Animal Diversity Web

Ge­o­graphic Range

The ge­o­graphic range of adult Eu­ro­pean eels in­cludes the Eng­lish Chan­nel and coasts of the Mediter­ranean Sea and north­ern At­lantic Ocean from Ice­land to Mau­ri­ta­nia (Ringuet et al., 2002). Their range also en­com­passes the Baltic and North Seas, as well as all ac­ces­si­ble con­ti­nen­tal or coastal hy­drosys­tems (Ringuet et al., 2002). In the early spring months, Eu­ro­pean eels mi­grate to the Sar­gasso sea for breed­ing. Lar­vae are hatched from the Sar­gasso Sea and can also be found along the coast of Eu­rope. Sil­ver (ju­ve­nile) stage eels of An­guilla an­guilla live in trib­u­taries along the Eu­ro­pean coast. (Ringuet, et al., 2002; Ringuet, et al., 2002; Tsukamoto, et al., 1998)

• Biogeographic Regions
• palearctic
  • native
• atlantic ocean
  • native
• mediterranean sea
  • native

Habi­tat

De­pend­ing on the lifestage of the in­di­vid­ual eel, Eu­ro­pean eels can be found in ma­rine, fresh­wa­ter, and brack­ish aquatic en­vi­ron­ments. Typ­i­cally, the Eu­ro­pean eel is found in depths of 0-700 m, most often on the floor of the ocean or river in which it is liv­ing. (Tsukamoto, et al., 1998)

• Habitat Regions
• saltwater or marine
• freshwater

• Aquatic Biomes
• benthic
• coastal
• brackish water

• Other Habitat Features
• estuarine

• Range depth

  0 to 700 m

  0.00 to 2296.59 ft

Phys­i­cal De­scrip­tion

The ap­pear­ance of Eu­ro­pean eels varies greatly de­pend­ing on life stage. As lep­to­cephali, Eu­ro­pean eels are small, leaflike, and trans­par­ent (Deelder, 1970). After meta­mor­phos­ing into the sil­ver stage, Eu­ro­pean eels ap­pear sil­very in color with elon­gated dor­sal and anal fins that are con­tin­u­ous with the cau­dal fin (Deelder, 1970). Eu­ro­pean eels lack pelvic fins (Deelder, 1970). Upon full sex­ual mat­u­ra­tion, Eu­ro­pean eels de­velop en­larged eyes, lose their abil­ity to feed, and turn green, yel­low or brown­ish in color (Van Gin­niken and Thill­hart, 2000). (Van Gin­neken and Van Den Thillart, 2000; Deelder, 1970; Van Gin­neken and Van Den Thillart, 2000)

Fe­male eels are gen­er­ally sub­stan­tially larger than males. The largest recorded mass of a fe­male eel is 6.599 g (Dekker, van Os and van Willi­gen, 1998). The max­i­mum pub­lished length of a Eu­ro­pean eel was 133 cm. (Dekker, et al., 1998; Dekker, et al., 1998)

• Other Physical Features
• ectothermic
• heterothermic
• bilateral symmetry

• Sexual Dimorphism
• female larger

• Range mass

  6,599 (high) g

  oz

• Range length

  133 (high) cm

  52.36 (high) in

De­vel­op­ment

Eu­ro­pean eels begin their life cycle as eggs on the bot­tom of the Sar­gasso Sea. They hatch as lep­to­cephali, leaf-like lar­vae (Tsukamoto, Nakai and Tesch, 1998). After hatch­ing, lar­vae spend a max­i­mum of one year mi­grat­ing to Eu­rope, or oc­ca­sion­ally North Amer­ica, via ocean cur­rents. The lar­vae will then meta­mor­phose into 'glass eels,' the next stage of the life cycle, and enter es­tu­ar­ine areas. Male glass eels con­tineu to grow for ap­prox­i­mately 6 to 12 years; fe­males for 9 to 20 years (Deelder, 1970). After a final meta­mor­pho­sis, Eu­ro­pean eels mi­grate back to the Sar­gasso Sea to spawn. (Deelder, 1970; Tsukamoto, et al., 1998)

• Development - Life Cycle
• metamorphosis

Re­pro­duc­tion

Upon reach­ing sex­ual ma­tu­rity, Eu­ro­pean eels mi­grate from fresh­wa­ter streams back to the Sar­gasso Sea in order to spawn and die in the late win­ter months to the early sum­mer months. Eu­ro­pean eel males re­lease sperm into the water in which fe­male Eu­ro­pean eels have al­ready laid eggs, thereby fer­til­iz­ing the eggs (Horie et al., 2004). Very lit­tle is known about the ac­tual spawn­ing mech­a­nism, and time to hatch­ing is vari­able. (Oka­mura, et al., 2004)

• Mating System
• polygynandrous (promiscuous)

Eu­ro­pean eels spawn dur­ing the late win­ter to early spring months. There is lit­tle in­for­ma­tion on their re­pro­duc­tion, but since Eu­ro­pean eels are closely re­lated to Japan­ese eels, An­guilla japon­ica, sim­i­lar breed­ing pat­terns might be as­sumed. Fe­male A. japon­ica can lay from 2,000,000 to 10,000,000 eggs, but die soon after spawn­ing (Deelder, 1970). Eel lar­vae are in­de­pen­dent from time of birth until time of death. (Deelder, 1970)

• Key Reproductive Features
• semelparous
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• fertilization
  • external
• broadcast (group) spawning
• oviparous

• Breeding interval

  European eels breed only once during their lifetime. Once spawning is complete, European eels die .

• Breeding season

  European eels spawn in late winter to early spring.

• Range number of offspring

  2,000,000 to 10,000,000

• Range age at sexual or reproductive maturity (female)

  9 to 20 years

• Range age at sexual or reproductive maturity (male)

  6 to 12 years

Eu­ro­pean eels in­vest a sub­stan­tial amount of en­ergy in re­pro­duc­tion, and die shortly there­after (Deelder, 1970). Con­se­quently, the only re­source that fe­male eels give to their off­spring is enough food source to last the egg until hatch­ing. After hatch­ing, the lar­vae are com­pletely in­de­pen­dent and able to find food (Lecomte-Finiger, 1994). (Deelder, 1970; Lecomte-Finiger, 1994)

• Parental Investment
• no parental involvement
• pre-fertilization
  • provisioning

Lifes­pan/Longevity

The lifes­pan of Eu­ro­pean eels is de­pen­dent on mat­u­ra­tion time be­cause once eels ma­ture and spawn, they die. Eu­ro­pean eels can spawn as early as 7 years old. The max­i­mum re­ported age of a Eu­ro­pean eel in the wild is 85 years (Dekker, van Os and van Willi­gen, 1998). (Dekker, et al., 1998)

• Range lifespan
  Status: wild

  85 (high) years

• Typical lifespan
  Status: wild

  7 (low) years

• Average lifespan
  Status: captivity

  55.0 years

  Max Planck Institute for Demographic Research

Be­hav­ior

Eu­ro­pean eels are es­sen­tially a soli­tary species. Al­though nu­mer­ous eels can be found in a sin­gle lo­ca­tion, there is no ev­i­dence that any form of school­ing is pre­sent (Suzuki et al, 2003). Eu­ro­pean eels mi­grate to var­i­ous re­gions dur­ing dif­fer­ent stages of their life. They trans­port them­selves by ac­tively swim­ming with ocean cur­rents (Deelder, 1970). Eu­ro­pean eels are ac­tive mainly dur­ing the day. (Deelder, 1970; Tsukamoto, et al., 2003)

• Key Behaviors
• natatorial
• diurnal
• motile
• migratory
• solitary

Com­mu­ni­ca­tion and Per­cep­tion

Eu­ro­pean eels sense the en­vi­ron­ment using their sense of taste. They have been shown to lo­cate nec­es­sary amino acids via chemo­taxis (Sola and Ton­giorgi, 1998). Eu­ro­pean eels also uti­lize ol­fac­tion, most prob­a­bly for hom­ing pur­poses. There is lit­tle if any doc­u­men­ta­tion of so­cial com­mu­ni­ca­tion be­tween eels (Deelder, 1970). (Sola and Ton­giorgi, 1998; Sola and Ton­giorgi, 1998)

• Perception Channels
• visual
• tactile
• chemical

Food Habits

Eu­ro­pean eels have com­pletely dif­fer­ent diets dur­ing dif­fer­ent life stages. No food con­tents have ever been dis­cov­ered in the guts of lep­to­cephali, there­fore their diet is un­known (Fish­eries Global In­for­ma­tion Sys­tem, 2005). Glass eels con­sume in­sect lar­vae, dead fish, and small crus­taceans (Sinha and Jones, 1975). Adult eels have a fairly broad diet and eat fresh­wa­ter, ma­rine, or ter­res­trial fauna. Their pri­mary food source is aquatic in­ver­te­brates, but they will eat es­sen­tially any food they can find-- even dead or­gan­isms (Sinha and Jones, 1975). Eu­ro­pean eels are re­ported to leap out of the water dur­ing the win­ter and feed on ter­res­trial in­ver­te­brates (Deedler, 1970). ("Fish­eries Global In­for­ma­tion Sys­tem", 2001; Deelder, 1970; Sinha and Jones, 1975)

• Primary Diet
• carnivore
  • insectivore
  • eats non-insect arthropods
  • molluscivore
  • eats other marine invertebrates
  • scavenger

• Animal Foods
• fish
• eggs
• carrion
• insects
• mollusks
• terrestrial worms
• aquatic or marine worms
• aquatic crustaceans
• zooplankton

• Other Foods
• detritus

Pre­da­tion

Eu­ro­pean eels are preyed upon by larger eels and other fish and fish-con­sum­ing birds, such as cor­morants (Pha­lacro­co­rax) and herons (Ardei­dae) (Deelder, 1970). One de­fense mech­a­nism em­ployed by eels is that they hide under rocks and bur­row in the sand, thus avoid­ing their preda­tors. The col­or­ing of eels at var­i­ous life sta­gies (i.e. the trans­parency of lep­to­cephali, the dark grey to green color of adults, etc.) also serves as cam­ou­flage. (Deelder, 1970)

• Anti-predator Adaptations
• cryptic

• Known Predators

  • herons (Ardeidae)
  • cormorants (Phalacrocoracidae)
  • predatory fish (Actinopterygii)

Ecosys­tem Roles

Eu­ro­pean eels are both a food source and a preda­tor of or­gan­isms in their ecosys­tem. They are con­sumed by birds and large preda­tory fish (Deelder, 1970). Eu­ro­pean eels also act as a host for the ne­ma­tode Aguil­li­cola cras­sus which in­fects the swim blad­ders of Eu­ro­pean eels (Deelder, 1970). Eu­ro­pean eels dis­trib­ute nu­tri­ents be­tween ma­rine and fresh­wa­ter ecosys­tems be­cause they mi­grate be­tween those habi­tats (Deelder, 1970). (Deelder, 1970)

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Eu­ro­pean eels are a pop­u­lar food source for hu­mans, es­pe­cially in Eu­rope and Asia. The eels also feed on the eggs of preda­tory fish such as trout, which keep ecosys­tems from over­pop­u­la­tion (Deelder, 1970). (Deelder, 1970)

• Positive Impacts
• food
• controls pest population

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

Eu­ro­pean eels thrive on a diet of ma­rine and fresh­wa­ter fauna, so im­pact pop­u­la­tions of other ma­rine and fresh­wa­ter or­gan­isms (Deelder, 1970). There are no di­rect ad­verse ef­fects to hu­mans. (Deelder, 1970)

Con­ser­va­tion Sta­tus

Eu­ro­pean eel pop­u­la­tions are not cur­rently threat­ened.

• IUCN Red List

  Critically Endangered
  More information

• IUCN Red List

  Critically Endangered
  More information

• US Federal List

  No special status

• CITES

  No special status

Other Com­ments

Eu­ro­pean eels can sur­vive, and even re­pro­duce, at tem­per­a­tures as low as 0°C. Op­ti­mum tem­per­a­tures for ga­me­to­ge­n­e­sis in An­guilla an­guilla are be­tween 0°C and 30°C (Deelder, 1970)-- quite a large range! (Deelder, 1970)

Con­trib­u­tors

Tanya Dewey (ed­i­tor), An­i­mal Di­ver­sity Web.

Melissa Skupin (au­thor), Uni­ver­sity of Michi­gan-Ann Arbor, Kevin Wehrly (ed­i­tor, in­struc­tor), Uni­ver­sity of Michi­gan-Ann Arbor.

Ref­er­ences

2001. "Fish­eries Global In­for­ma­tion Sys­tem" (On-line). Ac­cessed De­cem­ber 01, 2005 at http://​www.​fao.​org/​figis/​servlet/​species?​fid=2203.

Deelder, C. 1970. Syn­op­sis of bi­o­log­i­cal data of the eel An­guilla an­guilla (Lin­naeus, 1758). FAO Fish. Synop., 80: 68.

Dekker, W., B. van Os, J. van Willi­gen. 1998. Min­i­mal and max­i­mal size of eel.. L'AN­GUILLE EU­ROPENNE. 10E RE­UNION DU GROUPE DE TRA­VAIL "AN­GUILLE" EIFAC/ICES..

Lecomte-Finiger, R. 1994. The Early Life of the Eu­ro­pean Eel. Na­ture, 370: 424-425.

Oka­mura, A., H. Zhang, T. Utoh, A. Akazawa, Y. Ya­mada, N. Horie, N. Mikawa, S. Tanaka, H. Oka. 2004. Ar­ti­fi­cial hy­brid be­tween An­guilla an­guilla and A. japon­ica. Jour­nal of Fish Bi­ol­ogy, 64/5: 1450.

Ringuet, S., F. Muto, C. Ray­mak­ers. 2002. Eels: Their Har­vest and Trade in Eu­rope and Asia. Traf­fic Bul­letin, 19/2: 2-27.

Sinha, V., J. Jones. 1975. The Eu­ro­pean Fresh­wa­ter Eel. Liv­er­pool: Liv­er­pool Uni­ver­sity Press.

Sola, C., P. Ton­giorgi. 1998. Be­hav­ioural re­sponses of glass eels of An­guilla an­guilla to non-pro­tein amino acids. Jour­nal of Fish Bi­ol­ogy, 53/6: 1253.

Tsukamoto, K., I. Nakai, W. Tesch. 1998. Do all fresh­wa­ter eels mi­grate?. Na­ture, 396: 635-636.

Tsukamoto, K., T. Otake, N. Mo­chioka, T. Lee, H. Fricke, T. In­a­gaki, J. Aoyama, S. Ishikawa, M. Miller, S. Kimura, H. Ha­sumoto, M. Oya, Y. Suzuki. 2003. Seamounts, new moon and eel spawn­ing: The search for the spawn­ing site of the Japan­ese eel. En­vi­ron­men­tal Bi­ol­ogy of Fishes, 66: 221-229.

Van Gin­neken, V., G. Van Den Thillart. 2000. Phys­i­ol­ogy: Eel fat stores are enough to reach the Sar­gasso. Na­ture, 403: 156-157.