— 100 — 



in comparison with the more numerous group from 1904. A further remark- 

 able fact is also seen, namely, that throughout several years and until the indi- 

 viduals have reached a considerable size the year-groups retain the 

 same character, that is, of abundance or scarcity. This appears very clearly 

 from tig. 32. The figure represents the average catch of all sizes per hour of fishing in 

 the various years of fishing. If now in the one year the Il-group is predominant, in the 

 next year the I-group, and both are numerous in the third though extremely rare in the 

 fourth year, it is evident that the size of the total catch and the relation between the 

 different sizes m it must undergo great variations. We see from the material that in 



1903 the average number for the whole North Sea was 59 spec, per hour of fishing 



1904 - — _.._ _ _27— — 



1905 -— _.._ __48- — 



1906 -— _.._ __7i_ _ 



These fluctuations show that a few years' investigations cannot yet 

 give us any reliable picture of the average stock of haddock in the North 

 Sea. The question here can only be, to obtain a correct picture of the 

 stock during the years in which the investigations were carried on. 



We remarked earlier, that it would not be right to consider the available material as 

 quite representative for the North Sea. In the first place it is too small, and in the 

 second it suffers from the following shortcomings: 



1. It does not contain hauls from all parts of the North Sea and it is also very 

 variable in regard to quantity and origin. None of the research steamers has been able 

 so far to devote itself to the study of the haddock, as all had to carry out many other 

 tasks at the same time. 



2. The hauls are not equally numerous at the different seasons. 



If we are thus unable to lay any special weight on the definite numbers which 

 express in the present report the results obtained, yet we believe nevertheless, that even 

 on many points the results suggest the general conditions which prevail in the North Sea 

 from year to year. 



We believe, for example, that the stock of haddock in the part of the North Sea 

 lying south of 58° or 59° N. Lat. may be regarded as consisting mainly of the first 

 4 year-groups. So great may be the fluctuations in the occurrence of these year-groups 

 from one year to another, that they are able to determine both the character and the 

 size of the catches. 



If the conditions were as above described, that the year-group spawned in 1903 is 

 small in numbers over the entire region investigated, whilst the year-group 1904 occurs 

 in abundance, we would obtain the following results: 



If large quantities of the smallest year-groups appear in any one year, we may 

 conclude that they will also be present in abundance in the next following years. 



