at most points. Seasonal and yearly changes 

 were of much greater nnagnitude, however, 

 and they affected extensive spawning areas. 



5. Spatial differences in dissolved oxygen 

 levels of intragravel water are described. 

 It was found that spatial differences were 

 greatest during periods of low discharge and 

 warnn weather. 



6. A random sampling procedure to eval- 

 uate mean dissolved oxygen levels within major 

 spawning areas is described. Random sampling 

 was found to provide a low-cost and precise 

 estimate of mean oxygen level within spawn- 

 ing gravels. 



LITERATURE CITED 



ALDERDICE, D. F., W. P. WICKETT, and 

 J. R. BRETT. 



1958. Some effects of temporary exposure 

 to low dissolved oxygen levels on Pacific 

 salmon eggs. Journal of the Fisheries 

 Research Board of Canada, vol. 15, 

 no. 2, p. 229-250. 



CHAMBERS, J. S., G. H. ALLEN, and R. T. 

 PRESSEY. 

 1955. Research relating to a study of spawn- 

 ing grounds in natural areas. Annual Re- 

 port of Washington Department of Fish- 

 eries to U.S. Army Corps of Engineers 

 under contract no. DA. 35-026-Eng- 

 20572, 175 p. 



DOUDOROFF, PETER. 



1957. Water quality requirements of fishes 

 and the effects of toxic substances. 

 In Brown, Margaret Elizabeth, editor. 

 Physiology of Fishes. Acadennic Press, 

 New York, vol. 2, chap. 9, p. 403-430. 



GANGMARK, HAROLD A., and RICHARD G. 

 BAKKALA. 



1959. Plastic standpipe for sampling 

 streambed environment of salmon 

 spawn. U.S. Fish and Wildlife Service, 

 Special Scientific Report--Fisheries 

 No. 261, 20 p. 



HARPER, E. L. 



1953. Semimicrodetermination of dissolved 

 oxygen. Analytical Chemistry, vol. 25, 

 p. 187-188. 



HUNTER, J. G. 



1948. Natural propagation of salmon in 

 the central coastal area of British 

 Columbia. Fisheries Research Board 

 of Canada, Progress Reports of the 

 Pacific Coast Stations, no. 77, p. 105- 

 106. 



NEAVE, FERRIS, and R. E. FOERSTER. 



1955. Problems of Pacific salmon nnanage- 

 ment. Transactions of the Twentieth 

 North Annerican Wildlife Conference, 

 p. 426-439. 



NEAVE, F., and W. P. WICKETT. 



1955. Transplantation of pink salmon into 

 the Eraser Valley in a barren year. 

 Fisheries Research Board of Canada, 

 Progress Reports of the Pacific Coast 

 Stations, no. 103, p. 14-15. 



POLLARD, R. A. 



1955. Measuring seepage through salmon 

 spawning gravel. Journal of the Fisher- 

 ies Research Board of Canada, vol. 12, 

 no. 5, p. 706-741. 



SHUMWAY, DEAN LEE. 



1960. The influence of water velocity on 

 the development of salmonid embryos 

 at low oxygen levels. M.S. thesis, Oregon 

 State College, Corvallis, Oregon, 49 p. 



SILVER, STUART JAYSON. 



1960. The influence of water velocity and 

 dissolved oxygen on the development 

 of salmonid embryos. M.S. thesis, Ore- 

 gon State College, Corvallis, Oregon, 

 50 p. 



TERHUNE, L. D. B. 



1958. The Mark VI groundwater standpipe 

 for measuring seepage through salmon 

 spawning gravel. Journal of the Fish- 

 eries Research Board of Canada, vol. 

 15, no. 5, p. 1027-1063. 



WICKETT, W. P[ERCY]. 



1952. Production of chum and pink salmon 

 in a controlled stream. Fisheries Re- 

 search Board of Canada, Progress Re- 

 ports of the Pacific Coast Stations, no. 

 93, p. 7-9. 



1954. The oxygen supply to salmon eggs 

 in spawning beds. Journal of the Fish- 

 eries Research Board of Canada, vol. 

 11, no. 6, p. 933-953. 



1958. Review of certain environmental fac- 

 tors affecting the production of pink 

 and chum salnnon. Journal of the Fish- 

 eries Research Board of Canada, vol. 

 15, no. 5, p. 1103-1126. 



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