FISHERY BULLETIN: VOL. 71, NO. 2 



TABLE 4. — Percentage of transported and nontrans- 

 ported (control) juvenile chinook salmon (released in 

 1968) that were recaptured as adults at Ice Harbor 

 Dam, 1 April through 30 September 1970 and 1971. 



' Adjusted for initial tag loss. 



- Based on a comparison of the known recovery of fish 

 with magnetized wire togs at Ice Harbor Dam and the 

 subsequent recovery of these and other marked fish at a 

 hatchery upstream from Ice Harbor. Returning fish identified 

 at the dam were marked with dart tags and released to 

 continue their migration upstream. Numbers of dart-togged 

 fish arriving at Rapid River Hatchery were compared with 

 the recovery of other wire-tagged fish not previously detected 

 and identified at Ice Harbor Dam. 



compared (Table 5), benefits from transporta- 

 tion are defined by time. Returns of spring 

 chinook salmon are in a ratio of 1.8:1 (trans- 

 port/control) and summer chinook salmon in 

 a ratio of 2.8:1. 



TABLE 5. — A comparison between transported and 

 nontransported groups of chinook salmon based on 

 numbers of transported and nontransported juvenile 

 fish (released at Bonneville and John Day Dams) that 

 were recaptured as adults at Ice Harbor Dam in 1970 

 and 1971. 



Seasonal races of chinook salmon in the Columbia River 

 system ore classified as spring, summer, or fall chinook 

 depending on the time of year that the adults enter the 

 river to spawn. We classified adult salmon captured at Ice 

 Harbor Dam prior to 2 June as spring chinook and those 

 taken from 2 June through 31 July as summer chinook, 



- Numbers recaptured adjusted in relation to numbers re- 

 leased (Table 1). 



Combined adult returns from the John Day 

 release were only slightly more than returns 

 from the controls. Although the poorer returns 

 from releases at John Day are unexplained 

 at this time, it is possible that the stress on 

 the fish from having to pass two dams (The 

 Dalles and Bonneville) plus the stress of being 

 hauled may have eliminated any benefit from 

 transport prior to spilling. If returns from 

 this release are again separated into seasonal 

 races, however, the ratio of transport to control 

 of the summer chinook salmon is about 1.3:1. 



A comparison of adult returns to Ice Harbor 

 Dam from the Bonneville releases with estimates 

 of juvenile survival at The Dalles Dam indicates 

 a correspondence. Prior to heavy spilling when 

 the majority of the spring chinook salmon 

 migrated, the recovery ratio of juveniles re- 

 leased before spilling began was 1.7:1 (trans- 

 port/controls); adult return ratio at Ice Harbor 

 was 1.8:1 for spring chinook salmon. After 

 heavy spilling when the majority of the summer 

 chinook salmon migrated, the recovery ratio 

 of juveniles released then was 3.5:1; adult 

 return ratio of summer chinook salmon was 

 2.8:1. 



Logically, the adult return ratios indicated 

 from those transported to Bonneville Dam 

 should show more benefit from transport than 

 the juvenile ratios showed at The Dalles Dam 

 because the controls still had to pass two 

 dams, The Dalles and Bonneville, before reach- 

 ing the ocean. This is not the case; only the 

 spring chinook salmon show a greater ratio; 

 the summer chinook salmon transport/control 

 return ratios for juvenile migrants were higher 

 than the adult ratios established at Ice Harbor 

 Dam. 



Returns of Adult Steelhead 

 Trout to Ice Harbor Dam 



The first adults returning from control re- 

 leases and those transported to John Day in 

 1969 appeared at Ice Harbor Dam in the fall 

 of 1970; in the following year, a second group 

 of older fish returned. We detected 143 steel- 

 head trout with coded wire tags and identified 

 them in the trap at Ice Harbor Dam in 1970 

 and 1971. Of these, 46 were from the control 



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