NORTH SEA FISHERIES 29 



has given it a surface, rich in many of the 

 essentials for marine life. These different 

 agents have almost filled up the North 

 Sea : in some places where the currents 

 have assisted in depositing the detrital 

 matter, the banks are so high as to be 

 dangerous to navigation. 



The European stream, a drift of sub- 

 tropical Atlantic water (often called the 

 Gulf Stream) which breaks in two parts 

 on the British Isles, runs in by the 

 Dover Strait on the south and between 

 'the Shetlands and the Faroe Isles on the 

 north ; this incoming water affects the 

 salinity and temperature of the North Sea 

 and gives another essential to marine life, 

 movement. These currents, together with 

 the rivers flowing in, bring in live water 

 laden with all 'kinds of the minute animal- 

 culse which fish require. The great amount 

 of fresh water entering the area from the 

 Baltic and North Sea rivers carries the 

 nitrogenous substances from the earth so 

 necessary to rapid growth of plant and 

 animal life. Consequently the numbers 

 of Diatoms, Peridinians, Copepods in these 

 waters are so enormous as often to discolour 



