— 50 - 



Thus while the whole average-number per trawl-hour varied comparatively 

 little from one year to another during the period 1903 -6, the variations within 

 the two smallest groups were particularly great. For instance unmarketable 



100 lOSu 



190^ 



Fig. 32. Average catch per trawl-hour of different sizes of cod (number of individuals) from each of 



the years 1903—6. 



constituted on an average hardly a seventh of the whole number in 1903, whereas 

 the same group was responsible for no less than three-fifths of the entire quantity 

 in 1906. Again the number of codling showed extreme variations though in 

 inverse order: there were many of them in 1903 (nearly two-thirds of the whole 



