18 EEPORT OF THE COMMISSIONER OF FISHERIES. 



and experimental hatchery, not only for the purposes of the present 

 investigation but for the study of the many other diseases affecting 

 fishes, both under domestication and in a state of nature. The Presi- 

 dent, in a special message to Congress dated April 9, 1910, urgently 

 recommended an appropriation for this purpose. 



During the year the Bureau was called on to investigate epidemics 

 among hatchery fish at Spruce Creek, Pa., and Roxbury, Vt. At the 

 former place the mortality was due in part to the thyroid tumor or 

 cancer before alluded to, but the majority of the deaths were appar- 

 ently caused by a bacterial infection which the Bureau has found at 

 other places, but which it has not the facilities to study at present. At 

 Roxbury the disease is also infectious and annually causes large 

 losses. The Bureau has likewise made investigations in Pennsylvania. 

 Ohio, and West Virginia upon the kindred subject of the pollution of 

 streams in its relation to fishes and the fisheries. 



4 



OTHER INQUIRIES AXD EXPERIMENTS. 



The investigations of the Pacific coast salmons have materially 

 advanced knowledge of the subjects during the year, particularly in 

 respect to parasitism and the changes in the tissues affecting the food 

 value of the fish at and near the breeding season, and in regard to 

 the relationship of the steelhead trout and rainbow trout. 



In connection with the State Geological and Natural History Sur- 

 vey, the Bureau has continued examination of lakes in Wisconsin, with 

 particular regard to the gaseous content of their waters. The rela- 

 tionship of this subject to practical fish culture is highly important, 

 and the data so far obtained have thrown light on certain failures in 

 the acclimatization of fishes, the causes of which have been obscure. 

 The study of the physical environment and habits of the salmon, smelt, 

 and other fishes of Sebago Lake. Maine, were continued, and in 

 response to a request a somewhat similar line of research was under- 

 taken in Sunapee Lake, New Hampshire. In the latter locality there 

 is a considerable fishery for smelts as they ascend the streams to 

 spawn, and it was learned that young chinook salmon planted in, the 

 brooks were taken with the smelts. 



The. survey of the fishing grounds and investigation of the aquatic 

 resources of the Philippine Islands, in which the steamer Albatross 

 has been employed since the autumn of 1907, was brought to a con- 

 clusion in October, 1909. The vessel returned to San Francisco on 

 May 4, 1910. The Philippine expedition has yielded extensive col- 

 lections and a large amount of information relating to the fisheries 

 and fishery resources, and the material is now in course of study 

 for the preparation of comprehensive reports on the scientific and 

 economic results. 



