Actual Report from River Weser - 04.08.2016
Catch of an Eel equipped with a transmitter in the lower Weser region
On 8.7.2016 an Eel equipped with a radio transmitter was caught in the so called "Strohauser Sieltief":
Length: 75 cm,
Transmitter Number: 300 041 - 300 is the id for frequency 150.300 mHz, 041 tells the number of the transmitter
Location: Germany, Landkreis Cuxhaven, Strohauser Sieltief (Lower River Weser)
Interested Anglers enquired where the transmitter might originate.
The research delivered 2 projects working with eel telemetry:
- Eel equipped with a transmitter in Motala-Ström in Norrköping in Middle Sweden on25.9.2013. This Eel though was clearly longer (88cm) and heavier (1.356 g). The codes also didn't match (300 046 und 300 049), so it could not have been this fish.
- Eel equipped with a transmitter in River Diemel near Warburg (NRW) on 14.10.2014. Length 76cm, weight 900 g. Transmitter code 300041. This transmitter had been specially marked with a kink in the antenna wire by telemetry expert Finn Ökland from NINA institute, Norway.
This cleary identifies the origin of the transmitter.
Background of the project:
This individual eel was set out as a part of a project that investigates the downstream migration at three hydorpower stations in the Rhine and Weser riversystems. This project ist carried out by the University of Cologne together with the Norwegian Institute for Nature Research (NINA) and is financed with state funds.
In the course of this research a number of participants expressed the wish to put up some centralized source of information for marking and telemetry projects to be able to identify fish that are found with suspicious features and assign them to their origin.
The association "Wanderfische ohne Grenzen" is planning to implement such a compilation as a part of their existing Migratory Fishes Database.
It became also very clear in the course of this research that it is extremely important, that the different project using marking and transmitter technology know from each other. This is important to enable the assignment of fish that are leaving the project area.
For future detections of fish with transmitter, markings or anything like it, the following data would be very helpful for evaluation:
- Name of the finder and contact data
- Exact location (geographic coordinates, e.g. from Google)
- Fishing device (rod, fish trap, net ..) or found dead
- Length and weight of the fish
- State of maturity of the eel or condition of other fish
- Condition of the operation suture (well healed?)
- Any other pecularities (wounds e.g.)?
- Photo
As long as there is no official contact address for cases like this, please send the information to stefan.ludwig[at]wanderfische.eu .
"Wanderfische ohne Grenzen" will then try to identify the project as quickly as possible.
Overview of different Marking Technologies (not complete):
visible from outside:
- Adipose fin clipping
- fin clipping
- Colour markings under skin – e.g. 2004 on River Oker
- Anchortags – see http://www.wanderfische.de/Aktuelles/Aktuelles_2009.htm (Einträge am 27.11. und 30.11.2009)
- VI-Tags (see Osteprojekt)
- Radiotelemetry-Transmitter (Antenna visible)
- wire-tags River Tay 1910
(http://wanderfische.de/Hindernisse/Monitoring/Tay/Tay_1910_e.html)
Not visible from outside:
- PIT-Tag = passive integrated tag. Used for example on River Weser-Ems, read more here… and in River Elbe
- Radio transmitter (see picture on top of page)
- Acoustic transmitter (see bottom of page) in different sizes
- CWT - coded wire tags
Transmitter of supplier HTI in big.... ...and for smaller fish
Vemco transmitter - NEDAP transmitter, commonly used in rivers,
used worldwide Rhine, Maas in NRW and the Netherlands
