1. Lakes & Large Impoundments Chapter 22

2. Lakes & Large Impoundments
Larger size means greater complexity

3. Differences between Lakes and Reservoirs
Impoundments have greater shoreline development

4. Differences between Lakes and Reservoirs
Impoundments have limited littoral zones
Steeper sloping basins

5. Differences between Lakes and Reservoirs
Impoundments have higher water flow-through
Turbidity and sediment input affects invertebrate production, fish spawning areas

6. Differences between Lakes and Reservoirs
Impoundments have wide internal variation in physicochemical factors

7. Differences between Lakes and Reservoirs
Impoundments have young age
Limited fish assemblage (stocking?)

8. Controls of Fish Production
Trophic state model - “from the bottom up”
Production, biomass of higher trophic levels controlled by nutrients, primary production

9. Controls of Fish Production
Food web models - “from the top down”
Consumer controlled - fish predation determines structure, abundance of prey
Both likely operate simultaneously

10. Increase Fish Yield By:
Increasing food resource base (fertility)
Increasing transfer efficiency between trophic levels

11. Problem of Variable Recruitment
Biological variation
Climatic variation
Water level fluctuations
Impoundment age

12. Reservoir Age

13. Assessing Fish Populations
Direct approach - growth rate, recruitment, size structure
Relative weight, proportional stock density

14. Assessing Fish Populations
Indirect approach - examination of fishery-impacted components
Primary, secondary productivity, zooplankton size structure

15. Management Problems