In the Ocqueoc River diiring the period of weir operation 

 (October 2ii, 19U8, to March 20, 19h9) , no partly- transformed sea 

 lampreys were taken. Foxir larvae of the silver laniprey were 

 trapped in November and December^ 19kQ, sjid one adult of that 

 species, 9''9 inches long, was taken on January'- 20, 19h9. 



Other than the kinds and numbers of lampreys described, 7^119 

 fish of 21 species were taken in the Carp Lalce River trap and 12? 

 fish of seven species in the Ocqueoc River weir and trap during 

 the operation of these structures. Predominant species captured 

 in the Carp Lake River were Great Lakes longnose dace, common 

 shiners, and common white suckers; presumably all were returning 

 to Lal<:e llichigan after spawning. Most fish trapped in the Ocqueoc 

 River were yellow perch ( Perca flavescens ) and irrmiatui^e common white 

 suckers. Very little downstream movement of these other species 

 of fishes occurred during those seasons when the recently-transformed 

 sea lampreys migrate downstream. 



X. Investigations of the adult , parasitic phase of the 

 sea lamprey's life cycle 



Methods of study 



In 19h7) 19li8, and 19h9, commercial fishermen and others co- 

 operated with me in obtaining parasitic, adult sea lampreys from 

 the Great Lalces for the purposes of securing information upon their 

 distribution and habits and to provide materials for estimating the 

 duration of the parasitic phase of the life cycle. In all, 33S 

 specimens comprising llit separate collections were obtained. Of 

 the total sample, 23 specimens were taken in 19hl , 197 in 19^8, and 

 135 in 19U9. By location, 2UU individuals were captured in Lake 

 Huron, 78 in the Straits of Mackinac, 23 in Lake Michigan, 1 in 

 Lake Superior, 3 in inland Burt and Mullet Lakes (Cheboygan County), 

 and 6 in the Ocqueoc River weir and trap. Most lampreys taken viere 

 captured in conjunction ivith commercial catches of whitefish 

 (Goregonus c. clupeaf ormis ) , chubs (primarily Leucichthys johannae 

 and others), white and redhorse suckers, and yellow perch. Other 

 species taken to "rahich lampreys were attached were (in order of 

 decreasing frequency): lake trout ( Cristivomer n. namaycush ), rarJi- 

 bow trout, burbot (Lota lota maculosa ), and nortEem channel catfish 

 ( Ictalurus 1. lacustris ) . Trapnet fishermen accounted for 63 '9 per- 

 cent of the sample of lampreys; gillnet fishermen took 33-2 percent 

 during the open fishing season. The greater number taken by trapnet 

 fishermen is due primarily to the fact that I had a greater numbei- 

 of contacts with fishermen using that type of gear than with those 

 fishing gillnets. The remaining 2,9 percent of the lampreys were 

 taken from fish caught by gillnet fishing through the ice, by 

 angling (trolling), and attached to migrating fish captured in the 

 Ocqueoc River weir and traps. 



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