ARCHIV - 13.08.2022, Brandenburg, Lebus: Viele tote Fische treiben im Wasser des deutsch-polnischen Grenzflusses Oder. Das Fischsterben in der Oder gibt weiter Rätsel auf. Die gute Nachricht: Nach nur wenigen Jahren könnte sich der Bestand erholt haben. (zu dpa «Fischsterben in der Oder: Viele Landtiere könnten verschont bleiben») Foto: Patrick Pleul/dpa +++ dpa-Bildfunk +++

According to State Minister of Agriculture Axel Vogel (Greens), the fish kill in the Old Oder is not comparable to the massive fish kill in the Oder. The Alte Oder is a tributary that branches off from the Oder. On Sunday, the authorities officially warned against contact with the water of the Alte Oder, as dead fish were increasingly washed up in the Oderberg area (Barnim district).

According to current knowledge, the fish die-off in the Alte Oder was caused by oxygen depletion, said Vogel on Monday in Potsdam. The dimension and the cause are not comparable to what happened in the Oder. This is not about discharges into the river. “Fish deaths are not just fish deaths,” said Vogel.

The Alte Oder was sealed off after the first wave of dead fish came down the Oder, the minister said. Therefore, no fresh water was supplied for several days. As a result, due to the high temperatures and evaporation, the amount of water in the Alte Oder dropped. “The fish suffocate because they don’t have any more oxygen,” Vogel said.

According to the minister, the Institute for Inland Fisheries is investigating the death of fish in the Old Oder. The State Office for the Environment is taking samples, said the ministry spokeswoman.

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The warning from Sunday said: “Starting from the Wriezener Alten Oder in the Oderberg area, dead fish are increasingly being washed up again. People and animals should stay away from water bodies. Don’t fish! Don’t touch dead fish! Don’t swim in the Alte Wriezener Oder and neighboring waters!”

The exact cause of the massive fish kill in the Oder has not yet been finally clarified. The final report of a German-Polish group of experts should be available by the end of September. Scientists assume that high salinity in the river is a major reason, combined with low water, high temperatures and a toxic species of algae. According to the Environment Ministry in Potsdam, the discharge of salt could have been legal.