THE SMELT AND ITS ALLIES 231 



smelt fishery is valued at 1125,000. Smelt eggs are arti- 

 ficially hatched and planted in rivers previously unin- 

 habited by them. Smelt are said to return to these rivers 

 after spending the winter in the sea. The early settlers 

 on our Eastern coast, like the Indians before them, used 

 smelt to fertilize the land. At present this wasteful pro- 

 ceeding is illegal ; but the bones and scraps from the 

 canning factories are used to make commercial fertilizers, 

 since they are rich in phosphorus an important plant 

 food. 



The family Salmonidae includes some of our most im- 

 portant food fishes. It is distinguished from other fami- 

 lies of Physostomi by the circumstances that both ventral 

 and adipose fins are present, that both p rein axilla and 

 maxilla bear teeth l and form the margin of the upper jaw, 

 and that the head is naked, body scaly, belly rounded, and 

 pseudobranchise present. Besides the smelt there are 

 numerous important species. The salmon proper 2 are 

 restricted to the north temperate and arctic regions, and 

 live either in the sea, migrating to fresh water to spawn, 

 or exclusively in brooks and lakes. The migrations of 

 salmon from the sea up the rivers are remarkable.. Hun- 

 dreds of miles are sometimes journeyed, rapids swum, and 

 falls leaped, for the purpose of laying eggs in some remote 

 lake. The females, with their burden of eggs, have be- 

 come so exhausted at the end of the migration that most, 

 or all of them, die immediately after laying the eggs. On 

 the Atlantic coast the Penobscot River has the most im- 

 portant run of salmon. The Pacific salmon passes up the 

 Sacramento and Columbia rivers, and up many rivers of 

 British Columbia and Alaska. In these rivers the fish 

 iFig.. 211, 2 pi. 212, 



