LIFE HISTORY OF LAKE HERRING OF LAKE HURON 



391 



the calculated lengths of these fish, as shown in Table 59, are employed. In Table 

 59 are given the computed average lengths, as determined from measurements of 

 scales, for each year of life. To obtain these averages, I computed the lengths for 

 each year of life of all the year classes of a sample and then averaged these lengths 

 of corresponding years of all year classes. In this way some comparable general norms 

 of growth of the herring of the several localities are obtained. A variable error, due to 

 the "apparent change in growth rate," is introduced into the averages by this method; 

 but as each sample considered consists of approximately the same age groups, the 



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£AST 

 TAWA5 



ysAfts or 



Fig. 43.— Showing the total length attained at the end of each year of life by lake herring 

 taken at various ports on Lake Huron. The curves are plotted from the computed lengths 

 of Table 59 



averages are still roughly comparable. Considering the number of specimens employed 

 for each locality, the averages of length are at best approximate. The computed total 

 lengths of the herring of the above-mentioned localities are plotted in Figure 43. 

 (For location of each port see fig. 1.) 



Table 58. — Average total length, as determined by actual measurements of fish, attained at end of each 

 year of life by lake herring collected at various ports on Lake Huron ' 



' Number upon which an average is based is shown in parentheses. Some of the averages may be a little too low, as some of 

 the fLsh were captured in late summer or early fall and therefore did not complete their last growth year. See Table 1 for the dates 

 of capture. 



99760—29 9 



