How to determine the age of the caught fish. Fish Age Definitions

The age of fish can be determined by the number of concentric rings on the scales. A. Leeuwenhoek (1684) was the first to pay attention to the correspondence of the number of rings on the scales to the number of years lived by the fish. The method for counting rings is quite simple. To determine the age, scales from the area at the base of the first dorsal fin are usually used.

The scales are washed in a solution of ammonia, wiped, clamped between two glass slides and viewed under a magnifying glass or at low magnification of a microscope. (It is advisable to smear small scales with glycerin before viewing.) Often additional rings are viewed between the annual rings, the origin of which is associated with spawning (salmon, herring) or a change in the intensity of nutrition (cyprinids). Additional rings are expressed not along the entire length, but only on one side of the scale.

It should be recognized that not all fish species have scales with clearly visible annual rings. Therefore, to clarify the result of counting the number of annual rings, annual rings of bones are used. Various bones are suitable for this purpose: in perches - the gill cover, in sturgeons - the rays of the pectoral fins, in pike perch and catfish - the rays of the dorsal or anal fin (Fig. 1). The age of many marine fish It is more convenient to determine the annual rings on the otoliths (flounder, notothenia, cod). In these cases, a transverse cut of the bones is made or thin sections are made. Annual rings are examined under a magnifying glass (sections of rays - under a microscope), if necessary, for greater clarity, the preparations are lubricated with glycerin or moistened with water.
The interpretation of the obtained results can be difficult or ambiguous.

Rice. 1. Annual rings on the cut of a ray of fish, the pectoral fin of stellate sturgeon in water bodies of medium and high latitudes, certain terminology and special designations have been adopted to characterize the age of fish by annual rings.

The number of rings on the scales (bones, rays, otoliths) and the calendar age of the fish are linked as follows:

Movement should be considered as the most important property of all living things. At the subcellular level, along with the irritability of the cell, it is a hallmark of life. However, movement in the microcosm is characteristic of both plants and animals. The movement of multicellular structures with the help of specialized cells and tissues (muscle) is a distinctive feature of animal organisms. The emergence of the ability to move marked a new stage in evolution. The emergence of striated muscles in animals allowed them to conquer the entire biosphere.

In evolutionary terms, it was movement that gave rise to the nervous system in the animal world. As the motor activity of animals became more complex, their nervous system became more complex. Within any class of both invertebrates and vertebrates, the level of development of the nervous system reflects the degree of complexity of motor activity. In vertebrates, the level of development of the musculoskeletal system correlates with the complexity of the structure of the nervous system and determines the complexity of behavioral reactions that provide nutrition, resettlement, reproduction, development of new territories, intra- and interspecific relationships.

Movement allows animals to effectively adapt to changes in the external environment, that is, to maintain their viability, preserve the population and the species as a whole. The adaptability of the organism is based on two motor processes: avoidance (protection) from an unfavorable factor or a change in itself. In the first case, the animal uses the musculoskeletal system (avoids danger, finds food, builds a shelter). In the second case, the animal adapts its body: it increases blood circulation, increases the respiratory rate, enhances (reduces) heat transfer, etc. However, in both cases, structures that include contractile elements act as executive organs.

Question "How to determine the age of fish?" has long been of interest to scientists and, as it turned out, it is not so difficult to do this.

If we examine the scales of fish under a microscope or even under the most ordinary magnifying glass with a tenfold increase, then you can easily see rings similar to rings on a saw cut. Each of the rings corresponds to 1 year of life of the fish and is called "winter", although in some cases it may appear in spring or summer. It is curious that these annual rings are also formed on the scales of fish in equatorial waters, as well as in fish living at great depths, although it would seem that they constantly live in unchanging climatic conditions. Therefore, the answer to the question "How to determine age and age is the same - the habitat does not affect this.

fish in different years of her life?

By the scales, one can determine not only the age of the fish, but also the length that it reached annually. Suppose a meter radius is one centimeter. The distance from the first annual ring to the center of the scale is 6 millimeters. Therefore, at the age of one year, the fish was 60 centimeters long.

If, for example, we consider the scales of salmon, we can easily see that the first two years of life, the fish grew very slowly. The inner annual rings are very close to each other. Then growth accelerated markedly. And this means that the young fish went out to sea from the river, where there was much less food. On the surface of the scales, traces of fish participation in spawning and past diseases may remain. As a result, for a knowledgeable ichthyologist, a fish scale serves as a genuine passport, making it possible to find out the age, annual size, time spent in the sea, river, and the number of spawning.

How to determine the age of fish that do not have scales or are they very small?

In this case, the necessary analysis can be done on the gill cover, transverse cut of the vertebrae and auditory pebbles. Thanks to modern methods for determining the age of fish, many misconceptions about the extraordinary longevity of carps, pikes and catfish have been dispelled. Although to this day in popular and educational literature they mention a pike, which supposedly lived 267 years and reached a weight of nine pounds. The portrait and skeleton of this pike were shown in German museums for a long time. Later, the calculation of the vertebrae in the skeleton showed that it was assembled from the bones of two (or more) large pikes and was the fruit of the creation of the enterprising ancestors of the well-known Ostap Bender.

And if we operate only with reliable data, then the age limit for pike, catfish and halibut is 80 years, cod - more than thirty, beluga - about a hundred, oceanic herring - 25, carp - 20, pink salmon - 2, and Azov anchovy - 3. However , 30-year-old cod are less common than 100-year-olds. Sea bass grows much slower than cod. Specimens prevailing in the catches, about 40 centimeters long, have a respectable age (up to 17 years!). As a rule, all grow very slowly. The increase in length of fish slows down over the years, and weight gain usually accelerates.

How to determine the age of marine fish by other signs?

He's good

determined by the bones: each year lived by the fish is indicated by a stripe on the gill covers. Ichthyologists have found that they even have annual rings. They form on thick rays that are located at the base of the pectoral fins. And in some species of fish, age is determined by otoliths. When sawing it, annual rings are clearly visible. Scientists are very seriously thinking about how to determine the age of fish as accurately as possible, since this is of purely practical importance. To predict the abundance of a particular species, you need to understand the dynamics of the development of this species. A large number of fish reach sexual maturity rather late. So, the Amur salmon spawns for the first time at the age of twenty. During this time, they are carefully monitored, since even minor changes in their habitat can cause the death of the entire species.

So how do you determine the age of a fish?

It turns out that there is nothing complicated here, and there are many ways to do this. There are more complicated methods, but there are very simple ones, accessible to any of us. You just need to arm yourself with a magnifying glass.

Without knowing the growth rate and life span of trees, it is impossible to conduct forestry; without knowing the age and height of domestic animals, it is impossible to properly engage in cattle breeding. The arborist has long learned to determine the age of trees by annual rings on a cross section. The growth of livestock takes place before the eyes of the owner. And what about the fish? The fish farmer encounters great difficulties in determining the age and growth of fish.

Some fish live very long lives. Longevity differs pike. Many books described a pike weighing 8 pounds 30 pounds and more than 8 arshins long, caught in 1497. On it, allegedly, there was a mark of 1230, that is, the pike was caught 267 years after the mark. This message was long considered plausible, but later it came to be treated with distrust. More reliable data show that pikes can live up to 100 years.

Catfish, beluga and other large fish differ in longevity. However, we know little about the limiting ages of large fish. In lakes and rivers where fishing is developed, rare fish live up to their age limit. The fishermen noticed that a large catfish lives in such and such a hole - they will definitely catch it, if not this year, then next. They are well aware that catfish are reluctant to change their place of residence.

Amur kaluga is found in the fishery at the age of 50–55 years, when its weight is 650 kilograms, but sometimes there are specimens that weigh almost twice as much. Their age is over 100 years. Many years ago, a Caspian beluga weighing 1,500 kilograms was caught. The author of this book happened to see a beluga weighing 880 kilograms.

Sometimes there are specimens of the Volga sterlet more than a meter long, their age is at least 50 years. In 1913 I saw sterlets that had been kept for 35 years in the Nikolsky fish hatchery.

Nelma usually lives for more than 10 years; the life expectancy of the Yenisei nelma is over 25 years.

Of the cyprinids, bream is distinguished by longevity - there are individuals that are over 20 years old.

Most whitefish in the European part of Russia live less than 12–10 years. Smelt does not reach this age either.

The maximum lifespan of Far Eastern salmon is 8 years.

The largest representatives of a particular species should be registered. It is important to correctly determine their age, as this will allow you to get a rough idea of ​​the age limit of a particular fish, which is important for the regulation of the fishery. When breeding fish, this also has to be considered.

If it is important to know the age limit of fish, then it is even more important to find out the rate of their growth. Fish of the same species in different reservoirs grow differently: in one reservoir, the length and weight of fish are greater than the corresponding indicators for fish of the same age taken from another reservoir. It turns out that in one reservoir the fish grows better, in another worse. It also happens this way: in the same reservoir, one group of fish grows faster than another group of the same species. Hence, these groups belong to biological varieties. So, in Lake Peipsi there is a fast-growing whitefish and a slow-growing whitefish belonging to the same subspecies.

The first example indicates that the growth rate of fish is affected by the food supply of the reservoir, the second shows that fish of different breeds of the same species develop differently under the same conditions. The first example allows you to evaluate the reservoir, the second - the breed of fish.

Determining the age of the fish caught by the fishery, they find out which age groups make up the main part of the prey, which are caught to a lesser extent and which are absent. The age composition of the caught fish indicates the state of stocks of one or another species. Fishing without regard to the age composition of fish can undermine fish stocks.

For a number of years, trawl fishing for whitefish has existed in Lake Ladoga. The cell of guns was of such size that a huge number of young whitefish were also caught. As a result, whitefish stocks have declined so much that trawling has had to be banned.

Studies conducted at the beginning of this century showed that the Amur kaluga spawns for the first time at the age of 18–20 years. In the interests of preserving the stocks of this most valuable fish, its catch should be limited to the first spawning.

It also happens. The fishery, having little interest in ruff and perch, leaves their stocks almost untouched. There are many perches and ruffs of older ages. In this case, the recommendation is different - to increase the capture of these fish.

Thus, knowledge of the age of fish is necessary not only to satisfy curiosity, but also for the proper management of fisheries.

How is the age of fish determined?

fish scales

You probably paid attention to the fact that on the shell of the toothless (there are many of them in rivers and lakes) semicircles are visible. Each of them corresponds to one year of the animal's life. The same rings as on the shell of the toothless and on the transverse cut of the tree are visible on the scales of fish, on the bones of the gill covers and other bones.

The scales of such fish as salmon, cyprinids and others is a rather thin plate, on which there are many rings and, in addition to them, several sharply distinguished wide circles. The number of wide circles indicates the number of years lived by the fish.

Not on every scale and not on every fish, one annual ring differs sharply from another. It is usually difficult to distinguish the first (central) ring from the second. In this case, the researcher takes into account the size of the fish and compares several scales of the studied fish.

Annual rings are clearly visible on the scales of pike, flounder, young pike perch, but it is very difficult to distinguish them on the scales of tench, eel, burbot, loach and other fish.

It was said above that the life expectancy of pink salmon is usually 1.5 years. How did these 1.5 years affect the scales of the fish? On page 141 is a photograph of pink salmon scales. The fish was taken by me on July 14, 1928, at Cape Jaore in the southern part of the Amur Estuary, opposite Sakhalin Island. Pink salmon went to spawn in the river and had a body length of 43 centimeters. This was the average size of pink salmon caught in the Amur Estuary. In total, to determine the age, I examined about 3000 fish, and more than 8000 scales. The picture was the same everywhere.

What did scales say about age? It is worth carefully considering the scales of lake salmon and salmon - sea salmon. Lake salmon goes to spawn from the lake to the river. After hatching, the fry remain in the river for 2–4 years. There is not as much food here as in the lake, and the juveniles grow slowly in the first years. The slow growth of salmon in the river is also reflected in the growth of scales.

So, the age of the salmon, the scales of which we examined, is the fourth year: two years were spent in the river and one in the lake. So, we see that the scales can not only determine the age of the fish, but also establish the various periods of its life.

However, the fish "passport" is not always so easy to read. In addition to spawning rings, there are other (so-called additional) rings on the scales, which arise under the influence of environmental factors, as well as depending on the general condition of the fish itself. The lack of oxygen or food in the water slows down growth, favorable conditions accelerate it. Additional rings, if you understand them, will tell a lot about the life of fish.

We studied carp on the Volga from the moment of its release from spawning and for 4-5 months. An amazing picture was on the scales of the fish! The scales of a young carp, which lived only one summer, had 5 rings, each of which corresponded to certain conditions for the life of the fish.

By the tenth day of life, the length of the fry was 10 millimeters. This period corresponds to the first ring. The second ring was formed during the full life of the fry, when it had an unlimited amount of food, grew intensively: for 12 days of life in the expanses of a flooded meadow, the growth of the fish was 42 millimeters. The third ring, small and dense, appeared at a time when carp lived in a drying baklusha (temporary lake) in exceptionally difficult conditions - in highly overheated water, with a large crowding of fish. Naturally, the sazanchiki almost did not increase in growth. The fourth ring arose in the fish we took out of dirty buckets and transplanted into the spacious pond of the water station, where the water was clean and there was enough food; here we also carried out artificial feeding. Fry for 39 days of stay in the pond gave an increase in body length by 107.5 mm. The fifth ring indicated a new growth inhibition caused by poor nutrition: the fry were deprived of additional food.

If we did not know the exact age of carp, did not observe changes in conditions, then we could easily make a mistake by determining the age of carp at more than two years (instead of the actual 4–5 months). The fish on the scales wrote an autobiography, a diary of her life!

In a word, the scales tell not only about the years lived by the fish, but also about periods of prosperity and adversity. If we learn how to read the fish passport correctly, we will learn a lot of interesting things about the life of a particular fish.

Determination of the age of fish by bones

The age of the fish is reflected not only on the scales, but also on all its bones - “documents” that are stronger than the scales. After all, there are fish without scales. Many catfish do not have scales. There are no scales in some gobies. In sharks, rays and other lower fish, instead of the usual scales, the body is covered with plates with teeth (such plates are called placoid scales). In sturgeons, scales are replaced by five longitudinal rows of strong cone-shaped spikes - bugs.

From the plates of sharks and from the bugs of sturgeon, they have not yet learned how to determine the age of fish, since annual rings are not visible on them. But sturgeon fish have bones in their heads (as strong as those of bony fish), on which annual rings or planes are visible, which make it possible to determine the age of fish.

Ichthyologists have found that there are also annual bands on the cuts of the rays of the fins, and they can be used to determine the age of the fish.

If the fish has a bony spine, then the age is easy to determine by the vertebrae.

Finally, the age of fish is also determined by otoliths - calcareous stones located in the auditory capsule of fish.

It has long been noticed that there are stripes on the bones of fish. These stripes were sketched and reproduced in old books, but for a long time no one thought of connecting these stripes with the age of the fish. Only at the beginning of this century did they begin to study the age of fish from bones. The bones of flounder, cod and other commercial fish of the North and Baltic Seas were studied, as a result of which they came to the conclusion that it is more convenient to determine the age by flat bones similar to plates. Russian scientists E. K. Suvorov, V. K. Soldatov, V. O. Kler, and others worked hard in this direction.

If you remove the skin or muscles from the gill bones, cook the bones a little and clean them with a toothbrush, then even with a simple eye annual stripes will be visible. When viewed through a magnifying glass (5-10 times magnification), they are even more clearly visible. On the bones, annual bands are usually clearly visible, but in large fish over 10 years old, the first annual bands (one or two) are often barely visible.

The vertebrae are ground vertically for age determination.

Ichthyologists have learned to determine the age of fish not only by flat thin bones, but also by bones that have a compact structure. A strong thick ray of the pectoral fin of sturgeons or catfish is taken and an incision is made at its base. Then a plate is sawn out, on which, after grinding, annual planes can be found. 10 stripes - the sterlet was 10 years old.

Annual bands are visible on ray sections of many, probably all fish. The age of cod is easy to determine by the rays of the dorsal fin, the age of catfish, whitefish, asp and other fish - by the rays of the pectoral fin.

However, it is not yet known how to determine the age of lampreys. This animal is very special: it has neither gill covers nor vertebrae, and the rays of the fins are very soft. However, over time, ichthyologists will learn to determine the age of such fish. Ichthyological science penetrates deeper and deeper into the secrets of the life of fish. If it is impossible to determine the age of the lamprey from the structure of the body, then direct observations of it in nature and in the aquarium must be used for this purpose.



There is a common expression: silent as a fish. However, with a smart approach and knowledge of some theoretical foundations, you can “talk” even a freshly caught pike. In particular, you can get fairly accurate information about the number of years she lived. It is necessary for ichthyologists to determine the age of fish for scientific research as part of their professional activities, environmentalists are concerned with this issue in terms of the impact of the environment on the population of a particular fish, employees of the fishing fleet are concerned about the economic benefits of the catch.

An amateur fisherman is rarely occupied with such global problems: usually his interests lie in the field of practice. For example, it is unreasonable to fry or dry an old pike, but to stuff a “veteran” or use it in the form of cutlets is the very thing. Yes, the number of lives can be roughly estimated by the size of the fish, but this method is very inaccurate. A well-fed fish and an individual on a half-starvation ration, with the same number of years lived, will be very different in size. Fortunately, there are much more accurate ways to study age. Ideally, they require the use of a microscope, but when fishing, only approximate data can be obtained by eye.

Determination of age by scales

The study of scales is the most common and reliable method of research in this direction. It applies to most. Its essence lies in the study of scales for the number of annual rings. The fact is that, ideally, every year of a fish's life is marked by the appearance of a new ring, according to the tree principle.

For research in the laboratory, a microscope is used: a fresh or specially prepared flake is washed with a weak solution of ammonia and placed between glass slides under the eyepiece. A significant increase is not necessary - it even blurs the picture. To obtain approximate data, the sharp eye of an experienced angler or his own, armed with a magnifying glass, is sufficient.

The disadvantage of the method lies in its dependence on a number of conditions. The number of rings on the scale is not always ideal for age. Additional, less pronounced rings may appear due to changes in the lifestyle or diet of the fish. For example, this is typical for the transition from fry to regular food, fasting periods and. In addition, the annual rings may be less than the years actually lived by the fish: for example, eel scales appear at 3-4 years of age.

Examination of bones and otoliths

To study the age of some fish species, the “scaly” research method is either uninformative or in principle inapplicable. For example, to determine the exact age of the river perch, ichthyologists use an integrated approach: the method of studying the scales described above is combined with the analysis of flat bones. To obtain objective data, the results of all studies are taken into account.

Usually for this purpose gill covers are used: the growth rings on them are no less pronounced than on the scales. Examination under a microscope is not carried out: the gill bones are large enough for an ordinary visual inspection (you can use a magnifying glass). The material for analysis is prepared simply: the bone is separated from the carcass, cleaned of soft tissues and dried. A prerequisite: the fish must be fresh - lying in formalin or rotten is not good.

In cod fish and flounder, the scales are very small and delicate, therefore, in addition to studying it, the age of individuals of these species is determined by otoliths(colloquially - ear stones). They are removed from the labyrinth, carefully degreased, and sometimes sanded to give maximum transparency. Large specimens are broken, fixed on a glass slide with a plastic mass, clarified and scrupulously examined visually. It is clear that this method is applicable only in laboratory conditions.

How to find out the age by the ray of the fin?

Another purely scientific technique used in the laboratory is the study of the ray of the fin. Ichthyologists and oceanologists widely use it when analyzing the age of sharks: the scales of marine predators resemble large sandpaper and are unsuitable for research. In the case of sharks, the ray of the unpaired fin is taken as material.

Among freshwater fish, this research method is the most informative for all breeds of sturgeons, as well as catfish. If in the case of sharks, annual rings are immediately visible, it is enough to remove and clean the beam, then for the above freshwater fish, this method of determining age is much more labor- and science-intensive. Preparation of a preparation for examination under a microscope is impossible without the use of a special machine and reagents: it is necessary to make the thinnest section of the pectoral fin ray, process it and fix it on a glass slide. The technique is very informative and accurate, but, unfortunately, unrealizable at home.

And in general, the main thing is not the number of years lived by the fish and not even its size: it is important that you caught it yourself. And after receiving a fishing zen, you can ask about the age of the catch - purely for the purpose of self-development!

A huge number of fishermen and scientists from all over the world have long been wondering how to determine the age of a fish. The process of determining the age of a fish is somewhat similar to determining how old a tree is, only instead of studying the age rings of the cut, in the case of underwater inhabitants, they study the scales.

It is easiest to determine the age of a fish by the scales, as this is one of the most prominent and simple indicators. Some determine this indicator by the gills and bones, but this is a complex operation that only experienced fishermen or qualified scientists can handle.

When using various magnifying instruments, such as a microscope, you can see on the fish scales something similar to the age rings of trees. Underwater inhabitants have some similarities - each ring on the scales means one year of life lived. Scales help not only to determine the age of the fish, but also provides an opportunity to obtain information about the change in length over the past year.

As a rule, the diameter of the scales of fish that reach a length of up to 100 centimeters is about 10 millimeters. For example, if the distance between the initial ring and the center of the scale is about 5 millimeters, then we can safely say that in a year the fish has added about 50 centimeters to its length.

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Under magnifying devices, you can see another important feature of the structure of the scales - its surface is not entirely uniform. There are sclerites on the scales - these are peculiar depressions and ridges that are present on the scaly plate of each fish. Every year, the scales are overgrown with a large and small layer of sclerites, that is, there are two of them. The formation of a small layer indicates that the fish survived the autumn-winter period, and a large layer indicates the past year of life.

In order to understand how to determine the age of a fish by sclerites, you need to have certain skills. But, this method is the most accurate. When determining the number of sclerites on the scales, it is impossible to make a mistake, but it is necessary to have special equipment.

This method is suitable for fish that have large scales. But, some underwater inhabitants were not at all overgrown with scales, or overgrown, but covered with scales of small diameter. You can count age rings, but you will need magnifying equipment and certain skills.

If the fish does not have scales at all, or it is very small, then you can examine the gill cover. Thanks to such studies, scientists have completely refuted all the legends about centennial carps, pikes and catfish. But, in order to understand how to determine the age of a fish with small scales, you need to have certain skills, so it is better to use the simple table above.

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