226 FISHES 



Some fishes are clothed with spines as a protection from 

 their foes. Others are found in company with cei'tain 

 jellyfishes where they receive the pi-otection of the stinging 

 cells. Othei's creep within the shells of certain mollusks. 

 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 thi.s family of fishes a poison gland is con- 

 nected with the pectoral spine. 



Economic importance of the fishes. — The commercial 

 importance of this grou]5 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 cahed 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 

 metliods of preservation of oin- 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 tlie different ponds, lakes, and streams of the United 

 States and even the oceans bordering this country. For 

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

 tensive scale than any other marine fish. The number of 

 cod fry liberated l)y the United States Fish Commission 

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

 taken as an exam]:)le of the work done by the Commission 

 in maintaining the snp)ih' of fi'esh-\A'ater fishes. In the 

 fiscal year of 1905 the ITnited States Fish Commission 

 hatched and plantetl 268,405,000 whitefish fry. 



