EBEL, PARK, and JOHNSEN: EFFECTS OF TRANSPORTATION 



described by Ebel (1970). All releases were 

 made at dusk. Records were kept of mortality 

 during marking and at time of release. 



This general procedure has been repeated 

 during three downstream migrations — from 

 1968 through 1970. Each year our goal was 

 to mark at least 50,000 fish per group but, 

 because of low collection efficiency at the gate- 

 wells in 1969-70, this goal was reached only 

 in 1968. In 1969 and 1970, steelhead trout 

 were also included in the experiment. 



Collection, Marking, and 

 Hauling Procedures 



In 1968-69 fish were obtained for the experi- 

 ment by dipnetting them from gatewells (Bent- 

 ley and Raymond, 1969). An orifice bypass 

 system (Park and Farr, 1972) was completed 

 in 1970 by the U.S. Army Corps of Engineers; 

 we used this system as a source of fish in the 

 spring of 1970. In 1969 and 1970, fish collected 

 in the above manner were hauled by tank 

 truck to a holding facility where they were 

 held for about 24 hr before marking in de- 

 nitrified water which had been pumped from 

 the Snake River. Minor gas bubble disease 

 subsided during the holding period, and pre- 

 sumably our holding procedure relieved some 

 of the stress from this disease caused by the 

 newly constructed dams upstream. In 1968, 

 the disease was not a problem, and the fish 

 were held and marked on the intake deck of 

 the dam. 



Fingerlings were brought into a marking 

 building where they were anesthetized, exam- 

 ined for marks, and sorted by species. Marked 

 fish were returned to the river; each of the 

 remaining unmarked fish was cold-branded 

 with liquid nitrogen (Mighell, 1969), the adipose 

 fin was excised, and a magnetized wire tag 

 was inserted in the snout (Jefferts, Bergman, 

 and Fiscus, 1963). Before being placed into 

 the transport truck, each fish went through 

 a magnetic field (to magnetize the tag) and a 

 detection coil; an improperly tagged fish was 

 automatically rejected and returned to the 

 marker for retagging. Steelhead trout and 

 Chinook salmon were kept in separate com- 

 partments in the truck whenever both species 



were hauled simultaneously. Load densities 

 were governed by the size of a day's catch 

 which never exceeded 10,000 fish. Thus loads 

 were less than 60 g of fish per liter (Vz lb. 

 per gal) of water, which allowed a large margin 

 of safety without loss offish. 



Water chemistry measurements were taken 

 at the time of release for every load trans- 

 ported in 1968; in 1969 and 1970 only occa- 

 sional water chemistry checks were made. 

 Concentrations of ammonia, nitrogen, dissolved 

 oxygen, carbon dioxide, pH, and total alkalinity 

 were recorded. 



Evaluation of Downstream 

 Survival of Juveniles 



Comparisons of the downstream survival of 

 juvenile chinook salmon and steelhead trout 

 released in the pool above Ice Harbor Dam 

 and at John Day Dam were based on the 

 proportions of these groups recovered from 

 the gatewells by dipnetting at The Dalles Dam. 

 Additional sampling with beach seines and 

 purse seines was attempted in the Columbia 

 River estuary. Samples from the estuary were 

 to be used to evaluate survival to the sea. 



Evaluation of Returning Adults 



The effect of transportation on the survival 

 and homing of adult fish was evaluated by 

 comparing recoveries of transported and non- 

 transported groups at various sites in the river 

 system. These included returns to the sport, 

 commercial, and Indian fisheries in the lower 

 Columbia River; to Ice Harbor Dam on the 

 lower Snake River; to Rapid River Hatchery 

 (Idaho); and to the spawning grounds. 



At Ice Harbor Dam about 80% of the run 

 of adult fish ascends the south ladder enroute 

 to the spawning grounds. We installed in this 

 ladder a tag detector and adult separator device 

 that intercepted tagged salmon and trout 

 (Durkin, Ebel, and Smith, 1969) and diverted 

 them into a holding pen (Figure 2). The tagged 

 fish from our study were readily identified 

 by the missing adipose fin. These were anesthe- 

 tized and further examined for brands. If the 

 brand was recognizable, the origin of the fish 



551 



