date to insure that the average stage of de- 

 velopment of ennbryos in the samples was not 

 influenced materially by the sampling pro- 

 cedure. To determine the percentage with 

 pigmented eyes, we examined a subsample of 

 150 randomly selected eggs under low naagnifi- 

 cation (35X). Embryos with pigmented eyes 

 were dissected and examined under higher 

 magnification (lOOX). The microscope had a 

 micrometer eyepiece to measure diameter of 

 the eye and length of the pectoral fin. The eye 

 was pigmented in 62 percent of the embryos 

 from the upper segment and 56 percent from 

 the middle. Also, embryos from the upper 

 segment had the larger eye diameter and the 

 longer pectoral fin (table 2). 



November samples .-- Embryos and alevins 

 were sampled on November 19-21 for measure- 

 ments of length of body and pectoral fin and 

 diameter of eye. Indications in September that 

 growth was more rapid in the upper segment 

 than in the middle were reinforced in November 

 (table 3). Furthermore, 77 percent of the 

 surviving eggs had hatched in the upper seg- 

 ment compared with only 30 percent in the 

 middle. (By contrast, only 1 1 percent of the eggs 

 had hatched in the lower segment; the tendency 



of late females to spawn in the lower segment 

 undoubtedly contributed to the delayed hatching 

 there. ) 



March samples . --By March, all the live 

 embryos had hatched to alevins. Subsamples 

 of alevins were examined for external yolk and 

 weighed, and body length, diameter of the eye, 

 and length of the pectoral fin were measured 

 (table 4). Alevins from the upper stream seg- 

 ment continued to be larger and more ad- 

 vanced in development. 



SOME EFFECTS OF WATER QUALITY 

 ON GROWTH AND DEVELOPMENT 



In all 3 years of the study, embryos and 

 alevins grew faster and developed more rapidly 

 in the upper segment of the Sashin Creek 

 spawning ground than in the middle and lower 

 segments. This favorable growth may have been 

 due to the relatively better quality of the intra- 

 gravel water in the upper segment, as indicated 

 by the higher levels of dissolved oxygen 

 (table 1). 



The content of dissolved oxygen in intra- 

 gravel water is controlled both by biological 



Table 3. — Development and size of pink salmon embryos and alevins in 

 upper and middle segments of Sashin Creek, November 19-21, 1965 (Mean 

 values and 90-percent confidence limits are given) 



■"■ Alevins only; estimated from random subsample of 150. 

 ^ Alevins and embryos combined, estimated from random subsample of 

 150. 



Table 4 Development and size of pink salmon alevins in upper and middle segments of Sashin 



Creek, March 21-26, 1966 (Mean values and 90-percent confidence limits are given) 



Segment 



Live 

 specimens 

 in sample 



Alevins with 

 external yolk 



Length 

 of body^ 



Wet weight 

 (with yolk)^ 



Diameter 

 of eye-'' 



Length of 



pectoral 



fin^ 



Upper 

 Middle 



Number 

 1,864 

 2,231 



Percent 

 0.53 

 0.54 



Mm. ' 

 32+0.5 

 31+0.5 



Mg. Mm. Mm. 



263+4 2.50*0.02 2.43+0.06 

 257+4 2.43+0.02 2.22+0.06 



•*■ Estimated from random subsample of 150. 



