Effort is being made to characterize the function of each pheromone, each part of each pheromone, and if they can be used in a targeted effort at environmentally friendly lamprey control. It is the hope of the Great Lakes Fisheries Commission that at least some of this brilliant work into sea lamprey genetics as well as pheromones will pan out into a successful, effective management technique that could one day drastically reduce the need for TFM treatments of spawning grounds. Despite millions put into research however, the most effective control measures are still being undertaken by control agents of State and Federal Agencies but involve the somewhat publicly unacceptable dumping of TFM into rivers.


  1. Nonindigenous Aquatic Species Factsheet: Petromyzon marinus U.S. Geological Survey (USGS), Nonindigenous Aquatic Species Program (NAS). Retrieved on 2007-08-04.

External links

  • Invading Ontario Ministry of Natural Resources and Ontario Federation of Anglers and Hunters
  • [97224] 'Prehistoric bloodsucker in Thames', BBC News website.

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