Ecology: European eels are nocturnal, finding hiding places or burrowing into mud (or under stones) during the day and coming out in search of food at dusk. The cold months are spent in hibernation (Reshetnikov 2003; Froese and Pauly 2005). Eels are remarkably mobile, and are capable of movement over dams, weirs and even land (McCosker 1989).
The diet is broad, and includes marine, estuarine and freshwater fauna. The principal food is invertebrates (esp. molluscs and crustaceans) and fishes (Sinha and Jones 1975; Maitland 1977). Eels also scavenge on dead fishes (Coad 2005). Small eels feed on insect larvae, molluscs, worms, and crustaceans. The diet of larger specimens consists predominately of other fishes. European eels do not feed during the cold months (Reshetnikov 2003). The species is reported to leave the water and enter fields to feed on terrestrial fauna, such as slugs and worms (Deedler 1970; Coad 2005).
McCosker (1989) noted that European eels can survive near freezing temperatures. Deedler (1970) gave a range of roughly 0 – 30 ºC for survival.
Anguillid eels are catadromous, spending their adult lives in freshwater or estuarine habitats, then migrating to the ocean (sometimes over long distances) to reproduce. The leaf-shaped larvae common to all anguillids (called a leptocephalus) is especially suited to long distance migration. The larvae drift in the plankton for an average of 7-11 months; however, this stage may last as long as three years (Maitland 1977). Just before reaching coastal waters, the leptocephalus undergoes a metamorphosis into the "glass eel" stage that results in a shortening of the body and formation into a more cylindrical shape (Sinha and Jones 1975). The glass eels gain pigmentation, transform into elvers and move into freshwaters. During this life stage (e.g. in freshwater), the fish are known as "yellow eels" (Sinha and Jones 1975). Eels are stimulated to move upstream toward lower temperatures and salinities (Tosi et al. 1986; Vollestad et al. 1986). Eels may also migrate more readily when influenced by population pressure in the lower reaches of rivers (Moriarty 1986). After migration to brackish or fresh waters, eels feed and grow (males for 6-12 years; females for 9-20 years) before returning to sea for reproduction (Froese and Pauly 2005). Eels are called "silver" eels when migrating from freshwaters to the sea (Sinha and Jones 1975). Eels appear to be stimulated to migrate downstream at night during the new moon and especially during floods (Sinha and Jones 1975). For a detailed review of eel reproduction and migration see Sinha and Jones (1975). Mature females contain 3 million eggs per 1 kg body weight (Coad 2005). The average life span is 10 – 20 years. The maximum reported age for a specimen kept in aquarium is 85 years (Svärdson 1949 in Deedler 1970; Froese and Pauly 2005).
Anguilla anguilla has been artificially hybridized with the Japanese eel A. japonica (Okamura et al. 2004).
References: (click for full references)
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