_ I^ _ B. Hp;iJ,ANI)-HANSEN 



not possible in this connection to utilise for comparison D'A'rcy Thompson's map 

 for "Total Haddocks"; for the weights depend far more upon the large haddock 

 than the numbers do. Neither can the map showing "Extra Smalls" be compared 

 with our averages of the numbers; since the weight of fish of this size brought 

 to market does not truly represent the quantity which the trawlers have actually 

 caught. 



It is also worth noting that the number of young fish in area J is com- 

 paratively large; the quantity is practically the same as we get in the Northern 

 group on the whole, and it is considerably greater than in the more southerly 

 areas. 



When alluding again to these three groups of areas we will henceforth 

 designate them the Northerly, Mid and Southerly areas. It must however be 

 borne in mind that the Northerly group is not identical with the Northern North 

 Sea, but coincides chiefly with the northern parts of the North Sea's central 

 portion. The Southerly group also includes the westerly parts off the coast of 

 Jutland. 



A similar investigation into the averages of the numbers can also be made 

 for the different years. The relation between the total number of individuals 

 and the total number of trawl-hours (for the whole North Sea, where examined) 

 works out as follows for the years 1903 — 6: 



in 1903 average 59 individuals per trawl-hour 



- 1904 — 27 — — 



- 1905 — 48 — — 



- 1906 — 71 — — 



These figures illustrate the relative 'movement' of the aggregate 

 mass of haddocks, which is thus seen to be strikingly great. Thus 

 in 1906 the number of haddocks caught by our trawlings in the 

 North Sea was between two and three times as great as in 1904. 



For the three groups of areas previously mentioned the numbers per trawl- 

 hour are as follows: 



Northerly Mid. Southerly 



Year a. B.c. D.E. J. F.G.H.K.O. L.M. 



According to this table the numerical variations from year to year per trawl- 

 hour have been comparatively small in the Southerly group of areas. In the 

 Mid areas we find values that are everywhere a little less than those previously 

 shown for the whole of the North Sea where examined. The variations are the 

 same; a marked reduction from 1903 to 1904, and then an increase which reaches 

 its maximum in 1906. In the Northerly group of areas the average-number each 



