The European eel, Anguilla anguilla, is a species of eel, a snake-like, catadromous fish. They can reach (in exceptional cases) a length of 1.5 m (4 ft 11 in), but are normally much smaller, about 60–80 cm (2.0–2.6 ft), and rarely more than 1 m (3 ft 3 in).
Much of the European eel’s life history was a mystery for centuries, as fishermen never caught anything they could identify as a young eel. Unlike many other migrating fish, eels begin their life cycle in the ocean and spend most of their lives in fresh water, returning to the ocean to spawn and then die. In the early 1900s, Danish researcher Johannes Schmidt identified the Sargasso Sea as the most likely spawning grounds for European eels. The larvae (Leptocephalus) drift towards Europe in a three-hundred-day migration. When approaching the European coast, the larvae metamorphose into a transparent larval stage called "glass eel", enter estuaries and start migrating upstream. After entering fresh water, the glass eels metamorphose into elvers, miniature versions of the adult eels. As the eel grows, it becomes known as a "yellow eel" due to the brownish-yellow color of their sides and belly. After 5–20 years in fresh water, the eels become sexually mature, their eyes grow larger, their flanks become silver and belly white in color. In this stage the eels are known as "silver eels", and they begin their migration back to the Sargasso sea to spawn.
The European Eel is a critically endangered species. Since the 1970s, the numbers of eels reaching Europe is thought to have declined by around 90% (possibly even 98%). Contributing factors include overfishing, parasites such as Anguillicola crassus, barriers to migration such as hydroelectric plants, and natural changes in the North Atlantic oscillation, Gulf Stream and the North Atlantic drift. Recent work suggests that PCB pollution may be a factor in the decline.
Eels have been important sources of food both as adults (including the famous jellied eels of East London) and as glass eels. Glass eel fishing using basket traps has been of significant economic value in many river estuaries on the western seaboard of Europe.
In captivity European eels can become very old.
In 2010, Greenpeace International has added the European eel to its seafood red list. "The Greenpeace International seafood red list is a list of fish that are commonly sold in supermarkets around the world, and which have a very high risk of being sourced from unsustainable fisheries."
Decreasing population numbers and breeding projects
For quite some time, the population number of European eels has been falling. For this reason, a research project has been started by Innovatie Netwerk, led by Henk Huizing to see whether it is possible to breed European eels in captivity. The breeding of European eel is very difficult, since eel is generally only able to reproduce after having swum a distance of 6,500 kilometres (4,000 mi). In the project, this is being simulated by means of a hometrainer for the fish. Innovatie Netwerk has also started a breeding project, called InnoFisk Volendam.
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- "Anguilla anguilla". Integrated Taxonomic Information System. http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=161128. Retrieved 11 March 2006.
- Schmidt, J. (1912) Danish researches in the Atlantic and Mediterranean on the life-history of the Fresh-water Eel (Anguilla vulgaris, Turt.). Internationale Revue der gesamten Hydrobiologie und Hydrographie 5: 317-342.
- "FAO Fisheries & Aquaculture Anguilla anguilla". Fao.org. 2004-01-01. http://www.fao.org/fishery/culturedspecies/Anguilla_anguilla/en#tcN90078. Retrieved 2012-08-02.
- The IUCN Red List of Threatened Species, 2008.
- "PCBs are killing off eels". New Scientist 2452: 6. 2006. http://www.newscientist.com/channel/earth/mg18925423.000-pcbs-are-killing-off-eels.html.
- (Swedish) Branteviksålen kan vara världens äldsta, 2008.
- Greenpeace International Seafood Red list
- EOAS magazine, september 2010
- Innofisk Volendam breedign project
- Based on data sourced from the FishStat database, FAO.