The numerical mortalities are indeed consistently lower for the shorter time 

 lapse. That spring and summer distributional differences do not invalidate this com- 

 parison is evidenced by the fact, which will be shown in a later section, that 

 distributional differences of the various age groups are merely found in relation to 

 depth and not to subarea. Therefore, all age classes were uniformly sampled as 

 regards the four subareas under consideration . 



Abundance and Age Composition in Individual Subareas 



Summer 



The catch per tow (total and by ages) and the percentage age composition by 

 subarea for the years 1948, 1949, and 1950 and the 1949-1950 means are presented 

 in figures 5 and 6 and table A-2. Upon comparing the histograms for the three years, 

 it is apparent that poor catches in subarea M in 1948 were responsible for the dis- 

 crepancies previously mentioned. In 1949 and 1950 the major portion of the fish were 

 found in subareas J and M which was as expected from the catch records of the 

 commercial fleet. 



In order to evaluate subareas as regards availability of fish, the mean catch 

 per tow for each year was assigned a value of unity. The index number was then 

 determined for individual subareas relative to this value . These comparisons are 

 presented in figure 7 . 



As stated above, the catches in subareas J and M were consistently high while 

 the catches in other subareas fluctuated considerably from year to year with subarea 

 O usually having the poorest yield. 



Two -year -old fish were dominant in the 1948 catches (figs. 5 and 6) and 

 this predominance held true for all subareas except G, N, and O. In subareas N 

 and O zero -ring fish made up the greater proportion of the catch, while in subarea 

 G, 3 -year -old fish were most plentiful. Subareas G and H were distinct in that they 

 were the only subareas in which an appreciable number of fish older than 4 years 

 were caught. 



In 1949 the catch per tow was greatest in subarea M and one-year-old fish 

 dominated the catch in all subareas with the exception of G and J where 3 and 4-year- 

 old fish, respectively, prevailed. In subareas N and O no fish older than 2 years 

 were caught. The proportion of older fish (5 years) was greatest in subareas G and 

 H, although the total abundance was less than in other subareas . 



14 



