Table 15. --Catch per tow of 5-9-* vear-oid haddock by depth and bottom 

 type during the summer of 1948, 1949, and 1950 



The variance ratio values were as follows: 



Difference between years. F = 1 .79 

 Difference between depths. F = 5.51 

 Difference between bottoms. F -1.01 



(not significant) . 

 (significant), 

 (not significant) . 



Thus it is seen that the summer distribution of older haddock was consistent 

 during the three years, and that depth rather than bottom type was the controlling 

 factor in this distribution. This is as expected for the only locations in which rela- 

 tively large numbers of older haddock were caught over mud bottom were locations 

 in which tJie depth was greater than 90 fathoms (subareas G and H). 



It appears, however, that the character of the bottom sediments does serve to 

 differentiate the 61-90 fathom depth zone from the shallower bank water and the 

 deeper Gulf of Maine and oceanic water. More detailed analyses by Stetson (1938) 

 and Northrop (1951) show that there is a certain uniformity in the arrangement of 

 bottom sediments of the continental shelf when they are considered by regions . 

 Profile lines from the glaciated section (New England and north), irrespective of 

 slope, have certain characteristics in common They all start with a zone of relatively 

 fine sand near shore, followed by a belt of coarse sands and gravel, which in turn are 

 succeeded by a zone of sand and gravel plus varying amounts of silts and clays lying 

 on the middle and outer parts of the shelf. Lines crossing the break in the continental 

 slope show a definite coarsening of texture there. All the traverses show a remarkable 

 correspondence in the depth of water at which these zones occur, which is obviously 

 the controlling factor as the lines are of varying length. Consequently, on lines from 

 the Gulf of Maine where deep water is soon reached, the succession of zones is 



38 



