lampreys escaped upstream through the power dam boat locks into the 

 Mullett Lake — #urt Lake drainage. 



Specimens for tagging we^e obtained by dipnetting at night below 

 the paper mill power dam on the Cheboygan River. Sea lampreys collected 

 early in one night were held in live boxes overnight and tagged the 

 following morning. Originally a special experimental trapnet was 

 ooerated but it proved to be inefficient because of improper mesh-size^ 

 strong cu rents, and the accumulation of large amounts of detritus on 

 the webbing. 



Two types of tags were used in the experiment. The first groups 

 of the lampreys (1,585 individuals) were tagged with numbered Peterson- 

 type tags, three-eights of an inch in diameter. One disc was red and 

 the other was white. These were applied with 1 3/u nickel wire pins 

 through the dorsal musculature just anterior to the first dorsal fin 

 (Fig, 9). The remainder of the lampreys (1,258 individuals) were marked 

 with numbered jaw tags of fingerling size. The jaw tags were clamped 

 through the anterior portion of the first dorsal fin just above its 

 juncture with the back. Prior to tagging, the lampreys were anesthetized 

 with a 5-percent solution of urethane. Anesthetized lampreys were 

 measured, tagged, and held in a live box until they had recovered fully. 

 They were then released. No lampreys so handled were held in excess of 

 2 hours. **ny individuals not appearing fully recovered in this time were 

 destroyed to exclude them from the experiment. 



There was evidently a difference in the efficiency of the two types 

 of tags used, Of the 2l\l tags recovered, only 7k were jaw-type tags, ^t 

 was noted that lampreys taken in commercial gear were almost always cap- 

 tured when the Peterson-type tag became entangled in the mesh. The jaw 

 tag could not similarly ensnare the lamprey. If the 3k Peterson- type 

 tags recovered in the commercial fishery are disregarded, the jaw tags 

 still made up only 35 percent of the tags recovered although kk percent 

 of the lampreys were marked with this type of tag. The difference in 

 efficiency still evident in the figures after this adjustment is probably 

 attributable to difficulty in detecting the small tags under night work- 

 ing conditions at the weirs. The large red and white disc tags were 

 highly visible even in subdued light. 



The recovery of 2 [ Sk marked lampreys in the weirs and traps of Con- 

 trol &one H-l indicates that at least 9 percent of the blocked Cheboygan 

 River run was diverted to other streams within the zone in both direct- 

 ions along the shoreline. The Cheboygan River sea lamprey run was 

 conservatively estimated by experienced observers at U0,000 migrant 

 individuals. On the basis of this estimate, the total number tagged, 

 and the percentage recovery of tags, it appears that about 3,600 of 

 the spawning run -ea lampreys captured in the streams of the control 

 zone were diverted Cheboygan River migrants. By the same token, 91 

 percent or an estimated 36, uOO sea lampreys from the blocked run were 

 diverted into streams outside the control area or wandered aimlessly 

 in the lakes, presumably to die without spawning. 



31 



