In other fish, such as the bluegill, the scales overlap each other more at certain 

 times in the life of the fish than at others. In these fish, it is necessary to correct 

 the body lengths calculated from scale measiirements in order to obtain a close approxima- 

 tion of the actual body lengths. 



The most convenient measurement of a scale is the distance from the focus, or center 

 of the scale, to the anterior edge. Scales from the side of the fish a little below the 

 dorsal fin are uniform in size. These are the ones that are used in making comparisons of 

 scale measurements and lengths of fish. In bass, the anterior radii of these scales seem 

 to be directly proportional to the total length of the fish for all sizes from fingerlings 

 up, fig. 6. When measurements of the anterior radii of scales against total lengths of 

 bluegills are plotted, the result is not a straight line, as in the bass, but one that is 

 slightly S-shaped, fig. 7. When the lengths of bluegills were calculated from scale 

 measurements, a smoothed curve was drawn and body lengths were read directly from the 

 curve. 



TOTAL LENGTH OF FISH, INCHES 



FIG. 6. — The relationship between increase of body length 

 and anterior radius of scales in largemouth bass. 



COMPARISON OF THE GROOTH OF BLUEGILLS IN TWO LAKES 



The breeder bluegills of Fork Lake spent their life, imtil 1938, in Homewood Lake, 

 where they were crowded and forced to compete with a dense population of fish of other 

 kinds. Age determinations and grovrth measurements made from their scales allow us to 

 compare the growth in these two small lakes of a number of these fish collected in 1939. 



TABLE 7. —AVERAGE CALCULATED TOTAL LENGTHS OF ORIGINAL BREEDER BLUEGILLS IN 

 HOMEWOOD LAKE AND AVERAGE MEASURED TOTAL LENGTHS (UNDERSCORED FIGURES) 

 AFTER THE FISH HAD SPENT A YEAR IN FORK LAKE. 



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