_ 19 — JOH. HJORT AND 0. G. JOH. PETERSEN 



To be able to demonstrate tMs, it was necessary to study the systematic of the various 

 stages thoroughly as these were formerly little known. We are at present, especially 

 throug'li Schmidt's researches, in a position to be able to distinguish very early stages of 

 the different species. 



At Iceland, the investigations of the steamer "Thor" have shown that the 4 most impor- 

 tant species, green cod (G. virens), cod (G. callarias), haddock (G. seglefinus) and whiting (G. 

 merlangus) seek the bottom and give up the pelagic mode of life in the order named. The 

 green cod and the cod go later as small young fish nearer to the coasts and are found, for 

 example in summer, close to the shore on the Iceland coast; the young of the haddock on the 

 other hand, could be found in quantities principally in deeper water, for example, at a size of 

 4 — 6 cm. in depths of 63 — 72 m. ; the young whiting remain pelagic for a very long time. 



We have made similar observations on the Norwegian coast and in the North Sea. During 1904 

 especially, a very comprehensive material has been collected by the various investigation-steamers. 

 As however, it has not been yet possible to complete the great work of determining and 

 coordinating the material, we shall give here only a short description of the results obtained 

 by a single steamer ("Michael Sars") for the years 1900 — 1903, stating at the same time, 

 that the results for the year 1904 will agree with these in their entirety, perhaps even display 

 the relations of the separate regions much more clearly. 



The Norwegian material for the years 1900 — 1904, has been arranged in such a way 

 that a chart with the number of stations in series has been drawn up for each of the four 

 species, green cod, cod, haddock and whiting. On each chart is stated: 



1) whether the young fish are pelagic or bottom-stages; 



2) whether their size is greater or less than 2 cm; and 



3) whether the stations were made before or after the first of June. 



It would be desirable perhaps, that the charts should also contain data of the hauls 

 which give no results for one or more of the 4 species of gadoids. As negative experiments 

 however, had to be made in great number, and this had not yet occurred on preparing these 

 charts, we shall only mention them in the following text. A comparison of the 4 charts, PI. 

 V — VIII, will give for the rest an idea of the extent of the observations. 



Chart 1, PI. V refers to the 83 stations on whicli cod of the 0-group were found in the 

 period from 1900 — 1903. It appears from the chart, that pelagic young fish over 2 cm. 

 were found after the 1st of June only in the Norwegian Sea, with but one exception. In the 

 many hauls which were undertaken in the North Sea, on the surface and in the middle layers, 

 we only obtained other gadoids after the 1st of June (see e. g. Chart 4). We find tlie small 

 larvae under 2 cm. in the North Sea, chiefly in the neighbourhood of the coastal banks; for 

 the Norwegian Sea, the numerous catches of these stages have not been marked, so as not 

 to put too much on one chart (see Section III). 



The relation is therefore as follows: pelagic cod over 2 cm. (up to 9.5 cm. indeed) have 

 been found in the Norwegian Sea, whilst only a single pelagic cod of 2.5 cm. was found in the 

 North Sea. The numerous investigations of the year 1904 have shown, that the small cod in 

 the North Sea seek the bottom already at a size of 2 cm, and that they have been found 



' Schmidt, 1. c. p. 81-84. 



3* 



