The Cause of Massive Fish Mortality in Sevanberd Reservoir Identified

Recently, information regarding the circumstances surrounding the mass mortality of fish in the Sevanberd reservoir located in the Kotayk region of Armenia has been revealed. Employees of the Environmental and Mining Inspection Body of the Kotayk Territorial Division conducted field inspections, water sampling, and collected a specific batch of fish.

The results of the analytical studies conducted by the laboratory of the Environmental Inspection Body indicated that the amount of dissolved oxygen in the water was below the acceptable limits, while the levels of ammonium, ammonia, nitrite, and sulfide ions exceeded the permissible thresholds.

According to a report from the Veterinary and Sanitary Laboratory Services Center of the Ministry of Health, the batch of dead fish sent for laboratory investigation was found to be decomposed and therefore unsuitable for microbiological testing.

We learned from the Water Committee of the Ministry of Territorial Administration and Infrastructure that the reservoir basin was covered with a polyethylene membrane, which had malfunctioned and was not providing the necessary water insulation. In 2019, water did not accumulate in the reservoir, and the water entering from the melting snow in the catchment basin was minimal. During the winter period, the reservoir basin entered almost empty, with only some water remaining in the sedimentation area adjacent to the siphon tower and in the nearby stagnant waters. This situation led to the freezing of the water surface during winter in conditions of high elevation and consequently resulted in fish mortality due to oxygen depletion (known as oxygen starvation).

After the freeze melted, the already decomposed dead fish were washed up to the shoreline, causing a foul odor.

Regarding the elevated levels of ions present in the water, it is believed that this was a result of the decomposition and decay process of the dead fish, according to information provided by the Ministry of Environment.