— 1:38 — 



as shown b}' fig. 11 the curves of 2°, 3°, 4°, 5° and 6° run quite close to one another. 

 But in passing from W. Iceland southwards to the extreme south-west of the Bay of 

 Biscay, we find that the temperature in 1000 meters depth rises very evenly from 4° to 

 10°. With regard to the salinity in 1000 meters depth fig. 12 shows that it exceeds 

 35 "/oo south of the submarine ridge. From the Fseroe Bank to the large bank W. of Ire- 

 land it is about 35-25 "/oo, but south of this it is considerably greater, namely, ca. 35-50 "/oo 

 or more, even up to ca. 35-80 "Ion in the Bay of Biscay. Such high salinities can scarcely 

 be explained without the supposition that the water has had its origin in the Mediter- 

 ranean ^ 



For present purposes I subdivide the deep Atlantic region S. and W. of the submarine 

 ridge into two parts, the first of which (IIA) extends southwards as far as the large 

 Outer Bank west of Ireland, whilst the second (II B) includes the waters south of this, 

 that is the deep water S.W. and S. of Ireland, off the Channel and the Bay of Biscay. 

 The characteristics of the latter in contrast to the former are that in 1000 meters depth 

 the temperatures exceed ca. 8° and the salinities are very high, ca. 35-50 "/oo or more. 



Of the gadoids dealt with in this work not many spawn in deep water, in all only 4, 

 namely, the blue ling {Molva byrkelange), the Mediterranean ling {Molva elongata). Silvery 

 pout {Gadiculus argenteus) and the Poutassou (Gadiis Poutassou), of which only the 

 first-named is of any economical importance. 



The production of these species is however far from being equally great everywhere 

 within the deep-water regions investigated. The two lings M. byrkelange and M. elongata 

 are restricted each to its own region, the former to the northern the latter to the south- 

 ern region (cf. Chart VIII), whilst the fry of the two other species [Gadus Poutassou 

 and Gadiculus argenteus) are produced in both the northern and southern region (see 

 the Charts I and IV). 



Our northern region of the Atlantic deep water (II A), i. e. the waters from West 

 Iceland to West Ireland, are thus characterized by the fact that the blue ling reproduces 

 there, and also the Poutassou and the Silvery pout, but the latter do not spawn in any 

 very great quantity in the northernmost part of tbe region until off the W. and S. W. of 

 the Fseroes. 



Our southern region of the Atlantic deep water, i. e. from S. W. of Ireland to the 

 Bay of Biscay inclusive (II B) is characterized in the first place by the presence of the 

 Mediterranean ling though perhaps not in great quantities, also by the absence of the 

 blue ling {M. byrkelange) and further by the fact that both the Poutassou and G. argen- 

 teus reproduce here in quantities. 



From what has been said it will appear that the importance of the hydrographical 

 conditions for the reproduction of the different species is far from being less for the deep- 

 water species than for those spawning in shallower water. This will be mentioned later 

 under the description of the species, where also a comparison will be drawn between the 

 Atlantic and the Norwegian Sea in regard to the reproduction of the gadoids. 



' I. >f. Ntelsen, Meddel. Kom. Havimders. Serie Hydrografi, Bind I. No. 9, 1907, pp. 21—22. 



