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Sci Adv. 2016 Sep 5;2(10):e1501694. eCollection 2016 Oct.

Empirical observations of the spawning migration of European eels: The long and dangerous road to the Sargasso Sea.

Author information

Cefas Laboratory, Pakefield Road, Lowestoft, Suffolk NR33 0HT, U.K.
Institute of Freshwater Research, Department of Aquatic Resources, Swedish University of Agricultural Sciences, SE-178 93 Drottningholm, Sweden.
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.
Norwegian Institute for Nature Research, P. O. Box 5685, Sluppen, NO-7485 Trondheim, Norway.
Inland Fisheries Ireland, 3044 Lake Drive, Citywest Business Campus, Dublin 24, Ireland.
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.
Museo Nacional de Ciencias Naturales (CSIC), C/ Jose Gutierrez Abascal 2, 28006 Madrid, Spain.
Institute of Inland Fisheries e.V. Potsdam-Sacrow, Im Königswald 2, D-14469 Potsdam, Germany.
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.
Technical University of Denmark, National Institute of Aquatic Resources, Vejlsøevej 39, DK-8600 Silkeborg, Denmark.


The spawning migration of the European eel (Anguilla anguilla L.) 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.


European eels; animal migration; electronic tags; escapement; predation; spawning; vertical migration

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