LIFE HISTORY OF THE HAKE 



93 



SESSIONAL PAPER No. 38a 



Taking the means of the curves based upon the scale diagrams as ordinates and 

 the corresponding number of years as abscissae, a rate of growth-curve was now con- 

 structed for each sex (fig. Y). These curves show that the rate of growth is fairly 

 uniform during the first three years, but is greatest in the first year, as* would be 

 expected, and decreases in each of the two succeeding years. They also show that 

 the difference between the rates of growth of the two sexes increases in each succeed- 

 ing year. It appears besides that the species is a rapidly growing one, while the 

 uniformity of the curve indicates that it does not spawn before the fourth year, the 

 spawning period always being marked by a decrease in the rate of growth. 



The mean weights were calculated for the thirty-eight males and for the forty- 

 three females in their fourth year, of which the length-frequency curves are illus- 

 trated in fig 3. The mean weight of the males was found to be 957 grams, while that 



r/^-7 



Fig. 7. — Rate of growth curves for male and female 

 hake constructed upon the basis of the curves 

 in Figs. 5 and 6. 



of the females was 1,440 grams, showing that the females exceed the males in weight 

 as well as in length. The ratio of the mean weight of the males to that of the females 

 is -642. If the cubes of the mean lengths, as marked in fig. 3, be calculated it is found 

 that their ratio is -604. Thus the excess in weight of the females over the males is 

 a little less than one would expect from their excess in length, indicating that the 

 males are generally slightly thicker than are the females in proportion to their length. 

 This conclusion with regard to the shape of the males may not be justified, however, 

 as the ovary, etc., are lighter than muscle, so that the female may exceed the male 

 in bulk more than she does in weight. 



As a sample of the data obtained, the records for fifty fish are tabulated at the 

 end of this paper. The dates and locality will be found upon the first page of this 

 paper. 



