680 EVOLUTION OF ANIMALS Part V 



age. There once were and still are Atlantic salmon. Thousands of them once 

 went up the Connecticut River to spawn. Now when a few swim up the river 

 it is an event for the newspapers. The New Englanders took too many fishes 

 from an easy catch. 



Two federal dams now span the Columbia River, the Bonneville dam, 152 

 miles from the sea, and the Grand Coulee, 552 miles from it. They are in the 

 direct way of the salmon. Bonneville supplies fish ladders. The Federal Gov- 

 ernment tried education on the offspring of salmon headed for the Grand 

 Coulee. Eggs and sperm were collected from the migrating fishes and mixed 

 together for fertilization. The resulting young fishes were placed in streams that 

 entered the Columbia below the Coulee. In time, these fishes left the stream 

 and entered the ocean. In a later time, they returned to the streams below the 

 Coulee, known to them but not to their parents or grandparents. As an experi- 

 ment, at least, it was successful. 



The journeyings of the eels (Anguilla), true bony fishes of the east coast of 

 North America and west coast of Europe, are directly opposite those of sal- 

 mon. They are hatched in the Sargasso Sea, northeast of the West Indies where 

 seaweeds (Sargassum) float in the relatively calm water. Here the spawning 

 grounds of American and European species are near together, yet separate, 

 and the young eels take their own routes to their respective continents. The 

 larvae are slender and thin, so different from their parents that their relation 

 was for a long time unknown. On the first part of their journey, the young eels 

 ride on the great ocean currents, the American ones chiefly in the Gulf Stream. 

 They are one-quarter of an inch long when they leave the Sargasso Sea. A year 

 later, when they reach the mouths of the North American rivers, they are 3 

 inches long. There they are transformed into elvers, that look and act like little 

 eels. In the Gulf Stream as larvae they were carried; in the rivers as elvers they 

 swim upstream into tributary streams and into lakes. There they live for five 

 years or more until they are fully mature. Then they swim downstream to the 

 river mouths and as silver eels probably colored from guanin crystals, they 

 pass out into the ocean. 



The eels, true bony fishes, of the Pacific live in the coastal waters and do 

 not migrate to fresh water. Salmon, trout, and other fishes that go upstream to 

 spawn are termed anadromous, meaning up the river and eels are catadromous, 

 meaning down the river. Next to birds, fishes are the great travelers. These 

 migrations are examples of much coming and going, to and from deeper water, 

 in winter and summer, in daylight and dark. 



