108 REPORT OF THE SECRETARY OF COMMERCE 



a reduced output. The feature seriously affecting the work on Lake 

 Ontario is the fact that the most suitable spa^Yning area for white- 

 fish and lake trout is in Canadian waters and no satisfactory ar- 

 langenients can be made Avhereby the Bureau can obtain eggs from 

 that source. Similar limitations kept the production of lake trout at 

 a low level. 



Game species. — A large increase in the production of black-spotted 

 trout was made possible through increased egg collections at Yellow- 

 stone Park. The greater portion of these fish were distributed in 

 National Park waters. Fewer brook, rainbow, and loch-leven trout 

 were distributed, but many of these were planted at large size, 

 increasing their value for stocking purposes. Eifforts to develop a 

 satisfactory and economical trout food under actual operating prac- 

 tices have continued. An important feature of the Bureau's work 

 with game fish is the assignment of trout eggs, particularly of the 

 rainbow trout, to various other fish-cultural agencies. Shipments 

 of rainbow trout eggs and panfish were made to Puerto Rico, while 

 eggs of various species were supplied to Venezuela and Argentina. It 

 is again gratifying to report that the production of bass, a species 

 which merits its great popularity among the sportsmen, exceeded all 

 previous records. 



It should be pointed out that practically all new hatchery develop- 

 ments within recent years, exclusive of some minor developments in 

 the Pacific salmon area, have been for the propagation of game 

 species. This is due to the fact that the fishes sought for sport are 

 largely denizens of the lesser fresh waters. They are consequently 

 more vulnerable to the increased fishing pressure of recent years, 

 and, further, suffer from environmental changes, such as pollution, 

 which mark our national development. 



Since hatchery efforts are wasted unless the fish are stocked prop- 

 erly, more intensive consideration was given to the distribution 

 problem. Eight large trucks were acquired, as the nucleus of a fleet, 

 and these were being equipped with special tanks and apparatus 

 at the close of the year. Attempts to economize by inducing private 

 applicants to transport their allotments of fish have been unsatis- 

 factory, due chiefly to the applicants inexperience in handling live 

 fish. 



RESCUE OPERATIONS 



Due to the development of the 9-foot channel in the Upper Mis- 

 sissippi River, the number of fish rescued in that area was below 

 that of 1937. However, there were salvaged a total of 42,202,000 

 fish, comprising 10 species. Of this number over 411/2 million were 

 returned directly to the main river channels. 



The canalization of the Mississippi to the Twin Cities will make 

 the salvage work virtually unnecessary and impossible in the future. 

 In lieu of this the Bureau is constructing large artificial ponds for 

 the propagation of fish in the areas adjacent to the pools created by 

 the new dams. The ponds already constructed and operated have 

 proved very successful. The two in operation at Genoa, Wis., last 

 year produced over 864,000 fingerling black bass alone. 



