26 REPORT OF THE COMMISSIONER OF FISHERIES. 



stomach contents of many examples of several different species were 

 critically examined and much valuable information was obtained. The 

 results of these various investigations will be published in a special 

 report in due time. 



FISH DISEASES, WATER POLLUTIONS, ETC. 



A number of investigations of fish epidemics and stream contamina- 

 tion by factory and other refuse have been conducted during the year. 

 These subjects are of very great and growing importance, and the 

 Bureau, in addition to the consideration of diseases affecting fishes at 

 its own stations, is constantly consulted by the state authorities regard- 

 ing them. Instances of especial interest and requiring extended inves- 

 tigation have been an epidemic among brook trout at the Cold Spring 

 Harbor station of the New York Forest, Fish, and Game commission; 

 an epidemic that attacked the fish in the trout preserves of the South 

 Side Sportsmen's Club, at Oakdale, Long Island; distress and mortal- 

 ity among fishes in the Bureau's aquarial exhibit at the Louisiana Pur- 

 chase Exposition, where the service water contained an excess of lime 

 due to the clarification process used by the city; and a mortality among 

 trout at the Bayfield hatchery of the Wisconsin fish commission, which 

 was being studied at the close of the year. Laboratory experiments 

 have been conducted to determine the effects upon fishes of waters pol- 

 luted with various industrial wastes, and at the request of the Mary- 

 land fish warden an effort was made to discover the cause of the weak- 

 ness and death of numbers of fish in the Potomac at Cumberland and 

 above, with the result that acid wastes from mining operations were 

 found to be responsible. 



MARINE BIOLOGICAL LABORATORIES. 



The marine biological laboratories of the Bureau at Woods Hole, 

 Mass., and Beaufort, N. C, were open during the usual summer season, 

 and their tables were occupied by investigators from the principal 

 institutions of learning in all parts of the United States. The facili- 

 ties of the laboratories were used for the investigation of various 

 questions important in the work of the Bureau and in marine biology 

 in general, and a number of researches were made at the Bureau's 

 instance and in its particular interest. 



At the Woods Hole laboratory the principal feature of the work for 

 the past two seasons has been the biological survey of neighboring 

 waters and the cataloguing of results. The dredgings made by the 

 steamers Fish Hawk and Phalarope, which were detailed for the pur- 

 pose, furnish data from which, when complete, it is intended to com- 

 pile records of the distribution of the entire fauna and flora of the 

 region. Of other investigations of scientific and practical interest there 



