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Petromyzon marinus

Petromyzon marinus

Cladus: Eukaryota
Supergroup: Opisthokonta
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Cladus: Hyperoartia
Cladus: Cephalaspidomorphi
Ordo: Petromyzontiformes
Familia: Petromyzontidae
Subfamilia: Petromyzontinae
Genus: Petromyzon
Species: Petromyzon marinus

Name

Petromyzon marinus L., 1758

Vernacular Name
Internationalization
English: Sea lamprey
Galego: Lamprea
Polski: Minog morski
Svenska: Havsnejonöga

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The sea lamprey (Petromyzon marinus) is a parasitic lamprey found on the Atlantic coasts of Europe and North America, in the western Mediterranean Sea, and in the Great Lakes. 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 7 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.
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.

Attacks on humans

While lamprey attacks on humans remain few and far between, they have been known to occur. Most recently in the early hours of the 28 August 2010, a swimmer participating in a relay swim of the English Channel, was attacked by a lamprey which attached itself to the athletes lower back. It remained there until the swimmer returned to the pilot boat at the end of his swim, where it was removed and returned to the water. The swimmer made a full recovery.

Invasion of Great Lakes

Lake Superior, historically, was a fertile, healthy ecosystem until overfishing and introduction of exotic species caused serious declines in fish populations, and an overall collapse of the ecosystem. It seemed that a body of water this size wouldn’t show the effects of the introduction of an exotic species, but this was proved possible with the introduction of the most invasive species introduced to the Lake Superior, the sea lamprey (Petromyzon marinus). Sea lampreys are considered a pest in the Great Lakes region. The species is native to the inland Finger Lakes and Lake Champlain in New York and Vermont. It is not clear whether it is native to Lake Ontario, where it was first noticed in the 1830s, or whether it was introduced through the Erie Canal, which opened in 1825.[1] It is thought that improvements to the Welland Canal 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 Michigan, Lake Huron, and Lake Superior, 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. The lake trout plays a vital role in the Lake Superior ecosystem. The lake trout is considered an apex predator which means that the entire system relies on its presence to be diverse and healthy. With the removal of an apex predator from a system, the entire system feels the effects all the way down the food chain. The sea lamprey is an aggressive predator by nature which gives it a competitive advantage in a lake system where it has no predators, and its prey lacks defenses against it. The sea lamprey played a large role in the destruction of the Lake Superior lake trout population. Lampreys are not entirely to blame for the crash of Great Lake fisheries, but their introduction, along with poor unsustainable fishing practices caused the lake trout populations to decline drastically. This resulted in the relationship between predators and prey in the Great Lakes' Ecosystem became unbalanced. Control efforts, including electric current, chemical lampricides, and barriers, have met with varied success. The control programs are carried out under the Great Lakes Fishery 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 frog 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; other, a sex pheromone, 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 Fishery Commission that at least some of this 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. Another technique used in the prevention of lamprey population growth is the use of barriers in major reproduction streams of high value to the lamprey. The barriers are placed in areas downstream of highly productive lamprey spawning grounds. The purpose is to block upstream migration of the lampreys to allow for minimal reproduction. The issue with these barriers is that other aquatic species are also inhibited by this barrier. Fish that use tributaries are impeded from travelling upstream to spawn. To account for the issue, barriers have been altered and designed to allow the passage of most fish species but still impede others. This is another indirect negative impact that the sea lamprey has on Lake Superior, and the entire Great Lakes Ecosystem as a whole. Today the lamprey population in Lake Superior is in check, but there is still a prevalent population. Lake trout numbers have increased dramatically due to natural reproduction and intense stocking programs. The future of the Lake Superior ecosystem is unknown and much research is being conducted to find new ways to eliminate the sea lamprey. The lake ecosystem will never be how it once was because of new exotic species entering the lake at an alarming rate. However new regulation and a sense of urgency have lead to strong movements to return the lake to the diverse, healthy ecosystem it was in the past.

References

Notes

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

* McClelland, Edward. Great Lake Invaders. E - The Environmental Magazine Mar/Apr2008, Vol. 19 Issue 2, p10-11, 2008

* Binder, Thomas R. Relative Importance of Water Temperature, Water Level, and Lunar Cycle to Migratory Activity in Spawning-Phase Sea Lampreys in Lake Ontario. Transactions of the American Fisheries Society v. 139 no. 3 (May 2010) p. 700-12, 2010

* Pratt, T. C., O’Connor, L. M., Hallett, A. G .Balancing Aquatic Habitat Fragmentation and Control of Invasive Species: Enhancing Selective Fish Passage at Sea Lamprey Control Barriers. Transactions of the American Fisheries Society v. 138 no. 3 (May 2009) p. 652-65 Year, 2009

* http://www.law.umkc.edu/faculty/projects/ftrials/superior/superiorfacts.html

* http://www.glsc.usgs.gov/main.php?content=research_lamprey&title=Invasive%20Fish0&menu=researchinvasive fish

* http://www.lakescientist.com/2010/sea-lamprey-increase-could-be-due-to-rising-lake-superior-temperatures

* http://www.in.gov/dnr/files/SEA_LAMPREY1.pdf

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