LIFE HISTORY OF LAKE HERRING OF LAKE HURON 



323 



The series of body-scale ratios are included in Table 10. They are based on 

 specially selected (X) scales of the herring taken at Bay City, October 29, 1921. It 

 may be seen that while the Ejac ratios vary in one direction, decreasing consistently 

 with age, the KjV fractions vary only slightly at random. Further, computations 

 show that the difference (0.87) between the extreme averages of Z/F (years III and 

 VI) is outy 1.22 times its probable error, while that (5.90) between the extreme aver- 

 ages of Kjac (years III and VI) is 3.35 times its probable error. Again, the coefficients 

 of variability of the KjV ratios of years III and VI, for example, are computed to be 

 6.50 per cent ±0.5966 and 6.74 per cent ±0.8300, respectively, while those of Kjac 

 for the same years are calculated to be 9.38 per cent ±0.8609 and 7.85 per cent 

 ± 0.9666, respectively. These data indicate (1) that the Z'/F ratios vary less with the 

 age groups than the EInc; that is, the diameter of a scale increases in length more 

 nearly proportional with the body than the anterior radius, and (2) that the Ej V ratios 

 vary less than the E/ac ratios with the individuals of an age group. The diameter 

 of a scale, then, appears to be a better dimension to employ for length computations 

 of growth in the lake herring than the anterior radius. 



Table 16. — Measured lengths, at time of capture, of Bay City herring collected in 1921, 192S, and 

 1933, and lengths at end of each -preceding year of life, as calculated from both the diameter {V) 

 and anterior radius (ac) of the scales 



BAY CITY HERRING COLLECTED OCTOBER 29, 1921 



BAY CITY HERRINQ COLLECTED NOVEMBER 1, 1922 



BAY CITY HERRING COLLECTED NOVEMBER 12, 1923 



n... 

 in.. 



IV.. 

 V... 

 VI.. 



vn. 



2 



170 



240 



90 



15 



2 



221 

 233 

 243 

 251 

 263 

 263 



137 126 



142 ' 



133 I 120 



119 

 113 

 119 



105 

 99 

 106 



' Average of the diflerences, (Kon V)-(Kon ac), year 1, 13.2 



201 I 

 192 

 179 I 

 166 I 

 157 



186 

 170 

 155 

 150 



224 



213 

 203 

 184 



237 

 228 

 210 



236 

 225 

 204 



247 

 234 



247 

 230 



248 



248 



year II, 8.7; year III, 5.3; year IV, 3.6; year V, 2.4; year VI, 0.5 



