Smith. — The Freshwater Eel 299 



of the samples of eels from Europe and America, respectively. As far 

 as I remember, the number of American specimens in European samples 

 only amounted to a few per thousand. The whole eel question, in my 

 eyes, has become much more interesting than when I started work 15 

 years ago, and when it was believed that the problem had to be solved 

 in the Mediterranean (from Grassi's publications). That the theatre 

 has been moved to 60° W. longitude and that the problem of the European 

 eel can only be solved in close connection with that of the American 

 species, makes the whole question of still more interest, in my opinion 

 at least. 



I should mention that our work is done by towing 3 nets (2 meters 

 in diameter) attached to the wire in the same way as described in Hjort 

 and Murray's "Depths of the Ocean." The deepest net has 150 meters 

 of wire out, then follows the second with 100 meters of wire out, and 

 finally the third with 50 meters of wire out. (You understand that all 

 three nets are towed at the same time.) The nets are towed with a 

 speed of 2 1/2 knots in two hours during night. The leptocephali under- 

 take vertical migrations during the night, and it is therefore absolutely 

 necessary to use more than one net at the same time. It has happened 

 to us to take the enormous number of 800 anguilla larvae in the 50 

 meter net and nearly none in the two others towed at the same time, and 

 the following night all the larvae were taken in the 100 or 150 meter 

 net! As you are aware, hauls made during the day will give no results 

 at all in regard to leptocephali. The smallest and most important larvae 

 occur deepest down, and we used to get them in the 150 meter net only. 



These larvae which Dr. Schmidt has collected out there in 

 mid-ocean pass to the shores of the respective continents, 

 requiring about a year to make the journey. They change 

 their form and size as they come shoreward, and begin to 

 take color when they get within close distance of the conti- 

 nents. They start their upstream migration in spring. Many 

 of you have seen eels coming up the small streams in spring. 

 There is a very early separation of the sexes, the females for 

 the most part going to the headwaters of the streams, and the 

 males remaining lower down, many of them doubtless not 

 going beyond tidewater. The females remain in the upper 

 waters until they attain a considerable age — probably five, 

 six or seven years or older — and then they start downstream 

 in the fall on their first and only spawning migration. All 

 eels of more than 15 inches in length are females; no males 

 have ever been found that were more than 15 inches in lensfth. 



