226 FISHES 



Some fishes are clothed with spines as a protection from 

 their foes. Others are found in company with certain 

 jellyfishes where they receive the protection of the stinging 

 cells. Others creep within the shells of certain moUusks. 

 Among the bullheads and catfish, the first ray of the dorsal 

 and pectoral fins is developed into a sharp, stiff, serrated 

 spine which inflicts severe wounds. In the members of 

 two genera of this family of fishes a poison gland is con- 

 nected with the pectoral spine. 



Economic importance of the fishes. — The commercial 

 importance of this group of animals is very great. The 

 place that the fishes fill in the food supply of the American 

 people is so important that the United States government, 

 long ago, established the United States Fish Commission 

 (now called the Bureau of Fisheries) and annually appro- 

 priates large sums of money to enable the members of this 

 commission to study the habits, distribution, food, and 

 methods of preservation of our most important food 

 fishes. The fast-failing supply of many of our most im- 

 portant food fishes has caused the government to establish 

 extensive fish hatcheries at favorable locations. From 

 these hatcheries thousands of young fish and eggs are sent 

 to the different ponds, lakes, and streams of the United 

 States and even the oceans bordering this country. For 

 example, the cod is propagated artificially on a more ex- 

 tensive scale than any other marine fish. The number of 

 cod fry hberated by the United States Fish Commission 

 in 1905 was 169,577,000. The common whitefish may be 

 taken as an example of the work done by the Commission 

 in maintaining the supply of fresh-water fishes. In the 

 fiscal year of 1905 the United States Fish Commission 

 hatched and planted 268,405,000 whitefish fry. 



