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Survival and progression rates of large European silver eel Anguilla anguilla in late freshwater and early marine phases

2010; Inter-Research; Volume: 9; Issue: 3 Linguagem: Inglês

10.3354/ab00260

2195-2744

Kim Aarestrup, EB Thorstad, Anders Koed, Jon C. Svendsen, Niels Jepsen, Michael Ingemann Pedersen, Finn Økland,

Aquaculture Nutrition and Growth

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 9:263-270 (2010) - DOI: https://doi.org/10.3354/ab00260 Survival and progression rates of large European silver eel Anguilla anguilla in late freshwater and early marine phases Kim Aarestrup1,*, Eva B. Thorstad2, Anders Koed1, Jon C. Svendsen1, Niels Jepsen1, Michael I. Pedersen1, Finn Økland2 1Technical University of Denmark, National Institute of Aquatic Resources, Vejlsøvej 39, 8600 Silkeborg, Denmark 2Norwegian Institute for Nature Research, 7485 Trondheim, Norway *Email: kaa@aqua.dtu.dk ABSTRACT: The population of European silver eel Anguilla anguilla has declined tremendously in the last decades. The cause of this decline is unknown, and it is necessary to investigate the migratory behaviour and survival rates of silver eels during the reproductive migration in order to understand if the decline is related to factors acting during that migration. We estimated survival and progression rates of European silver eel migrating in the lower part of the River Gudenaa and during the first phase of the marine migration in the Randers Fjord in Denmark. Fifty migrating silver eel (total body length: 56 to 84 cm) were captured, and each was equipped with an acoustic transmitter. Their migration was subsequently monitored using an array of automatic listening stations, and progression rate and mortality in the river, inner part of the fjord and outer part of the fjord were estimated. Survival was high in fresh water. However, 60% of eels were lost in the inner and outer fjord, supporting the hypothesis that mortality is large in the early phase of the marine migration and that fishing may be a major cause of mortality of silver eels. There was no indication that the slowest-migrating individuals were more prone to fishing mortality than the faster-migrating individuals. Progression rate increased as the eels proceeded downriver and out of the fjord. The migration was predominantly nocturnal, both in the river and fjord. Based on the available evidence, a considerable increase in eel survival in the river–fjord system will be needed in order to fulfil the goals in the European Union recovery plan for eels. KEY WORDS: Anguilla anguilla · Migration speed · Survival · Migration · Fishing mortality · Acoustic telemetry Full text in pdf format PreviousNextCite this article as: Aarestrup K, Thorstad EB, Koed A, Svendsen JC, Jepsen N, Pedersen MI, Økland F (2010) Survival and progression rates of large European silver eel Anguilla anguilla in late freshwater and early marine phases. Aquat Biol 9:263-270. https://doi.org/10.3354/ab00260Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 9, No. 3. Online publication date: June 10, 2010 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2010 Inter-Research.