408 



BULLETIN OF THE BUREAU OF FISHERIES 



Table 64 shows that the Saginaw Bay fishermen caught 1,333,793 pounds of 

 herring in 1921, valued at $48,964. In 1922 they took 3,002,784 pounds, valued at 

 $64,582, and in 1923 some 1,830,398 pounds, valued at $41,203. The actual age 

 composition of the catches of these years, as taken from Table 29, follows: 



The actual average length of each age group of these herring is shown in Table 

 29 also. These lengths and the theoretical weights (in ounces) are as fofiows: 



The total weight of the individuals of each age group- of each sample, the 

 percentage of weight contributed by each age group to the sample, and the number 

 of pounds contributed by each age group to the commercial catches of 1921, 1922, 

 and 1923 are given below: 



The sample of 1921 weighed (theoretically) 3,560.02 ounces, that of 1922 weighed 

 2,581.53 ounces, and that of 1923, 2,912.73 ounces. To determine the percentage of 

 weight under normal of the herring taken in these three years, I compared the average 

 theoretical weights of their age groups with those of corresponding age groups taken 

 in 1924. (See figures for Tobico and Nayanquing samples combined, Table 31.) 

 The heriing captured in 1921 will be considered first. As the 2 and 3 year individuals 

 had not been subjected to the pollution (throughout this discussion we ignore the 

 fact that the normal growth rate did not return until 1921 in the 1-year fish) and the 

 loss for the 7-year fish can not be ascertained, these age groups need no consideration 

 here. It was found (see data in table below, p. 409) that the 4-year fish of 1921, which 



