Evening Republican, Volume 21, Number 247, Rensselaer, Jasper County, 2 November 1917 — To Tell a Fish’s Age. [ARTICLE]

To Tell a Fish’s Age.

Could you tell the age of a fish if isked to do so? It has been found that the age of a tish may be read from its scales. L'hese increase in—size by annular growths, two rings being formed each year. The "otoliths,” or ear stones, which lie in two sacs on either side of the base of the cranial cavity, afford mother means of determination. Like the scales, the otoliths increase •by two rings annually. Each spring a white ring is formed, and each autumn a black one. Thus the number of either white or black rings in an otolith gives the age of the fish in years. In the case of flatfish the latter method has beeu found more reliable, whereas in the case of the cod the scales give a better result. Although varying much in size and shape in different species, the otoliths show a remarkable constancy in the same species; hence they are of considerable value in the diagnosis of a species.