Recommendations for future work 



It \rl'^l be necessarys in the future, to recheck all streams with a 

 productive potential, to determine whether or not they are being used by 

 adult sea lampreys „ It is probable that a large number of these streams 

 ■will never be in need of control measures; spawning may be inhibited by 

 lovf temperatures J, steep gradients ^ high velocitiesj relatively small 

 size of a number of streams, and excessive turbidities (lake clay areas 

 of Ontonagon and Gogebic Counties) , The more questionable or marginal 

 streams should be rechecked during the regular spawning season to deter- 

 mine accurately their temperatures, velocities, and water levels o The 

 true extent of spawning activity in many streams (notably in Ontonagon 

 and Gogebic Counties) can be determined only by rechecking during the 

 spawning season before most of the nests are destroyed by freshets » 



It will be necessary also to carry out further initial surveys of 

 all of the remaining unsurveyed streams flowing into Lake Superior^ if 

 the sea lamprey is to be successfully controlled (Wisconsin^ Minnesota, 

 Ontario streams, and those on Isle Royale and other islands which have 

 not yet been examined) . Many of the unsurveyed areas are relatively 

 inaccessible, and will call for much more highly organized surveys than 

 those carried out to date., 



Despite the fact that various types of control structures have 

 been recommended for streams which have a productive potential^ it will 

 be necessary to experiment further in order to develop the most practical 

 types o Many Lake Superior streams have characteristics (steep gradients, 

 high velocities, rapid fluctuations in water levels, and extremely heavy 

 turbidity) which, when combined with relative inaccessibility, may present 

 control problems not encountered in previous experimental control opera= 

 tions (Applegate and Smith, 19^1) o 



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