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BEHAVIOR AND PHYSIOLOGY OF MARKED FISH
<br />ings suggested that this assumption is invalid; we
<br />therefore recommend that at least 24 h elapse be-
<br />tween mark and recapture efforts. Rapid obser-
<br />vations by snorkeling may be used to count marked
<br />fish and observe behavior in a section before a
<br />recapture effort begins to ensure the validity of
<br />assumptions. Habitat quality (i.e., the amount and
<br />type of instream cover) seems to be an important
<br />variable to consider in population estimates based
<br />on electrofishing. Electrofishing may fail to pro-
<br />duce adequate electrotaxis if fish are in low-con-
<br />ductivity water and under heavy cover. The effi-
<br />cacy of electrofishing depends on many factors,
<br />and our results are not applicable to all situations.
<br />However, an understanding of the behavioral and
<br />physiological consequences of electrofishing will
<br />help improve the effectiveness of a technique
<br />seemingly all too often taken for granted.
<br />Acknowledgments
<br />We thank Fred Everest, Mark Hixon, and Paul
<br />Eschmeyer for reviewing the manuscript; Hiram
<br />Li for his thoughtful and helpful discussions of
<br />fish behavior; Gordon Reeves, Fred Everest, and
<br />Pacific Northwest Research Station RWU-4202
<br />for providing the artificial stream; and LaVon
<br />Mauer and Adrian Hunter for their help in prep-
<br />aration of this manuscript. This work was made
<br />possible by the professional and financial support
<br />of Al Fox and Bill Nelson of the U.S. Fish and
<br />Wildlife Service. This is Oregon Agricultural Ex-
<br />periment Station Technical Paper 8778.
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