ILXA.iSTRATIOKS 



Figure Page 



1. Map of upper Gi-eat Lalces showing the location 



of sea ianprey contrcl cie:vi(^s£ operated in 1951 2 



2. Rate of increase of sea lanp^r-eys in Lalces H''Ji-on 



and Michigan as i"if Iecte;d hj -iireir and trap 



catches in the Ocqueoc River, P;:'esqu.''^ Isle 



Coixatj,, Michigan (LsJ^e Pfjron bas-in.) and Hibbard's 



Creek. Door Co"anty, Wisconsin (Lake I,Iichigar> 



basin) ........ 7 



3. Experimental sea laaiprsy bai'/rier dam in -the Black 



Ri.ver, Mackina-ar Co'onty, Miciiigan 32 



U. Black River bai-rier dam. '.■:iose--'ap of bai'rier dam 

 shomng overhanging, o-uc-ved lip of sheet steel 

 attached to "wall of dam. , 32 



$. Portable-type WBir and trap in Carp Creek, Presque 

 Isle CoTonty, Ifi-chigaii, after inst.allation of 

 permanent sills, ■'M'ap base, ard abutmenbs of 

 concrete . . . . <. 3h 



6. Diagramatic plans of concrete sills, trap base, and 

 abutments used to protclde per:ianent base for 

 poi'table-tj'pe sea lampj'ey weir and trap. . o ..... . 35 



