January to March the yellow perch dominated 

 the shallow- water zone and alewives the in- 

 termediate and deepwater zones. During the 

 April to June period alewives were found at 

 tinnes in all depth zones and dominated the 

 zone when present. Chubs were also common 

 in all three zones during this period. From 

 July through September alewives were taken 

 most abundantly in shallow water, chubs in 

 intermediate depths, and sculpins (mainly the 

 deepwater sculpin, Myoxocephalus thompsoni) 

 in deep water. The percentage of alewives 

 from catches in shallow water and inter- 

 mediate depth increased from October to De- 

 cen-iber because the chubs moved into deeper 

 water. Late in this period alewives moved 

 into the intermediate and deepwater zones. 



Species composition varied by area in south- 

 ern Lake Michigan. Smelt, which were only 

 0.8 percent of the total catch, made up Z per- 

 cent of the catch in drags from Port Washing- 

 ton to Manitowoc. The percentages of lake 

 herring and whitefish in the lake were higher 

 on the east side than on the west side. 



DISCUSSION BY SPECIES 



The following sections describe fishing re- 

 sults for each of the innportant comnnercial 

 species taken during the study. The order of 



discussion is based on total poundage for the 

 14 cruises. Carp is considered a miscellan- 

 eous species even though it exceeded whitefish 

 in total landings (193 pounds to 168 pounds). 

 Although these species are taken infrequently, 

 whitefish is important to commercial trawlers 

 in southern Lake Michigan because it com- 

 mands a high price whereas carp brings a 

 low price. 



Alewife 



The alewife had the highest catch rate and 

 highest average catch for effective effort of 

 the species taken. The catch rate for alewives 

 was 168 pounds, and alewives occurred in 63 

 percent of all drags for an average catch for 

 effective effort of 265 pounds. Catch records 

 of alewives by cruise and year are sunnma- 

 rized in table 8. Catch rates varied by cruise 

 but were generally higher on cruises made 

 during the spring spawning run or in winter 

 when alewives were concentrated in deep 

 water. The highest catch rates per cruise 

 were obtained on cruise 17 (581 pounds) and 

 cruise 30 (580 pounds). Three of the cruises 

 (15, 17, and 30) had average catches for effec- 

 tive effort of over 500 pounds. Comnnercially 

 significant catches (500 pounds or more per 



Table 8. 



-Summary of catch records of alewives in southern Lake Michigan by 

 cruise and year, 1962-65 



10 



