CONTENTS 



Page 



Introduction 1 



Methods 1 



Test facility 1 



Test fish and fish-holding procedures prior to experiment 2 



Test tanks and fish-holding procedures during experiment 2 



Procedures to determine water quality 3 



Relation between Columbia River water and water in test tanks 3 



Mortality and incidence of symptoms of gas-bubble disease 5 



Mortality and symptoms in relation to type of tank 5 



Mortality and symptoms in relation to species and size of fish 7 



Effect of water depth on fish survival 8 



Acknowledgement 8 



Literature cited 8 



Figures 



1. Location of study area and National Marine Fisheries Service facility on the Columbia River 



near Prescott, Oreg 2 



2. Schematic diagram of holding tanks and water supply system 2 



3. View of gas equilibration device used to reduce concentration of gas in river water to about 



100% of saturation 3 



4. Examples of external symptoms of gas-bubble disease as noted throughout the experiment. 4 



5. Nitrogen concentrations and accumulative mortality of fish in deep test tank (river water, 



tank 2.5 m deep) during test 6 



6. Nitrogen concentrations and accumulative mortality of fish in shallow test tank (river water, 



tank 1 m deep) during test 7 



7. Fitted regression lines for average body length of samples (20 fish each) of juvenile coho and 



chinook salmon during test 7 



8. Calculated regression lines of average body length of samples of live fish (20 fish each) as 



compared to average size of dead fish taken daily from shallow test tank during test. ... 8 



Tables 



1. Number of daily water samples analyzed from the river and each holding tank during the test 



period 5 



2. Concentration (percentage saturation) of dissolved nitrogen gas in the Columbia River and 



deep test tank, from samples taken every 4 h during a 24-h period, 14-15 June 1972. ... 5 



3. Maximum and average difference from river values of water quality data monitored in each 



holding tank 5 



4. Incidence (percentage) of symptoms of gas-bubble disease on samples (20 fish each) taken 



from the holding tanks on the dates indicated 6 



5. Number of dead fish and percentage with symptoms of gas-bubble disease in each holding 



tank 7 



Appendix Tables 



1. Daily mortality of fish and water quality in deep test tank (river water, tank 2.5 m deep) 



throughout test 10 



2. Daily mortality of fish and water quality in shallow test tank (river water, tank 1 m deep) 



throughout test 13 



3. Daily mortality of fish and water quality in control tank (nitrogen gas about 100% of satura- 



tion, tank 1 m deep) 16 



4. Water quality data monitored in Columbia River throughout test 19 



ui 



