to the Nemadji River at Superior, Wis. The 

 operation of the barriers was described by 

 Erkkila, Smith, and McLain (1956). The traps 

 at each barrier are framed with wood and 

 enclosed with l/2-inch mesh galvanized iron 

 hardware cloth. No facilities were maintained 

 to capture fish moving down stream. We have 

 used many records of fish collected at these 

 barriers. Because weirs were not operated 

 along the Minnesota shore, collections there 

 were limited to fish stunned by electric 

 shockers and fish unavoidably killed by lamprey 

 larvicides. 



ELECTRIC SHOCKERS 



Surveys to determine the presence and 

 distribution of sea lampreys in streams 

 tributary to Lake Superior were made with 

 electric shockers, developed exclusively for 

 collecting ammocetes (Braem and Ebel, 1961). 

 The electric power available from these units 

 limits their effectiveness for collecting but 

 many fish were taken. Streams containing sea 



lamprey larvae are surveyed intensively; 

 consequently, fish collections are more repre- 

 sentative for these streams. 



FYKE NETS 



Fyke nets have been fished on selected 

 streams to provide information on larval and 

 newly metamorphosed sea lampreys. The nets 

 are constructed of l/4-inch-bar synthetic 

 netting with a screen liner (18 by 14 openings 

 to the square inch). Large numbers of small 

 fish are taken by fyke nets. 



CHEMICAL TREATMENTS 



Chemical treatment of streams (tributary 

 to Lake Superior) has resulted in mortality 

 of some fish other than lamprey (Applegate 

 and King, 1962). Weaker members of most 

 fish species succumb to the lampricide. Repre- 

 sentative samples of fish are collected from 

 each stream during chemical treatment. 



