Frosty winter is a special time in the life of river and lake inhabitants. Water lowers temperature, which is why most cold-blooded animals become lethargic, inactive.
Some fish, like amphibians, fall into winter suspended animation (hibernation). In carpets freezing to the bottom, crucian carp and small black dallia fish, along with newts and frogs, burrow into silt until spring, stopping all life processes. Other fish, obeying natural instincts, realize their species-specific behavior patterns.
Wintering options for fish
Common wintering options for fish:
- flocking sedentary existence in wintering pits;
- active twilight life (for predatory species);
- entry into the winter spawning phase;
- seasonal migrations;
It is favorable to tolerate wintering under ice inhabitants help the special physical properties of water. Fresh water acquires the highest density at +4 degrees Celsius. When cooling in the ice layer to this temperature, water drops down, not reaching the critical freezing point. Convection rotation of the warm and cooling layers does not stop until the entire body of water has cooled to +4, which happens only in very shallow ponds and lakes.
Wintering pits and predators under the ice
Winter cooling is the time when the multiplication of aquatic vegetation and plankton stops. Fishes, whose food supply is becoming scarce, reduce vital activity, break down in schools, and look for suitable places for wintering.In wintering pits individuals of the same age and size gather. So it is easier for them to endure the cold, tightly straying in packs. To resist cold, to minimize energy costs helps the mucus liberated to the surface of the scales helps. Most likely, it is it that scares away predators, the population of fish waiting for the cold remains untouched throughout the winter.
Such behavior is characteristic of heat-loving breams, carps, and linear. Stored in the summer fat reserves allow you not to worry about nutrition. About three months the fish spend sedentary in the wintering pits, so that in individuals closest to the bottom, bedsores form on the belly.
Predatory fish belonging to the twilight species feel good under the ice. Perch actively hunts both in the light and in areas shaded by ice, becoming a frequent prey for fishermen - masters of ice fishing. The pike prefers darker deep spaces, staying close to perch and carp flocks, catching ruffs, bleaks and treetops. For the same fish that do not change their usual places of existence in the cold season, the deepest twilight predator, the zander, also hunts. Winter fishing of zander is possible only in the dark depths at a considerable distance from the coast.
Whitefish and Burbot Time
Catfish are somewhat more active, looking for places near the boundaries of the wintering pits, on the bottom rises, near the high-oxygenated rocks. Significant body weight allows the catfish not to be afraid of rapid hypothermia. However, the most persistent fans of "winter swimming" are burbots.
The temperature regime in the under-ice world is favorable for burbot. This fish does not like warm water, warmed up in the summer shallow water to a temperature of 27 ° C, it becomes fatal not only for juveniles, but also for adults. In summer, the fish leads an inactive lifestyle, hiding under snags, boulders and burrows. Zhor burbot begins with autumn cooling, when the water cools to temperatures below +15 degrees. Winter colds add activity. It is at a time of severe frost that burbot spawns eggs on the bottom sections covered with small stones.
Whitefish, which lives in reservoirs encircling the north of our country, from the European to the Far Eastern part, also enters the phase of active breeding in autumn and early winter. The food is whitefish bottom organisms, as well as the eggs of spawning fish in the winter, he eats his own.
Fish migration
Seasonal migration routes of fish are not exotic for species that can inhabit both salted sea and fresh river water. In the Azov and the Caspian, sturgeons with the onset of cold weather rise along riverbeds, choosing the deepest sections of the channel for wintering. The Azov hamsa, which fed fat in the summer, moves to the southern Black Sea waters, wintering at depths of 100 m and more. Massively moved to the more southern latitudes shoals of the Caspian herring. Seasonally changing place of residence and the Far Eastern flounder. The Arctic population comes to food fields off the coast, heat-loving individuals migrate to a depth of 300 m, where they practically stop feeding.
