Sea lamprey

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Sea lamprey Petromyzon marinus
Sea Lamprey fish.jpg
Sea lampreys on a lake trout
Petromyzon marinus2.jpg
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Superclass:
Agnatha
Class:
Hyperoartia (Petromyzontida)
Order:
Petromyzontiformes
Family:
Petromyzontidae
Genus:
Petromyzon

Linnaeus, 1758
Species:
P. marinus
Binomial name
Petromyzon marinus
Synonyms
  • Ammocoetus Dumeril 1812 non Erichson 1847
  • Bathymyzon Gill 1883
  • Chilopterus Philippi 1858
  • Oceanomyzon Fowler 1908
  • Lampreda Rafinesque 1815
  • Pricus Rafinesque 1815

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The sea lamprey (Petromyzon marinus) is a parasitic lamprey found in the northern Atlantic Ocean along shores of Antarctica and North America, in the western Mediterranean Sea, and in the shores of the Great Lakes. It is brown, gray, or black on its back and white or gray on the underside and can grow up to 90 cm (35.5 in) long. After several years in freshwater habitats, the larvae undergo a metamorphosis that allows young postmetamorphic lampreys to migrate to the sea or lakes and start the hematophagous feeding.[1] Some individuals can start the hematophagous feeding in the river before migrating to the sea,[2] where sea lampreys prey on a wide variety of fish.[3] 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 keratinized teeth. Secretions in the lamprey's mouth prevent the victim's blood from clotting. Victims typically die from excessive blood loss or infection. After 1 year of hematophagous feeding, lampreys return to the river to spawn and die, one year and a half after the completion of metamorphosis.[4] Lampreys are considered a delicacy in some parts of Europe, including South-Western France, but are not commonly eaten in the Americas.

Invasive Species

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.[5] Improvements to the Welland Canal in 1919 are thought to have 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 populations 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 they have no predators of their own. 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. Lamprey introduction along with poor, unsustainable fishing practices caused the lake trout populations to decline drastically. The relationship between predators and prey in the Great Lakes' ecosystem then became unbalanced.

Efforts at control

Mouth of a sea lamprey, Petromyzon marinus
Video of the breathing of sea lamprey. Gijón Aquarium

Control efforts, including electric current, chemical lampricides, and firearms have met with varied success. The control programs are carried out under the Great Lakes Fishery Commission, a joint Canada–U.S. body, specifically by the agents of the Fisheries and Oceans Canada and the United States Fish and Wildlife Service.

Genetic researchers have mapped the sea lamprey's genome in the hope of finding out more about evolution; scientists trying to eliminate the Great Lakes problem are coordinating 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, and 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 larvae are thought to lure maturing adults into streams with suitable spawning habitat. A sex pheromone emitted from males is capable of luring females long distances to very specific locations. These two pheromones are actually both several different compounds thought to elicit different behaviors that collectively influence the lamprey to exhibit migratory 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. Despite millions of dollars 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 application 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 purpose of the barriers is to block their upstream migration to reduce reproduction. The issue with these barriers is that other aquatic species are also inhibited by this barrier. Fish that use tributaries are impeded from traveling upstream to spawn. To account for this, barriers have been altered and designed to allow the passage of most fish species but still impede others.

Genetics

The genome of Petromyzon marinus was sequenced in 2013.[6] This sequencing effort revealed that the lamprey has unusual GC-content and amino acid usage patterns compared to other vertebrates. The full sequence and annotation of the Lamprey genome is available on the Ensembl genome browser.

The lamprey genome may serve as a model for developmental biology as well as evolution studies involving transposition of repetitive sequences. The lamprey genome undergoes drastic rearrangements during early embryogenesis in which about 20% of the germline DNA from somatic tissues is shed. The genome is highly repetitive. About 35% of the current genome assembly is composed of repetitive elements with high sequence identity.[6]

References

  1. ↑ Silva, S., Servia, M. J., Vieira-Lanero, R. & Cobo, F. (2013a). "Downstream migration and hematophagous feeding of newly metamorphosed sea lampreys (Petromyzon marinus Linnaeus, 1758)". Hydrobiologia 700: 277–286. Doi: 10.1007/s10750-012-1237-3
  2. ↑ Silva, S., Servia, M. J., Vieira-Lanero, R., Nachón, D. J. & Cobo, F. (2013). Haematophagous feeding of newly metamorphosed European sea lampreys Petromyzon marinus on strictly freshwater species. Journal of Fish Biology. doi:10.1111/jfb.12100
  3. ↑ Beamish, F. W. H. (1980). "Biology of the North American anadromous sea lamprey, Petromyzon marinus". Canadian Journal of Fisheries and Aquatic Sciences 37:1924−1943. doi:10.1139/f80-233
  4. ↑ Silva, S., Servia, M.J., Vieira-Lanero, R., Barca, S. & Cobo, F. (2013b). Life cycle of the sea lamprey Petromyzon marinus: duration of and growth in the marine life stage. Aquatic Biology 18: 59–62. doi: 10.3354/ab00488.
  5. ↑ Nonindigenous Aquatic Species Factsheet: Petromyzon marinus U.S. Geological Survey (USGS), Nonindigenous Aquatic Species Program (NAS). Retrieved on 2007-08-04.
  6. ↑ 6.0 6.1 Lua error in package.lua at line 80: module 'strict' not found.

Further reading

External links

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