Table 19 . - - Mortality (percentage) based on commercial and weighted 



1949, July & Aug. 



to Commercial 



1950, July & Aug. fleet 60.0 80.1 73.3 57.4 50.7 5^.9 



St. 4 90.3 80.3 66.2 30.0 57.5 



73.1 66.8 27.7 



years and in general a marked increase in the mortality of older haddock. To explain 

 this. It had been assumed that the older haddock were fished more intensively. The 

 census data, however, now show that the indicated increase in mortality with increasing 

 age is probably fallacious and is due to the decrease in availability with increasing age 

 caused by the migration of older fish to deeper, less fished regions . 



From statistics obtained from commercial -catch records giving the number of 

 days fished in each unit area during trips which were devoted primarily to catching 

 haddock, it has been possible to make up concentration charts showing where the major 

 effort was expended duiring July and August of 1949 and 195D. The following units of 

 effort in terms of days fished were chosen in the construction of these charts: 



Designation Number of days 



fished per month 

 Very heavy 45-60 



Heavy 30-45 



Medium 15-30 



Li^t 1-15 



45 



