96 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



spawns once and then dies. All the eggs of a female eel show the same 

 degree of maturity, while in the fish which spawn every year, besides 

 the large eggs which are ready to be deposited at the next spawning 

 period, there exist very many of much smaller size, which are destined 

 to mature hereafter, and to be deposited in other years. It is very hard 

 to understand how young eels could find room in the body of their 

 mother if they were retained until they had gained any considerable size. 

 The eel embryo can live and grow for a very long time suj)i)orted by the 

 little yolk, but when this is gone it can only obtain food outside of the 

 body of its mother. The following circumstances lead us to believe that 

 the spawning of the eel takes j)lace only in the sea : (I) that the male 

 eel is found only in the sea or brackish water, while female eels yearly 

 undertake a pilgrimage from the inland waters to the sea, a circum- 

 stance which has been known since the time of Aristotle, and upon the 

 knowledge of which the principal capture of eels by the use of fixed ap- 

 paratus is dependent; (il) that the young eels with the greatest regu- 

 larity ascend from the sea into the rivers and lakes. 



All statements in opposition to this theory are untenable, since the 

 young eels never find their way into land-locked ponds in the course of 

 their wanderings, while eels planted in such isolated bodies of water 

 thrive and grow raj^idly but never increase in numbers. Another still 

 more convincing argument is the fact that in lakes which formerly 

 contained many eels, but which, by the erection of impassable weirs, 

 have been cut off from the sea, the supply of eels has diminished, and 

 after a time only scattering individuals, old and of great size are taken 

 in them. An instance of this sort occurred in Lake Miiskendorf, in West 

 Prussia. If an instance of the reproduction of the eel in fresh water 

 could be found, such occurrences as these would be quite inexplicable. 



In the upi^er stretches of long rivers, the migration of the eels begins 

 in April or May, in their lower stretches and shorter streams, later in 

 the season. In all running waters the eel fishery depends upon the 

 downward migrations ; the eels press up the streams with occasional 

 halts, remaining here and there for short periods, but always make their 

 way above. They ajipear to make the most progress during dark nights 

 when the water is troubled and stormy, for at this time they are cap- 

 tured in the greatest numbers. It is x^robable that after the eels have 

 once returned to the sea, and there deposit their spawn, they never can 

 return into fresh water but remain there to die. A great migration of 

 giown eels in spring or summer has never been reported, and it appears 

 certain that all the female eels which have once found their way to the 

 sea are lost to the fisherman. In No. 8 of t]ie German Fischerei Zei- 

 tung for 1878, Dr. Schock published certain statements sent to him 

 by Dr. Jacoby. It is remarked in this paper, among other things, 

 that after the deposition of the spawn, the female eel dies a phj^siologi- 

 cal death, and that occasionally the sea in the neighborhood of the 

 mouths of rivers has been found covered with dead eels whose ovaries 

 were empty. When, where, and by whom this observation was made, 



