1895 ^O- 9- HYDR.-BIOL. STUDIES OF THE XORW. FISHERIES 73 



U'c M ay, therefore, in respect, too, to the Herring, cotulude 

 that it, by degrees (wlten of a size of about 200 mm.), moves out to tJie 

 sea, and in the Fjords, into deep water, gradually assuming tJie habits of 

 tJie Ocean fishes.*- 



Resume. As a result of the foregoing, it wall appear that the fish 

 which give rise to our most important fisheries, the Cod, Herring and 

 Mackerel, both as eggs, pelagic fr>% and adult fish, stand in the most 

 dependent relations to the ocean currents along the coast, whilst, as 

 young fish they appear to be more independent of the changes which 

 the coastal waters undergo. 



The thickness of the fresher currents are. at the time the eggs are 

 spawned, of the greatest importance to the fr\- of each \ear, as they 

 (the currents) convey the eggs and pelagic fr\' many miles away from 

 the spot where they were deposited, and in cold Winters it is probable 

 that, in this manner, miUions of individuals are lost. 



During the spawning migration of the Cod and Herring in the 

 Winter (February- to April), the Coastal Waters exhibit the most different 

 conditions in different years. In some years the West and North Coasts 

 of Norway are washed throughout by salt and warm water from the 

 ocean without water of a salineness of 34 per 1000 and a temperature 

 of 5 ''^ . These years are specially favourable to the influx of the fish, 

 as the hydrographical conditions of Coastal Waters but slightly differ 

 from those of the open sea to which the habits of the adult fish are 

 assimilated. In other years, fresher and colder currents (of a salineness 

 imder }y2 per 1000, and a temperature varying from 2 " to i degree) 

 flows along the whole of the Norwegian Coast. These currents cover 

 the good spawning grounds, those grounds which form the best fishing 

 spots, and compel the fish to stay their course, and remain out at sea 

 in deep water. In such years, the fish are only seen in deep water, and 

 the roe of the Herring is found at a depth of over 100 mètres, whilst 

 in warm years, it is constantly met with at a depth of but a few mètres 

 up, in the region of the seaweed. 



The feeding migration of the Ocean Herring is found, too, to be 

 dependent on the Ocean Currents. In the years 1893 and 1894, during 

 the East Coast Fishen.-, the prey was only present in the salter layers 

 of the Bank Water which was of a considerable higher temperature 



