of the Great Lakes frequently possess a bi-directional, or re- 

 versing, water movement induced by wave action upon the shore. 

 It seemB unlikely that an ebb and flow water movement (or still 

 water) would elicit the presumably normal responses in the lajn- 

 prey which would result in an effective nest construction or 

 spawning act. Such water action would inhibit both of these 

 activities. Furthermore, in the shallowest areas of the lake 

 shoals, one to three feet in depth, which are comparable to the 

 depths selected in streams by the lampreys for spawning, there 

 is little likelihood of the survival of eggs because of molar 

 action of bottom materials subjected to wave action in such areas. 



(5) Post-spa'vning behavior 



Following the completion of spawning, spent females drop away 

 from the nests almost immediately, drifting downstream to die in 

 quieter eddies or pools. When held experimentally in enclosures, 

 they expired sooner after spawning than did the males. Males, 

 however, cling to the nest for one to three days after spawning 

 is completed, only dropping downstream when completely spent phy- 

 sically and very near death. Spent males curl themselves in the 

 deepest depression of the floor of the nest where they receive 

 the most protection from the current. In this position they cling 

 weakly to a stone (Figures 36, 39). This attitude is so character- 

 istic that spent individuals were readily spotted on the spawning 

 beds. 



Figure 39.— Spent male sea lamprey clinging to nest after the 



comoletion of spawning. (Ocqueoc River, Station IM, 

 June 8, 19U8.) 



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