question "How to determine the age of fish?"Scientists have long been interested, and, as it turned out, this is not so difficult.
Considering fish scales under the microscope or even under the most ordinary magnifying glass with a tenfold increase, it is easy to see the rings, like the rings on a tree saw cut.Each of the rings corresponds to 1 year of life of fish and called "winter", although in some cases it may appear in the spring or summer.It is curious that the annual rings are formed and on the scales of fish equatorial waters, and fish living at great depth, although it would seem, they always live in the unchanging climate.So the answer to the question "How to determine the age of river fish and sea fish age?"same - the habitat it has no effect.
How to determine the size of the fish at different times of her life?
On scales can determine not only the age of the fish, but also the length, which it reached every year.Suppose fish scales meter radius of one centimeter.Distance from the first annulus to the center scale is 6 millimeters.Therefore, one year old fish was 60 centimeters long.
If, for example, consider the scales of salmon, it is easy to notice that the first two years of life is very slow growing fish.Internal growth rings are located very close to each other.Then the growth has accelerated markedly.This means that the young fish left in the sea from the river, where there was much less food.On the surface, the scales may remain traces of participation in the spawning fish and past diseases.As a result, knowing ichthyologist fish flake serves authentic passport, enabling them to find out the age, the size of the annual time at sea, the river and the number of spawning.
How to determine the age of the fish, which do not have scales, or it is very small?
In this case, the analysis can be done on the gill cover, and cross sawing vertebra hearing pebbles.Thanks to modern methods to determine the age of fish were dispelled many misconceptions about the extraordinary longevity of carp, pike and catfish.Although to this day in the popular and academic literature mention pike, though he lived 267 years and has reached the weight of nine pounds.Portrait and the skeleton of the pike for a long time shown in German museums.Later, counting vertebrae in the skeleton revealed that he assembled from the bones of two (or more) large pike, and is the result of creation of enterprising ancestors well-known Ostap Bender.
And if you operate only with reliable data, the age limit of pike, catfish and halibut is 80 years, cod - over thirty, beluga - about a hundred, herring ocean - 25 carp - 20 pink salmon - 2, and the Azov anchovy - 3. However, the cod at age 30 is less common than the 100-year-old people.Significantly slower growing cod grouper.Prevailing in catches copies length of about 40 centimeters are advanced age (17 years!).As a rule, very slowly growing all the deep-sea fishes.Increasing the length of the fish in the course of time is slowed, and the weight gain normally accelerated.
How to determine the age of marine fish on other grounds?
He is well-defined by the bones: fish every passing year marked polosochkoj on the gill covers.Ichthyologists found that even cartilaginous fish have annual rings.They are formed in the thick beams, which are located at the base of the pectoral fins.And in some species of fish is determined by the age of the otoliths.When sawing its annual rings are clearly visible.Scientists very seriously think about the question of how to determine the age of fish as accurately as possible, as this is a purely practical value.To predict the number of a certain type, you need to understand the dynamics of this species.A large number of fish reach sexual maturity relatively late age.For example, the Amur salmon spawn for the first time in twenty years.During this time, behind him are carefully monitored, since even slight changes in their environment can cause the death of the species.
So how to determine the age of fish?
turns out, nothing complicated here, and the way to do this, there are many.There are more complicated methods, but there is very simple, available to any of us.You just need to arm a magnifying glass.
