ABSTRACT 



Scales of 1,603 lake trout, Salveliniis n. namaycush, presumably recoveries 

 from plantings of juveniles previously marked by clipping certain fins, were 

 studied. Their characteristics are described and illustrated. Age readings from 

 the scales are highly reliable. In addition to the annuli, an accessory mark 

 designated the O-mark, was found in the field of first-year growth. Annulus 

 formation occurs over a period of several months. 



Data presented show that most, probably all, of the 102 specimens caught 

 in the southern part of Lake Michigan and a considerable number (86) of those 

 captured in the northern part actually were from wild stock. 



In general, the lake trout caught in large-mesh nets were larger fish than 

 those taken in small-mesh nets. The fin-clipped lake trout caught in all nets 

 were slightly larger than the wild stock of the same year classes, but wild lake 

 trout of the earlier year classes, inhabitants of the lake before sea lampreys 

 became numerous, were even larger and faster growing than the fin-clipped 

 fish. The larger fish of the several year classes, caught in nets of either mesh- 

 size, were taken from the northern part of Lake Michigan and smaller fish from 

 the southern part of the lake. 



