THE COD FLSIIERIES NEAR THE LOFFODEN ISLANDS. 040 



in a southerly diicctiou. If we look at a map wc find that all these lines 

 point to the large and so (ar but little investigated portion of the sea 

 between Scotland, Iceland, and Norway. Many other reasons have de- 

 termined me to consider this as the proper home of the spring-herring. 

 Occasional soundings made in that portion of the sea have shown that 

 the depth is certainly very great, so great that fish like the spring-her- 

 ring, which undoubtedly pass part of the year near the surface, could 

 not be supposed to find an inviting place of sojourn at the bottom of 

 this basin. There is in my opinion no necessity for supposing this to 

 be the case. 



When thinking about the above-mentioned hypothesis advanced by 

 many modern zoologists regarding the place of sojourn of the spring- 

 herring, it has always appeared to me very improbable and contrary to 

 nature that a fish like the herring, whose whole build and inner organiza- 

 tion (its compressed wedge-shaped form, its large swimming-bladder, 

 wide respiratory organs, &c.) seem to be calculated for a free and roving 

 life near the surface of the sea, should follow such a mode of life only 

 during the short time of its spawning season, but should all the rest of 

 the year hide in the deep valleys of the ocean. Still less probable did 

 this seem to me after it had become perfectly clear to my mind that the 

 so-called summer-herring is not, as zoologists formerly believed, a dif- 

 ferent variety from the spring-herring, but simply the same herring at 

 a different age. The roving mode of life of the summer-herring can 

 easily be observed on our coasts during summer and autumn. It will 

 soon be seen that these herrings do not keep in the deep, unless it were 

 during the time that the full-grown herring (the spring-herring) leaves 

 it, and that they then are again chased away when the old herrings 

 return to the deep. The food of the summer-herring consists almost 

 exclusively of small crustaceans of the order of Copepods swimming 

 about freely, the so-called "herring-food," which, on account of the 

 unusual quantity of fatty oil contained in their bodies, are very nu- 

 tritious. All these small crustaceans keep more or less near the sur- 

 face of the water, never at the bottom, and it is their very wealth of oil 

 which enables them to keep continually near the surface. 



It is true that there are similar crustaceans near the bottom, but in 

 the first place their number is very small compared with those near the 

 surface, and in the second place they do not contain so much oil, which 

 circumstance is really what makes crustaceans such an important arti- 

 cle of food for fish. The spring-herrings would therefore scarcely find 

 suiScient food at the bottom, unless they would (which, however, is 

 highly improbable) be satisfied with a totally diflerent food. The sur- 

 face of the sea, on the other hand, -will all the year round richly supply 

 them with that food to which they have been accustomed from their 

 earliest age. 



It is likewise my conviction that the spring-herrings use exactly the 



