156 



approaches 133 '/b, as it has below Ice Harbor D;im, I would expect perhap;. as much as 

 9 % mortality' per day (5% mortalitj'.'day X 30 "o of fte fish X 24 /4 hrs day)^ 



Applying these data to Endangered Snake Ri\'er salmon, tiie calculated potential 

 increase in survival of 2.6 % per day from spill tt> achieve 80 % FPE, would be oif set by 

 a loss of 1 .3 °/o mortality per day at a gas level of 1 19 %, assuming no indirect mortality. 

 However, at a gas level of 133 %, the same 2.6 % benefit would be destroyed in about 7 

 hours . which is approximately the gas level and truvel time from Ice Harbor Dam to the 

 confluence with the Columbia River. 



The absence of floating dead smolts from gas bubble disease may trouble some, 

 but consider this: turbines may kill upward of 15 "b ol the smolts, yet in nearly 30 years, 

 I have never seen a single dead smolt in the Columbia River, nor do 1 know anyone who 

 has seen one, (On the other hand, tests have allo^vn that onlv about 2-7 % of tlie dead 

 adult salmon are found; I have seen some adult carcasses in the Columbia.) 



The risk to adult salmon is quite different tlinn exists for smolts, because adults are 

 unlikely to be preyed upon. The risk to adults is real and likely more important than 

 smolt mortality, but unfortunately, it is not well documented, At 120 % or less, adults are 

 unlikely to die directly from gas bubble disease, but if they did, each pair would cost tile 

 run about 5,000 eggs and invaluable genetic diversity. With adults, the main concern is 

 causing sublellial dysfunctions tiiat may interfere with migration, survival, and spawning. 

 For example, in the late 1960's it was common to see blind adult salmon, which most of us 

 ascribe to hemostasis from gas emboli in the ophthalmic rete, with subsequent 

 degeneration of the eye and it rots out of the eye socket. Several scientists including 

 ni>'self, speculate that so called "head bum" lesions in salmon at Snake River Dams are 

 the result of impaired xosion from sub lethal gas bubble disease. Dr. Ted Bjomn and 

 students believes that the timing of the spill and passage of chinook sabnon with head 

 scrapes over Lower Granite Dam arc circumsttuitial evidence that tlie head scrapes were 

 related to gas bubble disease. "Wliatever tlie case, in 1993 about 22% of the research- 

 tugged adult salmon that passed Lower Granite Dam had some degree of head bum. Of 

 those with head bum, approximately 38% are estimated to have died prior to spawning, 

 which is almost 70 % higher pre spawning mortality- than among non-head burned adults. 



4. Have there been investigations of the effect of supersaturated water on 

 resident ilsh? Have the restilts of these studies been incorporated into curi'ent 

 poUcy? 



Most of tiie investigations have been done in tiie laboratory, about 20 years ago. 

 coincidental to studies of salmon. No work lias been done on the effects of gas 

 supersaturation on rtie population dynamics of resident fish in tlie Colimibia River Basin. 

 This paucity of information reflects tlie low priority NMFS assigns to other fishery 

 resources, which tliey consider to be expendable trash. Conversely, many sportsmen 

 \alue the trophy walleye and smallmouth bass fishery in the Columbia and Snake Rivers, 

 as well as the sturgeon, catfishes. crappie. bluegills, and various other fishes. Equally 

 important to the resident fish and salmon are the aquatic invertebrates, especially those 



