Survival of hatchery-produced fall chinook salmon from 

 time of release of young from the hatchery to their return 

 as adults may be as low as four out of each thousand. A 

 systematic sampling of downstream migrants was begun in 

 1968 in the Columbia River estuary. The research was begun 

 to learn whether changes in hatchery production techniques 

 such as diet improvement, control of certain environmental 

 factors, size and time of release, and training to avoid preda- 

 tors could increase the production and survival of hatchery 

 fish. 



In the estuary studies, beach seines were set on each 

 shore and a purse seine was set at midchannel in the nar- 

 rows above Puget Island (fig. 33) . Fish from eight Federal 

 and State hatcheries were marked before release; some 

 releases were made several hundred miles upriver. Data 

 indicated a 50-percent loss of fish migrating past Bonneville 

 Dam, a 95-percent (total) loss past four other dams, and 

 a 50-percent loss past an area of suspected pollution. An 

 interesting discovery was that survival of yearling chinook 

 salmon reared in ponds at the Rapid River Hatchery (Snake 



Purse Seine Beach 

 Seine 

 RM 47 



Walloce Island 



FIGURE 3.3.— Sampling site for capture of juvenile salmon and 

 steelhead trout in the Columbia River estuary. 



River system) was nearly twice that of those reared in race- 

 ways. Higher survival was attributed to larger size, better 

 condition, and faster migration of pond-reared fish. 



As a result of our 1968 work, the Fish Commission of 

 Oregon has decided that all fall chinook salmon reared at 

 two hatcheries above Bonneville Dam should be released 

 below the dam. The Washington Department of Fisheries 

 will transport all fish from Ringold Hatchery (near Pasco. 

 Wash.) past three dams to Spring Creek Hatchery, some 

 175 miles downstream, and will intensify the study of sus- 

 pected pollution. State and Federal agencies will have 

 joint marking experiments in the spring and summer of 

 1969 to evaluate results of these measures. 



Temperature Laboratory 



In the fall of 1967, a covered barge (110 by 32 ft.) was 

 moved to the lower Columbia River at Prescott, Oreg., to 

 house research facilities for water temperature studies 

 (fig. 34). The site was selected because thermal nuclear 

 power plants are planned nearby on both sides of the river. 

 By examining the physical, chemical, and biological features 

 of the river before the plants are installed, biologists will 

 have data to determine environmental changes that may 

 occur after the plants are operating. In addition, native 

 fish taken directly from the river can be held and tested 

 in river water. 



Juvenile salmon are known to have a temperature tol- 

 erance zone between 38° and 68° F., depending on age, con- 

 dition, acclimation temperature, and other factors. Lethal 

 zones at upper temperature levels are 56 to 77° F. Less 

 thermal increase is required during summer than winter 

 to reach lethal values. 



In initial experiments, biologists investigated rapid death 

 (within seconds) from thermal shock and slow death from 

 exposure to heat beyond zones of tolerance. Juvenile chinook, 

 chum, coho, and sockeye salmon died in 4 to 11 seconds at 

 90° F. Rapid death differed with species, size and condition 



26 



