THE SMALL GAME OF THE SEA 



189 



42-8° F. and 44-6° F. Temperature, then, plays a predominant 

 part in determining the distribution of the fishes. It is interest- 

 ing to note that it is a no less important factor in the distribution 

 of the minute organisms on which the nutrition of fish depends. 



Distrihution of the Small Game 



Li Chapter VIII of Depths of the Ocean Hjort has a wealth of 

 interesting information on the ' small game ' which lives on the 

 sea-bottom. It appears that in the southern portion of the 

 North Sea (south of the Dogger) the summer temperature of 

 the water rises to 55° F. or 59° F. at depths down to 22 to 27 

 fathoms ; in winter it is cooled down to 39° F. or 41° F. The 

 bottom animals on these shallows accordingly consist of two 



68-^^ I— 66 2° 



February. August. 



Fig 22. — Surface temperature of the North Atlantic. 



contingents — the northern animals who are ' capable of adapt- 

 ing themselves to variations of temperature ', and a ' special 

 contingent that has wandered in through the Enghsh Channel 

 and requires high temperatures for at any rate part of the year. 

 Most of these latter forms are limited to the southernmost 

 portion, though a few follow the coasts towards the north, 

 penetrating on the east side even to the Skagerrak, and on the 

 west side to the coasts of Northumberland or perhaps still 

 further, but avoiding the deeper parts of the central area ' 



The whole of the northern part of the North Sea is covered 

 with Atlantic water. On its most northerly banks, where the 

 depth is over 54 fathoms, that is to say, on banks like the 

 * Witch Ground ' which is included in our ' F 1 ' area — the 

 waters are warmer than in the central parts. Here are found 

 again two contingents of animals. Firstly the ' special southern 



