tioii off the bottom is usually small (largest catches 

 in gill nets set obliquely from the surface to the 

 bottom are characteristically near the bottom). 



Bloaters on the bottom inhabit intermediate 

 and deep areas, but are sometimes in shallow water. 

 In Februai-y, March, and April tlie largest numbere 

 talven in the standard series were at 25 fathoms and 

 deeper; few were caught during this period at 

 depths less than 20 fathoms, and none were taken 

 in less than 12 fathoms (table 4). A shoreward 

 movement began in May, and by July the greatest 

 numbers were at depths shallower than 20 fathoms. 

 Bloaters avoided wann inshore water, but in the 

 July 7 series, when the insliore water was cooled 

 during nn upwelling, the largest catches were at 

 5 to 12 fathoms and two bloaters were taken at 3 

 fathoms. Movement into deeper water was pro- 

 nounce<:l in the fall. On October 14 and Xovembei- 

 4 few bloaters were shallower tlian 17 and 20 

 fathoms, respectively, and the largest catches were 

 at 35 fathoms. 



The above discussion based on the catches of the 

 standard series is, of course, limited to seasonal 

 distribution at depths of 50 fathoms and less. 

 Other experimental fishing indicates that the num- 

 ber of bloaters decreases progressively at depths 

 beyond 50 fathoms. Numbers are occasionally sub- 

 stantial at 60 fathoms but not often at 70 fathoms 

 or deeper. A few bloaters, however, are present in 

 the deepest portion of the southern basin (90 



fathoms) and at dejiths of at least 140 fathoms in 

 the northern basin. (One bloater was taken at 200 

 fathoms in a gill net fished from the E/V C'i^^ro in 

 Lake Superior in 1953.) 



The length of bloaters varied little witli depth 

 and season. Bloaters in the three shallowest depths 

 at whicli they were caught in each series, however, 

 usually averaged about 0.2 to 0.4 inch (0.5-1.0 cm.) 

 longer than those in deeper tows. The average 

 length of all bloaters was 8.4 inches (21.3 Cm.) ; 

 97.1 percent were between 7.0 and 9.9 inches (17.8- 

 25.1cm.). 



Jobes (1949) reported the greatest abundance 

 of bloaters in Lake Michigan at 20 to 59 fathoms. 

 He suspected a movement toward shore in smnmer 

 and a return to deeper water in fall. 



Distribution of bloaters in southeastern Lake 

 Michigan is shallower than in the Apostle Islajids 

 region of Lake Superior wliere largest numbers 

 were usually taken at 40 to 59 fathoms (Dryer, 

 1966). The shoreward movement in summer and 

 fall in Lake Superior was later and less pro- 

 nounced than that in Lake Michigan. None were 

 taken at depths less tlian 10 fathoms, and catches 

 at 10-29 fathoms wore never greater than at 40- 

 49 fathoms. 



AMERICAN SMELT 



American smelt in Lake Michigan move in in- 

 creasing numbers from a pelagic to a bottom exist- 



Table 4. — Nwnber of bloaters taken per 10-minute Irawl tow at various depths, February 13 to November 4, 1964 



Depth 



Feb. 

 13 



Date 



Mar. 

 11 



Apr. 

 15 



May 

 .5 



Mav 

 26" 



June 

 16 



July 



7 



July 



28 



Aug. 

 21 



Oct. 

 14 



Nov. 

 4 



Fatttoms 



3 



5 



7 



10 



12 



15 



17 .. 



20 



25 



30 



35 



40 



45 



50 



Number Number Number Number Number Number Number Number 























2 



13 



58 



158 



145 



92 



35 



(■) 



















6 



9 



25 



94 



63 



165 



483 



132 



126 



















1 







5 



31 



71 



57 



172 



300 



77 



151 







1 



1 



4 



12 



23 



31 



39 



74 



77 



63 



150 



71 



103 



















3 



53 



95 



80 



16 



30 



36 



62 



46 



81 







8 



59 



198 



170 



144 



134 



124 



102 



39 



87 



148 



38 



66 



2 



177 



301 



164 



119 



80 



57 



59 



53 



59 



47 



64 



67 



53 











1 



14 



178 



172 



207 



72 



62 



66 



65 



39 



58 



•27 











3 



188 



146 



137 



226 



162 



98 



148 



169 



89 



56 



12 















1 



4 



8 



95 



75 



95 



208 



391 



121 



84 



33 





 

 



1 



1 



11 



12 

 47 

 33 

 94 

 131 

 68 

 77 

 68 



1 No data. 



U.S. FISH AND WILDLIFE SERVICE 



