XXIV EEPOET TO THE SECRETARY OF COMMERCE 



Additional large-scale feeding experiments and work on the 

 selective breeding of superior stocks of trout have continued at the 

 Pittsford (Vt.) experimental hatchery, and excellent results have 

 been obtained in studies of sanitation and disease control and treat- 

 ment. Cooperative trout and bass cultural studies were also under- 

 taken at the Hackettstown (N. J.) station. 



Large-scale pond cultural experiments have been continued at the 

 Fairport (Iowa) laboratory, where pond fertilization and forage 

 fish culture have been adopted as routine practice in growing black 

 bass. Similar studies have been undertaken at the Tishomingo 

 (Okla.) station to adapt successful methods to the special conditions 

 of pond culture in Southern States. An investigation of fish culture 

 in the sloughs of the Upper Mississippi Wild Life and Fish Refuge 

 was completed, demonstrating only limited possibilities in this area 

 because of extreme variations in river level. 



FISHERY STUDIES IN NATIONAL PARKS AND FORESTS 



Recognizing the responsibility of the Federal Government of 

 maintaining the supply of fish as well as other wild life in the public 

 domain, arrangements were made with the Forest and Park Services 

 to develop a large-scale program of stocking lakes and streams, 

 particularly in the intermountain area. 



SIIELLFISHERY IN\TSTIGATIONS 



Two distinct lines of investigations regarding shellfish and shell- 

 fish culture have been continued by the bureau during the past year. 

 These are a study of the oyster and oyster farming, and the propaga- 

 tion of the fresh-water pearl mussel and the attendant problems of 

 river pollution. 



An experimental study of the physiology of spawning of Atlantic 

 coast oysters was continued at the Woods Hole laboratory and was 

 extended to the imported Japanese species. Later in the year studies 

 of the nutrition of oysters were undertaken in order to devise means 

 of improving the quality of the product and large-scale experiments 

 have been started on plats of planted oysters at Milford, Conn. 



Laboratory studies on the control of the starfish, which is such a 

 destructive pest on oyster and scallop beds, were conducted at Woods 

 Hole ; and field experiments using copper salts to kill the animals or 

 drive them from the beds have been conducted in Narragansett and 

 Buzzards Bays. 



Oyster cultural studies in the South Atlantic area have been re- 

 ferred to previously. 



On the Pacific coast investigations of the native Olympia oyster 

 are continuing at the laboratory at Olympia, Wash. 



The problems of the American pearl-button industry, which 

 depends upon the fresh-water mussel for its raw material, have re- 

 ceived continued attention from the bureau's investigators. A 

 rapidly diminishing supply of the valuable species led to the perfec- 

 tion of a practical method of propagation a few years ago only to 

 find that increasing pollution rendered vast stretches of our rivers 

 unfit for replanting with young. Even existing supplies of adult 

 mussels were doomed to destruction by accumulating wastes from 



