Comparison of weir catches of the larger fishes (food, game and 

 coarse species) with those of former years reflects a drastic decline 

 in the size of their spawning runs (Applegate 1950). Concurrently 

 with this decline, the percentage of lamorey-scarred individuals has 

 increased, for example, in Carp Creek and the Ocqueoc River (Control 

 Zone H-l) the spawning runs of suckers and the number and percentage of 

 lamorey-scarred individuals among them over a U-year period were as 

 follows t 



The decline of these runs most certainly reflects a severe de- 

 pletion of the stocks of suckers in the lake proper. Fishing operations 

 conducted in this area of the lake substantiate this view. It may be 

 reiterated here that the decline of these and other species of fishes has 

 been coincident with, and (directly) proportional to, the increase in the 

 numbers of sea lampreys (see text table, p.8 ). 



On the other hand, the numbers of smaller species of fish, primarily 

 cyprinids and presumably forage species, seem to have increased each year. 

 For example, the numbers of Great Lakes longnose dace taken in the Carp 

 Creek weir and t rap over a u-year period were as follows: 19h7-80lij 

 19U8-5,798j 19li9-l5,69l^ and 1950-30,028. These minnows, too small to be 

 preyed upon by the sea lamprey and in the absence of any effective numbers 

 of their normal predators, appear to be increasing apace. 



Some biological characteristics of the sea lamprey runs 



Sex ratio . --Records of sex were made for all or nearly all of the 

 sea lampreys taken in eight streams in Control Zone H-l and in one stream 

 tributary to Lake Superior (Table I4.). Examination of these data col- 

 lected in 1950 indicates that the sex ratio of entire runs in northern 

 Lake Huron continues to shift in favor of the males. Specific figures 

 for four consecutive years are as follows (where data for runs in more 

 than one stream are available, an average has been obtained for the 

 combined runs),, 



I ear 

 I9UT 

 19U8 



1/1*9 

 1950 



12 



