Drawdown reservoirs require special management strategies to maintain recreational fisheries. At Shasta Lake, California, cereal-grain grasses are planted to increase juvenile fish habitat, and localize productivity and food organisms. To determine the efficacy of these plantings, I analyzed juvenile bass abundance, periphyton (chlorophyll a) and macroinvertebrate prey levels in planted grass beds, artificial rope beds, and non-planted control sites.

When compared to controls; juvenile bass abundance averaged 53.5 times greater in the grass beds and 232 times greater in the artificial beds, grass beds did not increase periphyton or macroinvertebrate biomass, and artificial beds increased periphyton greater than 2 times and macroinvertebrate biomass greater than 12 times. These results indicate that long-term availability of physical structure, and not nutrient release associated with grass decomposition, drives the effectiveness of grass bed treatments. Future management decisions in drawdown reservoirs need to emphasize increasing the long-term availability and integrity of physical habitat improvements.