— 27 — KNUT DAHL 



If these temperatures, found in water possessing the optimum specific gravity of 

 cod larvae, are compared with the average size of the pelagic cod fry contemporaneously 

 caught, the correspondance in growth and rise of temperature is striking. 



The maximal size of the pelagic cod fry is shown by the table (page 26). Not one 

 pelagic young cod of a size above 28 millimetres has been found during my investigations 

 in the neighbourhood of Risoer. During the cruises of the "Michael Sars" in the 

 Skagerrack pelagic cod fry reaching 33 mm. in length were found in the last days of 

 June. In July pelagic young cod reaching 44 millimetres have been found during the 

 Danish investigations. Only exceptionally have pelagic cod fry of a larger size been 

 found in the Skagerrack and North Sea. In these relatively shallow waters young cod 

 above 3 — 4 cm. in length are as a rule only found along the bottom. 



The duration of the pelagic stages of the young cod cannot be exactly 

 determined. 



On the one hand our material shows , that pelagic cod fry after June become 

 comparatively scarce and also that the young cod in these waters appear in the littoral 

 region from the beginning of June. On the other hand however the actual occurrence 

 of pelagic cod fry has been ascertained also later on during summer and several facts 

 seem to indicate, that this occurrence plays an important part. 



After June only few and unsystematic examinations were undertaken in 1904. 

 However on the 7th of July the presence of cod larvae was ascertained in the Sondeled 

 Fjord (see table page 26) also cod eggs in the last stage of development. 



In 1905 the tow-net employed from the end of May could not retain larvae and 

 only very few hauls were made after June, the pelagic cod then becoming exceedingly 

 scarce, and the study of littoral fry demanding all my efforts. 



The cruises of the "Michael Sars" 1904 showed that pelagic young cod of small 

 size (8 millimeters) were found even in the last days of June. During the Swedish 

 investigations 1906 a pelagic cod 16 mm. long was found in the mouth of the Skagerrack 

 on the 10th of August (Lat. 57°56' Long. 9°40'). 



Besides these catches in July and August here mentioned, no pelagic young cod 

 have to my knowledge been found in late summer in the Skagerrack. However, 

 comparatively few investigations have been made in these waters during late summer 

 and autumn. 



Certain facts regarding the occurrence of littoral cod fry seem also to indicate that 

 pelagic cod fry must continually occur in these waters in summer as well as autumn, 

 possibly even all the year round, and a closer investigation of this matter will be 

 highly important. 



The littoral cod fry have in the waters around Risoer not been met with earlier 

 than in the last days of May and the first of June. 



In the following table I have recorded all the representative catches of littoral 

 cod fry made in the neighbourhood of Risoer (in fine-meshed seines) during the years 

 1904 and 1905. Finally a catch made in the autumn of 1907 is also recorded. 



In this table the preponderance of individuals less than one year of age, is denoted 

 by printing the last figure in heavy type. 



