' No jcllow prrch caught di-t^pcr than 25 fathoms. 



 No data. 



Ill tho summer, appreciable imiuliers of yellow 

 ])ercli follow warm upper strata farther out into 

 the Lake than their normal ranjje on the bottom. 

 They have been taken on several occasions from 

 the upper portions of g'lW nets set obliquely from 

 top to bottom at a bottom depth of liti.T fathoms 

 along the eastern shore of Lake Michigan. About 

 00 percent wore from the epilimnion (usually about 

 the upper 10 fathoms) ; all were from the up])er 

 17 fathoms. 



Yellow perch, usually in jtoor condition, occa- 

 sionally have been taken on the bottom at great 

 depths in Lake Michigan. The deepest recorded 

 by the R/V CUro was a fish taken at 140 fathoms 

 ok Frankfort, Mich. (June 29, 1955) ; another was 

 caught at 100 fathoms in Grand Traverse Bay 

 (Junes, 1955). 



Size of adult yellow perch varied somewhat with 

 dei>th. Larger ones were inclined to be in .shallower 

 ^\ater in February, March, and April ; among tows 

 in which at least 10 perch were taken the average 

 length was 8.8 inches (22.4 cm.) for the shallowest 

 tow and 7.7 inches (19.6 cm.) for the deepest (un- 

 weighted means of averages for each of the three 

 series). The size-depth relation was reversed in 

 May to August when average lengths for fish from 

 the shallowest and deepest tows were 7.2 and 8.0 

 inches (18.;'> and 20.:'> cm.), respectively. Size did 

 not change with de|ith in the fall. 



SLIMY SCULPIN 



Larval slimy sculpins are at midlevels, mostly in 

 the hypolimnion. Little else is known of the O 



group, except that some apparently appear on the 

 bottom in the fall. Most slimy sculpins caught in 

 tiie standard series were between 2 and 4 inches 

 (5.1 and 10.2 cm.) long and probably included 

 yearlings and older fish. In the series of November 

 4, however, the cat<"hes at 25 and 30 fathoms con- 

 tained 72 and 5 individuals, respectively, between 

 1.0 and 1.5 inches (2.5 and 3.8 cm.) long. Studies 

 of age and growth by Eottiers - suggest that these 

 fish were young of the year. They are not included 

 in the following discussion. 



The depth range of slimy sculpins extends be- 

 yond the nuiximum depth of the present standard 

 series of collections. Limited trawling data for 

 greater depths indicate that in summer slimy scul- 

 pins are present in small numbers at least to 71 

 fathoms but are rare or absent at 85 fathoms. 

 Deason (1939) found them in stomachs of lake 

 trout and burbot caught in Lake Michigan as deep 

 as 70 fathoms, but concluded that they were usually 

 lietween the shoi'e and 50 fathoms. 



The slimy sculpin is distriliuted over a wide 

 depth range in winter, liut aliandons shallow areas 

 in spring as soon as warming is significant and con- 

 tiinies a gradual movement away from shore 

 tiudugh suunner and fall. Greatest numbers of 

 slimy sculpins on February 13 were at 10 to 35 

 fathoms ( table 9). They were in all catches except 

 at 45 and 50 fathoms (where an occasional sjaeci- 

 men might have been overlooked because of the 



- Knttiprs. I>(niald V. Some aspects of the life histnr.v of Coitus 

 cngnatiis in I.jike Mirliij^nn. M.-ister's thesis, I'niversit.v of AUchi- 

 ^■an. lOfi.'i. 40 pp. 



10 



U.S. FISH AND WILDLIFE SERVICE 



