342 



BULLETIN OF THE BUREAU OF FISHERIES 



Table 27. — Comparison, for herring of age groups IV to VI of uncorrected computed lengths of various 

 years with computed lengths corrected from body-scale ratios {KjV) for disproportionate growth 

 of body and scale. The K/ V ratios are based on X scales and are taken from Table 1 ' 



Year 



VI. 

 VI. 

 VI. 

 V. 



v_ 



IV 



K/V 



48. 16 (52) 

 48. 16 (52) 



48. 16 (52) 

 48.84 (178) 

 48.84 (178) 



49. 11 (323) 



Year 



V 

 IV 

 III 

 IV 

 III 

 III 



K/V 



48.84 (178) 



49. 11 (323) 



49.83 (147) 



49.11 (323) 



49.83 (147) 



49.83 (147) 



K/V of older flsh 



K/V of younger flsh 



0.986 

 .981 

 .966 

 .995 

 .980 

 .986 



Uncorrected 

 calculated 



length, in 

 millimeters, 

 for younger 



fish from 

 scales of old- 

 er (Table 26) 



243 (112) 



223 (112) 



196 (112) 



229 (464) 



205 (464) 



220 (1, 132) 



Corrected 

 calculated 

 length, in 

 millimeters 

 Oength in 

 column 6 

 divided by 

 per cent in 

 column 6) 



246 

 227 

 203 

 230 

 209 

 223 



1 Tbe number of specimens employed is shown in parentheses. 



On this basis Table 27 was constructed. I determined what percentage (column 

 5) the £'/F ratio of each age group was of that of each lower age group, then computed 

 the average length for each lower age group from the scales of the higher (Table 26), 

 and finally corrected the calculated value on the basis that it equaled that percentage 

 of the true value that was obtained for the KjV ratio of the corresponding year 

 (Table 27, column 7). An inspection of Table 27 shows that such a correction for 

 disproportionate scale growth raises the computed lengths of all years, and that the 

 amount of correction for corresponding years of life increases with the age of the 

 fish whose scales were used. Thus, in the 6-year fish the averages are raised 3, 4, 

 and 7 millimeters, respectively, for the fifth, fourth, and third years of life; in the 

 5-year group they are raised 1 and 4 millimeters, respectively, for the fourth and third 

 years; while in the 4-year fish the average for the third year is increased 3 millimeters. 

 As the Kj V ratios of the 1 and 2 year herring undoubtedly are liigher than those of 

 the fish of year III, the amount of correction for the first and second years of life 

 must increase accordingly, and, if our general K/V ratios of Table 10 are reliable, 

 they must equal more than 7 millimeters in the 6-year herring, more than 4 millimeters 

 in the 5-year fish, and more than 3 millimeters in the 4-year fish. It is apparent that 

 when a correction for disproportionate scale growth is applied to the computed lengths 

 Lee's "phenomenon" becomes less pronounced. As was the case with late scale 

 formation, so also here no factorial relation exists between the disproportionate growth 

 rate of body and scale and the "phenomenon" in the direct measurements of scale 

 diameters in fish of the same year class. 



A review of the preceding discussion shows that the presence of Lee's "phenom- 

 enon" in the scale-diameter measurements of the lake herring and in the computa- 

 tions of length based on these measurements may be explained best on the assumption 

 that the late-maturing fish of a year class are the more slowly growing individuals 

 of their year class. This accounts for the progressive decrease with age in the scale 

 and body increments of the first two years of life. The disproportionate growth rate 

 of body and scale may be an additional factor for the "phenomenon " in the computed 

 lengths. The progressive increase with age in the increments of the third or fourth 

 and later years of life is, in part, the result of the principle of a compensation in growth 



