Land Use 



Some type of human- induced land disturbance has occurred within 

 all watersheds surveyed. The most common form was water 

 pollution resulting from sedimentation. All of the sites were 

 impacted by the cumulative effects of at least two upstream land 

 use practices; most of the sites by more. It was beyond the 

 scope of this survey to judge the tolerance of each species to 

 various forms of disturbance. Alterations which increase 

 sedimentation and temperature and weaken the riparian integrity, 

 could adversely affect the suitability of sculpin habitat at some 

 unknown threshold level. 



Sampling Methodology 



The electroshocker, in combination with the D-net, was the most 

 effective method for sampling sculpin. Young of the year were 

 typically found in habitat of minimal current (within 2 cm of 

 bottom substrate) , good cover (interstitial cobble) , and closer 

 to channel edges than larger sculpin. Visually estimating total 

 fish abundance and total habitat in small streams may prove 

 beneficial and an efficient means of complimenting and conducting 

 these surveys (Hankin and Reeves 1986) . 



Minnow traps proved to be an ineffective sampling device for 

 sculpin despite overnight sets. Sculpin are more active 

 (feeding, etc.) during hours of darkness. Also, it is reported 

 that they favor moving prey as food (Scott and Grossman 1979) . 

 Additionally, the lakes sampled were thermally stratified. The 

 minnow traps, for the most part, were set from the lake's shore 

 in warmer epilimnion shallows. Also, the traps were set in areas 

 of seemingly favorable substrate for sculpin. No sculpin were 

 captured using minnow traps. 



Glacier and Fire 



Other factors which may have had an effect on geographic 

 distribution of sculpin within this study area include glacial 

 action and fire. Glacial Lake Missoula could have effected the 

 distribution of shortheads (Gangemi 1992) . Alt and Hyndman 

 (1986) indicate that ice age glaciers approached their maximum 

 extent some 15,000 years ago. These filled the Purcell Valley 

 and advanced south into Idaho crossing the Clark Fork River 

 valley. This ice dam (20 miles wide and 6,000 feet thick) 

 impounded the Clark Fork River to form Glacial Lake Missoula. It 

 also impounded the Kootenai River and formed another glacial lake 

 that likely connected with Glacial Lake Missoula. Valleys such 



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