Investigations into mysterious fish deaths in Lake Constance 

Created: 09/19/2022, 10:26 am

Dead fish in the Oder: are fish dying now continuing on Lake Constance?

(Archive image, Uckermark on August 16, 2022).

© IMAGO/Christian Thiel

An attentive walker discovered about 100 dead white fish in Lake Constance on Saturday and reported his find to the authorities.

Investigations into the causes are ongoing.

Lake Constance - The death of fish in the Oder kept the authorities in suspense for a long time.

Now the authorities are apparently facing a new puzzle: On Saturday, the water police in Langenargen found numerous dead fish in Lake Constance after a walker pointed them out.

It's not the first incident of this kind this summer.

Fish kills on Lake Constance?

Water police are following leads

A passer-by reported that more than 100 small dead white fish were floating in the water, the police in Göppingen said on Saturday evening.

When the officials arrived, they found only part of it - the other dead animals had probably already been driven away by wind and waves, it said.

The cause of the fish kill was initially unclear.

The water police took fish and water samples and informed the authorities.

The investigations are currently ongoing.

On Sunday, the police could not give the local newspaper

any more precise information as to when the results of the tests would be available.

Not the first incident on Lake Constance: Dead eels were discovered in August

Numerous dead eels had already been discovered on Lake Constance in August.

At the time, authorities suspected that the heat was the reason for the death.

Because it was the hottest summer ever in Europe, according to data from the Copernicus earth observation program.

Already in the hot summers of 2003 and 2018, there was an eel die-off in Lake Constance due to long-lasting warm periods, as a spokesman for the Ministry of Agriculture in Stuttgart announced.

The high temperatures in August were also accompanied by extremely low water levels.

In addition, a green carpet of algae had formed in front of the municipalities of Langenargen and Eriskirch.

This is why fish react sensitively to high temperatures

Climate change is not only causing record temperatures and more natural disasters, but is also endangering the Bavarian lakes and their "inhabitants".

“Fish are cold-blooded animals and therefore cannot regulate their body temperature.

An increase in the temperature of the surrounding water thus has a direct effect on the body temperature of the fish and increases metabolic processes and thus the oxygen consumption of the fish," explained a spokesman for the Ministry of Food, Rural Areas and Consumer Protection in August at the request of the

.

As the water temperature rises, less and less oxygen dissolves in the water.

"In addition, an increased water temperature can lead to algae growth, which consumes additional oxygen at night," the spokesman continued.

This "heat stress" can also weaken the immune system of the animals and lead to infections.

This was "with a high degree of probability" the case with the eel die-off in August.

There were "no signs" of human influence, it said.

During the environmental catastrophe in the Oder, too, the high temperatures in the river were one of the reasons for the fish deaths.

According to scientists, in addition to the temperature of the water, the high salinity, low water and a toxic species of algae played a role