Oral Presentation International Conference on River Connectivity (Fish Passage 2018)

Do silver eel find their way along sluices and pumping stations in highly regulated water systems (#60)

Ben A.B. Griffioen 1 , Erwin H.V. Winter 1 , Olvin O.A. van Keeken 1 , Justine J. Brockotter 2 , Maeike M.L. Hoexum 3
  1. Wageningen Marine Research, IJmuiden, The Netherlands
  2. University of Stirling, Stirling, United Kingdom
  3. HZ University of Applied Sciences, Vlissingen, The Netherlands

In order to quantify abundance, to study migration behaviour and to evaluate passage success along a 26 long canal (North Sea Canal) in the Netherlands, a telemetry experiment was carried out by tagging 2630 silver eel (Anguilla anguilla).

A network of 64 VEMCO receivers was used to detect movement of silver eel tagged with V9 (n=280), V9P (n=50) acoustics transmitters and 32mm HDX PITtag. In addition, 2300 silver eel were tagged with 32mm HDX pittags for mark recapture purposes and fish pass evaluation. Fisherman along the canal were equipped with manual PITtag readers in case of a recapture during (commercial) fisheries.

Within this study eleven locations were selected to evaluate escapement from of freshwater polder systems into the canal and eventually towards the North Sea. Individual variation in observed patterns was large and not all routes were efficient in terms of energy used. Some eel swam up and down the canal before reaching the sea, while others (groups) did not succeed in escaping at all, showing a large barrier effect. Also, some eel swam back towards the polder using sluices and eel seemed to prefer the main water flow instead of a fish passage along a pumping station or migration facilities in sluices. Successful escapement showed part of the silver eel were detected in the Lifewatch network along the Belgian coast. Based on recapture assessment at least 110.000 silver eel successfully migrated along the sluices of Ijmuiden.

This research was funded by a unique collaboration of different water boards and partners along the canal.