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Fishmonitoring in the river Oker

During the 23.04.- 08.05.2004 and 17.11-21.11.2004 there was a broad monitoring in the river Oker in lower saxony/germany with the subject of examination of the downstream migration of salmon smolts an silver-eels.



Involved people/organisations:
Dipl.-Biol. Peter-C. Rathcke,das Niedersächsische Landesamt für Ökologie Dez. Binnenfischerei (heute LAVES), der AOLG (Aller-Oker-Lachs-Gemeinschaft), dem Danmarks Center for Vildlaks, dem Niedersächsischen Landesbetrieb für Wasserwirtschaft und Küstenschutz, der Bezirksregierung Braunschweig und der Berufsfischerei Nölke.

Aim: Estimation of the downstream migrationsuccess of smolt in spring on their way to the northsea. Controlling the usage of a bypass by silvereel on the autuum migration to the Sargasso-sea.

The salmonsmolts were marked with a colormark, different for each release point, as shown on the picture on the left. So it was possible to estimate the migration sucess at the hydropowerstation in Mueden (recatchpoint) in relation to the migrationdistance for a defined distance. The figure N= is the number of released,marked smolts.

The entire report you find here ...

In the publication of the LAVES-department inlandfisheries-ichtyological service
t: "Abwanderung von Fischen im Bereich von Wasserkraftanlagen",(downstream migration of fishes in the area of hydropowerstations)

(2006, price: 7,50 EURO (52 pages)

are the collected results of the surveys about the function of bypass tubes at 3 hydropowerstations and may be ordered at the LAVES under