— To- 

 on the western part of the Faeroe-lceland submarine ridge and along the most northern 

 coast of Norway. Molva byrkelange spawns, as has been proved, in the Norwegian 

 fjords but not in the Norwegian Sea itself. In the Atlantic Ocean it goes southwards 

 almost as far as the Irish deep-sea Bank and northwards as far as the north-west coast 

 of Iceland. The remaining 3 species occur in the south far beyond the region invest- 

 igated, they are common Atlantic forms. The two species Gadus poutassou and Gadi- 

 culus argenteus occur in the north as far as the deep-sea margin on the south coast of 

 Iceland. Molva elongata on the other hand does not go further north than to the Irish 

 deep-sea Bank. 



II. On the Natural Conditions in the Spawning Regions 



The spawning time of most, at least of the economically important, gadoids falls in 

 the spring months. They spawn in greatest abundance in the period from February to 

 April. Wherever a summer spawning also occurs, as happens with some species, this 

 has a much smaller extent and is also bound to other places than the main spawning. 

 It is consequently of special importance to consider the hydrographical conditions in the 

 region investigated during the spring months. In doing this we will specially discuss the 

 hydrographical conditions of February and March 1906, referring for the rest to the hy- 

 drographical summary given previously. 



The Chart, fig. 20, shows the distribution of the temperature and salinity on the sur- 

 face of the sea at the end of March 1906. The Atlantic water with a salinity of over 

 35,2 °/^^ covered at that time not only the Atlantic Ocean but also large parts of the 

 Northern North Sea. In the Norwegian Sea it extended only as a narrow tongue as far 

 as the Romsdal Bank. In this Atlantic water we find temperature curves of 9°, 8°, 7° and 

 in part 6° ; the latter temperature coincides at several places with the isohalin of 35,2 °/oo- 

 The isohalin 35 °l^^ penetrates somewhat further into the North Sea and in the north 

 into the Norwegian Sea. At Iceland and the Faeroes the surface water of the coastal 

 banks shows everywhere salinities as high as 35 °l^^ ; otherwise the coastal banks have 

 salinities of 34 °/ ^^ and less and temperatures between 3° and 5°. 



We may also consider the Chart, fig. 21, which represents the salinities and temp- 

 eratures along the bottom in February and March 1906; it appears from this that the 

 salinities on the Atlantic coastal banks amount to 35—35,3 "/o^. The temperatures vary 

 between 8° and 10° ; they are lowest in the neighbourhood of the land, e. g. towards the 

 Channel and the Irish Sea ; on the deep-sea margin, where the salinity amounts to 35,3 "/^o, 

 the temperature rises to 10°. This appears clearly from fig. 22, which has been taken 

 from the "Bulletin" and represents a section ("Atlantic III") beyond the west coast of 

 Ireland in February 1906. 



Towards the north the temperatures decrease both on the coastal banks and along 

 the deep-sea margin. This cannot be seen very clearly from the Chart; it may be noticed 

 however that the bottom temperatures at the Shetlands amount to 6° — 7°, and the same 

 temperatures also occur on the Atlantic deep-sea margin in the neighbourhood of the 

 Icelandic coasts. It may be concluded that the temperature steadily decreases from Ireland 

 to Iceland. 



The species of the gadoid group which was found to spawn in the main only on 

 the Atlantic coastal banks, namely, Gadus lus eus, minutus SiX\à. pollachius, have 



