CONCLUSIONS 



The Bureau of Commercial Fisheries Branch 

 of Exploratory Fishing made a trawling survey 

 of southern Lake Michigan over a 4-year 

 The aims of the study were ( 1 ) to learn about 

 the seasonal and depth distribution of the fish 

 so that more effective and efficient fishing 

 n-iethods could be used to harvest the existing 

 fish resources and (2) to give the fishing in- 

 dustry timely information on occurence of 

 fish. 



Alewives (51.4 percent) and chubs (44.0 

 percent) dominated the total trawl catch. The 

 percentage species composition in the trawl 

 catch shifted from 17 percent alewives and 77 

 percent chubs in 1962 to 74 percent alewives 

 and 23 percent chubs in 1965. In southern Lake 

 Michigan large underutilized populations of 

 these two species constitute the basis of a 

 growing trawl fishery. 



Alewives were taken in commercially sig- 

 nificant announts throughout the year; however, 

 catch rates dropped from early July to De- 

 cennber because alewives dispersed after 

 spawning. Alewives exhibited pronounced sea- 

 sonal movements and were found only at spe- 

 cific depths most of the year. Owing to this 

 pronounced vertical migration, the species 

 composition in different depth zones changed 

 from season to season. 



Chubs were taken in connmercially signifi- 

 cant announts in all seasons throughout the 

 study area. The seasonal movements of chubs 

 consisted mainly of a horizontal dispersal 

 inshore in the summer and back to deep water 

 in the fall. Chubs were found over a wide depth 

 range throughout the year. 



Two other species, yellow perch and smelt, 

 were taken occasionally in commercially sig- 

 nificant quantities. Commercially significant 

 catches of yellow perch were taken only off of 

 Waukegan, 111., and Saugatuck, Mich. Smelt 



was most abundant along the west shore from 

 Port Washington, Wis., to Manitowoc, Wis. 



LITERATURE CITED 



GORDON, WILLIAM G. 



1963. A trawling survey of southern Lake 

 Michigan (August- November I960). 

 Commer. Fish. Rev. 25(2): 1-6 



GORDON, WILLIAM G., and KIETH BROWIL- 

 LARD [Keith Brouillard]. 

 I960. Great Lakes fishernnen convert gill- 

 netters to trawling vessels. Fish Boat 

 5(8): 35-39. 

 HILE, RALPH. 



1962. Collection and analysis of comnner- 

 cial fishery statistics in the Great 

 Lakes. Great Lakes Fish. Connnn,, 

 Tech. Rep. 5, 31 pp. 

 HILE, RALPH, and HOWARD J. BUETTNER. 

 1955. Commercial fishery for chubs (cis- 

 coes) in Lake Michigan through 1953. 

 U.S. Fish Wildl. Serv., Spec, Sci. Rep. 

 Fish. 163, 49 pp. 

 HILE, RALPH, PAUL H. ESCHMEYER, and 

 GEORGE F. LUNGER. 

 1951. Decline of the lake trout fishery in 

 Lake Michigan. U.S. Fish Wildl. Serv., 

 Fish. Bull. 52: 77-95. 

 JOBES, FRANK W. 



1949. The age, growth, and bathymetric 

 distribution of the bloater, Leucichthys 

 hoyi (Gill), in Lake Michigan. Pap. 

 Mich. Acad. Sci., Arts, Lett. 33: 135- 

 172. 

 MOFFETT, JAMES W. 



1957. Recent changes in the deep-water fish 

 populations of Lake Michigan. Trans. 

 Amer. Fish. Soc. 86: 393-408. 

 SMITH, STANFORD H. 



1964. Status of the deepwater cisco popu- 

 lation of Lake Michigan. Trans. Amer. 

 Fish. Soc. 93: 155-163. 



18 



