THE LIFE-HISTORY OF THE COMMON 

 OR FRESHWATER EEL 



By C. TATE REGAN, M.A., F.R.S. 

 Keeper of Zoology in the British Museum [Natural History) 



The Common or Freshwater Eel {Anguilla angiiilla or A. 

 vulgaris) has a remarkable geographical distribution, occurring 

 on the coasts and in the rivers of Western Europe and the 

 countries bordering the Mediterranean, ranging from Iceland 

 and Northern Norway southwards to the Canaries and Morocco, 

 and from the Azores eastward to Palestine. This distribution 

 is anomalous and at first sight inexplicable ; one can hardly 

 believe that it is limited by temperature, seeing that the same 

 species is found in Iceland and in the Nile ; nor can it be a 

 question of food, for the Eel is somewhat of a scavenger, and 

 eats all kinds of animal food. In fresh water eels are found not 

 only in lakes and rivers, but in small streams and isolated 

 ponds ; they are abundant in estuaries and also in harbours 

 and other inlets where the water is quite salt ; indeed, at the 

 great eel-farm at Comacchio the water in the lagoons has, 

 towards the end of the summer, a salinity higher than that of 

 the Adriatic. Finally, the Eel is not represented by a related 

 species either in the Arctic Ocean, the Black Sea and its 

 tributaries, or West Africa south of Morocco. One may then 

 ask the question why this species, which lives in such a 

 variety of conditions, has not a much wider range. The 

 answer has been supplied by Dr. Johannes Schmidt, of Copen- 

 hagen, whose researches on the life-history of the Eel, begun 

 in 1904 and now practically concluded, are summarised in an 

 important paper recently issued by the Royal Society {Phil. 

 Trans. B., ccxi, pp. 179-208, pis. 17 and 18, April 1922). 



Twenty-five years ago all we knew of the breeding of the 

 Eel was that in the autumn full-grown eels moved down from 

 the rivers and lakes to the sea, and that in the spring the elvers, 

 or 3^oung eels about 2| inches long, appeared on the coasts and 

 made their way into the rivers, in some places in such swarms 

 as to form the object of an industry. It was naturally supposed 

 that these elvers were the progeny of the eels which had gone 



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