declined below 13° C and sturgeon movements 

 ceased by mid-October. If photoperiod were in- 

 volved, sturgeon movements in 1977 should have 

 stopped at about the same time as they did in 1975 

 and 1976. Complete cessation of movement >0.5 

 km in autumn may be related to cold-induced in- 

 activity. 



Linear regi-ession analyses comparing distances 

 moved by sturgeon with river flows at Priest 

 Rapids Dam produced scatter diagrams with re- 

 gression coefficients approaching zero. In contrast 

 to results of studies in the Snake River, Idaho 

 (Coon et al.'^), river flow apparently had no influ- 

 ence on long-distance sturgeon movements in the 

 Columbia River at Hanford. 



The complex interaction of water temperature, 

 light cycle, feeding, urge to spawn, and other fac- 

 tors undoubtedly influence sturgeon movements 

 in the mid-Columbia River. Although temperature 

 is a major influence stimulating seasonal move- 

 ments, light cycle and feeding probably influence 

 diel movements. 



Acknowledgments 



We thank C. D. Becker, who critically reviewed 

 the manuscript; and R. R Olson, S. W. Cubberly, D. 

 W. Crass, and R. W. Cordo, who assisted data col- 

 lection in the field. V. B. Kuechle, Bioelectronics 

 Laboratory at Cedar Creek, University of Min- 

 nesota, kindly provided information on tempera- 

 ture transmitter precision. The study was sup- 

 ported by the U.S. Department of Energy under 

 Contract EY-76-C-06-1830 with Battelle Memo- 

 rial Institute, Pacific Northwest Laboratories. 



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FEEDING PERIODICITY AND DIEL VARIATION 



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370 



fishery BULLETIN: VOL. 79, NO. 2. 1981. 



