290 



A HISTORY OF FISHES 



greenish coloration is replaced by a metallic silvery sheen 

 on the sides with a deep blackish back (Fig. 105). All these 

 characters become more and more accentuated as the time 

 for breeding approaches, and internally a Silver Eel may be 

 recognised by the riper reproductive organs and the shrunken 

 alimentary tract. They make their way down the rivers in the 

 late summer and autumn, and so powerful is the reproductive 

 call that even those individuals isolated in ponds and lakes 

 will make an effort to reach the sea if a river be fairly near at 



hand, wriggling across 

 stretches of meadow at nights 

 when the dew Ues on the 

 grass. Once in the sea our 

 knowledge of their activities 

 is more conjectural, but it is 

 known that they migrate 

 across the Atlantic Ocean to 

 their breeding-ground, which 

 Ues in the Western Atlantic, 

 south of Bermuda. It was 

 formerly thought that the Eels 

 from the countries bordering 

 the Mediterranean spawned 

 in the depths of that sea, 

 but it is now known that 

 even those from the farthest 

 regions at the mouth of the 

 Nile and the northern end of 

 the Adriatic Sea make their 

 way to the Atlantic for this 

 purpose. This stupendous 

 which may be as 

 - ^- ^^^^^^ ^^^' much as three thousand or 



even four thousand miles, is undertaken because it is only in this 

 particular part of the Atlantic that conditions suitable to the pro- 

 creation of the species are to be found. It is beheved that the Eels 

 spawn at a depth of about four hundred metres below the surface, 

 and that a fairly high temperature is required for the proper 

 development of the eggs, as well as water of a certain sahnity. 

 Having completed the extrusion and fertiHsation of the ova, 

 the parents die, for it is not to be expected that such a journey 

 could be undertaken more than once in a lifetime. 



The eggs float for a time, and the young, when hatched out. 



Fig. 105. 

 Heads of Fresh-water Eels (AnguUla 

 anguilla), X \. A. Yellow Eel ; B. Silver journey 

 Eel " '^"-^ — ^"' 



