Overseas phenomena: causes and prevention
Fish kills are the death of fish and aquatic invertebrates due to a decrease in dissolved oxygen in the water. Fish kills can occur at any time of the year. In winter, they occur due to complications in oxygen transfer from the air, as well as due to the decomposition of organic matter.
Most often, such phenomena occur in shallow, landlocked or poorly flowing lakes with a high content of organic matter, as well as in small rivers.
Factors leading to fish kills include: temperature and gas regimes, water turbidity, overgrowth of water bodies, hydrochemical parameters, etc.
The temperature regime seriously affects the solubility of oxygen in water. When high water temperatures are combined with abundant aquatic vegetation, the acid-base balance can be disrupted. In winter, the situation is complicated by thick ice, prolonged air temperature drops to -15°C and below, and a stable snow cover.
Fish kills may be observed not over the entire area, but in one or several sections. And the species composition of losses can be uneven, as each species reacts differently to a decrease in dissolved oxygen in the water.
Sometimes, human economic activities also cause fish kills. Pollution of reservoirs, for example, due to the discharge of untreated wastewater, leads to an increase in chemical reactions associated with oxygen consumption.
In winter, the main cause of fish kills is natural factors. Most of the country's reservoirs and watercourses are among the so-called fishing grounds where fishing is permitted. Some of them are leased for commercial fishing or granted for gratuitous use. The rest are part of the reserve fund.
The protection of fishing grounds in the reserve fund is carried out by local executive and administrative bodies or specially authorized legal entities. Measures to prevent fish kills and eliminate their consequences should be financed from local budgets. The same task is set for lessees and users of fishing grounds.
Even if fish kill has already begun, there is still a chance to save most aquatic inhabitants, the main thing is to act promptly. To this end, responsible persons carry out water aeration, liming, snow removal, and create ice holes and openings on lakes and rivers. The number of openings depends on the water body's area; they should be located in the center and along the perimeter of the water body. The assistance of the local population is very important in activities related to the prevention of fish kill phenomena.
We strongly urge all concerned citizens, especially fishermen, to report any signs of fish kill phenomena to the regional departments of the State Inspectorate or territorial bodies of the Ministry of Natural Resources and Environmental Protection.
For additional information or reports of poaching, please contact the Verkhnedvinsk Inter-district Inspectorate for Wildlife and Flora Protection at the following address: Verkhnedvinsk, Sovetskaya St. 193/2, or by calling the hotline at 6 17 23.
Senior State Inspector
Verkhnedvinsk Inter-district Inspectorate
V.A. Goncheronok