LAKE AND RIVER IN WINTER 301 



79. Review and Summary. 



Fish, crabs, and other animals which breathe by means 

 of gills are compelled to live in the water, and most of 

 them can breathe only the air that is dissolved in water. 

 Some, like the trout, prefer cold streams ; others, like the 

 tadpoles, like warm ponds. For their food they depend 

 upon plants, upon smaller animals, or upon one another. 

 Fishes must lay a large number of eggs, because they do not 

 take care of them, and they would soon become extinct if it 

 were not for the enormous number of eggs produced. 



Fresh-water and marine fish and salt-water lobsters fur- 

 nish food and work for many thousands of people. Our 

 lakes, rivers, ocean bays and banks, at one time, teemed 

 with fish, but ruthless slaughter has caused many good 

 grounds to be "fished out." Several states, as well as the 

 Federal Government, have established fish-hatcheries for 

 the purpose of stocking, or restocking, our waters with 

 valuable food and game fish. The fish in lakes and rivers 

 furnish so much healthful recreation to young and old, to 

 rich and poor, that their preservation is of even greater 

 importance than the preservation of other animals. 



Catch no fish in their spawning season, and promptly return 

 to the water all fish that are too small to be used, is the rule 

 of every intelligent fisherman. 



Much damage is often done to river fish by city and farm 

 sewerage and by the waste product of factories. 



