Those few reports that were received irere traceable to the para- 

 sitic activities of native species of lampreys or to sea lampreys 

 carried on fish that had migrated into a streajn from a large body 

 of water. 



Several exceptions have been notec^ hov;ever. On May 12^, 1914.3, 

 I examined a 5.0-inch, recently-transformed sea lamprey which was 

 taken from a rainbov/ trout caught in the Ocqueoc River about 5 

 miles above its estuary. Shetter {19hS) mentions four young sea 

 lajnpre3'"s being found on a rainbow trout caught on July 6, 19hS, in 

 the do^Tnstream trap of a weir in the Ocqueoc River. Gage (1928) 

 reported that lalce lampreys, kept in aquaria through their trans- 

 formation, attacked fish immediately after leaving their burrows 

 in the tank bottom (my similar specimens did not feed until various 

 times after emergence, never immediately) . 



Those exceptions noted for a Michigan stream I attribute to 

 stragglers of the general doimstream movement which did not find 

 their vray out of the watershed immediately and/or to individuals 

 wiiich had been to Lake Huron once and rode back into the stream 

 attached to some fish. Instances of this latter phenomenon were 

 observed in 19li.9 when young sea lampreys were found on three occa- 

 sions attached to migrating white suckers taken in the upstream 

 trap of the Ocqueoc River weir. 



Downstream movement of partially-transformed sea lampreys 



and of other species of lampreys and fishes 



Between June 1, 19li8, and June 30, 19U9, hlj- partly-transformed 

 sea lampreys came doimstream into the Carp Lake River trap. The 

 bullc of these were taken in late July and in the month of August 

 (Appendix I, Table U). Considering the time of year at v/hich these 

 individuals were tal<:en, I believe their movement doTmstream may in 

 some way be related to the shift in stream habitat affected by 

 some of the larger larvae and transforming individuals of the sea 

 lamprey (see previous discussion of larval lampreys). In the same 

 13H:nonth period, a small number of adults and partly-transformed 

 specimens of the silver lamprey were trapped, mostly during May 

 and June. A few larvae of this species drifted doiTOstream in al- 

 most every month of the year (Appendix I, Table U). Adults of the 

 American iarook lamprey (197 indi^^Lduals ) were captured almost ex- 

 clusively from mid-April through the first week in June. 



A total of ij.92 larval lampreys identifiable only as either 

 sea lajiipreys or American brook lampreys were talcen in the Carp Laka 

 River trap. A few of these came doivnstream in nearly every month 

 of the year. The majority, however, were trapped in April and May. 

 Some partly-transformed American brook lampreys accompanying the 

 larvae and their coincident movement with that of the adult American 

 brook lampreys makes it seem probable that these larvae were pre- 

 dominantly of that species. 



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