- 74 — 



ling and coalflsh. Between Metiuccius on the one side and ling and coalfish on the 

 other we have the same difference as between the two groups of the forms which spawn 

 in shallow water. 



Merluccius belongs to the southernmost part of the region, becomes rarer further 

 north and ceases on the west coast of Scotland. The Chart (fig. 2i) shows that its 

 region (between lOO and 200 M.) possesses the high salinity of more than 35,, 7oo and a 

 temperature of over 10° (see fig. 17). 



On the other hand, the ling and coalflsh go southward only as far as to the northern 

 part of the Bay of Biscay, where they are already rare, and the principal region of their 

 occurrence begins on the Irish coasts. From here over the Tampen to Romsdal Bank 

 and on the other side to the Fasroe Bank and the south coast of Iceland, we have the 

 main spawning region of these species, mostly in depths of 100 to 200 M. What is 

 characteristic of this region is that we have here the highest salinities , over 35,25 %o, 

 and temperatures of 6°— 10°, mostly between 7" and 8°. On the Norwegian coastal 

 banks the ling and coalfish only go so far north as this highest salinity occurs, which is 

 an extremely important factor (see Chart, fig. 21). Thus, they do not spawn at the 

 Lofotens, and not so far north on the west coast of Iceland as the cod. That it is not 

 only the depth which is the deciding factor in the choice of spawning place, appears from 

 the fact that spawning ceases on the North Sea slope (Revet) and does not occur in the 

 Skager Rak, where also we do not have the highest salinity (see Chart fig. 20 and the 

 sections fig. 11). 



The conditions on the Romsdal Bank are of special interest in understanding these 

 phenomena. 



Fig. 24 shows a section from the deep-sea margin of the Romsdal Bank (to the left 

 on the figure), across and over this into a fjord lying further in (to the right), which is 

 in connection with the deep water beyond the Bank by means of a deep channel. On 

 the slope of the Bank towards the sea the ling and coalfish spawn above depths of about 

 150 M.; here we find the temperature curve for 7° and salinities between 35,1 and 

 35,2 7oo- '^he latter curve touches the Bank at one or two places. Further up, in depths 

 of about 100 M. we find the haddock spawning; here the temperature is 6° and the 

 salinity 35 7oo- Up on the Bank where the cod spawns the temperature amounted to 

 ca. 5° and the salinity to somewhat over 34 °/oo. Naturally, small variations may occur 

 here from time to time. The deep station in the fjord shows a very different character 

 when compared with the sea. We miss here the unmixed Atlantic water and the temp- 

 erature 7°. The isohalin of 35 °/^^ is first found at a depth of 250 M. The mixed 

 layers are in much greater evidence and thus the movements and other conditions of 

 these layers are very different. Most of the principal species spawn in great quantities 

 on the Bank, in the fjords there is but little spawning. 



On the Atlantic deep-sea margin (see fig. 22) we find the high salinity and a 

 temperature of ca. 10°. Here also we have two groups of forms. To the one belongs 

 the torsk, the only gadoid which also spawns in the Norwegian Sea as well as here (on 

 the western part of the Faeroe-Shetland ridge and on the Norwegian margin to the 

 Norwegian Sea). 



In the south the species only goes as far as the Irish deep-sea Bank. The optimal 

 limits for the salinity and temperature at the spawning places of this species may be 

 taken to be: 



