Present distributional records convey the impression that 

 most sea lamprey spavming activity occurs in the northern half of 

 the Lower Peninsula of Michigan (Table 1 and Figure 3). This im- 

 pression is probably correct although I do not believe that the true 

 extent of the sea lamprey spaiming populations in the southern 

 half of the Lower Peninsula has been fully determined. The spring 

 of 19h7 was an extremely wet season, and in 19U7 and 19U8 more or 

 less sustained flood conditions existed in southern Michigan 

 (Region 3) streams during the migratory and spamiing period. Turbid, 

 flood waters interfered materially vrLth stream observations in these 

 years isrith the probable result that many runs were not discovered. 

 These conditions were particularly evident in southeastern Michigan 

 where very feir runs were reported in either year. For example, in 

 the Huron and Clinton rivers no runs were identified in these years. 

 These same streams were utilized by sea lampreys as early as 1932 

 and 1938 respectively. There is no reason to assume that these 

 •waters would no longer be in use. However, I do not believe that 

 extensive sea lamprey spatming activity will ever be found in this 

 region. Sluggish currents, and particularly the predominantly 

 sandy and/or silted character of many stream beds in this area, 

 preclude spawning by the sea lamprey. The lampreys require at 

 least some smflTi gravel with trtiich to build their nests and spaim- 

 ing was only observed in those streams of Region 3 in "which there 

 were at least small patches of gravel. 



The greatest activity in the Upper Peninsula (Region 1) was 

 confined to the Lake Michigan drainages. A survey of streams enter- 

 ing Lake Superior in the western third of the Upper Peninsula was 

 conducted in 19U7 and 19U8 by Mr. Leland Anderson, District Fishery 

 Biologist at Watersmeet. Fifty-six streams were examined by him in 

 each year between the last week of May and July 11. No evidence 

 of runs was found althou^ the habitats examined in this area were 

 generally suitable for lamprey use. In streams entering Lake 

 Superior from the eastern part of the Upper Peninsula, only a few 

 sea lamprey runs have been verified and these are located at the 

 most eastern extension of the lake. The paucity of data relative 

 to runs in this area may be due to the interaction of several 

 factors: (1) the area is quite inaccessible to observation and the 

 human population for spotting runs is sparse j (2) the species is in 

 its initial stages of penetration in Lake Superior j and, (3) there 

 may be a general ecological unsuitability for the species in this 

 basin. A moderate spawning run was observed in the Tahquamenon 

 River by Dr. Frank Jobes of the U. S. Fish and Wildlife Service in 

 June, I9U8, but not in any other Lake Superior drainage •;\toich he 

 examined in the eastern two-thirds of the peninsula. Field personnel 

 of the Conservation Department captured specimens to verify the 

 presence of the species in two additional eastern Lake Superior 

 tributaries . 



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