OF THE NORWEGIAN FISHERIES: A REVIEW. 



59 



of North Sea water. In such winters the sea along the coast is of 

 uniformly high salinity and temperature. 



In other winters, either calm or marked by a predominance of south- 

 east gales {e.g., that of 1894-5), the cold Baltic current is released from 

 the Cattegat, and flows along the west coast in a slender stream. This 

 layer in itself is much less thick (usually ten or twenty metres) in 

 winter than in summer, but it covers the sea with a cold sheet of water 

 of very low salinity and temperature, which serves to dilute and cool 

 the upper layers of bank water to a considerable degree. Thus the 

 surface temperature was, in February, 1895, 2-9° C, although 6'5° in 

 February, 1894, while the salinity of the inshore waters down to a 

 depth of thirty, forty, or even seventy metres, did not exceed 33 per 

 thousand. 



Such variations as these in the character of the inshore waters during 

 the winter season are of the highest interest and importance, as we 

 shall see below in the section dealing with the Fisheries. 



The deeper water off the coast also undergoes considerable changes 

 in successive seasons. The summer season, for example, is characterised 

 by the great height to which the Atlantic water rises off the shore 

 (within 100 metres of the surface), and also by the thinness of the 

 layers of bank water and North Sea water; while in winter Atlantic 

 water is only found at great depths (250 metres), and the layers of 

 bank water and North Sea water are of great thickness. 



These seasonal contrasts will best be comprehended by a comparison 

 of the statements made in the following parallel columns : — 



Wateii-layer(and Salinity), 



Baltic current [w]} to 327oo) • 

 (Salter off Norway than in 

 E. part of Skagerack). 



Bank water (327„„ and 33%J. 



North Sea water (34% J . 

 Atlantic water (357co) • 



Summer. 



Thick and wide 

 (50 metres x SO miles). 



Thin and inconsiderable 

 (10 or 20 metres thick). 



About 50 metres tiiick 



Jluch nearer surface than 

 in winter (100 metres) . 



Winter. 



Thin and narrow. . 



(10 or 20 metres X 16 or 20 

 miles) ; sometimes absent. 



A broad thick belt along the 

 whole west coast (50 to 150 

 metres thick). 



100 to 150 metres thick. 



Onl}^ at great depths (below 

 250 metres). 



2. Temperature Changes. 



The Baltic current is hot in summer, cold in winter. Since the 

 low salinity of its water ensures its occupying the surface of the 

 sea at all seasons of the year, the seasonal change in its temperature 

 causes the maximum temperature to sink below the surface in autumn, 

 and tlie minimum temperature to ascend to the surface in winter. 



