Oregon, and California) concerning the effect 

 of transportation of hatchery stocks of juvenile 

 Chinook salmon, coho salmon, O. kisutch, and 

 steelhead trout on homing indicates that the 

 homing mechanism is disrupted by the trans- 

 portation process. In these experiments, the 

 majority of the adults returned to the location 

 of release and not to the hatchery of origin. 

 We recognized this in pursuing our experi- 

 ments but felt confident that different results 

 would be obtained because we were dealing 

 with juvenile fish, captured during their sea- 

 ward migration, that had an entirely different 

 life experience before being collected and trans- 

 ported. The wild stocks among our captured 

 fish had lived for a year or more in their 

 parent stream, were actively smolting at the 

 time of capture, and had traversed several 

 hundred kilometers of stream before they were 

 transported. Captured hatchery stocks also 

 were actively smolting at the time of capture 

 and had traversed many kilometers before 

 being collected. Transport experiments done 

 by others have been conducted with hatchery 

 stocks taken directly with no stream experience 

 from hatchery ponds. Previous experiments 

 (Groves, Collins, and Trefethen, 1968; Hasler 

 and Wisby, 1951; and others) on mechanisms 

 used by fish for homing suggest that the 

 experience during the time that the juvenile 

 salmon migrates seaward is important in 

 enabling the fish to receive olfactory and visual 

 cues necessary for homing as an adult. Since 

 we were eliminating only a portion of the 

 fish's migration route by transporting, we 

 hypothesized that a fish would be successful 

 in seeking its home stream and that survival 

 to the spawning grounds as well as to the 

 fishery would be increased. 



The adult returns from releases of juvenile 

 Chinook salmon in 1968 and 1969 and of 

 juvenile steelhead trout in 1969 and 1970 

 were obtained in 1970 and 1971. This report 

 describes the results of the experiment based 

 on information compiled to date. Adult returns 

 from Chinook salmon releases in 1969 and 

 steelhead trout releases in 1970 were insuffi- 

 cient because 2- and 3-ocean returns are needed 

 from data that will be obtained in 1971 and 

 1972 and, therefore, are not included in this 



FISHERY BULLETIN: VOL. 71. NO. 2 



report. A supplementary report will be made 

 as additional information is received in future 

 years. 



METHODS 



General Experimental Design 



Three groups (one control and two trans- 

 ported) of migrating chinook salmon (spring- 

 and summer-run populations) and steelhead 

 trout were collected from gatewells at Ice 

 Harbor Dam. Gatewell dip net hauls were 

 mixed, then the test and control groups were 

 selected randomly from the pooled dip net 

 hauls. These were marked by removal of the 

 adipose fin and with a thermal brand and a 

 magnetized wire tag. The control, or non- 

 transported, group was released about 15 km 

 above Ice Harbor Dam. The transported groups 

 were released 5 km downstream from John 

 Day Dam on the Oregon side of the Columbia 

 River and 1 km downstream from Bonneville 

 on the Washington side of the river (Figure 1). 

 A separate brand was assigned to each group 

 and was changed weekly. A distinguishing 

 color-coded wire tag was also assigned to the 

 control and to the experimental groups. In 

 1968 one color-code was used on both trans- 

 ported groups. In 1969 and 1970 separate 

 codes were assigned to each transported group. 



All groups were hauled in a tank truck of 

 18,900-liter (5,000-gal) capacity that has been 



FIGURE 1. — Columbia and Snake Rivers, showing 

 release and recovery sites of migrating chinook salmon 

 and steelhead trout. 



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