European eel

European eel
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Anguilliformes
Family: Anguillidae
Genus: Anguilla
Species: A. anguilla
Binomial name
Anguilla anguilla
(Linnaeus, 1758)
Range for wild European eel
Synonyms

Muraena anguilla Linnaeus, 1758
Anguilla malgumora Kaup, 1856

The European eel (Anguilla anguilla)[2] is a species of eel, a snake-like, catadromous fish. They can reach a length of 1.5 m (4 ft 11 in) in exceptional cases, but are normally around 60–80 cm (2.0–2.6 ft), and rarely reach more than 1 m (3 ft 3 in).

Life history

Main article: Eel life history

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.[3] The larvae (leptocephali) drift towards Europe in a 300-day migration.[4] 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 their bellies 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.

Conservation status

The European eel is a critically endangered species.[1] 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 dams, and natural changes in the North Atlantic oscillation, Gulf Stream, and North Atlantic drift. Recent work suggests polychlorinated biphenyl pollution may be a factor in the decline.[5]

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 live for very long times.[6] According to a report in The Local, a specimen lived 155 years in the well of a family home in Brantevik, a fishing village in southern Sweden.[7]

Sustainable consumption

In 2010, Greenpeace International added the European eel to its seafood red list.[8] In 2010 The Sustainable Eel Group launched the Sustainable Eel Standard. [9]

Decreasing population numbers and breeding projects

As the European eel population has been falling for some time, a project started by Innovatie Netwerk (nl) is researching whether it is possible to breed European eels in captivity. Breeding the European eel is difficult because eels are generally only able to reproduce after having swum a distance of 6,500 km (4,000 mi). In the project, the swimming distance is being simulated by means of a type of swimming machine for the fish. Innovatie Netwerk has also started a breeding project, called InnoFisk Volendam.[10][11]

Commercial fisheries

Global production of European eels in tonnes as reported by the FAO
↑  Wild capture, 1950–2010 [12]
↑  Farmed production, 1950–2010 [12]
↑  Total production of European eel in thousands of tonnes as reported by the FAO, 1950–2010[12]
↑  Main European countries producing farmed European eel

References

  1. 1 2 Jacoby, D. & Gollock, M. (2014). "Anguilla anguilla". IUCN Red List of Threatened Species. Version 2014.1. International Union for Conservation of Nature. Retrieved 30 June 2014.
  2. ↑ "Anguilla anguilla". Integrated Taxonomic Information System. Retrieved 11 March 2006.
  3. ↑ 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.
  4. ↑ "FAO Fisheries & Aquaculture Anguilla anguilla". Fao.org. 2004-01-01. Retrieved 2012-08-02.
  5. ↑ "PCBs are killing off eels". New Scientist. 2452: 6. 2006.
  6. ↑ (Swedish) Branteviksålen kan vara världens äldsta, 2008.
  7. ↑ "World's oldest eel dies in Swedish well". The Local. 8 August 2014.
  8. ↑ Greenpeace International Seafood Red list Archived April 10, 2010, at the Wayback Machine.
  9. ↑ Sustainable Eel Standard
  10. ↑ EOAS magazine, september 2010
  11. ↑ Innofisk Volendam breedign project
  12. 1 2 3 Based on data sourced from the FishStat database Archived November 7, 2012, at the Wayback Machine., FAO.
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