PROGRESS IN BIOLOGICAL INQUIRIES, 1931 465 



able to defer any fornmlntion of results until more data are availa- 

 ble. Because of tlioir importance, however, the trend of work in 

 two phases may be mentioned. A satisfactory analysis of the catch 

 statistics, especially in re<2:ard to the intensity of fishin*^, a question 

 of prime importance, is impossible because of the inadequacy of the 

 data. It will be necessary to have recourse to figures supplied by 

 certain packers who have records of catches of individual boats over 

 a number of j'^ears. The inadequacj'^ of the fisheries statistics in the 

 States concerned is so serious a handicap to investigations of this 

 character that it is hoped in the future some of the far-sighted legis- 

 lators nuiy be able to remedy this unfortunate lack. 



With regard to the life history, the size-composition analysis of 

 the catch, particularly in Georgia, is furnishing valuable informa- 

 tion. Although it would be premature even to outline the life his- 

 tory, there can be little doubt that the life span is short and that 

 most of the fishery rests upon dangerously young or spaw-ning indi- 

 viduals. It can not be too strongly emphasized that under these 

 circumstances depletion, wdien it appears, is sure to run a tragically 

 rapid course and that every opportunitj^ should be embraced to 

 furnish reasonable protection to this valuable animal. 



GREAT LAKES FISHERY INVESTIGATIONS 



The major field investigations in the Great Lakes area during 

 1931 were conducted on Lakes Michigan and Huron, while minor 

 field operations w^ere carried on on Lake Erie and also on Lake 

 Champlain. Only one new major project was started in 1931, viz, 

 the investigation of deep trap nets on Lake Huron and upper Lake 

 Michigan. The other field investigations were continuations from 

 previous years, those on Lakes Erie and Champlain being completed 

 in 1931. As in previous years, the bureau enjoyed the fullest confi- 

 dence of the conservation departments of the various Great Lakes 

 States and of the fishermen and worked in close harmony with them. 

 In spite of the severe curtailment in their appropriations, the States 

 of Michigan and Wisconsin again gave liberal financial support to 

 the Lake Michigan program, while the State of Vermont gave gener- 

 ous financial assistance in the Lake Champlain work. 



CHUB-NET STUDIES IN LAKE MICHIGAN 



The Lake Michigan investigation on chub nets, started in 1930 

 (see report for 1930) and conducted jointly with the conservation 

 departments of Michigan and Wisconsin and a group of four fish- 

 net and twine companies located in the Great Lakes area, was re- 

 sumed in 1931, since it was found that in spite of the large numbers 

 of fish employed in our 1930 experiments they gave no conclusive 

 results. The primary objective of the Lake Michigan work was a 

 study of the catch of chub nets in order to determine the selectivity 

 of these nets with regard to chubs and to determine their destructive- 

 ness to immature trout. 



The bureau's vessel Fulmar^ again employed for the work, left its 

 winter quarters at Sturgeon Bay, Wis., on April 23 for the first 

 cruise of the season after having been thoroughly overhauled and 

 painted during the winter months. Field operations continued until 

 November 19. During this period the Futiimr covered a total dis- 



