PROGRESS IN BIOLOGICAL INQUIRIES, 1930 583 



tinned November 19, 1930. The program was interrupted from Au- 

 gust 22 to September 20 due to the installation of a new main engine, 

 and the cleaning and repairing of the boat. 



Before resuming operations on Lake Michigan, a short survey was 

 made of the herring fisheries in Green Ba}^ at the special request of 

 the Conservation Commission of the State of Wisconsin. This work, 

 carried on from September 20 to October 4, was designed to deter- 

 mine by experimental fishing whether a shifting of the line of 

 demarcation between bay fishing and lake fishing in Wisconsin 

 waters would be detrimental to lake trout and chubs. This line, 

 as defined by law, now extends from the mouth of the Menominee 

 River in Marinette County to Limekiln Bluff in Door County, a point 

 slightly westward of Little Sturgeon Bay. The waters northeast of 

 this line are defined as belonging to Lake Michigan and fishing 

 therein is governed by the Lake Michigan regulations Avhich i)re- 

 scribe among other things a 2%-inch mesh gill net for chubs and 

 herring in contrast to the 2%-inch mesh gill nets permitted in the 

 waters southwest of the line, defined by law as Green Bay, 



LAKE ERIE 



One investigator was assigned to the fishery work on Lake Erie 

 conducted during the period April 24 to December 4. In addition 

 to the collection of samples of the commercial catch, a careful study 

 was made of the fishing characteristics of a newly designed trap net 

 evolved from our previous experimental work. The field data indi- 

 cate that by the adoption of this net for commercial fishing in Lake 

 Erie significant millions of innnature fish will be saved in the lake 

 each year, a large amount of labor will be eliminated in the sorting 

 of fish by the fishermen, and thousands of dollars will be saved 

 the industry by the reduction of the wear and tear on nets during 

 sorting. 



Field operations on the limnology of western Lake Erie, carried 

 on by Dr. Stillman Wright in cooperation with the Ohio Division 

 of Conservation, have been completed. Observations were made 

 during the period April to October. The combined staff of six 

 investigators made an intensive study of the chemistry, ])lankton, 

 and bottom organisms near the mouths of important rivers in an 

 attempt to determine accurately the limits of polluted areas. 

 Reports by the various investigators are now being prepared. When 

 completed, they will l)e incorporated into a single report covering 

 five years of study. 



LAKE HURON 



Field work on the experimental fishing of pound nets in Saginaw 

 Bay was completed during the summer of 1930. This work described 

 in previous reports covered a period of two years and was carried 

 on jointly with the Conservation Department of the State of 

 Michigan. 



WISCONSIN INLAND LAKES INVESTIGATIONS 



The investigations of the inland lakes of northern Wisconsin 

 which the bureau conducted in cooperation with the Wisconsin geo- 

 logical and natural history survey in 1927 and 1928 were resumed 



75544—31 5 



