99 



Required reductions should also consider the adult equivalent 

 impact of the human- induced mortality caused by each action. As 

 a result, NMFS would compare, to the degree possible, the 

 anticipated reduction in mortality for each proposea action with 

 Che level of human- induced mortality caused by that action. 

 Where the level of mortality or the expected mortality reduction 

 is not known with certainty, NMFS will use the best available 

 information and its best scientific judgment to assess wnetner 

 proposed reduction is sufficient. 



Combined-Effects Analysis 



In the second step of the section 7 consultation analysis, NMFS 

 would evaluate the combined effects of all agency actions on the 

 listed sDecies. The goal is for the combined effects of ail 

 actions to allow the abundance of listed species to stabilize at 

 levels observed in recent vears within four life cycles. NMFS 

 would consider a DODuiation stabilized if the average numoer of 

 scawnina adults exoected during tne last five years or the tour 

 life cycle period (2004-2008) is equal to or greater than the 

 number' observed during the 1986-1990 base period. For Snake 

 River fall chinook salmon, the base population figure is 288 wild 

 adults Der year at Lower Granite Dam; for bnake River 

 spring/summer chinook salmon, it is 2,052 redds per year 'Schiewe 

 1992b) . 



The combined-effects analysis would be conducted using, in part, 

 the three available Snake/Columbia River salmon life cycle models 

 that were developed by the Joint State and Tribal Agencies, 

 Northwest Power Planning Council and Bonneville Power 

 Administration. These models project future aoundance of stocks 

 based on a depiction of existing conditions and consideration of 

 the effects of future improvements. The analysis assumes that 

 imorovements imDlemented in 1993, and others that are certain to 

 be" implemented In the near future, will be maintained through the 

 four life cycles. 



NMFS would use these models with caution as they are. new and 

 their scientific validity has not been proven. There are 

 discrepancies between models that are not resolved and 

 uncertainties with respect to input parameters and modeling 

 procedures. In addition, it will be difficult to quantify the 

 benefits of expected improvements in hatchery and habitat 

 activities and to incorporate the projected benefits into the 

 life cycle model analysis, except rather indirectly through 

 adjustments in model productivity functions. Efforts are 

 underway to address these uncertainties, but they will not be 

 fully resolved prior to the necessary consultations on 1993 

 actions. Nevertheless, NMFS believes that the models are 

 sufficiently developed to justify their use in the limited 

 context proposed here and that they represent the best available 



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