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DRAFT 



report proceeds with the premise that such predation is no longer considered natural, 

 but instead is a "human-influenced biological interaction" that has contributed 

 significantly to declines and/or lack of recovery of Oregon wild salmonids. These 

 conclusions are not supported by the information or analyses presented in the report. 



Freshwater System Alterations (pag es 102-103): 



The following statements are questionable: 



"Die large numbers of hatchery juveniles may buffer predation on wild 

 fish. ' 



The large numbers of hatchery juveniles may, conversely, stimulate predation via 

 functional response (Vigg 1988). 



"Predator populations may be increasing simply because there is an ever 

 increasing supply of prey. " 



Predator numbers are probably not regulated or affected by salmonids because these 

 fish are a small fraction of the diet ration (Poe et al. 1991). 



Fish predation (pages 103-105): 



"TTiese predator populations would otherwise decline if forced to rely 

 primarily on ever diminishing populations of wild native juvenile 

 salmonids. " 



Predators don't rely on wild native juvenile salmonids, instead use resident feeds 

 (invertebrates, sculpins, suckers, etc.) (Poe et al. 1991). 



"These results are similar to the findings of Uremovich et al. , (1980), 

 who estimated that northern squawfish may have eaten 3. 8 million 



juvenile salmonids in theforebay of Bonneville Dam in a five-month 



period in 1980 (Table 1. 7-1). " 



Estimates by Uremovich et al. (1980) are greatly inflated because of sampling design 

 problems. 



"Although no estimates of predation were given, Thompson and Tufts 

 (1967) reported that northern squawfish predation was significant on 

 juvenile sockeye salmon in Lake Wenatchee, Washington. " 



Incomplete... see Brown and Moyle (1981). 



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