358 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1914. 
the banks where it was supposed the fish had spawned. ‘The fol- 
lowing year, on the banks to the north of Norway, they gathered 
recently spawned eggs in great abundance above some shoals of 
spawning fish. A chart was carefully prepared showing the spawn- 
ing grounds, and, moreover, one of the commissions (commission A) 
named by the ‘‘Permanent International Council for the Exploration 
of the Sea”’ was given the task of preparing for the entire area of the 
North Sea a chart of the spawning grounds of the fishes of the very 
important family of Gadide (of which the cod (Gadus) is the type). 
Investigations have shown that each of the 15 species of Gadide 
caught on the coast of Norway chooses its particular spawning 
ground—sometimes extremely limited—which offers the natural 
conditions that that species seeks during the spawning period. Depth, 
temperature, and salinity appear to be predominant factors in this 
matter. While certain species, such as the hake, cod, and haddock, 
spawn on the littoral banks and at depths which speaking broadly 
never exceed 200 meters, most of the other species of this family 
breed in greater depths in water of oceanic character. The larve 
are carried far from the breeding places by the currents, which play a 
predominant réle in the transportation of young fish into different 
waters. This passive distribution of the pelagic stages has been 
made the object of joint investigations by the Danish, English, 
Germans, Dutch, and Norwegians. 
The herring, whose life history has been worked out so carefully by 
Heincke at the Heligoland biological station, has also been closely 
studied in Norway by several naturalists, who have distinguished 
on the coasts of their country four different types of herring cor- 
responding to different stages of development. The one which is 
given the name spring herring is in the state of sexual maturity, its 
length varying from 24 to 37 centimeters and its age from 3 to 14 
years. The same individual may spawn 10 or 14 times. Great 
differences have been found in the size of herring, according to locali- 
‘ties. While the spring herring of Norway reach 37 centimeters at 
10 to 14 years, that of the Zuyder Zee does not exceed 26 to 27 centi- 
meters, and that of Breitstadfjord not more than 23 to 24 centimeters. 
J. Hjort and Einar Lea have shown that, as G. O. Sars had supposed, 
the migrations of the herring are much more extended than had been 
previously suspected. All these facts are of the greatest importance 
from the point of view of the fishing industry. 
VI. 
In addition to investigations similar to the foregoing relative to the 
salmon and the sprat, the Michael Sars has been utilized also for 
fishing experiments and for practical investigations directed by its 
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