Ichthyologists often have to determine the age of fish caught from natural reservoirs. Knowing the exact age of the fish is necessary in order to understand at what age the commercial fish caught gets the ability to reproduce, how well they grow, the fish of what age is most often found in the catches of fishermen.
Instructions
Step 1
To find out the age of the fish, carefully examine the rings on its scales, and, if necessary, use viewing with a magnifying glass or microscope for a more accurate analysis. Since fish scales appear even at the fry stage, and then grow rather unevenly throughout the year, accumulations of tissue appear on them in the form of concentric grooves in the place where the scales "grow" into the skin of the fish in question. Carefully examine the scales of the fish being studied, and by its appearance you will almost accurately determine its age. As a rule, in one-year-old fish, all scales are thin and translucent, and concentric rings appear only in fish that have already survived the winter.
Step 2
Study the concentric circles on the scales to determine the age of the fish and how old the fish is. Since in winter fish hide in the bottom sand, burrow into clay and silt, plaque accumulates at the base of the scales, which is then noticeable in the form of a barely noticeable concentric circle. Count the number of such concentric circles, and you can easily find out the age of the fish, while the absence of such circles only indicates that the fish you are studying is just yesterday's fry, which has not yet had to winter in the reservoir.
Step 3
Determine the age of the fish not only by analyzing concentric circles on the scales, but also take into account the density of the scales. Every year, under the old scales, each fish has new ones, slightly protruding in size from under them. So, in a two-year-old fish, you will see double scales, in a three-year-old fish, you will see triple scales. And the older the fish you study, the more such scales it will have. Study with commercial fish - otolith sizes are solid formations that are responsible for the orientation of the fish in space. And the denser the formation data, the older the fish being studied.
Step 4
To accurately determine the age of commercial fish, use other methods of analysis, studying the results obtained in the aggregate. So compare the size of the otoliths, which is directly proportional to the age of the game fish, with the hard seals located on the dorsal fin of the fish being studied. Count the number of colored rims on fish scales to understand how many times such a fish had to spend the winter in a pond, and a cumulative analysis, taking into account all methods, will help you determine the age of the fish as accurately as possible.
