Hundreds of Fish Die in Oder River, 2% of Total Population

The cause of the accident was probably the weather, but the situation is now under control. Credit: Freepik (illustrative photo).

Bohumin, July 27 (CTK) – Hundreds of fish have died in the Oder River in Bohumin, near Karvina in the Moravian-Silesian Region by the Czech-Polish border. This was about 2% of the fish population in the river, Oder River Basin spokeswoman Sarka Vlckova told CTK this morning.

The weight of the dead fish totalled about one tonne. The cause of the accident was probably the weather, but the situation is now under control.

The water samples taken on Wednesday will be assessed within a few days, she added.

“But we can already say that it was most likely due to the weather. There was little water in the river and the water was warm. Then the rain came, which brought sewage into the river, contaminating the water and resulting in a loss of oxygen,” said Jiri Ovecka, spokesman for the Czech Environmental Inspectorate (CIZP).

This assumption is confirmed by the fact that on 21-22 July, similar events on a much smaller scale happened elsewhere. “Similar but incomparably smaller calamities occurred in the Orlovska struzka and Bernartice nad Odrou brooks,” Ovecka said. He said the fish in the Oder river died about two or three days ago.

Ovecka said that pH analysis of the acidity or alkalinity in water, and similar basic parameters can be checked immediately, but the main analysis will take five days. “It has to go through a process,” the spokesman said. Only then will it be possible to determine the exact cause of the fish deaths.

The exact cause of the fish deaths is yet to be determined, but experts believe from the beginning that it may have been caused by the lack of oxygen.

According to Vlckova, the dead fish included all species, but especially predatory fish that are more sensitive to the lack of oxygen.

“Hundreds of fish have died on the Oder River along a roughly four-kilometre stretch from the mouth of the Struzka River to the border in Bohumin. It is estimated that roughly 2% of the total fish population on the Oder River may have died. The situation is now subsiding and calming down. A high number of samples have been taken and will be assessed in the laboratory of the Oder River Basin state company. The results may be known in about two to three days, some in up to one week,” Vlckova said.

“The exact cause, however, can only really be established after the samples are assessed,” Vlckova said. She added that a floating wall built by firefighters was still in place on the river. The site will be monitored for several days and the remains of the dead fish will be collected today.

Polish Environment Minister Anna Moskwa announced on Wednesday that fish were dying in the Oder River on the Czech side. The Czech Environmental Inspectorate and the Oder River Basin state enterprise, which leaked water from the Sance dam and partly from the Moravka reservoir to dilute the water in the river, have started to deal with the case.

According to the preliminary assessment of the situation from Wednesday, the cause of the fish deaths was probably the lack of oxygen in the river.

Bohumin Town Hall spokeswoman Jana Koncitkova said neither the basin staff nor the inspectorate assumed that it was poisoning.

Experts say the lack of oxygen in the rivers may also be the result of the heat wave that has prevailed in the Czech Republic over the past three weeks. Oxygen dissolves less easily in water the higher the water temperature is. As the water temperature rises, the activity of the fish also increases, resulting in a rise in their oxygen consumption.

The weather was still warm over the weekend in the Moravian-Silesian Region, but on Monday afternoon, hailstorms hit the entire region.

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