A. M. Arias, www.ictioterm.es, (CC BY-NC-ND 3.0 ES)
The adult European eel (Anguilla anguilla) can reach lengths of 1.5 m, is silver in color, and has a long cylindrical body with small slits for gill openings. The lower jaw is slightly longer than the upper. The European eel has one pair of pectoral fins, no pelvic fins, and no spines on the anal or dorsal fins.
European eels present an ecological threat to the American eel (Anguilla rostrata), which is only found in North America. European eels have been recorded to carry a parasitic nematode, Anguillicola crassus, capable of causing severe damage to it's host. This parasite infects the swim bladder of the host resulting in acute inflammatory reactions such as fibrosis or fibrotic conglomerates, constriction of the intestine due to scar tissue, and complete rupture of the swim bladder in severe cases. This kind of damage can lead to unsuccessful migration, preventing spawning and death. With eel populations in decline, the spread of this nematode poses further risk to native American eel populations from exposure to infected European eels.
The European eel has an average life span of 10-20 years (with some records of up to 85 years in an aquaculture). Mature eels are stimulated to swim downstream from freshwater habitats to marine environments and migrate to spawning locations. Females can carry 3 million eggs per 1 kg of body weight. Once the larvae hatch, a period of migration lasting from 2-3 years occurs until the larvae arrives in coastal waters and completes metamorphism into the glass eel stage, changing shape to resemble the adult. Once the eel acquires pigmentation and enters freshwater it is called an elver. After migration, the eel feeds and grows before returning to the ocean for reproduction.
The European eel inhabits the Atlantic Ocean from Europe to North America. This eel is native to the Atlantic Ocean off the coast of Europe and migrates to North Africa, and North America during spawning events. The larval eels drift on the ocean currents from the spawning location to the European coasts. This migration takes about 2 years to complete by the larval European eel.
Native Origin: Atlantic Ocean from Scandinavia to Morocco coasts
U.S. Habitat: European eels are nocturnal and hunt for food in a variety of habitats from marine, to estuarine, and sometimes even on land. The adult eel spends most of its life in fresh water estuarine habitats, but migrates to the Atlantic Ocean for spawning.
U.S. Present: The European eel has been recorded on the East coast and spreading south to Florida. Historical data stated the eel was found off the coast of California, but no populations were established due to an overall unfavorable habitat for the European eel.
Eels from the genus Anguilla do not reproduce in captivity and thus are captured from the wild for use of food or sale. These eels are capable of traveling long distances and are not easily contained, increasing chances of escaping captivity. It is important to ensure eels of this genus are contained when in aquaculture. No current management plans have been set due to the current fragility of the population with overall declining numbers.
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Kettle, James A., and Keith Haines. 2006. How does the European eel (Anguilla anguilla) retain its population structure during its larval migration across the North Atlantic Ocean? Canadian Journal of Fish and Aquatic Science 63: 90-106.
McCosker, J. E. 1989. Freshwater eels (Family Anguillidae) in California: current conditions and future scenarios. Calif. Fish and Game 75: 4-11.
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