PROGRESS IN BIOLOGICAL INQUIRIES, 1936 21 
carried out in 1908 in the same general locality as that of the present 
experiment. In the earlier work, a total of 59 fish were tagged in a 
single experiment, of which 25 were chinooks, 16 were silvers, and 
18 were steelheads. 
The tagging this season consisted of nine experiments carried on 
from August 16 to September 2, inclusive, in which a total of 1,059 
chinooks were tagged and liberated. The experiments were con- 
ducted at one location, about 484 miles upstream from the mouth of 
the river. 
Of the fish tagged, 220, or 20.8 percent, were recovered. Six, 
or 0.6 percent, of the recoveries were taken outside the mouth of 
the river, 5 of which were caught by troll in the vicinity of the 
Columbia River lightship, while 1 tag was secured from a fish which 
had migrated north to Willapa Harbor and was taken in the Nasel 
River by a gill net. A total of 30 tags, or 2.83 percent, were recovered 
at hatcheries on the Columbia River system. By considering this 
percentage in relation to the total number of fish entering the 
hatcheries, it is possible to estimate the total escapement and thus 
the percentage of the migrants that return to hatcheries. The re- 
mainder of the tagged fish were caught in the main Columbia River 
from near the point of tagging to Celilo Falls, 190 miles upstream. 
The results of this experiment will be set forth in a report for 
publication. 
Further information on the size and seasonal occurrence of the 
runs of migratory fish in the upper Columbia River was obtained by 
means of counting weirs placed in the fish ladders of the Rock Island 
Dam of the Puget Sound Power & Light Co., located about 14 miles 
southeast of Wenatchee, Wash. Weirs were placed in all three fish- 
ways and men were employed to count the fish passing through at all 
times that the counting gates were open. A complete count of all 
fish passing upstream and over the dam was therefore made during 
the period from May 6, 1936 to September 29, 1936, inclusive. These 
counts were made as a cooperative effort of the Washington Game 
Commission, the Washington Fisheries Department, the United 
States Reclamation Service, and the United States Bureau of Fisher- 
ies. During the period of time mentioned above, 7,301 chinook sal- 
mon, 16,501 blueback salmon, and 2,374 steelhead trout passed 
through the ladders. These counts represent the entire run of blue- 
backs passing Rock Island, because the period of time during which 
the counting was done included all of the time when bluebacks are 
present in the river. The total given for chinooks includes the major 
portion but not all of the run, because some of these fish passed the 
dam before and after the counts were made. For the same reason it 
is probably true that the greater part of the steelhead run is not 
represented in the count. These observations are of value not only 
because they indicate the dates of the migratory runs in the upper 
Columbia and furnish an index of the number of each species, but 
also because they provide important data relating to the problem of 
fish protection at the Grand Coulee Dam, which is being constructed 
about 170 miles above the Rock Island Dam, 
In order to obtain information on the number of blueback salmon 
spawning in tributaries of the upper Columbia, weirs were built and 
counts made of the fish ascending the Wenatchee and Okanogan Riv- 
