— 130 — 



The same problem also appears in the case of the haddock. For both species the 

 observations made in such regions, as e. g. at Iceland, where the deep water comes near 

 to the coasts, are very instructive. Are the conditions in the North Sea and in the Nor- 

 wegian coastal waters different from those at Iceland? We have here one of the principal 

 problems for future investigation, which an international organisation can best hope to 

 solve, since indeed no land can by itself investigate these large regions of the sea. A 

 second very important observation is, that the spawning cod can on the whole attain so 

 great an age. We shall see in the following, that this is also the case with the spawn- 

 ing coalfish. We have here quantities of fish which become very old with the oppor- 

 tunity to reproduce their species several times in the course of their lives. This observation 

 entitles us to hope that such species are not the victims of irrational fishing. 



III. Whiting 



In his excellent papers Fulton has shown by means of the measurement method that 

 the growth of the whiting is rhythmical, 3/^ths of its growth for the whole year taking 

 place in the period from May to August. Of great interest also is the evidence he brings 

 forward, to show, that this rhythmical growth is most marked where the differences of 

 temperature are greatest in the different seasons of the year and that the growth is 

 greatest just in the regions where the highest summer temperature prevails. The condi- 

 tions we have previously discussed in describing the pelagic stages agree with this, 

 namely, that these stages only seek the bottom where the summer warmth reaches down- 

 wards, whereas they remain swimming in such places where the summer warmth, as 

 in the Northern North Sea, only penetrates to the upper layers and where the bottom 

 layers are in summer just the coldest (see the hydrographical summary, especially the 

 North Sea sections fig. 9). It has also been shown, that the whiting leads a pelagic 

 existence until an advanced age, which may presumably be explained by the dependency 

 of the species on the temperature. 



Damas gives in his paper the result of some scale determinations on whiting taken 

 in September 1906 in 8 hauls with the trawl in the North Sea. We may cite here the 

 following : 



o-group, spawned 1906, in size 11 — 13 cm. 



1- — — 1905, — 15 — 26 — maximum ca. 20 cm. 



2- — — 1904, — 17—30 — — - 24 — 



3- — — 1903, — 22—35 — — - 30 — 



4- - — 1902, - 28—39 - — - 34 — 

 5 — 1901, — 33-44 — — - 38 — 



of the 6- — — 1900, only a single specimen 39 cm. long occurred. 



IV. Coalfish 



The coalfish grows very rapidly in summer, more slowly in autumn and almost not 

 at all in winter. There is a slower period in summer, however, which causes the appear- 

 ance of a secondary ring in the structure of the scales. For the rest, the growth is ex- 

 tremely regular throughout all the years of its life, except in the period of "old age" 



