— 149 — JÜHS. SCHBIIÜT 



3. G roiipiüfi- Ol' tliü species according to salinity 



The observations on the inliuenco of the salinity on the spawning regions for the 

 various species have not yet been carried out to the same extent as those for the temperature, 

 and the accompanying Table can only be regarded therefore as the very first preliminary 

 trial in this direction. As already mentioned earlier, the Atlantic region where the isoha- 

 lincs run close to one another is not well suited to study the influence of the salinity. 

 Waters such as the North Sea, Skager Rak and Kattegat are much better in this regard, 

 and data for these regions are therefore included in this summary. 



Minimum salinity at 

 which s])awning' of any Species 



importance occurs ("loo) 

 ca. 35-50 Mediterranean ling {Molva elongata) 



- 35-25 — 30 Poutassou (Gadus Foutassou) 



- 35-25 Silvery pout {Gadicidus argenteus) 



- 35-10—20 Blue ling {Molva hyrkelange) 



Common ling {Molva molva) 

 Coalfish {G. virens) 



- 35-00 Torsk {Brosmius hrosme) 



_ 34-50— 35-00 Haddock (G. œglefinus) 



Norway pout {G. Esmarki) 



under 20-00 Cod {G. callarias) 



Of the outer factors mentioned as having influence on the spawning, it has been 

 chiefly the temperature which has been more closely investigated here. We have already 

 seen striking examples of the extent to which this factor, naturally in combination with 

 the depths and salinity , is determinative of what species will spawn in any given water. 

 I need only refer here to the conditions described on p. 127 — 28, namely, that there was a 

 much greater agreement between South Iceland and South Ireland in spite of the great 

 distance between them than between S. Iceland and E. Iceland with regard to the spawn- 

 ing gadoids, which is in agreement with the conditions as to the temperature, as can be 

 seen for example from fig. 11 p. 137. 



The subdivision p. 148 of our Atlantic species into a "northern" and a "southern" group 

 is thus based on the temperature, that is, on the minimum temperature required for spawn- 

 ing. It would have been undoubtedly possible also to subdivide the species according to the 

 maximum temperature, but for this in the case of the "southern" group investigations 

 further to the south (e. g. in the Mediterranean) than I could make would have been required. 



In the list over the separate species pp. 139—147 both the maximum temperature 

 (where this could be determined) and the minimum temperature were given. It can be seen 

 from this that the range for the different species varies according to their greater or 

 less sensitiveness. In general however the range is but small, usually 3°^4° — 5°. 

 It seems to be greatest in the species spawning in shallowest water, e. g. cod {G. callarias), 

 least in those spawning in deepest water, e. g. torsk {Brosmius brosme) and blue ling 



