Michael Ingemann Pedersen

Oceanic Spawning Migration of the European Eel (Anguilla anguilla)

Satellite tracking technology has allowed scientists to map part of the migration route of the European eel. European eels (Anguilla anguilla) undertake a ~5000-kilometer (km) spawning migration from Europe to the Sargasso Sea. The larvae are transported back to European waters by the Gulf Stream and North Atlantic Drift. However, details of the spawning migration remain unknown because tracking eels in the Atlantic Ocean has, so far, eluded study. Recent advances in satellite tracking enable investigation of migratory behavior of large ocean-dwelling animals. However, sizes of available tags have precluded tracking smaller animals like European eels. Here, we present information about the swimming direction, depth, and migratory behavior of European eels during spawning migration, based on a miniaturized pop-up satellite archival transmitter. Although the tagging experiment fell short of revealing the full migration to the Sargasso Sea, the data covered the first 1300 km and provided unique insights.

Eels in Culture, Fisheries and Science in Denmark

As in many other parts of the world, eels and their mysterious life cycle have always fascinated Danes. Almost everyone in Denmark, no matter their age, knows something about eels. In fact, the eel was once one of the country’s most important food fish, and Denmark itself was one of the main European nations fishing it, partly because of the seasonal abundance of migrating silver eels leaving the Baltic Sea through the narrow Straits of Denmark. Eels were fished year-round even during winter (Fig. 3.1). Although the Danish eel fishery was carried out mainly by smallholders, eels were for many years traded extensively with other European countries. Today, though, fisheries for eels are limited by low abundance and consequently restrictive laws.

Proceedings of the Seventh Conference on Fish Telemetry held in Europe

The use of telemetry in studies of aquatic animals hasbecome widespread throughout the world. Develop-ment of technology and methodologies has acceler-ated, and today management of aquatic resources areoften based on results from telemetry studies. The FirstConference on Fish Telemetry in Europe was held inLiege in 1993, and since then each of these bi-annualconferences has been successful events attracting par-ticipants from the around world. The conferences arerather informal, but very informative, aiming at bringtogether scientists and telemetry experts and discussthe latest developments and results within aquatictelemetry.The Seventh Conference on Fish Telemetry was heldin Silkeborg, Denmark, from 17 to 21 June 2007, andhosted by The Technical University of Denmark,National Institute of Aquatic Resources (DTU-Aqua)(former Danish Institute for Fisheries Research). Theevent attracted 118 delegates from 25 countries, withfive continents represented. Eight exhibitors of tele-metry equipment participated.The scope of the science presented at this conferencewas divided into four themes: Marine fish and fisheries,acknowledging the increasing use of acoustic telemetryoff-shore and implementation of the results in com-mercial fisheries management; Migration and dispersal,including life history and migration strategies, popu-lation dynamics, horizontal distribution patterns,homing and dispersal, long- and short-term move-ments; Telemetry and management, demonstrating thatthe widespread use of telemetry has led to betterknowledge-based management in several fields andchanged management practise; and New techniques,new technology and novel applications, a forum forsharing experiences with new gear, new methodsor alternative data analyses. The possibility of using3D-telemetry and real-time tracking showed promisingresults and will likely bring new insight into fishbehaviour in the future. In general, the conferencehighlighted the importance of using telemetry in amultidisciplinary and integrative approach in futureresearch. The importance of telemetry in appliedresearch was in focus, but the conference also revealedan increased use of telemetry methods for basic sciencepurposes. Telemetry is used in an increasing number ofcountries and environments around the world, and theconference also demonstrated an increasing focus onnon-salmonid species. At the conference, 64 oral and29 posters were presented. After review by referees, theeditorial group selected 18 papers for inclusion withinthis special issue of Fisheries Management and Ecology,representing the four themes of the conference.We would like to thank the Technical University ofDenmark for hosting the conference and everyone whoassisted in the conference arrangements, including theDTU-Aqua staff as well as the staff at the FreshwaterCentre, for their efforts. We also wish to thank alldelegates for participating in the conference, keynotespeakers and Scientific Committee members for con-tributing to the scientific debate, and Editorial Boardand reviewers for help with the editing of papers.Lene Jacobsen, Soren Berg, Christian Skov,Kim A˚restrup & Michael PedersenNational Institute of Aquatic Resources(e-mail: lj@aqua.dtu.dk)Scientific and Organizing Committees/Editorial Board:Eva Thorstad, NINA, NorwayMarie-Laure Begout Anras, CREMA, FranceNiels Jepsen, JRC, ItalyPedro Almeida, University of E´vora, PortugalStefan Larsson, Umea˚ Marine Science Centre, SwedenSteven Cooke, Carleton University, CanadaChristan Skov, DTU-Aqua, DenmarkKim Aarestrup, DTU-Aqua, DenmarkLene Jacobsen, DTU-Aqua, DenmarkMichael Pedersen, DTU-Aqua, DenmarkSoren Berg, DTU-Aqua, Denmark