Fish kill in winter: features, possible causes and ways to prevent

2024 Author: Henry Conors | [email protected]. Last modified: 2024-02-12 02:45

Recently, many owners of country houses and summer cottages are increasingly paying their attention to open water where you can fish or just have a good time by organizing a picnic on the shore. However, in the spring they can expect a very unpleasant surprise in the form of fish thrown ashore. It is worth looking into in more detail when fish freeze occurs most often.

This kind of tragedy happens mainly in frosty winters, when under a thick layer of snow and ice, various living creatures begin to die at a slow but inevitable pace - swimming beetles, dragonfly larvae and decorative, expensive species of aquatic inhabitants. Often fish kill is noticeable after the ice has melted, when a mass of half-decomposed fish corpses appears off the coast. But oxygen starvation occurs in living organisms in late February - early March, since dissolved oxygen has already been absorbed, and fresh oxygen has not yet arrived. The harsher the winter, the worse the consequences can be.

Mankind knows several reasons why fish die in winter.

Whatcan negatively affect the life of fish in winter

• Inadequate access to oxygen (or even its absence) during the period of surface aeration under a layer of ice. In addition, oxygen is consumed not only by fish, but also by the decaying mass of zoo- and phytoplankton that has accumulated over the summer.
• The death of a significant amount of algae when the air temperature drops (even the remaining vegetation cannot produce enough oxygen during photosynthesis in cold conditions and with low light).
• Water pollution by industrial or municipal waste, sewage.
• Poisoning of the natural habitat of fish due to harmful gases remaining under the ice layer (carbon dioxide and monoxide or methane and hydrogen sulfide, etc.). All these accumulations also reduce the level of dissolved oxygen in the water.

The cold weather's only benefit to freshwater may be slower respiration and rotting. But the excess of the expendable part of the oxygen balance in the pond over the incoming one inevitably leads to such a phenomenon as the death of fish.

How to save fish from death in winter

Despite the fact that the winter kill of fish is a rather serious problem, it can be solved in fairly simple ways. It is enough to install an aerator in the pond, and for small ponds, a compressor with an air spray function is perfect. However, a conventional atomizer will not provide sufficient circulation if the area of the pond exceeds at leastone tenth of a hectare. In this case, the appearance of local dead zones is inevitable. Therefore, owners of large closed reservoirs are advised to install special flow-forming aerators that will not only saturate the water with oxygen, but also create the effect of a steady flow that mixes the entire water column.

How to determine the level of oxygen in water

Anyone who wants to know the exact temperature of the water and its degree of oxygen saturation can do this with a thermooximeter. Also, this device will help save electricity, because with sufficient water saturation, there will be no need to turn on the aerator. It is important to know that fish kill begins when the oxygen level drops to 6-7 mg/l (approximately 50 to 60% of normal saturation). Experts recommend purchasing a thermooximeter with a maintenance-free probe and a sufficiently long cable (at least 3-5 m).

How to keep fish from freezing if there is no aerator

Many experienced owners of reservoirs know that when fish die-off begins, it is important to have time to make a hole, thereby ensuring the flow of oxygen into the water. To do this, it is enough to periodically (at least twice a week) cut or break ice. It is also advisable to freeze sheaves of reeds, reeds, straw in the openings. You can use a pump (fountain pump), pumping water under the ice. This method will be very convenient for those who live far enough away and do not have the opportunity to often come to the reservoir.

It is worth noting that experts are skepticalrefer to folk ways of saving fish from starvation. They assure that the effect of them is only psychotherapeutic, since ice holes are needed solely to monitor the behavior of underwater inhabitants in the winter (in closed reservoirs at the bottom, it is possible to see the dead individuals).

In addition, the usefulness of "bald spots" in the ice may be erroneous for the reason that initially during the kill, the fish desperately strives for air, after which it disappears somewhere, supposedly "breathing". In fact, she simply dies or is looking for safer places. The opinion is strengthened by the identification of living individuals in spring and summer.

What is important to pay attention to to avoid starvation

Also in winter, a fish kill can begin due to invasive diseases (chilodonellosis, ichthyophthiriosis, trichodiniasis) or infectious diseases (pseudomonosis). Water exchange, which improves the habitat of fish, will also help ensure safe wintering. In addition, it is important to pay attention to the minimum allowable depth of the reservoir - it must be at least 2 meters. Treat the pond with quicklime before wintering (about 100 kg per hectare) and do a laboratory analysis of the water from the source that feeds the pond. The results obtained should be carefully studied and compared with the standards established for water in fishery reservoirs.

Should fish be fed in winter

In conditions of low temperatures, fish easily endure starvation, so it is not necessary to feed it. Moreover, the remains of food can decompose at the bottom and be harmful. Butthe exception is trout - it absorbs a small amount of food at water temperatures above +2 degrees. It is recommended to feed her in moderation several times a week. Feed is recommended to stop giving under the condition of passive eating. It is better to install a special feeder, thanks to which the fish independently chooses the time of feeding and the amount of food.

Identify the freeze will help winter fishing

True fishermen do not waste time at any time of the year - they tend to the pond in the thaw and even in the cold. But catching fish in a freeze can negatively affect the catch, so it is better to identify the tragedy in a timely manner and prevent it.

So, you can determine the freeze by the following signs:

• Quick death of live bait.
• Darkening of fishing line, brass and copper spinners.
• Dead aquatic insects on the surface.
• Throwing young animals in search of clean water.
• Stopping fish in the holes.

Under such conditions, fishing promises to be just a failure. Moreover, catching fish at the moment of its active move to the holes is considered poaching.

It is important not to panic and remember that winter freezes are a solvable problem. Ensure successful wintering of fish with the above methods in mind and keep an eye on the condition of the water in the pond to avoid unpleasant surprises.