title: Empirical observations of the spawning migration of European eels: The long and dangerous road to the Sargasso Sea.
abstract: The spawning migration of the European eel (Anguilla anguillaL.) to the Sargasso Sea is one of the greatest animal migrations. However, the duration and route of the migration remain uncertain. Using fishery data from 20 rivers across Europe, we show that most eels begin their oceanic migration between August and December. We used electronic tagging techniques to map the oceanic migration from eels released from four regions in Europe. Of 707 eels tagged, we received 206 data sets. Many migrations ended soon after release because of predation events, but we were able to reconstruct in detail the migration routes of >80 eels. The route extended from western mainland Europe to the Azores region, more than 5000 km toward the Sargasso Sea. All eels exhibited diel vertical migrations, moving from deeper water during the day into shallower water at night. The range of migration speeds was 3 to 47 km day-1. Using data from larval surveys in the Sargasso Sea, we show that spawning likely begins in December and peaks in February. Synthesizing these results, we show that the timing of autumn escapement and the rate of migration are inconsistent with the century-long held assumption that eels spawn as a single reproductive cohort in the springtime following their escapement. Instead, we suggest that European eels adopt a mixed migratory strategy, with some individuals able to achieve a rapid migration, whereas others arrive only in time for the following spawning season. Our results have consequences for eel management.
authors.affiliation: Cefas Laboratory, Pakefield Road, Lowestoft, Suffolk NR33 0HT, U.K.
authors.forename: David
authors.initials: D
authors.lastname: Righton
authors.affiliation: Institute of Freshwater Research, Department of Aquatic Resources, Swedish University of Agricultural Sciences, SE-178 93 Drottningholm, Sweden.
authors.forename: Håkan
authors.initials: H
authors.lastname: Westerberg
authors.affiliation: Muséum National d'Histoire Naturelle (MNHN), UMR 7208 BOREA, MNHN-CNRS-UPMC-IRD-Unicaen-Station Marine de Dinard, CRESCO, 38 rue du Port Blanc, 35800 Dinard, France.
authors.forename: Eric
authors.identifier: 0000-0001-7342-9148
authors.initials: E
authors.lastname: Feunteun
authors.affiliation: Norwegian Institute for Nature Research, P. O. Box 5685, Sluppen, NO-7485 Trondheim, Norway.
authors.forename: Finn
authors.initials: F
authors.lastname: Økland
authors.affiliation: Inland Fisheries Ireland, 3044 Lake Drive, Citywest Business Campus, Dublin 24, Ireland.
authors.forename: Patrick
authors.initials: P
authors.lastname: Gargan
authors.affiliation: Centre de Formation et de Recherche sur les Environnements Méditerranéens (Cefrem), UMR 5110 CNRS-Université de Perpignan Via Domitia, 52 Avenue Paul Alduy, F-66860 Perpignan Cedex, France.
authors.forename: Elsa
authors.initials: E
authors.lastname: Amilhat
authors.affiliation: Cefas Laboratory, Pakefield Road, Lowestoft, Suffolk NR33 0HT, U.K.
authors.forename: Julian
authors.initials: J
authors.lastname: Metcalfe
authors.affiliation: Museo Nacional de Ciencias Naturales (CSIC), C/ Jose Gutierrez Abascal 2, 28006 Madrid, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Lobon-Cervia
authors.affiliation: Institute of Freshwater Research, Department of Aquatic Resources, Swedish University of Agricultural Sciences, SE-178 93 Drottningholm, Sweden.
authors.forename: Niklas
authors.identifier: 0000-0002-9803-7260
authors.initials: N
authors.lastname: Sjöberg
authors.affiliation: Institute of Inland Fisheries e.V. Potsdam-Sacrow, Im Königswald 2, D-14469 Potsdam, Germany.
authors.forename: Janek
authors.initials: J
authors.lastname: Simon
authors.affiliation: Muséum National d'Histoire Naturelle (MNHN), UMR 7208 BOREA, MNHN-CNRS-UPMC-IRD-Unicaen-Station Marine de Dinard, CRESCO, 38 rue du Port Blanc, 35800 Dinard, France.
authors.forename: Anthony
authors.initials: A
authors.lastname: Acou
authors.affiliation: Centro de Investigação em Biodiversidade e Recursos Genéticos (CIBIO), Universidade do Porto, Campus Agrário de Vairão, Rua Padre Armando Quintas no. 7, 4485-661 Vairão, Portugal.
authors.forename: Marisa
authors.identifier: 0000-0001-7336-3732
authors.initials: M
authors.lastname: Vedor
authors.affiliation: Cefas Laboratory, Pakefield Road, Lowestoft, Suffolk NR33 0HT, U.K.
authors.forename: Alan
authors.initials: A
authors.lastname: Walker
authors.affiliation: Muséum National d'Histoire Naturelle (MNHN), UMR 7208 BOREA, MNHN-CNRS-UPMC-IRD-Unicaen-Station Marine de Dinard, CRESCO, 38 rue du Port Blanc, 35800 Dinard, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Trancart
authors.affiliation: Institute of Inland Fisheries e.V. Potsdam-Sacrow, Im Königswald 2, D-14469 Potsdam, Germany.
authors.forename: Uwe
authors.identifier: 0000-0002-9204-5104
authors.initials: U
authors.lastname: Brämick
authors.affiliation: Technical University of Denmark, National Institute of Aquatic Resources, Vejlsøevej 39, DK-8600 Silkeborg, Denmark.
authors.forename: Kim
authors.initials: K
authors.lastname: Aarestrup
mesh_terms: D025041:Animal Migration / Q000502:physiology*; D000818:Animals; D004524:Eels / Q000502:physiology*; D005260:Female; D008297:Male; D009792:Oceans and Seas; D012098:Reproduction / Q000502:physiology*
keywords: European eels; animal migration; electronic tags; escapement; predation; spawning; vertical migration