How do fish hibernate? I have always been interested in the question: where does the fish go for the winter? On the one hand, it is clear where - it goes to winter, but it is still interesting: how all of a sudden whole hordes of crucians, ruins, ides disappear without a trace. Come on, if only the crucian carp and the tench, the bream, which, in theory, does not belong to such heat-loving fish at all, disappear almost completely in many bodies of water. In my opinion, the wintering of fish is one of the most interesting natural phenomena.
When I started to deal with this issue, first of all I was attracted bream... I could not suppress my curiosity and not find out where this fish went. It turned out that bream is one of the most organized inhabitants of rivers and lakes in terms of wintering. In late autumn, this fish moves in large flocks to their permanent wintering grounds. Mainly thanks to bream, such a concept as a wintering pit appeared. Bream is the main inhabitant there. The first to enter the pit are the largest individuals, which occupy the deepest, that is, advantageous places. Those bream, which are smaller, are located on a higher level, and on the edges and at the top - undergrowth. I, of course, portrayed all this too exaggerated, but in fact, something like it looks like. The multi-storey arrangement of fish in wintering pits is also confirmed by bedsores on the belly, which are observed in the largest individuals (of course, such a mass presses from above). Most often, this phenomenon is observed in carp fish farms, where there is little wintering space, and the fish weigh decently.
It has long been known to ichthyologists that fish of the same species and age hibernate together and in large concentrations. If the pit is small in size, then absolutely identical individuals are located in it. This has been repeatedly confirmed in practice, without special scientific research. It happens that, due to oversight or for some other reason, the nets of fishing brigades, no-no, scoop up fish from the wintering pit. And then the fishermen are surprised - all the fish (as a rule, it is bream) as a match, one to one.
Yes, it is truly a mystery of nature. Scientists explain such an interesting phenomenon by the fact that the mass accumulation of fish of the same species and age provides better conditions for their wintering, since the metabolic processes in the body are less intense than it would be if the fish hibernate alone. In addition, the mucus secreted by the fish bodies as an insulating agent is more efficiently used. By the way, ruffs are often the closest wintering neighbors of bream. And anglers are familiar with this phenomenon, it's not for nothing that there is even such a sign: "a ruff appeared on the hook - wait for a bream soon." This fact is also very curious in itself, because, as you know, ruff mucus is destructive for other species of fish and most of them avoid the proximity of prickly ones. But, as we see, there are no bream at all.
Judging by the fact that in some reservoirs bream is caught well in winter, and in others it is not at all, it can be assumed that they endure winter processes in different ways. Most likely, this is due to some features of the reservoir, but just with which ones, it is completely incomprehensible. In theory, in a more flowing reservoir, where the oxygen content in the water throughout the entire wintering period is quite high, bream should be the most active, but in fact, everything is far from simple. It even seems that there are some subjective factors that are completely incomprehensible to a person. To understand fish, you need to think like them, and this, alas, and perhaps fortunately, is practically impossible.
But I digress, let's see how, for example, predators hibernate.
It turns out that they winter not at all like all normal white, that is, predominantly peaceful fish. You will not find predators in wintering pits. Sometimes they hang around somewhere nearby to seize the moment and grab a sleepy scoundrel, but this is an exception. For the most part, pike, perch and pike perch, either out of a sense of compassion - they say, how bad you are under the ice, or they are simply afraid of a large crowd of fish, but they do not touch the wintering fish in an organized way, preferring to hunt for those who have an ice shell above The head is not how much - it is, first of all, perch, roach and ruff. So nature, in a sense, took care of its wards here, too, because if a predator was lighter, it could easily provide itself with a well-fed existence all winter.
Due to a significant decrease in water temperature, a decrease in the amount of oxygen dissolved in it, a change in the length of daylight hours, quite serious processes take place in the organisms of the inhabitants of wintering pits, making them very vulnerable. In many warm-water fish, and not only fish, during the winter there is a significant decrease in the level of vital activity and metabolism, a slowdown in growth processes, inhibition of reaction to stimuli, a decrease in heart rate and other physiological processes. In some species falling into suspended animation, this is primarily crucian carp and tench, life processes change so much that there are almost no visible life processes. The fishermen probably noticed that the crucian carp and tench caught on the eve of winter show miracles of vitality: after lying for more than one day in the refrigerator and being then released into the bath, they can swim as if nothing had happened. This is because the life processes in the body of the fish have already slowed down and they almost fell into a trance, so by and large they do not care where they spend the winter, in the mud of the reservoir or in your refrigerator (just kidding). However, even with the deliberately heat-loving fish, not everything is as simple as it seems.
How many of you caught carp in winter? I am sure there are many. For some purely carp-like reasons, these fish are not averse to eating a moth or two under the ice. True, this happens most often during thaws, reminiscent of the coming spring, or during the first ice, when the memories of autumn are still fresh in the fish's memory. By the way, the same thing happens not only with fish, but also with bears or hedgehogs, for example. Prolonged February thaws often mislead the clubfoot and thorny ones, forcing them to leave their winter shelters. I can imagine how the bears are bursting back into their dens later, when the deceptive February heat is replaced by severe frosts. It is easier for crucians in this regard - there is no need to hide anywhere, they just sank onto the silt and froze until better times. By the way, even if the crucian carp is not caught from the ice on a jig, this does not mean at all that he fell asleep somewhere in an inaccessible place until better times. Once in the wilderness, I wandered into one inconspicuous backwater of the reservoir, located next to a small village. Out of purely sporting interest, he began to fish this section of the reservoir and found suspicious sticks on the ice with ropes tied to them. Naturally, he began to pull them out and found so-called "TVs" at the other end. He made several holes around and, risking his life (suddenly the owners would show up), began to take them out onto the ice one by one. And what do you think? In three of the five, half-kilogram crucians sat and did not behave at all as they should behave in winter: at first they tried to get out of my hands with all their foolishness, and then for a long time and angrily tossed and turned in their backpack. I suppose that local residents, knowing about such crucian characteristics of their backwater in winter, put poaching gear there on a regular basis. Probably, somewhere nearby and the networks were.
Now answer me this question: "How many of you have caught tench in the winter?" Perhaps, not many will answer in the affirmative, but there will certainly be such. You don't need to go far for an example - several of my friends regularly during the ice season take out several golden-sided lugs on a jig. And all the time on the same reservoir. The winter lines look somewhat different from the summer ones, and therefore it was even suggested that these are not at all familiar lines with the Latin name. Tincatinca peck from under the ice, but a completely different kind - tench golden. Ichthyologists, at my request, considered this option, but did not accept it, believing that this was the most common Tincatinca, who simply cannot sleep for some reason. The reasons were also given - most likely rather strong springs are beating at the bottom of the reservoir, near which the waking fish gathers. If there is an opportunity to spend the winter not in hibernation, then why not take advantage of it? In my opinion, so, because there is a lot of interesting things you can oversleep.
The need for oxygen is one of the most vital wintering conditions for fish. Everyone has heard of such a phenomenon as death. Most often, small and overgrown reservoirs suffer from it, in which the process of photosynthesis stops under a thick layer of snow. However, even on lakes and reservoirs favorable from the point of view of freezing, there is a hidden death of fish. This is observed firsthand during the extraction of bloodworms, when, along with the mosquito larvae, a dead fish appears in the bucket. Most often, for some reason, they are perches. Although some fish species are much more demanding on oxygen content in water than this predator. It is interesting that the first to suffer from oxygen starvation are fish, which are very active in winter - burbot, for example. The threshold oxygen content in water is also high for grayling, chub, gudgeon. When crucian carp, tench and loach appear at the holes, it means that things are very bad. It is gratifying that anglers help the fish family in many ways. The more holes they drill in the ice, the better the fish will be.
However, according to experts, death is a natural phenomenon and should not be perceived as something extraordinary. However, preventive measures will not hurt. One of the latest innovations in this regard is the introduction of herbivorous fish into highly overgrown reservoirs - grass carp and silver carp... These fish are released every year in many free, but valuable from the commercial point of view of water bodies, and then caught in the fall. During the season, the cupid manages to decently thin the thickets of emerging vegetation, and the silver carp - to eat up the microalgae. True, there is also such a moment that these herbivorous comrades destroy spawning grounds for fish, and they are undesirable in the reserves, otherwise there will be fewer rare plants there.
The very same wintering in natural (but not native for these settlers) reservoirs, cupid and silver carp tolerate well. I have already heard about the facts of capturing cupids from the ice. This fish, as a rule, is large and many people certainly want to catch such exotic things. Despite the fact that it is quite easy to detect winter accumulations of cupids by the so-called "pasta" - filaments of mucus washed off by water that envelop the body of a fish - few succeed in catching newcomers from the Far East. It is much more common to catch a carp in winter. Sometimes huge fish peck from the ice even on those reservoirs where no one even suspected their existence. Moreover, such cases are becoming more and more. Here's another winter mystery of nature.
The under-ice world is truly amazing!
Winter is a rather stressful period for flora and fauna. And if in most cases we see how they survive the cold and frost, then we can only guess how the fish winter. Today we will look at this question to dot the i's.
Changing living conditions
It's worth starting with the fact that with the onset of winter, fish collide with changing living conditions... Daylight hours are getting shorter, fish receive less sunlight, a significant decrease in water temperature is observed, the upper layer of the reservoir is covered with ice and covered with snow, which further reduces visibility. Thus, the fish is in sufficient difficult conditions- in dark, cold, almost oxygen-deprived water.
Fish life
Accordingly, in order to survive in such conditions, the fish organism must adjust to new circumstances... And so it happens. All the processes of its vital activity slow down: food consumption is significantly reduced, and sometimes even stops altogether, the heart rate drops, the metabolism almost completely stops and is maintained with the help of previously accumulated fats.
Do fish hibernate?
For some reason, there is an opinion that with the onset of frost, fish hibernate. It is still not completely clear who was the first to put forward this theory, and on what facts it was built, but in fact, fish does not hibernate! The point is that fish is an exothermic living organism. What does it mean? That her body temperature is determined by the ambient temperature. Cold water is cold fish, warm water is warm fish. Exothermic organisms by definition, they cannot hibernate, unlike endothermic creatures... For example, a bear is a representative of endothermic organisms. The temperature of his body is generated by his own body system and a decrease or increase in temperature by at least a degree can negatively affect his life. Therefore, they can hibernate in order to survive the stressful period for the body as safely as possible. At the same time, the heart rate can decrease by almost by 95%.
Although there is something in common between hibernation and the dormant state that is characteristic of fish - this is fat accumulation before a decrease in metabolic processes.
Winter pits
In order to survive the winter as painlessly as possible, many heat-loving fish gather in schools and go to the wintering pits. In such pits, they are practically motionless throughout the winter. Scientists explain this interesting fact of grouping in schools by the fact that thus fish better use up mucus, which is allocated by them as an isolating agent. This helps them get through the winter safer than alone.
Moreover, not all fish hibernate in wintering pits. For example, catfish give preference to space above such pits or elevations of the bottom. The fact is that after the reservoir is covered with ice, in the wintering pits, the oxygen level decreases... Its number there becomes so insignificant that catfish would not survive in such conditions.
Predators
Predatory fish do not hide with the onset of winter, but they also do not take advantage of the moment, eating the flock gathered in the wintering pit. They hunt fish that are loyal to the cold and do not change their usual places of residence.
Most predatory fish see perfectly at dusk, and therefore, as soon as the reservoir is overgrown with ice and snow, not letting in sunlight, they begin to hunt. In these early days, fish turn into real killers, not sparing their victims. This phenomenon is called "First-flyer".
"Moving"
There are fish that, like many people, do not like winter and prefer to move to warmer regions. For example, anchovy, which usually lives in the Sea of Azov, prepares for wintering, stocking up on fat since summer. As soon as she feels the first signs of a cold snap, begins its migration to the Black Sea, at the bottom of which it survives the winter.
"Cryogenic chamber"
What about small bodies of water that can completely freeze over in winter? Pisces have adapted to this too. They bury themselves in the silt... But when the water freezes to the very bottom, the fish also freezes into ice... Yes, yes, it is possible. She is in this state until the reservoir begins to thaw. Having freed themselves from their "cryogenic chamber", the fish begin to feed themselves, preparing for the next winter.
As you can see, each type of fish experiences winter in its own way. Depending on their habitat, they adapt to the peculiarities of wintering, thus, safely transferring this period.
With the onset of winter, great changes occur in water bodies that affect the behavior of underwater inhabitants. The water temperature drops. The daylight period gradually decreases. Then the reservoirs are covered with an ice cover, from above it is covered with snow - the illumination drops even more. For a long 4 months, underwater inhabitants exist in conditions of cold, oxygen deficiency and semi-darkness. During the wintering period, fish activity sharply decreases, food consumption almost completely stops, growth processes slow down, heart rate decreases, reactions to stimuli slow down, the metabolic rate in the body slows down and is maintained due to fat reserves accumulated in summer.
Winter pits
Different fish species survive this difficult period differently. Many types of heat-loving fish such as bream, carp, tench, already in October-November they gather in huge flocks and go to wintering pits. Here they spend about 3 months with little or no movement, like herring in a barrel! In those fish that are at the very bottom, bedsores even form on the belly.
At the same time, fish of the same species and age hibernate together and in large concentrations. If the pit is small, then absolutely identical individuals are arranged in it! Scientists-ichthyologists explain this mystery of nature by the fact that the mass accumulation of fish of the same species and age provides them with optimal conditions for wintering, because the metabolic processes in the fish body are less intense than it would be if the fish were wintering alone. In addition, it makes more rational use of mucus, which fish secrete as an insulating agent.
And here catfish they are attached higher, near wintering pits - at the outlets from the depths, at the boundaries of pits and bottom rises. This is due to the fact that in the pit itself, already a month after the formation of the ice cover, the oxygen regime changes sharply for the worse, which the catfish cannot tolerate.
How predatory fish winter
Predatory fish do not hide in wintering pits. But for some reason, the inhabitants of such pits are not touched either, although they could thus ensure a well-fed existence for the whole winter. For the most part, pike, perch and walleye hunt for those fish for which the ice shell above their heads is at ease and they do not leave their usual habitats for the winter - this is perch, roach, bleak, verhovka and ruff.
With the appearance of ice cover, the behavior of predatory fish changes. Predatory fish are divided in relation to light: for example, perch is a crepuscular-day predator, pike is crepuscular, pike perch is deep twilight.
At the beginning of winter, semi-darkness is created under the ice, which plays into the hands of twilight predators. And then they, in the first days of the establishment of the ice cover, arrange a bloody massacre for their victims. This predator's zhor is called "first-ice".
But for burbot it is winter that is a favorable season. Warm summer water oppresses him. At temperatures above 15-16 ° C, burbot stops feeding and goes into hibernation, hiding in coastal burrows, under large stones or driftwood, and at a temperature of 27 ° C it dies. Only in autumn, when the water in the rivers cools down noticeably, it awakens and begins to intensively feed itself. Burbots prefer to hunt at night. Young burbots feed on zooplankton, and yearlings switch to a "fish diet". When crackling frosts break out and the rivers are covered with a thick layer of ice (in November-December in the north or in December-February in the temperate zone), burbot becomes even more active and begins to reproduce, spawning its eggs on rocky areas of the bottom.
Fish migration
Some fish of temperate and arctic latitudes do not want to change their usual way of life in winter. They prefer to move to warmer waters. Hamsa, which lives in the Sea of Azov, feeds intensively in summer, accumulating fat. With the cooling of the water, it migrates through the Kerch Strait to the Black Sea and hibernates there, sinking to a depth of 100-150 m. It is during the wintering migration of the Azov anchovy that fishing for this fish begins. Caspian herring migrate to the south in winter, where the water is warmer.
"Frozen fish"
And if the reservoir is shallow, stagnant and freezes through in winter? There are such lakes in the Arctic. Their inhabitants are common carp and black fish dallia with the onset of winter, they burrow into silt. When such bodies of water freeze to the very bottom, fish often find themselves frozen into the ice. But their resistance to low temperatures is amazing. Even being in ice captivity, fish do not die - unless the gills and body fluids freeze. In the spring, when the reservoirs thaw, dallia comes to life and in the short polar summer manages to fatten up and leave offspring.
Sometimes it happens...
In equatorial waters, where there is never winter, fish can be active throughout the year. However, some of them also have problems during the winter months. Only they are connected, of course, not with a cold snap, but, on the contrary, with unbearable heat and drought. Some tropical fish burrow into silt and fall asleep. This helps them withstand heat and the associated lack of oxygen.
If crucian carp and dallia are the most frost-resistant freshwater fish, then a small fish from the genus karpozubik - Cyprinodon macularius (cyprinodon macularis), living in the south of North America, holds the record for withstanding the highest water temperatures. She lives and manages not to cook in the hot springs of California, the water temperature of which is 52 ° C! For reference: it is impossible to hold your hand for any length of time in water with such a temperature.
Frosty winter is a special time in the life of river and lake inhabitants. Dense ice depletes atmospheric oxygen saturation in water. The snow cover reduces the access of sunlight to the under-ice space. Water lowers the temperature, which is why most cold-blooded animals become lethargic, inactive.
Some fish, like amphibians, go into winter hibernation (hibernation). In water bodies freezing to the bottom, crucian carp and small black fish Dallia, together with newts and frogs, burrow into silt until spring, suspending all life processes. Other fish, obeying natural instincts, implement their specific behavior patterns.
Wintering options for fish
Common options for wintering fish:
- gregarious sedentary existence in wintering pits;
- active twilight life (for predatory species);
- entry into the winter spawning phase;
- seasonal migrations;
The special physical properties of water help to transfer wintering favorably to the inhabitants of ice. Fresh water acquires the highest density at +4 degrees Celsius. Cooling down in the under-ice layer to this temperature, the water sinks down before reaching the critical freezing point. Convection rotation of warm and cooling layers does not stop until the entire reservoir has cooled to +4, which happens only in very shallow ponds and lakes.
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Winter pits and predators under the ice
Winter cooling is the time when the growth of aquatic vegetation and plankton stops. Fish, the food supply of which is scarce, reduce their vital activity, huddle in flocks, looking for suitable places for wintering. Individuals of the same age and size gather in wintering pits. So it is easier for them to endure the cold, densely huddling in flocks. Mucus plentifully excreted on the surface of the scales helps to withstand the cold, to minimize the expenditure of energy. Most likely, it is she who scares away predators, the population of fish waiting out the cold remains untouched throughout the winter.
This behavior is typical for thermophilic bream, carp, and tench. Fat reserves stored in the summer allow you not to worry about nutrition. For about three months, the fish spend inactively in wintering pits, so that in the individuals closest to the bottom, bedsores form on the belly.
Twilight predatory fish feel good under the ice. Perch actively hunts both in the light and in areas shaded by ice, becoming a frequent prey of fishermen - ice fishing masters. The pike prefers darker deep spaces, staying close to perch and roach flocks, catching ruffs, bleaks and verkhovki. The same fishes, which do not change their usual places of existence in the cold season, are also hunted by the deepest twilight predator - pike perch. Winter fishing for zander is possible only in dark depths at a considerable distance from the coast.
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Whitefish and burbot time
Catfish are somewhat more active, looking for places near the boundaries of wintering pits, on elevations of the bottom, near rapids, more saturated with oxygen. Significant body weight allows the catfish not to be afraid of rapid hypothermia. However, the most staunch fans of "winter swimming" are burbots.
Burbot - winter fish The temperature regime in the under-ice world is favorable for burbot. This fish does not like warm water, warmed up in 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 driftwood, boulders and in holes. Zhor of burbot begins with an autumn cold snap, when the water cools down to temperatures below +15 degrees. The winter chills add activity. It is at the time of severe frosts that burbot spawns on areas of the bottom covered with small stones.
Whitefish, inhabiting the water bodies encircling the north of our country, from the European to the Far Eastern part, also enters the phase of active reproduction in autumn and early winter. Bottom organisms serve as food for whitefish, as well as caviar of fish spawning in winter, it also eats its own.
Winter migrants
