HOW TO TELL AGE OF FISH

Nelson Evening Mail, Volume LVI, 27 March 1922, Page 2

HOW TO TELL AGE OF FISH

You may imagine you can tell -a fish's age.by its size and weight. These have nothing to do with it, for, says the Sunday Times of London, the size and weight of a fish depend bn the feeding-grounds that the fish frequents. The fish tolls its own ago just as a tree does—by its rings.. You cut or saw a tree down, and count the rings on the flat section —-each ring represents one year. The fish has annual rings also, but not in it»_ body. They are on the scales protecting its body. Put a fish scale under a magnifier and you notice the scale is covered with little rings—some close together and some farther apart.' When the fish grows slowly because food is scarce and, the water is chilly, th®e rings He close together, but, when its fond is plentiful and the water is warmer, and the fish grows _ bigger quickly—ns it were, stretches its skin with good feeding—then the ’ rings on It r- scales lie well apart. Each of Hi se rings represents one year in' the age of the fish. There is another way. P i« .by tracing out the markings op what are termed the; carstones of the fish—the, tiny hard, things got in its inner ear. Put these carstones under a powerful miscvoscope, and you , see tinv light and dark rings. Every light ring tells of one year’s _ growth. So. by counting these light rings you f.rrive at the fish’s ,age. i- ;