Wenatchee River throughout its lower 7 miles except for a short stretch near 

 the lake, A l/2-miie reach at the outlet of Lake Wenatchee, and the lower 2 

 miles cf Nason Creek are used also. Smaller spawning populations scatter down 

 the Wenatchee River to the town of Plain, Tvro areas on the shore of Lake 

 Wenatchee where -ander^rfater seepage enters the lake are used alsOo 



Tow of these spawning-stream sections are downstream from the lakeo It 

 was once thought that ail bluebacks proceed through a lake in their migration 

 and spawn in i;he lalie's tributaries | however^, bluebacks are seen spawning 

 below Lake Wenatchee each year. Scale samples takea from these spai^mers re- 

 vealed a freshwater life history no different from those taken from above 

 the lake, suggesting that they were hatched above the lake, or migrated up- 

 stream to it shortly after hatching. On further inquiry, it was found that 

 this anomalous behavior is quite common in Karluk and Bristol Bay, Alaska, 

 and also in sockeye (blueback) streams in Canadao The chances of sun/ival 

 of the resu]i.ting young fish are questionable. If they could swim back up 

 into the lakej their chances of sujrvival would be equal to the chances for 

 survival of fry hatched in streams above the lake. But if they proceed to 

 sea shortly after attaining the free-swimming stage, there is a fair indi- 

 cation, not to be taken as conclusive, that they would experience a mortality 

 far in excess of those which migrated in their second and third years 

 (Gilbert 1912, p. 6l) . 



The procedure for making the spawning surveys was to enumerate the fish 

 in each section of stream oeriodically until the peak of the run had been 

 observed in each instanceo Some stream conditions influenced the accuracy 

 of the counts. For exan^le, the North Fork of the '.ilhite River and the main 

 stem below become very turbid after a rain storm and poor visibility is the 

 result. Also flooding conditions in the Osoyoos region in 19U6 made counts 

 in the major portion of the stream impossible. 



The maximum counts made in various streams appear in table 2. In an 

 attempt to account for the total number of fish utilizing each section of 

 stream, certain estimates can be made provided the necessary assiimptions are 

 made alsoo The maxirn'orn counts in each spawning section will give an absolute 

 minimum estimate because we know that many successive groups of fish utilized 

 the spawning gravel in the course of the spawning season. This does not, 

 however, account for the total nuiiiber of fish utilizing the various spavming 

 grounds but merely represents the "standing crop" of spavmers, which during 

 the entire spawning period are being added to by late arrivals and diminished 

 by dying spawned-out salmon. 



The counts (table 2) for the four survey years, when the hatchery- 

 spawned bluebacks and maxim^jm stream coimts are added, total 12,176 in 19U7, 

 16,209 in 19h8, 2669 in 19li9, and 7,089 in 1951 for the Wenatchee area, com- 

 pared mth Rock Island counts of 79,833, 81i,626, 18,601, and 101,782. 



11 



