Appendix Table 3. — Number of floaters tagged at search 

 stations near Bonneville Dam and percentage recovered, 

 April It to 22, 1955 



Chinook salmon Sockcyc salmon Stcclhcad trout 



Tagging Re- Re- Re- 



location Tagged covered Tagged covered Tagged covered 



A'umber Number Number Number Number Number 



The Dalles 17 1 4 



Bonneville' 32 5 2 



Cape Horn 75 6 21 



Reed Island 92 13 3 1 3 



Ellsworth 17 4 15 1 2 



Willamette 63 4 13 1 4 i 



St. Helens 3 3 1 



Total '299 '31 61 3 11 2 



Percent 

 recovered 11 5 19 



> McOowan and Moffett Creek stations comliined. 



' Including 26 released twice and five released a third time. 



• Including tive second recoveries. 



Tags from eight of the 272 chinook and three 

 of the 57 sockeye salmon released downstream 

 from the dam were returned by fishermen; the 

 rest were recovered at search stations. 



Forty-four chinook and 12 sockeye salmon were 

 released at stations 1 (St. Helens) and 2 (Willam- 

 ette) when there was no search effort farther 

 downriver. These fish, therefore, had no chance 

 for recovery at search stations. In both years, 

 carcasses released at stations farther downstream 

 had less chance of recovery than those released 

 farther upriver because the number of search 

 stations was smaller downstream from the dam. 



Only five of the 22 chinook salmon floaters 

 recovered at search stations in 1955 traveled 

 more than 16 km., and all but one were found the 



same day they were released. Thus, the small 

 number of second recoveries of tagged floaters 

 was indicative of their rapid disappearance. 



Tagging and recovery of floaters also provided 

 useful information on their rate of travel: during 

 our experiment in July 1955, when river flow was 

 high, the rate below Bonneville Dam was from 

 3.4 to 5.1 km.p.h. (average 4.2 km.p.h.). 



Thus, during the period of recovery of tagged 

 floaters for the mortality estimate, a floater re- 

 quired a maximum of only 16 hours to pass 

 through the entire search area between the dam 

 and the mouth of the Willamette River, a distance 

 of 70 km. 



From these facts, the following conclusions 

 may be drawn regarding disappearance and rate 

 of travel of floaters: 



1. Floaters appearing at the surface near 

 Bonneville Dam would pass through the 70-km. 

 search area between the dam and the mouth of 

 the Willamette River in less than 16 hours, pro- 

 vided they remained in the current. 



2. Floaters would pass through the entire search 

 area during the night between successive days of 

 sampling, eliminating any possibility of being 

 observed. 



3. Floaters originating near the dam would 

 reach the mouth of the Columbia River in 3 or 4 

 days. 



492 



U.S. FISH AND WILDLIFE SERVICE 



