Differences between mean values of August 

 16 and October 27 and of October 27 and Feb- 

 ruary 23 were evaluated with a t-test. Except 

 for the fraction retained by the 0.417-mni. 

 sieve, all differences were significant at the 

 10-percent level at least. 



SUMMARY 



Permeability of bottom materials is prob- 

 ably an importantfactor limiting fry production 

 in spawning beds. It has been shown how 

 permeability is related to size composition 

 of bottom materials, and it is possible to 

 compare relative permeability of spawning 

 beds by determining average size composi- 

 tion. Hence, a simple and direct method of 

 measuring physical properties of spawning 

 beds pertaining directly to their capacity to 

 produce fry has been provided through develop- 

 ing techniques for measuring size composi- 

 tion of bottom materials. 



Pronounced differences in size composition 

 of bottom materials were observed among 

 several pink salmon spawning streams. The 

 more productive spawning streams had the 

 highest permeability coefficients. 



The volume of fine materials within par- 

 ticular spawning beds changes with time. 

 A reduction in volumes is caused primarily 

 by forces that produce gravel movement (e.g., 

 redd digging and flooding). Silts and fine sands 

 accruing to spawning beds and reducing their 

 permeability are transported in part from 

 watersheds into spawning streams. Logging 

 increases the amountof transported materials. 



LITERATURE CITED 



ANDREW, F. J., and G. H. GEEN. 



1960. Sockeye and pink salmon production 

 in relation to proposed dams in the 

 Eraser River system. International Pa- 

 cific Salmon Fisheries Commission, 

 BuUetin No. 11, 259 p. 



CHAMBERS, JOHN S., GEORGE H. ALLEN, 

 and R[ICHARD] T. PRESSEY. 

 1955. Research relating to study of spawn- 

 ing grounds in natural areas. Annual 

 report (June 22, 1954 to June 22, 1955), 

 Washington Department of Fisheries to 

 U.S. Army Corps of Engineers. 

 [Processed.] 



CHILDS, E. C, N. COLLIS-GEORGE, and 



J. W. HOLMES. 



1957. Permeability measurements in the 



field as an assessment of anisotropy 



and structure development. Journal of 



Soil Science, vol. 8, no. 1, p. 27-41. 



CORDONE, ALMO J., and DON W. KELLEY. 

 1961. The influences of inorganic sediment 

 on the aquatic life of streams. Cali- 

 fornia Fish and Game, vol. 47, no. 2, 

 p. 189-228, 



FAIR, GORDON M., and L[ORANUS] P. HATCH. 

 1933. Fundamental factors governing 

 streamline flow of water through sand. 

 Journal of the American Water Works 

 Association, vol. 25, no. 11, p. 1551- 

 1565. 



FRANZINI, JOSEPH B. 



1951. Porosity factor for case of laminar 

 flow through granular media. Transac- 

 tions American Geophysical Union, vol. 

 32, no. 3, p. 443-446. 



FREVERT, RICHARD K., and DON KIRKHAM. 

 1948. A field method for measuring the 

 permeability of soil below a water table. 

 National Research Council, Proceedings 

 of the Highway Research Board, vol. 28, 

 p. 433-442. 



HARRISON, C. W. 



1923. Planting eyed salmon and trout eggs. 

 Transactions of the American Fisheries 

 Society, vol. 53, p. 191-199. 



BURNER. CLIFFORD J. 



1951. Characteristics of spawning nests of 

 Columbia River salmon. U.S. Fish and 

 Wildlife Service, Fishery Bulletin 61, 

 vol. 52, p. 97-110. 



HATCH, RICHARD W. 



1957. Success of natural spawning of rain- 

 bow trout in the Finger Lakes region 

 of New York. New York Fish and Game 

 Journal, vol. 4, no. 1, p. 69-87. 



14 



