How to determine the age of fish?

The question "How to determine the age of fish?" Has long been interested in scientists and, as it turned out, this is not so difficult.

If we consider scales of fish under a microscope or even under the most ordinary magnifying glass with a tenfold increase, then it is easy to see rings similar to rings on a wood chip. Each of the rings corresponds to 1 year of fish life and is called "winter", although in some cases it may appear in spring or summer. It is curious that these annual rings are formed on the scales of fish of equatorial waters, as well as in fish living at great depth, although it would seem that they constantly live in unchanging climatic conditions. Therefore, the answer to the question "How to determine the age of river fish and the age of marine fish?" The same - the habitat does not exert any influence on this.

How to determine the size of fish in different years of her life?

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

If, for example, to consider salmon, then it is easy to see that the first two years of life the fish grew very slowly. The inner rings are very close to each other. Then the growth markedly accelerated. And this means that the young fish went to sea from the river, where there was much less food. On the surface of the scales there may be traces of the participation of fish in spawning and transferred diseases. As a result, for a knowledgeable fish ichthyologist, the scales serve as a true passport, which gives an opportunity to know the age, annual size, time spent at sea, the river and the number of spawning.

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

In this case, the necessary analysis can be made on the gill cover, transverse vertebrae and auditory stones. Thanks to modern methods for determining the age of fish, many misconceptions about the extraordinary longevity of carp, pike and catfish have been dispelled. Although, until today, the popular and educational literature mentions a pike, which supposedly lived 267 years and reached the weight of nine poods. 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 mounted from the bones of two (or more) large pikes and is the fruit of the creation of enterprising ancestors to the well-known Ostap Bender.

And if you only use reliable data, then the age limit of pike, catfish and white halibut is 80 years, cod - more than thirty, beluga - about a hundred, herring of oceanic - 25, sazana - 20, pink salmon - 2, and Azov anchovy - 3. However , Cod at the age of 30 years is less common than 100-year-old people. Significantly slower than cod grows sea bass. Prevailing in the catches of a specimen about 40 centimeters in length have a respectable age (up to 17 years!). As a rule, all deep-sea fish grow very slowly . The increase in fish length is slowing down over the years, and weight gain is usually accelerated.

How to determine the age of marine fish on other grounds?

He's good Is determined by the bones: each year lived by the fish is marked with a strip on the gill covers. Ichthyologists have established that even cartilaginous fishes have annual rings. They are formed on thick rays, which are located at the base of the pectoral fins. And in some species of fish, age is determined by otoliths. When it is cut, the annual rings are clearly visible. Scientists are very serious about the question of how to determine the age of fish as accurately as possible, since this has a purely practical significance. To predict the number of a certain species, one must understand the dynamics of development of this species. A large number of fish reach sexual maturity quite late. So, the Amur salmon for the first time spawns in twenty years. During this time, he is closely watched, since even minor changes in their habitat can cause the death of the whole species.

So how to determine the age of fish?

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