PROGRESS IN BIOLOGICAL INQUIRIES, 193 2 117 



The Great Lakes staff has contributed to nearly every issue the 

 feature article of a newly established monthly magazine devoted 

 exclusively to the commercial fisheries of the Great Lakes. 



CHUB FISHERIES OF LAKE MICHIGAN AND GREEN BAY 



The cooperative studies on the chub fisheries of Lake Michigan car- 

 ried on in 1930 and 1931 (for details see report for 1931) were resimied 

 in 1932. The Bureau's vessel Fulmar, employed for the work, was 

 placed in drydock for repairs early in April and left Sturgeon Bay, 

 Wis., on April 19 for the first cruise of the season. From April 19 to 

 May 31 the work was restricted to Green Bay (for details of problem 

 see report for 1930) and from June 1 to September 13 operations 

 w^ere limited to Upper Lake Michigan north of Frankfort, Mich., and 

 Sturgeon Bay, Wis. The 1930 and 1931 operations had been restricted 

 to that part of the lake which lies south of this line. During the 

 1932 season the Fulmar covered a total distance of some 6,096 statute 

 miles and lifted some 161 miles of chub gill nets at 67 different stations. 

 Fishing operations were conducted out of the ports of Marinette, Wis., 

 and Escanaba, Mich., on Green Bay, and out of Manistique, Charle- 

 voix, and Frankfort, Mich., on Lake Michigan. As was the case in 

 previous years, nets were fished simultaneously out of those ports 

 located on the same body of water. 



In 1930 and 1931 five sizes of gill-net mesh were employed in Lake 

 Michigan proper, but in 1932 only three sizes were used there, viz: 

 2K, 2y^, and 2% inches. The 2%- and the 3-inch mesh were eliminated, 

 as previous work showed that neither of these two sizes of meshes could 

 be recommended for use in the chub fisheries. In Green Bay, how- 

 ever, the 2%-inch mesh was fished in addition to the 2%-, 2%-, and 2%- 

 inch. The lifting and setting of approximately 2 miles of gill nets, 

 7 nets of each size mesh, constituted 1 day's fishing operations in 

 upper Lake Michigan. Some 3,276 lake trout that weighed 2,649 

 pounds and some 32,846 chubs that weighed 14,619 pounds were 

 taken in upper Lake Michigan, while some 2,845 lake trout, 2,873 

 lake herring, and 1,367 chubs that weighed 1,616, 1,289, and 585 

 pounds, respectively, were taken in Green Bay. Biological data w^ere 

 secured for each individual fish, to the extent that time permitted, 

 on the following: Length, weight, sex, maturity, scales (chubs only), 

 stomachs (lake trout and lawyers only) . A large series of chubs and 

 lake trout were preserved for future study in the laboratory. 



In addition there were collected 173 plankton samples, 91 samples 

 of bottom organisms, and 69 soil samples for geological analysis. 

 Temperatures were recorded whenever weather permitted. The 

 study of surface currents by means of drift bottles was continued from 

 1931. In 1932 some 462 bottles were released and of this number 304 

 have been recovered to date, yielding a percentage return of 65.8, 

 which is approximately 2 percent higher than the returns of 1931. 



The data of the Lake Michigan chub-net investigation have been 

 summarized for the 3 years, 1930 to 1932, and conclusions perti- 

 nent to legislative recommendations have been drawn and submitted 

 to the conservation departments of Michigan and Wisconsin. The 

 data are undergoing further analysis with a view toward detailed 

 presentation in published form. Some of the outstanding conclusions 

 follow : 



