— 135 — .TOHS. SCHMIDT 



From these observations we may draw the following conclusions. The salinity in the 

 Bay of Biscay is everywhere very high, especially in the southern parts, where we find 

 35-0 1 "loo in 100 meters at St. 41 "Thor" a few miles from the north coast of Spain. 

 Such high salinities do not occur under similar conditions in any other part of the regions 

 investigated. 



The temperatures in the Bay show an even rise from north to south both at the sur- 

 face and bottom, especially naturally the first. As will be seen from Table C the differ- 

 ence in the May temperature between the most northern and most southern part of the 

 region was 1-17° in 100 meters depth, 1-27° in 50 meters and even in ca. 25 meters not 

 more than 1-43°. 



Whilst the surface temperature undergoes relatively considerable fluctuations in the 

 course of the year (as much as ca. 8°, see Tables A and B) , this does not hold good for 

 the temperatures somewhat deeper down. Thus Table B shows that the range in 50 

 meters was hardly IVs", and it is naturally even smaller at still greater depths. As the 

 majority of the principal gadoids spawn at the end of winter and in spring the observa- 

 tions of temperature in Feb. and May will be of importance in this connection. Table B 

 shows further that the difference between the temperatures (at all depths) for February 

 and May is extremely small, only ca. ^U°—^li° ^. 



The depths which come specially into consideration are those about 50 — 100 meters, 

 but from Table C we see that there is but little difference in regard to temperature be- 

 tween 25 and 140 meters. 



It appears from Tables B and C that no lower temperatures than ca. 10° occur in 

 February and May, even in the most northern part of the Bay. In the most southern 

 part (off San Sebastian) the temperature was ca. lVh° and in the intermediate region 

 ca. 11°. We may therefore conclude that the majority of the gadoids spawn in the Bay 

 at temperatures which vary from ca. 10° to ca. 12°, that is higher temperatures than any- 

 where else in the coastal waters within the regions investigated. The nearest approach 

 to these temperatures is found in the western part of the Channel and S. W. and W. of 

 Ireland. 



With regard to the production of the gadoid fry, the Bay is specially characterized 

 by such species ^ as the hake (Merluccius), which spawns here in large quantities, the bib 

 (6r. luscus), poor cod {G. minutus) and pollack [G. poUachius) and in deeper water the 

 Mediterranean ling {Molva elongata) , silvery pout [Gadic. argenteus) and Poutassou {G. 



^ This difference is scarcely everywhere so small in these waters as in the most northern part at 

 E4, but when we see from Table A that the difference between Feb. and May in the most southern 

 parts (off Santander) even at the surface is only ca. I'l2°, we may assume that it must be very small in 

 the depths where the spawning of the gadoids takes place, e. g. in 50—100 meters. And our observations 

 fi'om the "Thor" in the beginning of May are therefore undoubtedly quite applicable in the endeavour 

 to determine the approximate temperatures under which the spawning of the gadoids takes place in the 

 Bay of Biscay. 



^ Dr. Ad. Clignt of Boulognesurmer, who has often examined the catches of the French trawlers 

 fishing in the Bay of Biscay, has kindly given me the following information on the gadoids occurring there: 

 "Besides Merluccius, Gadus luscus, minutus and pollachius, I may record from my own experience Gadus 

 Poutassou, which is very common, Phycis blennoides, Molva molva, M. byrkelange var. elongata, all pretty 

 common. G. œglefinus occurs but exceptionally in the Bay of Biscay even on the south coast of Brit- 

 tany. G. merlangus abounds in the Channel especially in the eastern part ; it becomes rarer towards 

 the west and is very rare on the south coast of Brittany" (A. Cligny in üt.). 



