3 



Distribution, Growth and Migfrations of the older Stag-es 



We have endeavoured to give a brief description of the spawning places of 17 

 different gadoids; at present, however, we are far from being able to describe the occur- 

 rence and migrations of these species at all their different stages and sizes. As the 

 plankton eggs and larvse are so much easier to catch than the larger fish, the study of 

 the distribution of these young stages is also much easier than that of the older fish. 



The Committee has therefore agreed from the beginning to limit the investigations 

 on the older stages to a few species, especially the cod. Later, the haddock and as 

 the occasion offered also the coal fish and whiting were included in the investigations. 

 In consideration of the short time during which the work has been carried on, and of the 

 fact that the naturalists and their research steamers could only devote a part of the time 

 to the work of Committee A, it is clear that no more than this could be attempted. 



In spite of these difficulties in the investigation, our knowledge of the natural history 

 of the gadoids considered has been considerably increased during the last 6 years, espec- 

 ially as regards the haddock and cod. Many and important data regarding the occur- 

 rence, distribution and migrations of the older fishes of both these species have been 

 collected and the development of a better method for the determination of the age made 

 it possible to obtain valuable conclusions regarding the frequencies of the different year- 

 groups in the different parts of the region investigated, regarding the age at first maturity 

 and other points. The material obtained is certainly not sufficient to enable us to give 

 a quite exact and trustworthy picture of the biological conditions of these fishes, but it 

 possesses a very great value in regard to methods for the further investigations in this 

 region. The results described in the paper by Helland-Hansen appended to this report 

 are essentially of such value in regard to methods and a good example of the promise 

 of these or similar investigations. 



This paper deals with the measurements of some tens of thousands of haddock and 

 cod from the North Sea, which were taken by the German and English research-steamers 

 "Poseidon" and "Huxley" during the years 1902 — 1906. 



To avoid misunderstanding, we would note the following regarding the value of this mate- 

 rial. It is evident, that even if the number of fish measured is large, larger than has ever been, 

 at the disposal of earlier investigations, it is yet too small to satisfy the requirement: to 

 represent the countless millions of haddock and cod in the North Sea, which the science 

 of statistics makes in general of representative statistics. And it may be maintained 

 against the material, not only that the numbers are too few, but also amongst other 



