Table 9 . - - Areal extent of each d ep th zone in each statistical subarea 

 of Georges Bank (area in square miles) 



Depth zone Statistical subarea 

 (in fathoms) 



G H T M N O Total 



Total 3,545 3,484 2,115 3,121 3.919 4,838 21,012 



In subareas,M, N, and O the area of water greater than 90 fathoms was 

 negligible. Therefore, these subareas were omitted in the study of the regional 

 aspects of the depth -age relationship. 



The 1949 and 1950 data were averaged in terms of weight per tow by depth zone 

 for the three other subareas and are presented in table 10. ^' 



Comparing table 8 with table 10 it is seen that the weight per tow of each age 

 group in each of the three subareas was in general similar to that for the whole bank . 

 The weight per tow of large haddock (5-9-1- years) was greatest and the weight per tow 

 of discards (0-2 years) was least in depth zone IV in each subarea, except in subarea 

 H where the weight per tow of 5-9+-year-oid haddock was slightly less in depth zone 

 IV than in depth zone I . 



Regarding the sharp and consistently lower catch per tow of all ages of haddock 

 in depth zone III, several causes could be postulated. The area hounded by the 60 

 and 90 fathom contour lines consists for the most part of a narrow band along the 

 edge of the bank representing to the north a transition zone between the shallow bank 

 water and the deeper water of the Gulf of Maine, and to the south and east a transition 

 between the shallow bank water and deep water off the continental shelf. Because the 

 graidient between tlie 60 and 90 fathom lines is greater than that above or below this 

 zone, it was thougjit that possibly the efficiency of the otter trawl was affected by 



ZJ The catch per tow by depth zones for individual subajseas are presented in 

 tables A-4, A-5, A-6, A-7, and A -8 in the Appendix. 



28 



