BUREAU OF FISHERIES XXIII 



of gear. Similar studies with gill nets were conducted in Green Bay, 

 Lake Michigan, and in Lake Huron. In Lake Michigan a compre- 

 hensive program of experimental fishing with gill nets at numerous 

 points typical of the entire lake has been continued, employing the 

 fisheries motor ship Fulmar, in an effort to perfect fishing gear which 

 will be eflfective for catching chubs without at the same time destroy- 

 ing a great number of immature lake trout. Experimental fishing- 

 gear studies have contributed much information on the life histories 

 of the important fishes taken, and such data accumulating as tlie 

 field work progresses will be of material value in the drafting of 

 fishery regulations by the various States. 



Field studies on the international dispute concerning pike-perch 

 fishing in Lake Champlain were completed during the fiscal year, 

 and a report is in process of preparation. 



In the Wisconsin lakes detailed studies of the rate of growth of 

 various food and game fishes were made by the bureau's investigators 

 in the hope of correlating these data with the great mass of limno- 

 logical observations obtained by the Wisconsin Geological and Nat- 

 ural History Survey in a study of the factors affecting fish growth 

 and reproduction. 



FISHERIES OF THE PACIFIC COAST AND ALASKA 



The results of fishery investigations in Alaska are utilized 

 throughout the fishing season and from year to year in the formula- 

 tion and in the prompt application of fishery regulations over the 

 entire area in the interest of conservation. A knowledge of the 

 routes of migration of the important salmon runs, enumeration of 

 spawning fish passing weirs on their way to headwaters of streams 

 for propagation, and the age composition of the various runs are 

 essential to the . bureau's program of regulation of the fisheries. 

 During the fiscal year the third section of the report on the statistics 

 of the Alaska salmon fishery was completed for publication. This 

 report covers the statistics from earliest times to 1927 for the Prince 

 William Sound and adjacent territory. 



An important contribution to the knowledge of the biology of the 

 Pacific herring was j^ublished during the year, and a second report 

 on the fluctuations in the supply of herring in Prince William 

 Sound has been prepared. The herring fishery has suffered deple- 

 tion in restricted areas, and scientific information obtained from 

 these studies has been of assistance in placing additional restrictions 

 upon the fishery to prevent exhaustion in areas now productive. 



During May, 1931, another regular b ennial census of the razor- 

 clam beds near Cordova, Alaska, was made to determine the state 

 of the resource, in order that canning operations in that vicinity may 

 be so regulated as to permit continued productivity of the beds. 



In the United States, salmon investigations by the bureau have 

 been restricted to the Columbia River. One new marking experi- 

 ment dealing with land-locked salmon of that river was initiated 

 during the spring of 1931, and the records of recovered fish resulting 

 from previous marking experiments on other species were collected 

 and analyzed. 



