— 29 — KNUT DA HI. 



size ut' llieso cod fry. The miiiiber o( Lliese iniiiule yumiji seems lu vary soinevvliaL 

 in different years. In 1904 their actual occuri'ence in decreasing numbers has been 

 stated as lono; as we have examined — (until the beginning of October). 



In l'J05 however we will observe that the colunms I'rum September onwards (see 

 table page !28) are very far from showing a decrease in the number of fry of these 

 minimal sizes. On the contrary, these very small fry rather seem to increase in number 

 compared to the other sizes. Thus in December 1905 we find an accessory maximal 

 frequency of fry about 6—7 cm. 



The sample from '*iii 1907 also recorded in the table .shows this still more plainly. 

 This year the minule young from 4 — 7 cui. in length constitute the majority of the fry 

 of the season. 



These small fry ai'e evidently continually arriving in the littoral region. 

 On the one hand we will have to consider the possibility, that the small size of 

 these fry and their continuous arrival in the littoral region may be dependent on their 

 having previously in the season lived in other localities and under other conditions 

 than their larger brothers in the littoral region. During the cruise of the "Michael Sars" 

 in 1906 and during Danish investigations in 1907 small cod fry were ascertained to 

 live at considerable depths near or at the bottom in the Skagerrack during July and 

 August. These young may be supposed to reach the bottom in deeper water and 

 later in autumn appear in the littoral region. It may also be thought, that the growth 

 of these fry would be slower than in the littoral region. 



On the other hand the contrast in size between the normal fry of the littoral 

 region and these minute fry of the autumn is obviously too large to be explained by 

 the above-mentioned possibilities alone. 



These facts now seem to indicate that the stock of fish in these fjords and along 

 the coast of the Skagerrack not only depends on the spawning and hatching taking 

 place in spring. It may evidently also be dependent on a spawning and hatching, 

 which occurs much later and almost continuously. 



In some years e. g. 1907 this production of small and late fry must have been 

 much more important to the stock of fish along the coast of the Skagerrack than the 

 production of early fry. The formation of secondary maximal frequencies in the curve 

 of the fry late in autumn indicates that in late summer and autumn a greater intensity 

 must exist in the conditions, which cause this late immigration of fry to the shore. 



With our present knowledge it is impossible to fully explain this phenomenon 

 and to clearly define the conditions which cause it. Where these small young cod of 

 the autumn really come from cannot be proved. 



In this connection however I think it is justifiable to review our present knowledge 

 on the question, to wliat extent late spawning of the cod has been observed in the 

 Skagerrack and adjacent waters. 



1) God eggs in the last stage of development have been found by me on July 7, 1904. 



2) According to Dr. Strodtmann^ spawning cod have been observed in great numbers 

 in the Baltic (by Bornholm) in August and eggs and pelagic fry have at the same 

 time been found floating in the water. 



' Laichen und Wandern der Ostseefische 1906. 



