- If, — 



LATER STAGES OF GADOIDS 







Fig. 22. Percentage of Large Haddock in 



the Total Catch of Haddock, in the several 



zones of depth; 1906 — 10. 



facts reappear consistently during each of the five years now under consideration. My 



figure (fig. 20) illustrates this phenomenon for the mean of the whole five years and it 



further shows that in the B areas, the percentage of large Haddock is somewhat less 



than in the deeper C areas, a curious fact which 



reappears in every one of the five years under con- 

 sideration (fig. 21). But not only is there a difference 



between the actual proportions of the two classes in 



the several years, but furthermore we can trace with 



great regularity the progressive changes from year 



to year. 



In regard to this latter point the two following 



diagrams (22, 23) indicate that we must distinguish 



between the three shallower zones A.-C. (that is to 



say the zones below 60 meters or 30 fathoms depth) 



and the areas D, E, and F of 60 to 200 meters (30 



to 100 fathoms). 



In areas A, B and C, the proportion of large 



Haddock steadily increases (fig. 22), and the small 



Haddock almost as steadily falls (fig. 23), year by 



year, from I906— 1909; while in 19LO these gradual 



changes are arrested and small Haddock have begun to increase and large to diminish. 



In the case of areas D. E. and F. we have, on the other hand, a tendency of the large 



Haddock to diminish at first and increase afterwards, while the small, on the other hand, 



at first increase and afterwards fall to a point much 

 lower than the starting point in 1906. These varia- 

 tions need not be further described in detail, for they 

 are shown with great clearness and simplicity in the 

 diagrams. It is obvious that in all zones of depth 

 there was a marked abundance of small Haddock in 

 1906, and that that relative abundance continued or 

 increased for two years later. A renewed period of 

 increasing abundance set in with 1910, but the ten- 

 dency to increase so far as that year is concerned 

 was only manifested in the shallow waters. 



On the whole, taking all areas alike into con- 

 sideration, large Haddock have pretty steadily in- 

 creased, and small have decreased in relative abund- 

 ance during the whole period of five years. Here, 

 in short, is a case where great variations in the 

 natural increase of the fish are conspicuously evident ; 



and where they have, in this instance, wholly overshadowed any tendency that may exist 



(or that we sometimes suppose to exist) for the average size of the fish to diminish 



through the operations of man. 



These marked changes from year to year in the relative abundance of large and 



small Haddock constitute so striking and important a phenomenon that we must at once 



Fig. 23. Percentage of Small Haddock in 



Total Catch of Haddock, in the several zones 



of depth; 1906 — 10. 



