138 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



This was done by the "transformation" method 

 of Walford (1946). This is a graphic method of 

 describing the growth of animals above the point 

 of inflection, the self-inliibiting phase of growth. 



5.0 



150 160 170 180 

 A 



190 200 



Figure 4. — Deviations of monthly frequency distribution 

 from the mean monthly frequency distribution (in per- 

 centage) for combined and smoothed 1948 and 1949 data. 4,0 



Using the above criterion, values of modes were 

 selected as shown in figure 6. Each mode has 

 been labeled with the age group to which it was 

 presumed to belong. In order to plot modal 

 positions against successive months, January of 

 group A'^ was arbitrarily assumed to occur in 

 month 37. Thus the mode of group .A^ in Feb- 

 ruary, March, April, and so on, was plotted in 

 figure 5 against 38, 39, 40, and so on. Modes 

 corresponding to groups which are presumed to be 

 a year younger or older were then plotted 12 

 months above or below the month value corre- 

 sponding to group A'^. 



Assuming group A'^— I to be 1 year younger than 

 A'^ and group 7V+I to be 1 year older, A^+II 2 

 years older, and so on, we proceeded to determine 

 whether a regular growth curve fitted the data. 



200 



B 



FiGllRB 



5.— Theoretical conditions demonstrating the 

 criterion used in selection of modes. 



