once as tlioy o^row older. First-year tisli (0 group) 

 live in the upper levels until the fall (or very late 

 siunnier) wlien at least some move to the bottom. 

 Ill their second year (I group) they may be either 

 at midlevels (commonly in the thermocline) or on 

 tlie bottom. After their second year (II group and 

 older) tliey are mostly on the bottom. Ferguson 

 (1965) reported a diurnal vertical migration of 

 adult smelt in ea.stern Lake Erie. In the discussion 

 below "young"' refers to young of the year and 

 "adults"' (arbitrarily) to older fish. 



Young 



Apprecialilc numbers of young smelt were 

 caught in the trawls on October 14 and November 

 4, mostly at 10 to 15 fathoms (table 2). No change 

 in distribution appeared lietween the two periods. 

 Xone had l)een taken prior to October 14, but the 

 nearly 2-montli span since the immediately pre- 

 ceding series on August 21 precludes a statement 

 of the exact time they hrst appear on the bottom. 

 Most young smelt in the Apostle Islands region of 

 Lake Superior were caught at less than 10 fathoms 

 and seldom were deeper than 19 fathoms (Dryer, 

 196(5). In eastern Lake Erie they frequented the 

 shallow epilimnial waters and at times were highly 

 concentrated near shore (Ferguson, 1965). 



Adults 



Adult smelt on the bottom occupy shallow and 

 intermediate deptlis in southeastern Lake Michi- 

 gan. They were caught consistently during stand- 



ard series but never in large numbers (table 5). 

 They were widely scattered from 7 to 35 fathoms 

 on Februaiy 13, but most had abandoned the 

 deeper water by March 11, when greatest numbers 

 were at 10 to 17 fathoms. Most older smelt had 

 moved into very shallow spawning areas by April 

 15, when few were caught. Smelt reappeared in 

 the catches on May 5, at depths of 3 to 10 fathoms. 

 Tliey had extended their range to 20 fathoms by- 

 May 2C. Thereafter none were taken deeper than 20 

 fathoms but they avoided warm water near shore. 



Tlie length of smelt varied with depth. In spring 

 and summer (except during the spawning season) 

 those in shallow water were largely yearlings 

 (which averaged 3.2 inches or 8.1 cm.) and tliose 

 in deeper water were mainly older fish (average 

 5.3 inches or 13.5 cm.). In the fall, yearlings and 

 older fish could not be separated readily by size, 

 but the larger fish still pi'efcrred deeper water. The 

 a\'erage length on Xovemljer 4 was 5.4 inches (13.7 

 cm.) at 5 to 7 fatjioms and 6.8 inches (17.3 cm.) 

 at 10 to 20 fathoms. 



Adult smelt in northern Lake Michigan, where 

 tiiey are far more abundant than in the southeast- 

 ern portion of the Lake, extend their summer 

 range into deeper water than in southeastern Lake 

 Michigan. They were commonly taken in the north- 

 ern area by the R/V Cisco in 1961 at 25 to 35 fath- 

 oms and occasionally in small numbers at 50 

 fathoms. The largest catches were at 15 fathoms 

 (usually the shallowest water fished). 



Table 5. — A'umber of adult American smell taken per 10-minule trawl low at various depths, February 13 



to November 4, 1964 



Dopth 



Date 



Feb. 

 13 



Mar. 

 11 



Apr. 

 15 



May 

 5 



May 

 26 



June 

 16 



July 



7 



July 



28 



Aug. 

 21 



Oct. 

 14 



1 No adult smelt were caught deeper than 35 fathoms. 2 No data. 



FISH DISTRIBUTION IX SOUTHEASTERN LAKE MICHIGAN 



Nov. 

 4 



