108 



significance of these symptoms for the overall well being of resident fish populations 

 is not known. 



In contrast to the monitoring at the dams, pen holding studies of juvenile salmon 

 conducted by NMFS below Ice harbor dam have produced quite a few dead juvenile 

 salmon, especially during uncontrolled spill events earlier this vear. The net pen 

 studies are conducted for the purposes of reproducing effects of laboratory studies, 

 and they are not indicative of survival of fi-ee swimming juveniles in the reservoirs. 

 The net pens unnaturally restrict the movements of the juveniles, and small 

 changes in depth can protect the juveniles fi-om the effects of even severe 

 supersaturation. Hence the pen holding studies are implemented for the purposes 

 of describing pathology, and not for determining the svirvival benefits of spill. 



3. Are there risks to migrating smolts and returning adults associated with high 

 levels of dissolved nitrogen resulting from spill? 



Nitrogen supersaturation poses risk to migrating salmon and to resident species, 

 since prolonged exposure to nitrogen saturation levels above approximately 115 per- 

 cent at the surface has been demonstrated in the laboratory and in net pens held 

 in natural waters to be lethal to fish. The risks mav be negligible or serious, de- 

 pending on the degree to which the distribution of the fish coincides with the dis- 

 tribution of the supersatvirated waters. 



To put nitrogen supersaturation risk into perspective, I do not regard the risks 

 of mortality for salmon which are actively migrating through nitrogen 

 supersaturated waters to be as serious as the risks posed by migrating through tur- 

 bines or bjrpasses for a number of reasons. Number one, supersaturation drops off 

 sharply witn depth. For example, the potentially lethal total dissolved gas level of 

 140 percent at tne surface is reduced to the still potentially lethal, but lower, level 

 of about 126 percent just 39 inches below the surface, and it is reduced to a safe 

 level of about 113 percent less than eight feet below the surface. Number two, mi- 

 grating adult Chinook are known to travel closer to the bottom than to the surface 

 of the reservoirs when they have the opportunity. Number three, although juveniles 

 have been observed at all depths in the water column, the m^'ority of juvenile salm- 

 on are likely to travel at an average depth of about ten feet according to one study. 

 Number four, if gas bubble trauma is affecting large numbers of juveniles, I would 

 expect to see much higher rates of symptomatic juveniles than the negligible rates 

 observed in 1995. Number five, although the depths occupied by resident fish de- 

 pend on factors such as feeding and reproductive behavior, monitoring studies have 

 found few resident fish with gas bubble trauma symptoms. Number six, the effects 

 of nitrogen supersaturation on juvenile salmon appear to be reversible, since juve- 

 nile salmon are fi-equently reported to recover from the effects of exposure to nitro- 

 gen siipersaturated water when they are free to move. 



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

 fish? Have the results of these studies been incorporated into current policy? 



Yes, there have been studies which examine resident fish for sjmiptoms of gas 

 bubble trauma conducted by the Idaho Department of Fish and Game. Yes, the im- 

 pacts of spill on resident species are incorporated into current spill policy. I under- 

 stand the IDFG studies were conducted in order to advise Federal spiU managers 

 of the potential risks to resident fish species. Since these studies have revealed no 

 apparent effects of nitrogen supersaturation on resident fish, there was no need to 

 alter current spill management actions. 



5. To what extent has scientific research from the states been incorporated into the 

 current spill policy? How can the present decision making process be improved? 



Analyses of available data conducted by scientists employed by the stetes of 

 Idaho, Oregon and Washington, and the treaty fishing tribes were instrumental in 

 establishing the current spill policy. These analyses called into question the effec- 

 tiveness of juvenile salmon transportation, and at the same time indicated that spill 

 could provide survival benefits under certain circumstances. Hence, the scientific 

 work of the states and tribes was central to establishing the scientific basis of the 

 NMFS spill policy. 



The decision making process functions on at least two levels, the management 

 process of executing operational procedures at the dams to implement the spill pol- 

 icy, and the research process of esteblishing the scientific basis of these manage- 

 ment actions. I do not wish to comment on uie management decision process, since 

 I have never been a part of it. The management process now involves only rep- 

 resentetives of Federal agencies with statutory authorities and responsibilities for 

 implementation of the Endangered Species Act and operation of the Federal power 

 system. 



I do, however believe it is important for me to comment on how the decision mak- 

 ing process may be improved by improving its scientific basis. The lack of estimates 

 of the survivals of juvenile sedmonids through the Federal hydroelectric power sys- 



