— 128 — 



■' It:.is at^once obvious, that the maxima of- these 5 hauls grow higher in â series 

 from north to south. Whilst the northernmost haul shows a maximum between 70— 75 ciri;, 

 the'southern North Sea curve .has a maximum between 95 and 100 Cm. The'spawning 

 fish are thus much larger in the North. Sea and on the southern Norwegian coastal banks 

 than on those furthest north. From the North Sea we possess an insufficient number of 

 age determinations, though numerous from the Norwegian coastal banks. So far as 

 regards these coastal banks, we may- believe that, the varying size of rhature fish 

 on the southern and northern banks is to be' referred to varying rate of growth and not 

 to different age. They show us further, that the spawning cod are very old, the majo^ 

 rity between 8 and 12. years and large specimens reach an age of 15 

 years. As example we may give here an analysis of the Lofoten cod. First of all, 95 

 specimens of 53 — 71 cm. in length were investigated'; only 9 were less than 7 years, old 

 (5—6 years), the remainder were 7 — 12 years old. 25 specimens of " 78 cm. in length 

 were: 8 — 11 years^ the largest 95— -114 "cm. were 11 — 15 years old. 



We have seen in the foregoing numerous examples of the growth of the cod under 

 different conditions. Great differences appear according to the degree of latitude and the 

 distance' from the open sea, that is, according to the hydrographical conditions. As the 

 scales enable us not only to determine the age, but also to judge of the growth of each 

 individual at its different ages , the possibility is here opened up of obtaining a deeper 

 understanding of the resorts or dwelling places of the cod during the whole of its life; 

 The question, how extensive are the areas within which the single individuals migrate, is 

 of special importance. As we have seen earlier, Schmidt was able to show .directly by 

 his marking experiments that the cod at Iceland migrate from the shallow into the> deeper 

 water.... Such marking , experiments were also begun in the Norwegian part of the Nor- 

 wegian Sea, -but so far they have not yielded sufficient results. Thus, we still lack an 

 experimental answer to the question, whether the cod as they grow older migrate from 

 thé strand-region arid frorn the coast of Finmark towards the coastal banks and there form 

 the masses of skrej. We lack likewise an answer to the question, which immediately 

 rises here, if namely the mainly younger cod of the North Sea» which were taken by the 

 research steamers and which are described by Helland-Hansen in his report, are essen- 

 tially only the younger year-groups to the larger spawning fish, which amongst other 

 things yielded the material for the North Sea curves on fig. 51. We receive the impres- 

 sion from D'Arcy Tho.mpson's description of the seasonal migrations of the cod, that 

 such -a -connection exists and that the larger cod undertake considerable migrations from 

 and to. the; spawning places. 



The investigations thus bring us in sight of an important aim Of the researches '-of 

 the future, namely, to discover the connnection between the stocks in the deeper and 

 shallower regions of the sea. Our .investigaitions show us clearly also, how impossible it 

 is to judge, for example, of the stock in the Southern North Sea, without being clear as 

 to whether the minority or small numbers of the older sizes should be ascribed to mi- 

 gration into deeper water or to overfishing. The entire; North-S.ea Bank must be 

 dealt with connectedly as a whole and material collected from all its 

 areas. ' '" ' '" ' " '.',.,'. 



