256 



DRAFT 



"Because these marine mammal populations have been recently 

 increasing. . .it is reasonable to assume that their consumption of 

 salmonids has increased at a similar rate. ' 



It is not "reasonable", as stated in the report, to simply assume that the consumption of 

 salmonids by marine mammals has increased at a rate similar to estimated increases in 

 some of their population numbers. It is not scientifically valid to assume that there are 

 simple, direct linkages between rates of population growth and rates of selected prey 

 species consumption: predator-prey relationships are much more complex than this 

 simple assumption portrays. 



'...it follows, then, that marine mammal predation has contributed to 

 the receru decline in Oregon salmonid abundance. ' 



Contrary to this statement, it does not follow from the "data" presented in the report 

 that marine mammal predation has contributed to the recent decline in Oregon sjdmonid 

 abundance. This statement appears to be a conclusion of the authors that is not 

 substantiated by the scientific information presented in the report. 



'Seal and sea lion populations have been increasing in Oregon while 

 salmonid fishery resources have been declining. " 



This statement is incorrect. The report does not present scientific information to 

 suggest that a direct causal relationship exists between these two trends. While some 

 seal and sea lion populations have increased, others have not; and while some salmonid 

 populations have declined, others have not. It is impossible to prove that a direct 

 causal relationship exists given the evidence providwl in this report. The complexity of 

 salmonid declines has been linked to a variety of possible factors including freshwater 

 habitat degradation, harvest, water diversion, dam construction, and other human 

 activities. Given the multitude of possible factors, it is wrong to suggest that a direct 

 causal relationship exists between these declines and marine mammal abundance. 



'Presently, these marine mammals are consuming a higher proportion of 

 salmonids than they did in the recent past. ' 



This conclusion is not supported by the scientific information presented in the report. 



A-50 



