— 123 — .TOHS. SCHMIDT 



immense quantitios, so much so llial the production of these species there is perhaps 

 greater than anywhere else within the regions investigated, at least it is not greater 

 elsewhere. The coalfish {G. virens) and torsk [Brostnius brosme) also spawn there in very 

 large quantities, and likewise the whiting (G. merJang^is) and ling (Molva molva) but on a 

 smaller scale. None the less characteristic on the other hand is the total absence of 

 pollack (G. pollachiiis), poor cod (G. minutus) and bib {G. luscus), lesser forkbeard {Rani- 

 ceps ranimes) and hake {Merluccius vulgaris). 



The production of the fry of the different species is however not equally great every- 

 where even within the warm portion of the Icelandic waters. Some species mainly spawn 

 only in the very warmest part of the region, e.g. ling (Molva molva) and whiting (G.mer- 

 laiigiis), as will be seen from the Charts of distribution III and VII, which show that the 

 pelagic fry of these species are practically only taken on the south and most southerly 

 part of the west coast. The coalfish ((?. virens), torsk (Brosmius brosme) and haddock 

 (G. œglefinus) are somewhat less particular, the first also spawning on the southern part 

 of the west coast, the two others on the northern part. Lastly, we have the cod (G. 

 callarias) as the species which spawns on the largest scale furthest to the 

 north. 



It may be said in general that in the species which spawn both on the south and 

 west coasts spawning is somewhat later (May, in part June) on the latter coast than on 

 the former. This is certainly in connection with the fact that the temperatures on the 

 west coast (especially the northern portion) are later in reaching the same height as those 

 found already in March— April on the south coast. 



The slight "after-spawning" already mentioned of the cod in the colder parts of the 

 Icelandic waters, especially the western part of the north coast, in the summer time 

 may be explained in the same way, namely, as being connected with the rise of 

 temperature which takes place on the north coast in summer and which even in the 

 middle of June is already sufficiently high to permit of the cod spawning in these waters, 

 where in spring the water was too cold (cf. figs. 5 and 7)^. Even if this summer produc- 

 tion of cod fry on the colder parts of Iceland is in extent quite inappreciable and un- 

 important in comparison with the spring spawning, it has the great scientific interest that 

 it shows to what a degree the reproduction of the fishes and the period for reproduction 

 depend upon the temperature (cf. the summer spawning of the cod in the Baltic, and the 

 late spawning of the two really Atlantic species Gadus pollachiiis and minutus in the 

 North Sea and Skager Rak, where the temperature under which the spring spawning 

 occurs in the Atlantic is not met with before in early summer, p. 131). 



It will be evident from the foregoing that the Icelandic waters with their extremely 

 diverse hydrographical conditions are peculiarly well-suited to the study of the importance of 

 these conditions especially temperature for the spawning of the fishes, and this is the reason 



1 Thus on June 17th 1903 at Stat. 139 off the western part of the north coast (66° 13' N.,20° 29' W., 

 depth 60 meters) we found a surface temperature of 484° and a bottom temperature of 4-00°. The rise 

 of temperature on the, north coast in the course of the summer is also distinctly seen from the averages 

 for G-rimsey in the table p. 115. Concerning the hydrographical conditions at N. Iceland see I. N. 

 Nielsen, Meddel. Kom. Havunders. Serie Hydrografi, Bind I, No. 7, 1905. 



16* 



