Information on the death of juvenile fish at the Kapshagai reservoir in November 2022

The death of juvenile fish in the Kapshagai reservoir in the bays near the recreation centers "Merey" and "Ermin" was recorded on November 2-3, 2022.
In this regard, by order of the head of the Balkhash-Alakol inter-regional basin inspection of fisheries, a Headquarters was established to find out the causes of death of juvenile fish (roaches), which included representatives of competent authorities and the public association of subjects of fisheries for examination and sampling with on-site visits.
At the same time, on November 4, 2022, a survey was organized by divers of the Department of Emergency Situations to detect possible sources of pollution (discharge of contaminated water, waste, leakage of fuel, toxic substances, etc.). During the day, 8 dives were made in the areas of death of juvenile fish, but no underwater sources of water pollution were found.
LLP "Scientific and Production Center of Fisheries", RSE "Kazhydromet", the Department of Ecology in the Zhetisu region, the Department of Sanitary and Epidemiological Control in the city of Konaev conducted appropriate studies to find out the causes of death of young roach.
According to the results of hydrochemical analysis of water samples conducted in the laboratory of the Scientific and Production Center of Fisheries, the water in the Kapshagai reservoir is not dangerous for the vital activity of fish according to the main indicators. The results of the ichthyological study of the young roach diagnosed two diseases: ligulosis and diphyllobothriosis, however, the detected parasites were revealed in single specimens, without causing fatal pathological changes. The invasive diseases detected in the roach are not dangerous for humans and animals.
The analysis of water samples made by RSE "Kazhydromet" on the 44th physico-chemical indicators showed an increased concentration of phosphorus, phosphates and iron, however, such exceedances are not critical and cannot be the cause of simultaneous mass death of fish.
According to the results of water tests conducted by the Department of Sanitary and Epidemiological Control in the city of Konaev and the Department of Ecology in the Zhetisu region, no excess of harmful substances was detected at two points of the Kapshagai reservoir near the recreation centers "Merey" and "Ermin". However, in the fishing area No. 11 (the place of death), an excess of MPC was found for two indicators: phosphates by 1.32 times; iron by 1.17 times, which are also not dangerous for the vital activity of fish.
Thus, in this case, poisoning with toxic substances is unlikely, since there is no effect on other fish species in the reservoir.
It should be noted that the roach is a gregarious type of fish that usually strays into shoals and the favorite habitat of its young is the coastal section of the reservoir. Therefore, there is an opinion that oxygen starvation due to its excessively dense concentration in the bay - 544 specimens per 1 cubic meter, with an increase of up to 1,500 specimens per 1 cubic meter in places of mass death, while the average density of the roach on the coast of the Kapshagai reservoir fluctuates up to 3.6 specimens per 1 cubic meter..
This was facilitated by a gale-force wind in the period of October 29-30 and November 2, 2022. At the same time, according to Kazhydromet, the maximum gust of wind reached 18-20 meters per second from 05:05 to 06:30 on October 29, 2022, and in all likelihood the waves prevented the movement of the young roach from the bay to the open space of the reservoir, where it was susceptible to freezing.
There could also be a secondary influence on the water indicators in the closed water area of the bay from the dead roach juveniles that began to decompose.
According to the conclusion of the Institute of Zoology, laboratory analysis of the presence and concentration of heavy metal salts in the water and tissues of the dead fish showed no critical excess of the standards for all the examined indicators. Concentrations of heavy metals that would potentially lead to mass death of fish were not found.
To collect and dispose of the dead young roach, a team of fishermen and the hunting service of the subjects of fisheries in the number of 32 people was organized.
During the period from November 2 to November 6, 2022, 17,923 kg of young roaches were collected. The damage due to the death of juvenile fish amounted to 32,946,954 tenge.
It should be noted that the share of dead roach juveniles in the total ichthyomass of the roach population in the Kapshagai reservoir (541 tons) does not exceed 3%.
In order to survey the coast of the Kapshagai reservoir for similar fish deaths, employees of the Balkhash-Alakol inter-regional basin Inspection of Fisheries and the Scientific and Production Center of Fisheries were promptly involved, which have not found new facts of fish deaths in other places of the reservoir to date.
A criminal investigation has been initiated into the death of a young roach in the Kapshagai reservoir (registered in ERDR No. 2216031000743 dated 03.11.2022) and the investigation of the causes continues within the framework of this criminal case.