92 



UNIVERSITY OF COLORADO STUDIES 



Genus ANGUILLA Shaw 

 The Eels 

 Anguilla Shaw, General Zoology, Vol. IV, p. 15, 1804. 



Anguilla chrysypa Rafinesque 

 American Eel, Fresh- Water Eel 

 Anguilla chrysypa Rafinesque, Amer. Monthly Magazine, p. 120, 1817 (Lake George; Hudson 

 River; Lake Champlain). 



Anguilla tyrannus Girard, U.S. and Mexican Boundary Survey, p. 75, 1859 (Rio Grande). 



Body terete, much elongate; head long and conical; teeth small, in irregular 

 bands on both jaws and vomer; lower jaw slightly longer than the upper; size 

 large, length up to 5 feet. 



General color greenish or bluish brown above, shading to golden yellow or 

 yellowish white below. 



The American eel is a carnivorous fish, feeding upon small crustaceans and 

 upon other fishes. Because of the excellent flavor and the firm consistency of its 

 flesh it is a food fish of considerable importance in the localities where it is abun- 

 dant. From a zoological standpoint its life-cycle is of particular interest. The 

 adult eels migrate in the fall from fresh water to the ocean. At this time they 

 become quite silvery in color and the eyes of the male greatly enlarged. These 

 eels returning to the salt water migrate in large schools traveling largely at night. 

 After they reach salt water their course has not been followed and their spawning 

 habits are not known. Smith' states that the eggs are laid in water at least 1,000 

 meters deep and that the eggs hatch at or near the surface where they are carried 

 by their natural buoyancy. From the number of immature eggs taken from adult 

 eels in fresh water it seems probable that each female produces over 10,000,000 

 eggs. The young eels do not have the same form as the adult, being thin trans- 

 parent animals living near the surface of the ocean well out from land. The larval 

 eels known as Leptocephali spend the first year of their life in salt water, growing 

 to a size of about three inches. After this stage is reached they graduaUy assume 

 the adult shape, enter fresh water and migrate upstream. Only the female eels 

 continue this migration to the headwater streams, the males remaining in the lower 

 waters. Large schools of the young eels known as "Elvers" are regularly seen at 

 the mouth of the Mississippi and other large rivers. 



The adult eel has been reported from the Rio Grande in Colorado frequently 

 but unfortunately no specimens collected in this state have been preserved to 

 verify the records. In July, 191 2, while in Alamosa, Colorado, the writer was told 

 by several fishermen that the eel is occasionally taken from the Rio Grande at 

 that point and that it is more abundant farther south near the New Mexico line. 

 Professor A. E. Beardsley of the State Teachers' College also states that on several 

 occasions he was assured by local fishermen that there were eels in the Rio Grande 



' National Geographic Magi^zine, Vol. XXIV, p. 1143, 1913. 



