82 BULLETIN OF THE BUREAU OF FISHERIES 



joiirneys out beyond the continental slope into the oceanic basin before depositing 

 its eggs. From the captures of its youngest larvae Schmidt has been able to outline 

 the chief spawning center of the American species as from latitudes 20° to 30° N. 

 and from longitudes 60° to 78° W. — that is, east of Florida and the Bahamas and 

 south of Bermuda, whUe it may spawn (always in deep water) much farther north. 



Our eel spawns in midwinter, thus occupying one to two months in its journey 

 from the coast to the spawning ground, for Schmidt found very young larvae (7 

 to 8 mm.) in February. Eels, like Pacific salmon, die after spawning, the evidence 

 of this being that no spent eels have ever been seen and that large eels have never 

 been known to run upstream again. Smith suggests that they probably jellify 

 and disintegrate, as does the conger. Eel eggs have not been seen, but certainly they 

 are provided with an oU globule, as this is present both in unripe ovarian eggs and in 

 the vestiges of the yolk sac of the youngest embryos. Eels (European) are among 

 the most prolific of fish, ordinary females averaging five to ten miUion eggs and the 

 largest ones certainly fifteen to twenty million. The larval, so-caUed "lepto- 

 cephalus" stage (figs. 336, c, and d), as with aU eels, is very different in appearance 

 from the adult, being ribbonlike and perfectly transparent, with small pointed 

 head and very large teeth, though it is generally believed that it takes no food 

 until the time of metamorphosis. These leptocephali, which live near the surface, 

 have been found off oiu- coasts as far north as the Grand Banks, but never east of 

 longitude 50°. Inasmuch as the breeding areas of the American and European 

 eels overlap, not the least interesting phase of the lives of the two is that the larvae 

 of the American species should work to the western side of the Atlantic and the 

 Eiuropean to the eastern side, and that no specimen of the former has ever been 

 taken in Europe or of the latter in America. 



The American species takes only about a third as long as the European to 

 pass through the larval stage, that is, hardly a year as against two to three years. 

 The leptocephali reach their full length of 60 to 65 mm. by December or January, 

 when metamorphosis to the "elver" takes place, in which the most obvious changes 

 are a shrinkage in the depth and length of the body but an increase in thickness to 

 cylindrical form, loss of the larval teeth, and total alteration in the aspect of head 

 and jaws, while the digestive tract becomes functional. It is not until they approach 

 our shores, however, that the adult pigmentation develops or that the elver begins to 

 feed, a change that is accompanied by a second decrease in size. How such feeble 

 swimmers as the leptocephali find their way in to the neighborhood of the land 

 remains a mystery. It seems certain, however, that all the young eels bound for 

 the Gulf of Maine complete the major part of their metamorphosis while stiU far 

 offshore, not only because we have never taken a leptocephalus in the Gulf of Maine 

 in all our tow-nettings, but (and this is more significant) because the Albatross 

 towed three young eels in the so-called "glass eel" stage, 54 to 59 mm. long — that 

 is, of practically adult form but still transparent — during her spring cruise in 1920, 

 one of them on Georges Bank, March 11; a second on Browns Bank, April 16; and 

 one in the western basin of the Gulf off Cape iVnn, February 23. Evidently they 



