36 BIOLOGY OF THE SEAS OF THE U.S.S.R. 



islands, the warming up of the Polar waters, a decrease in icing and easier 

 navigation for shipping in high latitudes. 



As early as 1921-26 (taking average annual data) a rise of almost Г degree, 

 as compared with 1900-01, was observed in the temperature of the bottom 

 layers of water along the meridian of Kola ; the rise in the temperature of the 

 upper 200 m layer was on the average almost 2°. During that time the ice in 

 the Barents Sea decreased considerably (by 13 per cent). 



The waters of the Kara Sea have been affected by a no less sharp rise in 

 temperature. This made possible the voyage in 1939 of the Sibiryakov, when 

 she rounded Severnaya Zemlya from the north, reaching a latitude of 80° N 

 in one season. On her passage from Cape Zhelaniye to Wiese Island and on 

 to the Pioner Island in 1933 the Taimyr never encountered a surface tempera- 

 ture below zero, while in some places the temperature of the water reached 

 4-5°. 



The sea fauna, that extremely sensitive indicator of changes of temperature, 

 reacts to climatic changes, by changes both qualitative and quantitative in its 

 composition. Many warmth-loving sea dwellers new to the Arctic penetrate 

 far into it, while, on the other hand, forms characteristic of cold waters move 

 deeper into it from the more southerly parts of the Arctic regions. This con- 

 cerns not only individual forms ; whole communities change their composition 

 both qualitatively and quantitatively. All aspects of the biology of Arctic flora 

 and fauna are influenced by this general change towards a warmer climate ; 

 the Arctic's outposts — the Barents and Kara Seas — are particularly affected by 

 it. Fisheries are also affected since the regions of the shoaling of commercial 

 fish — cod, haddock, herring, bass, cambala — have moved east and north. The 

 Danish scientist Ad. S. Jensen (1939) thinks that the great development of cod 

 fishing off the southwestern shores of Greenland is due to the mass arrival of 

 cod in this region as a result of the increase in temperature of the Arctic. The 

 annual catch of this industry has increased since the 1920s from 400 to 8,000 

 tons. 



Moreover Ad. S. Jensen notes that fish which were either absent or rare 

 off the western shores of Greenland have now become common there. This 

 includes haddock (Gadus aeglefinus), brismak (Brosmius brosme), sea pike 

 (Molva vulgaris) and others. Cod, herring, coalfish, salmon and others have 

 become common and are even fished there. Halibut and caplin are widely 

 distributed and, finally, some fish, e.g. bass, have begun to spawn there. 

 Hence according to Ad. S. Jensen's data, the fish of the Davis Strait have 

 undergone a complete change owing to the warming up of its waters. Among 

 others the common asterid (Asterias rubens) is widely propagated there. On 

 the other hand many forms have moved from the south to the northern parts 

 of the Davis Strait and Baffin Bay. The main shoaling of Delphinapterus leucas 

 and such fish as the fjord cod {Gadus ogac) and Greenland flatfish {Reinhardt- 

 ius hippoglossoides) have moved. 



All these far-reaching changes in the composition and distribution of the 

 fauna of Greenland's western shores are the result of the intensification of 

 the stream of Atlantic water entering the Davis Strait from the south and of the 

 general Г to 2° rise in the temperature of the waters. A comparison of water 



