EBEL. PARK, and JOHNSEN: EFFECTS OF TRANSPORTATION 



and most fish probably died from factors other 

 than stress from hauling. 



One test, conducted with steelhead trout 

 on 27-28 May, gives insight into the effect of 

 transportation on smolts. Two groups of about 

 3,500 smolts each were released at the control 

 group release site. Group I was treated sim- 

 ilarly to that of our normal control group; 

 i.e.. the fish were hauled for about 1 hr before 

 being released in the impoundment upstream 

 from Ice Harbor Dam. Group II was treated 

 in a like manner but was hauled for 7 hr before 

 being released at the same site as group I. 

 (This was approximately 2 hr longer than 

 our typical hauls to date, but if transport 

 tests in the future are made from points up- 

 stream, it is conceivable that 7 hr would be a 

 minimum trip.) Upon examination of returns 

 at Ice Harbor Dam, significantly (X- = 4.300; 

 d.f. = 1) fewer fish returned from the long-haul 

 group. More tests are required to establish 

 an accurate posttransport mortality percentage. 



Tag loss does not affect our information 

 relating to effect of transportation on down- 

 stream survival. All data were adjusted for 

 marking, handling, and transport mortality. 

 Loss of tags is important when considering 

 the results from returning adult fish. Insofar 

 as affecting results of this study, apparent 

 "tag loss" can occur in three ways: 1) Faulty 

 machine operation — the smolt may never 

 have been tagged; 2) the tag may be rejected 

 at some time after being properly inserted in 

 the snout; and 3) the fish can be tagged but 

 the tag is not adequately magnetized. All have 

 the same result — the returning fish cannot 



be detected. In 1968 our best information on 

 initial tag loss was obtained from sampling 

 at The Dalles Dam and from releases below 

 Bonneville Dam. Although tag loss differed 

 between release groups, overall weighted aver- 

 age tag loss on chinook salmon was 9.2%. 

 Numbers of chinook salmon (transported and 

 control) mentioned in this report have been 

 adjusted on this basis. Tagging procedures 

 were refined in 1969-70 so that tag loss is 

 now less than 1% for both chinook salmon 

 and steelhead trout. 



Effect of Transportation on 



Downstream Survival of 



Juveniles 



The best information concerning the effect 

 of transportation on downstream survival of 

 juveniles was obtained from catches in the 

 gatewells of The Dalles Dam. The numbers of 

 transported and nontransported (control) chi- 

 nook salmon and steelhead trout that were 

 marked and released are shown in Table 1. 

 Recoveries at The Dalles Dam included only 

 those fish transported to John Day Dam and 

 the control releases above Ice Harbor Dam. 

 Survival of the transported groups released 

 at Bonneville Dam was estimated by recoveries 

 in the estuary. Marked chinook salmon ob- 

 tained from beach seine catches in the estuary 

 were too limited (40 in 1968; none in 1969 

 and 1970) to reveal significant information. 

 Table 2 compares recaptures of control and 

 transported fish in 1968 that were released 

 before and after heavy spilling began at The 



TABLE 1. — Number of transported and nontransported (control) juvenile 

 chinook salmon and steelhead trout that were marked and released, 1968-70 

 (figures adjusted for tag loss). 



553 



