LIFE HISTORY OF LAKE HERRING OF LAKE HURON 307 



Thompson, 1924) that the scales situated below the third dorsal fin are "practically 

 representative throughout of the growth of the fish." 



Van Oosten (1923) detemiined that in the whitefish the diameter of scales grew 

 more nearly proportionally with the body than either the anterior or posterior radius, 

 and that lengths computed from diameter measurements corresponded more nearly 

 \vith the comparable actual lengths than those calculated from either anterior or 

 posterior radii. 



Dunlop (1924) found that in the "stream type" of sockcye salmon "the size 

 of the scale relative to the fish is veiy small at 3 centimeters. It increases rapidly to 

 3.5 centimetei-s and less rapidly from that point. The increase from 3.5 to 10 centi- 

 meters is fairly constant. The rate of increase becomes less, and at 11.5 centimeters 

 it stops. From this point the growth of the scale becomes constantly less rapid than 

 that of the fish [p. 157]." He ascertained that computations made for a fish length 

 of about 7.1 centimeters are correct, but those made for fish lengths less than 7.1 

 centimetei's are too low and for fish lengths greater than 7.1 centimeters too high. 



Leim (1924) plotted a curve showing the relation between the total diameter of 

 the anterior field of the scales and the length of the shad {Alosa sapidissima (Wilson)). 



Johansen (1925) states that during the first year the scale of the cunner {Tauto- 

 goldbrus adspersus Walbaum) increases its size ahnost 8 times, while the fish increases 

 its size almost 20 times. During the second year both scales and fish double in size. 

 Johansen accepts the scale theory for age detenninations but does not calculate lengths 

 from scales. He judges the relative growth of the fish by the width of the various 

 zones on the scales. 



Watkin (1926), by observing whether the circuli of the first growth zone become 

 approximated with age, concluded that the progressive decrease with age in the 

 breadths of corresponding summer zones in his herring scales was not due to a contrac- 

 tion of the scales but must be due to the segregation of the large fish of a year class, 

 as explained by Lea. Watkin does not compute lengths from scales but makes direct 

 comparison between the actual measurements of the scale zones of the various age 

 groups. 



Greaser (1926) concluded that in the sunfish (Eupomotis gibhosus) the relation 

 of the posterior, anterior, and total length of the scale to the length of the fish is a 

 comphcated one, so that no simple fonnula can be stated for the calculation of the 

 length at past scale margins or annuli. The posterior field grows "proportionately 

 faster than the fish until the fish is about 60 millimeters long, at which time a direct 

 relation is estabhshed between the rate of scale growth and fish growth." The anterior 

 field at first gradually grows more rapidly in proportion than the fish, and the regres- 

 sion fine bends upward. "This continues and is increased more at a fish length of 

 about 80 milhmetei-s. As the fish reaches about 120 miUimetei-s in length the scale 

 grows proportionally less than the fish, resulting in a sharp turn of the curve followed 

 by a gradual downward trend. In this manner a characteristic sigmoid curve is 

 formed, showing that the relation of the anterior length of the scale to the length 

 of the fish is a changing one [p. 57]." The regression line, showing the relation between 

 total scale length and fish length, "rises in a straight line to a point corresponding to 

 a length of about 120 millimeters, after which the whole scale grows proportionately 

 less than the fish and the curve bends downward." 



