"Transformers" (metamorphosed larvae) move downstream to lake or sea where 

 they feed by attaching themselves to fishes, rasping a hole through the 

 body covering and sucking body juices. Depending in part on hunger and 

 size of the adult lampreys and size of their prey, one feeding can be fatal 

 or the prey can withstand several attacks. 



Figure 3. The mouth of the sea lamprey, which is lined with horny 

 teeth surrounding a rasping tongue in the center. 



Passage of the s 

 Niagara Falls (about 

 of the We Hand Canal 

 Niagara Falls. Movi 



Erie in 1921 

 Michigan and 

 the mid-1940 1 

 damaged, and 

 catastrophic 



The n 

 by the 

 s fish 

 similar 

 decline 



sea lamprey invasion 



ea lamprey to the upper Great Lakes was blocked by 

 50 m high) between Lakes Ontario and Erie. Completion 

 for shipping in 1829 enabled the sea lamprey to bypass 

 ng up the Great Lakes, the lamprey was recorded in Lake 

 id-1930's the animal had reached Lakes Huron and 

 1940 ' s it was firmly established in Lake Superior. By 

 stocks in Lakes Huron and Michigan had been severely 

 damage was predicted correctly for Lake Superior. The 

 in lake trout ( Salvelinus namaycush ) in relation to 

 is best traced in Lake Superior (Figure 4). 



221 



