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2023

Tidal and circadian patterns of European eel during their spawning migration in the North Sea and the English Channel

Verhelst, Pieterjan; Westerberg, Hakan; Coeck, Johan; Harrison, Lianne; Moens, Tom; Reubens, Jan; Van Wichelen, Jeroen; Righton, David

Abstract

Technological advances in tracking methods enable the mapping of anguillid eel migration routes from continental habitats to their spawning sites in the ocean. However, the behaviour and orientation abilities of anguillids are still poorly understood, and have only rarely been studied on the continental shelf. Here we present the results of a study into the vertical and horizontal movement behaviour of 42 European eels (Anguilla anguilla L.) tagged with electronic tags that migrated through the North Sea and English Channel towards and into the Atlantic Ocean during their spawning migration. We used actograms, periodograms and linear mixed effects models to determine the periodicity and significance of the timing and pattern of vertical movement and activity. Overall, eels had a complex behavioural repertoire that included classical diel vertical migration (DVM), reverse DVM and vertical movement behaviours that synchronized with tidal patterns. All of the eels that were tracked showed one or more of these behaviours during their time at liberty, and many exhibited all of them. We also observed that the eels had a higher horizontal migration speed when the current in the favourable direction was stronger. This, together with the vertical movement synchronized with the tides, suggests the eels adopt selective tidal stream transport. Finally, tracked eels had a higher vertical movement range at night compared to daytime. We hypothesize that these behaviours are driven by bio-energetic efficient movement, navigation and predator avoidance.

Keywords

Anguilla; Telemetry; Archival tags; Data storage tags; North Sea; English Channel; Diadromy; Selective tidal stream transport; Diel vertical migration; Circadian

Published in

Science of the Total Environment
2023, Volume: 905, article number: 167341
Publisher: ELSEVIER

    UKÄ Subject classification

    Fish and Aquacultural Science

    Publication identifier

    DOI: https://doi.org/10.1016/j.scitotenv.2023.167341

    Permanent link to this page (URI)

    https://res.slu.se/id/publ/128649