182 



Objective 4. Explore the pot«ntial effects of reservoir drawdown 



on predation through modeling studies. Identify 



critical processes and assumptions. 

 T*«l: 4.1 Review literature and identify appropriate 



modeling techniques. 

 Task 4.2 Screen or develop software necessary for 



predation aodeling studies. 

 Task 4.3 Conduct simulations to identify critical 



processes that »ay influence predation through 



drawdown-produced mechanisms. 



Rationale: Manipulation of complex ecosysteva^ soch 

 as drawdown of John Day Reservoir, often produces 

 unpredictable results. Models of the basic 

 processes in ecosystems (predation, prey movement, 

 habitat change, etc.) can often be constructed and 

 used to identify critical processes and data needs 

 (Adams and DeAngelis 1987) . Drawdown of John Day 

 Reservoir will b« a major manipulation that could 

 redistribute prey, reduce the foraging habitat of 

 ■ • northern sguawfish, and increase smolt migration 

 rate, GIS models could be used- to demonstrate how 

 shallow-water habitat might change at different 

 levels of drawdown, and individual-based models 

 could be used to simulate smolt migration responses 



11 



