— 47 - .TOHS. SCHMIDT 



'riio first, traces of the liypunil elements in the caudal fin are seen already at a length 

 of 4'/j — 5 mm. 



For the rest , 1 may refer to my earlier descriptions and figures (Gadus I, PI. I). I 

 would only add that the pigment in G. pollachlus on PI. I has generally been given too light 

 in comparison to that in G. virens, which is due to the circumstance that my drawings then 

 made of G.poUacJiiits were prepared from old spirit material from Plymouth, whilst I had 

 fresh specimens of G. virens. The fact is that the pigment in G. j^oUachius is extremely 

 dark and well-marked, even more so usually than in G. virens. 



§ 2. General features of the occurrence 



On the Chart of distribution II the pelagic young of Gadus poUachius and of Gadiis 

 virens are given together, in order to show the characteristic difference in the distribution 

 of these two so nearly related species. The Chart is only for the months of April, May 

 and June, as it would only lead to confusion if all the negative hauls were included for 

 July, August and September, by which period the great majority of the young pollack have 

 ceased to live pelagically and were therefore not taken in our hauls '. 



The eggs of the pollack are not known to me with certainty, and I am therefore un- 

 able to show their distribution on the charts or to discuss their occurrence. 



As 1 have not been able to distinguish the pollack eggs in our samples, it is difficult 

 to say anything certain regarding the spawning of this species. Yet the periods when we 

 took on the one hand the pelagic fry and on the other the early bottom stages point to 

 certain conclusions in this regard, so that we can say, in the first place, that the spawning 

 must throughout take place later than that of the cod and especially than that of the 

 coal fish. In the second place it can be said that the spawning, at any rate in the Channel 

 and W. of Ireland, must occur at least in March and April, as also that in the most 

 easterly part of the region we have investigated, namely, the Skager Rak, it must take 

 place later in the year, in May and June. So much appears from our investigations, 

 therefore, that the pollack spawns in the months from March to June inclusive, and that 

 the spawning time is probably somewhat different in the different waters, but more detailed 

 information regarding these matters I am unable to give (see further under the description 

 of the different waters). 



As regards the depths over which the pelagic fry occur, the pollack belongs to the 

 species living in the shallowest waters, and though it does not spawn in so shallow water 

 as the cod, yet it certainly does not require such great depths for this purpose as the 

 coalfish. With exception of a single specimen all the pelagic fry of the pollack we have 

 taken were found in shallow water within the 200, almost all even at or within 

 the 100-meter line, and this applies to the Skager Rak, North Sea, the Channel, Bay 

 of Biscay and the west coast of the British Isles. The single exception was a specimen 

 of ca. 2V3— 3 cm. in length, which was taken at St. 76, 1905, W. of Scotland, over a 

 depth of more than 1000 meters, but consideration of the Chart will show that the slope 



• In the eastern part however of the region which has been investigated by the "Thor", namely 

 the North Sea and the Skager Eak, a few small pelagic stages were found as late as in July. These 

 catches in the North Sea and Skager Rak are also inclnded on the Chart, bnt with a si)ecial mark and 

 only the stations which gave a positive reanlt in .Tnly. Angnst and September are shown. 



