86 THE SEAS 



they have been captured and marked. Their recapture 

 on their way to the North Sea shows that they had travelled 

 at the rate of about nine miles a day for some three months, 

 but they were only a very short way on their total journey, 

 for the next we know of them they must have arrived in 

 the deep central part of the North Atlantic, known as the 

 Sargasso Sea (a distance of some two to three thousand 

 miles), although none of the spawning eels have themselves 

 been seen there. There is, however, irrefutable evidence 

 that they must have been to those regions, because at the 

 end of winter and during spring the baby eels are there. 

 The young eels are very unlike their parents ; in fact so 

 unlike that the first time one was seen it was considered to be 

 a new species of fish and given the name of " Leptocephalus." 

 They vary from a quarter of an inch to three inches in 

 length according to their age. They are flattened sideways 

 so as to resemble a leaf, and are quite transparent (Plate 35). 

 These baby eels now start on the return journey and we can 

 in this case get some idea of the rate they travel, for Prof. 

 Schmidt has, by measuring very large numbers, shown that 

 they take three years to reach the European shores once 

 more. During the long journey across the Atlantic they 

 grow, and it is by their growth that their birthplace has 

 been located ; catches made between our shores and the 

 central Atlantic exhibit these eel larvae in ever decreasing 

 size (Fig. 13). Near the coasts they are about three 

 inches long, but down in the locality of their birth they are 

 only a quarter of an inch in length, and indeed, in this 

 region, eggs have been taken that are without a doubt 

 those of the parent eels themselves. The eggs are about the 

 size of a pea, quite transparent, and drift in the water layers 

 at depths of about a hundred fathoms, just like many of the 

 other fishes' eggs mentioned earlier in this chapter. 



When the eel larva? have reached their destination on the 



