It turns out that the reasons why this happens fish migration, much more complex and varied than those over which birds fly.

Firstly, fish go on long voyages in search of food. Starving and having lost all their strength after spawning, the cod undertakes a long journey from the coast of Norway to the north towards the Kola Peninsula, where they come from the Atlantic warm waters Gulf Stream currents. They bring with them plankton, which serves as the main food for this oceanic fish.

Secondly, salmon or salmon, like cod, move from the seas to rivers with the onset of spawning, because only in fresh water can they leave the game and hatch fry.

Many fish species do not change geographical places habitat.. Near the surface, fish feed, and in the depths they hatch their young. This type is called vertical. It is caused by the movement of a layer of water containing zooplankton, which occurs every year.

When in northern latitudes winter comes, zooplankton goes deeper. There the temperature does not drop below four to five degrees above zero Celsius. If zooplankton remained at the top, they would simply die from the cold.

For a long time, researchers believed that bottom-dwelling fish did not migrate. Indeed, flounder leads a sedentary lifestyle. The shape of her body is not well adapted to swimming long distances. However, as it turned out, flounder does not stay in one place. She sails from north to south along the coasts of all Europe. Shoals of flounder reach the Bay of Biscay. There the fish lay their eggs.

For example, vertical migration is carried out by flounder that lives in the North Sea. Schools of fish annually descend into the depths of the ocean, where they lay eggs. There, larvae appear in the dark and cold waters. As soon as they gain the ability to move, they begin their journey upward.

Observations have shown that a flounder larva, only 13 centimeters long, swims at least a kilometer per day. While swimming in warm coastal waters, it manages to grow and take on the form of an adult fish. For several months it feeds near the shore, but then again goes into the depths.

Fish migration occurs even in lakes. It is known that salmon leave Lake Ladoga every year to spawn in rivers. Lake smelt reproduces similarly.

Some fish annually travel from the lower reaches of the river to its sources and back. They are called walk-throughs. It has been established that they go to the upper reaches of the river to spawn. What forces them to return to the mouth is the presence of a variety of food in it.

Even river catfish, which live at the bottom of pools and are known for their sedentary lifestyle, go to shallow water during the breeding season. They need this in order to leave the eggs in running water rich in oxygen. Then they hide again in their secluded shelters.

Some species migrate only once in their lives. Having reached 1.5 years of age, the Far Eastern pink salmon returns to the rivers, to the place of its birth, spawns and then, exhausted, dies in order to become food for the offspring that are born.

Migrations are the regular movements of fish along certain paths at certain times of the year. These regular wanderings are one of the most interesting phenomena in the life of fish and are extremely important for their fishing.

Individuals, small groups of fish and large herds or schools can migrate. Rare fish lead a sedentary lifestyle, living all the time in a certain small area. Most fish undertake more or less extended movements, sometimes gathering for this purpose in very large schools or shoals. These schools are fished by fishermen in certain areas in which the fish come or through which they pass. The migration routes of fish do not always remain named. Sometimes due to change external conditions The migration routes of fish also change. Migrations can be divided into passive and active.

Passive migrations are the transfer of fish larvae or eggs by currents. An example of passive migration is the removal of hatched larvae of Murmansk herring by jets of the North Cape Current of the Gulf Stream from spawning grounds off the northwestern coast of Norway into the Barents Sea.

Adult fish migrate actively. Active migrations include feeding, spawning and wintering.

Migrations are divided into anadromous and cathodromic. Anadromous migrations are movements in which fish move up the river or from the sea to the shores. Cathodromic migrations are the movement of fish down a river or from the shores into the open sea.

Let us give examples characterizing certain types of migrations.

Feeding migrations. There are many examples of active migrations for the purpose of Nutrition. Black Sea mullet, sea fish in at a young age to feed on plant remains (detritus) in the spring they enter shallow brackish water coastal lakes- estuaries. They pass into them through narrow, sometimes specially dug channels. With the onset of cold weather, the mullet, which has fattened and reached commercial size, goes back to the sea. Or, for example, the migration of cod in the Barents Sea. This cod, after breeding off the coast of Norway near the Lofoten Islands, emaciated, skinny, hungry, moves, feeding, into the Barents Sea. Cod in the Barents Sea feeds mainly on fish: herring, capelin and, to a lesser extent, crustaceans. You can specify a number of other sea ​​fish, making extensive migrations for the purpose of feeding. Particularly significant are the movements of tuna, swordfish and some sharks, moving from one ocean to another in search of food.

Spawning migrations. The spawning migrations of migratory fish are especially interesting and most studied. A typical example is the migration of Atlantic salmon. Atlantic salmon for breeding from northern seas where it lives, it enters rivers and, as a rule, rises high along them. Thus, its spawning migrations are an example of anadromous migrations. Atlantic salmon spawn in the fall. They enter rivers at different times of the year, at different ages and in different sizes. The desire for breeding grounds is very strong in salmon. On its way up the river, it overcomes small rapids and even waterfalls, sometimes making huge jumps up to 4 m above the water. Salmon spawning occurs in shallow places in the upper reaches of the river with a flat sandy pebble bottom, with transparent and cold water. Another example of spawning anadromous migrations of anadromous fish is the migration of sturgeon fish (thorn, sturgeon, stellate sturgeon and beluga). Sturgeon begin their spawning migration in the spring. The height of their ascent along the river depends on the availability of places with a pebble bottom that are convenient for spawning.

Much less often among migratory fish, examples of cathodromic migrations are observed, when rivers are a feeding place for fish, and the sea is a breeding place. This type of migration is found in European river eels. Upon reaching sexual maturity, the European eel begins to leave the rivers where it fed and grew into the sea. In the sea, the eel moves from the shores of Europe to the shores of Central America, where its breeding grounds are located above great depths. Marine fish also make spawning migrations. Atlantic cod, for example, after finishing their feeding period, makes a spawning migration from the eastern part of the Barents Sea to the Lofoten Islands. Sea flounder usually moves away from the shore to considerable depths to spawn.

Freshwater fish also move higher up rivers or move from lakes to rivers to reproduce. These are sterlet, Volkhov whitefish, burbot, asp. However, usually the spawning migration routes of freshwater fish are shorter than those of anadromous or sea fish.

Wintering migrations. Wintering migrations of fish living in the Northern Caspian Sea are typical. Carp, bream, and pike perch gather in large schools in the fall and migrate to the banks and river deltas, mainly to the Volga. Here these fish lie in special pits for the winter. The wintering migrations of the Azov anchovy in the fall from Sea of ​​Azov through Kerch Strait to the Black Sea. Hamsa is a typically pelagic planktivorous fish. After fattening in the Sea of ​​Azov, it gathers in large flocks in the fall and exits through the Kerch Strait into the Black Sea. Then it moves to the southern shores of the Caucasus, descends in winter from the surface to the depths, where it spends the winter. In the spring, having risen to the surface, anchovy migrates back to the Sea of ​​Azov for spawning and feeding.

The above types of migrations cannot be considered in isolation. The migrations of each fish are connected with one another, transforming one into another. All types of migrations in fish represent separate stages of the general annual migration cycle.

Methods for studying migrations. The simplest way to study migrations is to analyze changes in commercial fish catches in individual fishing areas. By comparing increases and decreases in catches in individual fishing areas, one can get an idea of ​​the movements of fish.

The best method for studying fish migrations is tagging them. To obtain successful tagging results, a necessary condition is to carry out tagging on a mass scale and in those areas where fishing is sufficiently developed, since the main task is the return of tags or recaptured tagged fish. The tags used for individual tagging of fish are varied. The main requirements for them are that they do little damage to the fish, are light, and clearly visible. Currently, the most common are various hanging tags made of polyethylene tubes and films of the “ampoule” and “envelope” type, attached with a thin wire or nylon thread to the base dorsal fin fish.

Fish migrations are periodic mass movements of fish. Knowledge of the timing and directions of migrations, the patterns to which they obey, is of great practical importance. Sedentary image Only a few fish lead their lives (coral reef fish, some gobies, etc.). For most fish, migrations represent certain parts of the life cycle that are inextricably linked.

There are horizontal and vertical migrations. Horizontal migrations can be passive or active. During passive migrations, eggs and larvae are carried by currents from spawning areas to feeding areas. Thus, the eggs and larvae of Atlantic cod spawning near the Lofoten Islands (Norway) drift in the Gulf Stream into the Barents Sea; European eel larvae from the Sargasso Sea drift for 2.5–3 years to the shores of Europe, etc.

Active migrations, depending on the purpose, are: 1) spawning; 2) feed; 3) wintering.

The length of migrations varies significantly. Some species make small movements (flounder), others can migrate thousands of kilometers (eel, salmon).

Spawning migrations (movements from feeding or wintering areas to spawning areas).

In semi-anadromous fish, migrations are distinguished: 1) anadromous, fish go to spawn from the seas to rivers (salmon, sturgeon, etc.); 2) catadromous - from rivers to the sea (river eel, some species of gobies, galaxy fish).

In the process of evolution, intraspecific differentiation occurred in some migratory fish, which led to the formation of seasonal races - winter and spring (river lamprey, Atlantic salmon, some sturgeon, etc.). Fish of the spring race enter rivers with developed gonads shortly before spawning, and fish of the winter race enter the river in the fall with undeveloped reproductive products, spend in the river from several months to a year and reproduce the following year. In winter races, spawning migrations are combined with wintering ones. During spawning migrations, fish usually do not feed or feed poorly, and the fish accumulate the necessary energy resources for movement and development of the gonads in advance in the form of fat.

The reasons for anadromous migrations are primarily related to the fact that in fresh waters the conditions for reproduction and the survival of eggs and larvae are more favorable than in the sea.

Many marine and freshwater species make spawning migrations to the shores (cod, Atlantic herring, whitefish, etc.), and some of them go to great depths to spawn (sea flounder, big-eyed wolffish).

Feeding migrations (movements from breeding or wintering areas to feeding areas). For many fish, feeding migrations begin already at the egg stage. The transfer of pelagic eggs and larvae from spawning grounds to feeding grounds is passive feeding migration. A large number of eggs and larvae of freshwater fish are carried in rivers by currents from spawning grounds to lakes for feeding (whitefish, etc.).

Polycyclic fish, after reproduction, make feeding migrations of varying lengths. Atlantic salmon and sturgeon, after breeding in rivers, go to the sea to feed. Atlantic herring spawns off the coast of Norway and, after breeding, migrates to feed in the area of ​​Iceland and further north. Sometimes feeding migrations are combined with spawning migrations (Azov anchovy). Wintering migrations (movements from breeding or feeding grounds to wintering areas). Fish that are physiologically prepared and have reached a certain fatness and fat content begin their wintering migration. Thus, anchovy from the Sea of ​​Azov, after feeding in the fall, migrates to the Black Sea and winters at a depth of 100–150 m. Wintering migration can begin only when the fish accumulates a sufficient amount of fat (at least 14%). Fish that are not prepared for migration continue to feed and do not migrate. In migratory fish, wintering migrations are often the beginning of spawning migrations. The winter forms of some of them, after feeding in the sea, enter rivers in the fall and spend the winter in them (river lamprey, sturgeon, Atlantic salmon, etc.). Some species living in the Volga during the autumn cooling migrate to the lower reaches of the river and lie down in pits (bream, carp, catfish, pike perch).

In addition to horizontal migrations, fish are characterized by vertical migrations. Spawning vertical migrations are carried out by the Baikal golomyanka, which, before spawning larvae, emerges from a depth of about 700 m into the surface layers of water and dies after reproduction.

Many marine and freshwater species perform daily vertical migrations, moving after food items (herring, sprat, sprat, mackerel, horse mackerel, vendace, etc.). Juveniles of many fish species also migrate vertically, following food organisms.

Many pelagic fish in winter descend into deeper and less chilled layers than when feeding and form large, sedentary aggregations (herring, Azov anchovy, etc.).

Knowledge of the patterns of fish migration is important when organizing sustainable fishing. One method for studying migration is tagging. Marking can be individual (each mark has its own number) or group (all fish are marked equally). Tagging allows you to study migration routes, determine the speed of fish movement, population size, and the efficiency of fish farming.

20.PLACE OF FISH IN AQUATIC BIOCENOSES

The migrations of fish, that is, their journeys from one place to another, like the flights of birds, represent a phenomenon of the deepest biological meaning and majestic beauty. Fish migrations are also of great commercial and economic importance, since the main catch of fish is carried out along the routes of their mass movements, both in the sea and in lakes and rivers. The most ambitious in scale are the migrations of marine fish and migratory fish, which migrate to fresh waters at certain periods of their lives. But purely freshwater fish migrate for the same reasons as sea fish.

Fish migrate in search of food. The cod, emaciated during spawning off the coast of Norway, goes east to Murmansk waters, where it finds good pastures. This is feeding migration. Salmon from the sea is coming to rivers for reproduction - spawning migration. Some fish leave their summer places for the winter to deeper places - wintering migration.

Fish also have vertical migrations, when they move in whole herds from one depth to another, from the bottom to the surface and vice versa. These trips are often in the nature of feeding migrations. Zooplankton (the smallest animal organisms that serve as food for fish) are concentrated in upper layers water, deeper during the day. Following the plankton, the fish that feed on them move.

Fish migrations are also associated with temperature, light conditions, water flow, and wind direction. In many fish, eggs and larvae are carried by currents over long distances.

In 1911-1912, I traced in detail the migration of the Caspian lamprey. Until that time, such observations had not been made of this extremely secretive fish.

Migrations are clearly expressed in Atlantic, Pacific (Far Eastern), Caspian and Black Sea herring.
Atlantic, so-called Norwegian, herring approaches the shores of Norway in the spring, heading for spawning (spawning migration), after which it migrates to the Barents Sea pastures (feeding migration).

Bottom fish cod is of great commercial importance. Its fishery is well developed in the seas of the European north.

Do migrations exist in fish that are tied to the bottom and are poorly adapted to long-distance movements due to the shape of their bodies? Do flounders migrate? After all, it is difficult for them to swim for a long time, because their body cannot be positioned vertically when swimming?
Flounder have migrations, but their length is shorter than that of fish such as herring or cod.

Freshwater fish, which spend their entire lives in lakes and rivers, also make migrations, both vertical and horizontal, but the latter are shorter than those of marine fish.

I would like to especially dwell on the amazing migrations of the river eel. There is so much mystery, sometimes difficult to explain, in the behavior of this valuable commercial fish!
The eel lives in the rivers of the European coast Atlantic Ocean, where it is an important fishery object.

About freshwater fishMigrations of the Caspian lamprey

Fish migrations

The migrations of fish, that is, their journeys from one place to another, like the flights of birds, represent a phenomenon of the deepest biological meaning and majestic beauty. Fish migrations are also of great commercial and economic importance, since the main catch of fish is carried out along the routes of their mass movements, both in the sea and in lakes and rivers. The most ambitious in scale are the migrations of marine fish and migratory fish, which migrate to fresh waters at certain periods of their lives. But purely freshwater fish migrate for the same reasons as sea fish.

Fish migrate in search of food. The cod, emaciated during spawning off the coast of Norway, goes east to Murmansk waters, where it finds good pastures. This is feeding migration. Salmon from the sea goes to rivers to reproduce - spawning migration. Some fish leave their summer places for the winter to deeper places - wintering migration.

Fish also have vertical migrations, when they move in whole herds from one depth to another, from the bottom to the surface and vice versa. These trips are often in the nature of feeding migrations. Zooplankton (the smallest animal organisms that serve as food for fish) are concentrated in the upper layers of water at night, and deeper during the day. Following the plankton, the fish that feed on them move.

Fish migrations are also associated with temperature, light conditions, water flow, and wind direction. In many fish, eggs and larvae are carried by currents over long distances.

Migrations of the Caspian lamprey

In 1911–1912, I followed in detail the migration of the Caspian lamprey. Until that time, such observations had not been made of this extremely secretive fish. It turned out that the lamprey begins to enter the river from the sea in the fall at a water temperature of 10–11 ° and is directed mainly along those Volga branches where there is more fast current. The course of the lamprey was traced to Saratov. Near Saratov we established the spawning grounds of this fish.

The lamprey is most active at night. It's interesting that in dark nights it travels in herds, and during light (lunar) periods it travels in much smaller numbers and sticks to greater depths.

In those days, on the Volga, lamprey was caught using a “lantern”, believing that it was striving for light.

On the ice, above the ice hole, usually not very deep, where the lamprey was supposed to move most densely, a brightly burning lantern was placed near the ice hole, and at some distance from it several more ice holes were made, in which they scooped up the lamprey with sakami, believing that it was “swirling” around illuminated strip of water. Indeed, the lamprey gathers near the illuminated strip, but this is not explained by the fact that the fish strives for light, but by the fact that, on the contrary, it avoids it.

On page 60 there is a diagram of lamprey fishing with a lantern: s – light source, lantern; e – a column of water illuminated by a beam of light rays; d – ice surface; a and c – ice holes (a – with a lantern, c – where fishing takes place). The lamprey, moving all the time in the dark towards the fast-water stream, encounters the light (e) and, hiding from it, rises up into a darker space, where it falls into the catcher’s bag.

During its journey along the Volga, the Caspian lamprey travels 50 kilometers per day, and if we take into account that the lamprey travels mainly at night, it becomes clear that it moves very quickly. I was able to track the migration of the lamprey by tagging the fish by attaching woolen tags with a long-lasting color. Fish tagging is one of the the best ways observations of their migration.

The Volga lamprey makes spawning migrations. The fish enters the river, rises along it, driven by the instinct of reproduction.

Herring migrations

Migrations are clearly expressed in Atlantic, Pacific (Far Eastern), Caspian and Black Sea herring.

Atlantic, so-called Norwegian, herring approaches the shores of Norway in the spring, heading for spawning (spawning migration), after which it migrates to the Barents Sea pastures (feeding migration).

Together with adult fish, juveniles also migrate, starting from the larval stages. The herring larvae emerging from the eggs, falling into powerful current The Gulf Stream carries it to the north, but after a while the fish return to their native places. This is the general picture of the migrations of Norwegian herring, but this herring has several different stocks (races), the migrations of which vary. One thing is certain: the migrations of Atlantic herring are associated with spawning, fish feeding and the flow of water into the sea.

Atlantic herring, when immature, travels in small numbers from the Barents Sea to the White Sea, but soon returns to the Barents Sea. This kind of migration cannot be called spawning, and its food value, presumably, is small: it is unlikely that herring will find more food in the White Sea than in the Barents Sea. Apparently, this migration is connected with the flow of water in the throat of the White Sea and in the White Sea itself.

Several dates have been established for herring to approach Sakhalin. The first one happens early spring when the ice has just melted off the coast. Having found suitable places for spawning (thickets of algae), the herring lays eggs. After spawning, the fish quickly leaves the shores, making a reverse migration. After a few days or weeks, the second, and then the third, herring run begins. Herring also migrate to Peter the Great Bay, with groups of different ages in different times. In total, three or four herring movements to the shores are observed.

Researchers of Pacific herring migrations come to the conclusion that Sakhalin and coastal herring do not migrate far and approach the shores from nearby areas of the sea.

The migrations of Caspian herring have been well studied, among which there are groups of marine, semi-anadromous and migratory fish. The names of the groups show that the migration behavior of the herring of each group is unique.

Using the example of Caspian herring, one can see how great the influence of temperature and water currents on fish migrations. The Caspian Sea has a large extent from north to south, and therefore a significant difference in water temperatures. In winter, the northern part freezes almost completely. The northern zone of the middle part of the sea is also cooling. Under these conditions, the herring migrates to the south, where the water is warmer. There is a circular current (a kind of river inside the sea), in warm parts which holds the herring; in the cooled part of the current, near the western shore, there are few herring in winter. The hydrology of the Caspian Sea, especially the currents, has been well studied by the outstanding Russian scientist N. M. Knipovich. When spring warming begins, herring en masse approaches the western shore, then to the eastern shore, and from there to the northern Caspian Sea.

Semi-anadromous Caspian herring (bellied herring) live in the northern Caspian Sea, and spawn in certain areas of the Volga delta and in the ilmen. Migration of paunches is not far away.

More distant migrations were carried out by the anadromous herring of the Caspian Sea - the Volga herring and blackback. Volga herring in the lower reaches of the Volga moved in massive herds and before the construction of hydroelectric power stations reached not only the middle Volga, but partially reached Perm along the Kama, and sometimes rose higher. Another migratory herring, the blackback, also went approximately the same far into the rivers.

We have already talked about the Far Eastern sardine - ivasi. It is believed that Iwashi spends his entire life traveling. In our Far Eastern waters, Iwasi travels to summer time, sticking to areas where the water temperature is 8–10°. When the water temperature rises, the iwashi moves north. When the water temperature drops to 5°, the ivashi again changes its location, moving to the south.

In spring Iwasi from the southern part Sea of ​​Japan, possibly from more southern seas, heads north, forming two branches: one goes to our western coast of the Sea of ​​Japan and reaches Sakhalin, the other moves along the western coast of Japan and also reaches Sakhalin. Then both branches, united, descend to the south along our shores of the Sea of ​​​​Japan.

It is possible that in reality the migration routes of the Iwashi are more complex than they are shown in the figure, but the essence of the migrations remains the same.

Cod migrations

The bottom fish cod is of great commercial importance. Its fishery is well developed in the seas of the European north. Soviet and foreign researchers have been studying the biology of this fish for decades. The migrations of Norwegian cod, precisely the cod that forms the main subject of our Murmansk fishery, have been studied in detail.

In June-July, large Norwegian cod approaches the Murmansk coast, heading from west to east. In August, it can be said to fill the Barents Sea, moving from one bank to another, from one pasture to another. Cod also extends beyond the Barents Sea; packs her in warm years even penetrate into the Kara Sea. In search of food (small fish - capelin and gerbil), cod swims throughout the sea and comes close to the shores.

In September, the cod begins its return journey to the west. By the end of November, only a negligible amount of large cod remains in the Barents Sea.

The main spawning grounds for cod are off the coast of Norway. The spawning time is winter and spring, but sometimes also the summer months. The larvae emerging from the eggs are carried away by the Gulf Stream far from the shores; along the way they feed and grow. Some of the young fish end up in the Barents Sea, where they find abundant food. Having reached sexual maturity, cod from the Barents Sea goes to spawning grounds.

This is the general picture of the migrations of cod fished in the Barents Sea, but in detail this picture is more complex.

In the Barents Sea and to the west of it there are local cod stocks, the migrations of which differ from the migrations of the Norwegian cod.

Researchers tag cod every year. Thousands of fish are tagged by attaching metal tags that have a unique number on them, allowing the time and place of release of the cod into the sea to be determined. Using these marks, you can determine the path taken by the tagged cod and the speed of movement of the migrating fish. Thanks to tagging, it has been established that spawned Norwegian cod, having traveled from the western coast of Norway to the eastern limits of the Barents Sea, covers a distance of up to 2000 kilometers.

From cod fish Haddock also migrates over long distances. Its migrations are also well studied.

Flounder migrations

Do migrations exist in fish that are tied to the bottom and are poorly adapted to long-distance movements due to the shape of their bodies? Do flounders migrate? After all, it is difficult for them to swim for a long time, because their body cannot be positioned vertically when swimming?

Flounder have migrations, but their length is shorter than that of fish such as herring or cod. Migration has long been studied sea ​​flounder, distributed along the coasts of Europe, from the Barents Sea to the Bay of Biscay, as well as flounder, which lives in the North Sea. There are many similarities in the migrations of different flounders.

North Sea flounder for spawning moves away from the shores and descends to depths of several tens of meters. The larvae that emerge from the eggs begin to migrate to the shore. It was found that such seemingly helpless creatures as larvae can travel a distance of 120 kilometers, traveling 1 kilometer per day.

In body shape, flounder larvae are similar to the larvae of other fish, and they do not stay at the bottom, but in the water column. Having reached a length of 13–17 centimeters (by this time the body has already become flat), flounder sink to the bottom and feed near the shore. Tidal currents force young fish to approach the shore and then move away from it. Moving from one depth to another, fish also make vertical migrations.

Adult flounder are able to move longer distances than juveniles. Cases are described when a flounder traveled 600 kilometers in 289 days. Flounder migrations are associated with the search for food, changes in water temperature, and spawning.

Lake fish migrations

Freshwater fish, which spend their entire lives in lakes and rivers, also make migrations, both vertical and horizontal, but the latter are shorter than those of marine fish. Some lake fish temporarily leave the lake and go quite considerable distances into the river.

Salmon from Lake Ladoga go mainly to Svir and Vidlitsa for spawning; salmon from Lake Onega go to Shuya, Suna, and Vodla. Finnish and Soviet researchers tagged Ladoga salmon. This helped establish the time, direction and distance of migrations. It was revealed that salmon pastures are located mainly against the northwestern coast of Ladoga. After spawning, salmon return to their pastures, to places far removed from the spawning grounds.

Salmon tagged in the Svir River (downstream salmon) went to feed in the western and east coast northern part of Ladoga. During tagging, these fish were severely emaciated, since they had been in the river without food for a total of more than six months (before and after spawning). Once in the lake, the salmon quickly began to increase their weight. The salmon, tagged on June 1, 1929 at the mouth of the Svir, weighing 2.5 kilograms, when caught on August 11 of the same year slightly north of the mouth of the Vidlitsa River, weighed 3.25 kilograms, that is, in 72 days they increased in weight by 750 grams.

Onega salmon can travel along the Shuya River to its source, covering a distance of 150 kilometers.

The migrations of lake salmon are very similar to the migrations of sea salmon, but the difference is that lake salmon replace the sea with lakes, from which they migrate to rivers. Not all salmon that spawn in the river return to the lake, large number they die from exhaustion. Secondary spawning in salmon is rare.

Several breeds of whitefish live in Ladoga and Onega. Lake whitefish do not enter rivers; migratory whitefish head into rivers to breed and travel long distances along them.

The migratory whitefish of Ladoga is the Volkhov whitefish, which used to go to the Msta River to spawn. To reach it, the whitefish had to cross the Volkhov River. The construction of the Volkhov dam deprived whitefish of the opportunity to make such migrations. An incorrectly constructed fish passage in the dam does not help either. The Volkhov whitefish herd has noticeably decreased. That's how much the usual migrations mean in the life of fish! It would seem that, having encountered an insurmountable dam, the Volkhov whitefish could change the direction of its migrations, using neighboring rivers, but this occurs only to an insignificant extent. Therefore, the Volkhov whitefish herd can only be restored in the future.

Migratory whitefish are found in many rivers of the northwestern region. They also exist in Siberia.

Lake smelt can be called a semi-anadromous fish: it spawns in the rivers where it goes in the spring. But even a few months before spawning, the smelt living in Lake Ladoga makes mass migrations in the lake itself in the direction from north to south along the eastern shore. This direction is not accidental. From the southern part of the lake to the north near the eastern shore there is a lake stream, a kind of intra-lake river. The smelt moves towards him. After spawning, which occurs in the lower reaches of the rivers, it returns along the stream. Smelt migrates not only to spawn or in search of food, but also when the wind direction changes, causing a change in water temperature.

Many lakes contain small smelt, or smelt (Pskov, Belozersky, Vodlozersky). This fish spawns in the lakes themselves. But there are sea smelts that enter rivers and swim along them over very long distances. The Arctic Sea smelt rises 1000 kilometers along the Yenisei River, the White Sea smelt also enters the rivers, but its river path is very short. Sea, Neva, smelt rises along the Neva to the rapids and spawns here.

In the same way, the migrations of vendace are different. The Ladoga large vendace - ripus - is found only in negligible quantities in the lowermost part of the Volkhov River. This fish spawns in the lake opposite the mouth of the river. The migrations of the ripus resemble the migrations of the White Sea smelt, which from the Soroka Bay enters the Vyg River only 1–2 kilometers and spawns in the lip opposite the Vyg. Small lake vendace, which inhabits many water bodies, does not leave the lakes to spawn. In its migrations it is similar to smelt.

The examples given are interesting in that they allow us to find an answer to the question about the reasons for the migration of freshwater fish.

Many freshwater fish once lived in the sea. With their migration to fresh waters, migrations gradually changed: at first, fish migrated from lakes to rivers, then they were limited to approaches to the mouths of tributaries of lakes, and, finally, many switched to permanent residence into the lake. It can be assumed that in this way burbot, perch and other fish, which migrate only within their small lakes and rivers, gradually lost their habits of long migrations.

River eel migrations

I would like to especially dwell on the amazing migrations of the river eel. There is so much mystery, sometimes difficult to explain, in the behavior of this valuable commercial fish!

The eel lives in the rivers of the European Atlantic coast, where it is an important fishery object. In our country, eel fishing is developed in the Baltic states, including the Gulf of Finland. But eels are found here and in other places. There have been cases of eels being caught in the rivers of the White Sea and Black Sea rivers. Sometimes this fish is found in the lower reaches of Pechora and even in the Volga delta, that is, in two unrelated river systems north and south. Eels are also accidentally caught in the lakes of Karelia. Eels were also found in Lake Peipsi.

If we compare the named places, the question involuntarily arises: how does the eel get into these reservoirs that are so far apart from each other, and often poorly connected to rivers? Why has no one found spawning grounds for eels, their eggs and larvae in either rivers or lakes?

It is difficult to find any other fish whose life is so little observable as the life of the eel. No wonder there were the most fantastic stories about this fish. Some argued that eels come from earthworms, which they resemble in their bodies; others believed that the eel is born from the viviparous eelpout fish; still others said that eels reproduce differently from other fish, that they do not have eggs.

The tiny (less than 1 centimeter long) eel larvae found in the seas were mistaken for a special fish called “leptocephalus brevirostris” (these two words, one Greek, the other Latin, translated into Russian mean “small-headed, short-snouted”). Indeed, the leptocephalus has a very small head, ending with a short snout. Then researchers began to assume that the leptocephalus was not an adult fish, but a larva of some kind of fish.

In the end, 60–70 years ago, scientists came to the conclusion that the mysterious leptocephali are nothing more than eel larvae. They began to look for the location of the smallest eel larvae in order to find out in this way where adult eels spawn. For many years, scientists tried to solve this problem and finally succeeded. Here's what we now know about eel migrations.

Eels that grow up in rivers and lakes, after living here for 4–6 years and reaching sexual maturity, leave fresh water bodies. It is interesting that mostly females live in fresh waters, while male eels prefer salty and brackish water and enter fresh water bodies in negligible numbers; In the Gulf of Finland, male eels are not found at all.

The migration of an adult eel, prepared for spawning, occurs in an unusual way: not towards the flow of water, as migratory fish go to spawn, but along the current. The further path and behavior of the eel are even more surprising. Entering sea ​​waters, females descending from the rivers, and males located in the coastal parts of the sea, go further together, cross the Atlantic Ocean and in the ocean area between North and South America, in the Sargasso Sea, at a depth of about 1000 meters, where the water temperature is at least 7° , females spawn. The details of eel spawning remain unknown. Researchers believe that after spawning, eels die. No one has yet managed to find eels that spawn.

The worm-like larvae, 1–2 millimeters in size, emerging from the eggs, gradually rise from the depths to the surface and begin their long journey in the direction opposite to that in which the parents moved. For three or four years they float along the Gulf Stream to the shores of Europe.

In the first summer, the larvae reach a length of 25 millimeters and are located in the western part of the Atlantic Ocean, in the second summer they are 50–55 millimeters long, and they are already in the central part of the Atlantic Ocean, in the third summer the larvae approach the shores of Europe and begin their journey to fresh waters ; at this time their length is 75–80 millimeters.

During such a long journey, the larva's body undergoes great changes. In the first days of life, the eel larva has some similarities with the larvae of other fish - it is round in shape. Then the larva takes the form of a thin tree leaf (one-year-old larva), then, enlarging, it becomes like a flat fish (two-year-old larva), after some time (before entering the rivers) the larva turns into a fish with a tall body, then into a worm-shaped glassy eel and finally, in fresh water - into a large eel.

Sturgeon migrations

The most ancient of our migratory fish are sturgeons, which are found in the Black Sea, Azov, Caspian, Aral and Baltic Sea basins, in Baikal and in some reservoirs Far East. The closest ancestors of modern sturgeon lived in salty and brackish waters. Later they began to enter fresh waters, at first only in the lower reaches of rivers, and then in the middle and upper sections.

The Amur Kaluga rises along the Amur almost to its source, the Caspian beluga goes far along the Volga, the Aral sturgeon - thorn rises along the Syr Darya and Amu Darya. Sterlet has already become completely freshwater river fish, has lost contact with the sea, but temporarily it descends into the coastal sea zone, although it never spawns here. Baikal sturgeon too freshwater fish, never goes to sea, but this fish has maintained its migration to river waters. The Baltic sturgeon migrates from the sea to rivers, enters the Neva, along it reaches Lake Ladoga, and spawns in the Volkhov River. Apparently, this fish in Lake Ladoga can become purely lake fish, since it is found here at all ages. The Azov sturgeon climbed 1000 kilometers along the Don, the Caspian one goes to the Urals, Kura, Volga and other rivers.

After spawning, sturgeon return to the sea; Their fry also swim here. The very movement of sturgeon along the rivers presents an interesting picture. Sturgeons, bottom-living fish, would seem to have to stick to the bottom during migrations. But while the fish are moving, you can see from the shore how the sturgeon jumps out of the water and noisily dives again. In this case, fishermen say that the sturgeon “soared,” that is, rose steeply, like a bird. The frequency of such jumps is used to judge how gregariously the sturgeon moves.

Migrations against the flow of water are usually called catadromous (translated from Greek as “running up”), while migrations along the current are called anadromous (“running down”). Migration cannot but be influenced by the speed of the current. Some fish choose fast currents for their migrations, others quiet ones.

Each species of migratory fish has its own temperature optimum at which migration occurs. Knowing them helps to correctly determine the fishing time. In the past, Astrakhan industrial fishermen spent a lot of money on so-called test fisheries. In order not to miss the move, for example, roaches, they pulled the seine and looked at what kind of fish was coming and in what quantity. And when researchers established that the roach travels in the lower reaches of the Volga at a temperature of 10–15°, the travel (and fishing) time began to be determined not by the net, but by a thermometer.

Sea salmon migrations

Even more striking are the migrations of sea salmon that go from the sea to the rivers to breed. This refers to Atlantic salmon (salmon and taimen) and Pacific salmon (chum salmon, pink salmon and others), which are also called Far Eastern salmon.

Atlantic salmon enter the Neva from the end of May and continue migrating until mid-September with a break in mid-summer. Salmon are found in all parts of the river, from mouth to source. An insignificant amount enters Lake Ladoga (reaching its northern part). Sea salmon have been found near the Valaam Islands and even in the Vuoksa River. Perhaps this is evidence of more massive migrations of sea salmon to Ladoga in earlier times. Sea salmon previously reached Lake Onega through the Svir River, but they were found here extremely rarely.

From mid-October until winter, salmon, extremely exhausted after spawning, returns and rolls into the sea; many salmon die after the first spawn. In very rare cases, the same female salmon enters the Neva (or other rivers) three times to spawn. Only once in Scotland was a female salmon found that had spawned 5 times.

Taimen enters the Neva, Luga and rivers of the Karelian Isthmus, like ordinary salmon, in spring and autumn, but in very small quantities.

Salmon is the same as Atlantic salmon, but it breeds in our northern rivers, flowing into the Barents and White Sea. As an exception, salmon was found in the Kara River, which is the eastern limit of the distribution of this fish.

Research by Soviet and foreign scientists has established that salmon has two varieties - summer and autumn. Sexual products (caviar and milt) are the first to ripen in river water for short time, 2–3 months; reproductive products of the second – in 12–13 months. Summer salmon enters rivers in the summer, when its reproductive products are already well developed, and spawns in the fall of the same year; autumn salmon enters in the fall, with immature reproductive products, and spawns in the fall of the next year, that is, a year after entering river waters.

White Sea fishermen, based on centuries of observations, assigned special names to various salmon herds - “under-ice”, “ice-ice”, “close”, “low-water”, “tinda”, “autumn”.

Under-ice migrates into rivers at the very beginning of spring, when there is still ice in the river.

Ice is salmon that follows the opening of the river (in the White Sea rivers usually in early May).

The cutting starts from the beginning or half, sometimes from the end of June. The tail is represented predominantly by females with developed reproductive products. This is real summer salmon, also called spring salmon.

From mid-July, simultaneously with the closure, there is a low-water season - also summer salmon with a predominance of large males.

With low water comes the tinda - small males. The height of the Tinda period is the second half of July and the beginning of August.

Autumn season starts from mid-August until freeze-up.

Podice and ice latch are sometimes mistaken for autumn salmon that have overwintered in the lower reaches of the river, which in the spring resumes its journey to the spawning grounds.

Migration in individual rivers and in different years has its own characteristics, but the overall picture is quite uniform throughout.

After spawning, the surviving salmon returns to the sea thin, with great changes in the body. Such emaciated salmon were called “lokhov” and “valchak”. The silver, slender, handsome salmon becomes dark, red and orange spots appear on the sides of the body and head, similar to bruises, the snout lengthens, the jaws bend into hooks, and the front teeth on them become greatly enlarged. A huge number of male salmon die after spawning, and few females remain.

Previously, it was believed that White Sea salmon did not go far to the west. But here's what the tagging showed. A female salmon was caught in the Vyge River with a tag that indicated the fish was tagged off the west coast of Norway. Since salmon usually come to spawn in the river where they hatched, we can assume that the salmon caught in Vyg hatched in this river. Here she lived for three years as a fry, then went to the shores of Norway. There in the sea she grew for another three years (this can be seen from the scales), reached sexual maturity and returned again to Vyg.

The fish traveled about 2,500 kilometers in one direction and the same amount in the other. As the mark shows, it took the salmon about 50 days to return. This means that the fish traveled at least 50 kilometers per day. It is known from foreign sources that salmon can travel up to 100 kilometers per day. This is quite plausible, if we keep in mind that salmon migrating to rivers have a very great strength and is distinguished by significant swimming speed.

The young generation of salmon remaining in the river, after 1–5, more often after 2–3 years, slides into the sea and grows there quickly.

Among the fish of our waters, there is no other genus whose species have such complex migrations as the Pacific Far Eastern salmon - chum salmon, pink salmon, red salmon, coho salmon, chinook salmon and masu salmon. One Russian scientist, more than a hundred years ago, quite correctly called their migrations “nomadism until death.”

Chum salmon, like salmon, has summer and autumn varieties. Summer chum salmon comes to the Amur from July, autumn chum salmon - in August-September.

Three times (in 1925, 1926 and 1928) I observed the migration of chum salmon to the Amur and other rivers of the Amur Estuary, the Tatar Strait and to the Bolshaya River (on the western coast of Kamchatka). First of all, attention is drawn to the fact that chum salmon enter the river in separate herds, with interruptions. The reasons for the interruptions appear to be related to weather or different ages migrating fish.

To the Amur, chum salmon comes from the Sea of ​​Japan through the Tatar Strait, sometimes close to the shores, sometimes at a distance from them. The chum salmon along the Amur rises very high, enters its tributaries and spawns there, and the summer chum salmon is closer to the mouth of the river, the autumn chum salmon reaches the upper reaches of the Amur and its tributaries, which lie at a distance of more than 1–2 thousand kilometers from the lower reaches of the river.

Spawned chum salmon never return back to the sea - all the spawners die.

Near the city of Nikolaevsk, at the mouth of the Amur, pink salmon appear in June; at the same time it goes in the Tatar Strait and in the Amur Estuary. First the fish goes to small quantity, but then, after 10 days, a massive movement of pink salmon is observed within a half-month. Then the number of pink salmon going to spawn decreases and after a month from the start of the run it stops altogether. Only one month a year, and even then not every year, pink salmon appear in huge herds in the waters of the Amur. This month is a very busy time for fishermen.

In my hands was a tag taken from a pink salmon caught in the Amur Estuary on July 18, 1928. Through the Soviet representative office in Japan, it was possible to establish that this pink salmon was tagged by the Japanese off the coast of northeastern Korea on May 18, 1928. This means that pink salmon came to the Amur from the southern part of the Sea of ​​Japan, having traveled at least 1,600 kilometers in two months (covering 25 kilometers per day).

But there are other directions of migration of pink salmon. Often, a stock of pink salmon in the southern areas is discovered later than in the northern ones; Moreover, the timing of the migration of Amur pink salmon and Kamchatka salmon does not coincide. A comparison of migration dates suggests that pink salmon have several (probably many) stocks living in different parts of the sea.

When pink salmon are moving, the sea opposite the river mouths presents an extraordinary picture. Against the pink background of the evening dawn, everywhere you look, luminous splashes rise here and there - pink salmon are playing, jumping out of the water. The sun has set, the dawn has faded, and the fish fountains are still rising, all flaring up over the lead-dark surface of the Sea of ​​​​Okhotsk.

I also observed the progress of pink salmon along the Bolshaya River in Kamchatka. An amazing sight! The weather was calm and sunny. The play of rapid streams colliding near the river shallows only occasionally slightly changed the mirror-like surface of the water. Suddenly, from the middle of the river, from an underwater hump between two river fairways, a terrible noise was heard, reminiscent of the splashing of water boiling in a large cauldron.

From the shore we spent a long time admiring the movement of a huge school of pink salmon, which, like a strong stream, burst into the Bolshaya River and, overcoming its current, rushed further and further, higher and higher. The length of the school was at least 1 kilometer and the width was approximately 100 meters, so without exaggeration we can assume that there were more than one million fish in it.

For two weeks, from morning to evening, the humpbacked backs of male pink salmon and the silvery bellies of females, jumping high above the water, were visible rising above the surface and again slowly sinking into the water. This continuous dance of fish in the river did not stop at night.

The onset of pink salmon disease manifests itself from the moment it enters fresh water rivers. I will give my notes made 13 kilometers from the mouth of the Bolshoy River, that is, very close to the place where pink salmon enter the river from the sea. “A school of fish swims slowly between the piles of a fishing raft. Lots of wounded fish. I can clearly distinguish scratches made by seal claws (straight, usually sharply defined two or three parallel stripes), and lacerations, obtained from the same seals.

Many wounds rot, covered with a white web of marsupial fungi, which, like flakes of cotton wool, stick to different parts of the fish’s body. In some fish, these destructive flakes crawled over the eyes, in others they formed continuous muffs that encircled the caudal peduncle and deprived it of proper movements, in others the plaque began to appear near the base of the rays of the caudal fin. The fish does not grab food, although some individuals quickly rush to the surface of the water when we throw something from the raft. Every day the pink salmon’s movement becomes slower; it hides the joys and sorrows of its life more and more in underwater hiding places...”

In order not to return once again to the issue of the death of pink salmon after spawning, we will follow the fate of the fish to the end. Having reached the spawning grounds and laid eggs, pink salmon become completely exhausted. A huge number of half-corpses are carried downstream by the water; many fish die right there, on the spawning grounds, covering the river bottom with corpses. You see all this when you are sailing in a boat. After low tides, the banks of the river are exposed with many corpses of pink salmon.

Dogs and birds, which just recently hunted for pink salmon, have already had their fill. A dog will approach a pink salmon, bite its head and walk away. Birds only peck out the eyes. And the bears, whose paths from the taiga to the river are as well-trodden as the paths of livestock in our villages, make provisions for the winter - they pull out fish and bury them in a hole.

This is how the migration of pink salmon ends in tragedy! Only once in her life does she spawn and pay for it with her life. This is the fate of other Far Eastern salmon. The only difference is that other salmon live for a longer time before spawning, from 3 to 7 years, while pink salmon live only a year and a half.

Young pink salmon, emerging from eggs, roll into the sea in the spring or summer of the same year.

This is how fish live restlessly. They're in constant movement, everyone is striving somewhere, looking for something. Some leave the sea, go hundreds and thousands of kilometers to almost dry streams in order to lay prepared eggs there, others make a long journey to find food for themselves, a “piece of bread”, others, avoiding sunlight, descend into the gloomy depths, others, on the contrary, are in a hurry to rise to the surface, and so on.

True, there are also homebody fish. The burbot leaves its secluded corner (under stones and in the coastlines) only for a short time; The catfish does not leave its pool for many years. But even homebodies, willy-nilly, have to crawl out of their homes. About the travels of fish, read the fascinating book by P. Yu. Schmidt “Migrations of Fishes”.

So, we have found out the reasons for fish travel. But how can we explain that some fish choose one route, while others choose another? Some Siberian whitefish, caring about preserving their eggs and fry, go to spawn in rivers, but why do they need to spend so much effort to climb the river more than 1000 kilometers? Why not focus on tributaries close to the sea? big rivers? Why did the Caspian whitefish rise so high along the Volga and its tributaries? There are many such “whys”.

The migration routes of fish are rightly associated with the movement of ice in ice age. But if we imagine the directions of these migrations, we get an extremely complex picture. The migration of northern fish to the south and their return from south to north can easily be explained by the paths of glaciers from northwest to southeast and back. But the eel goes from east to west, the salmon from west to east and from east to west. As you can see, there is still a lot to think about in order to unravel the reasons for the emergence of certain fish migration routes.

We have already said that salmon and Far Eastern salmon come to spawn in the rivers in which they hatched. Observations of salmon in nature and experiments on transplanting them into rivers confirm that, for example, pink salmon “remember” their homeland and breed a new generation in their “native” river. The pink salmon fry that emerge from the eggs swim somewhere out to sea a few months after birth, but the next year they go to the same river where they were born. They have no guides; their parents died a year ago. The path of pink salmon is not lined with any buoys or milestones. How does she find “her” river? There is no consensus on this matter. Some scientists believe that salmon go to their native rivers by instinct. They are guided, as American scientists say, by the “homing instinct,” that is, the instinct of home, homeland.