An individual-based model of nesting smallmouth bass, Micropterus dolomieu, is used to predict the effects of water level fluctuations on reproductive success. The model simulates daily nest site selection, spawning, nest guarding, and development and survival of eggs, embryos, and larvae until dispersal. The model was configured for Brownlee Reservoir, Idaho-Oregon. Each reservoir bank is represented as a rectangular grid of cells, with each cell characterized by an assigned slope, substrate, and elevation, and by a water depth that varied daily. Nest site (cell) selection is determined from a habitat suitability index (HSI) based on substrate, slope, and depth. Development of young is temperature-dependent. Mortality of young occurs via attrition, abandonment by the guarding male, and probabilistic whole-nest catastrophe. Simulations were performed that used observed data for 1991 to 1996. Model predicted nest habitat selection and egg-to-dispersal survival rates were similar to observed values. Additional model simulations showed that: (1) nest habitat selection was best predicted when depth, slope, and substrate were considered together rather than singly, (2) egg-to-dispersal survival was related to the magnitude of water level fluctuations during the peak spawning period, (3) relating mortality to HSI values resulted in lower survival, while relating growth to HSI values resulted in higher survival, and (4) spawning habitat is not limiting in Brownlee Reservoir. Suggestions for future monitoring of reservoir-based smallmouth bass populations are discussed.
Bibliographical noteFunding Information:
M. Bevelhimer, H. Jager, M. Mangel, and an anonymous reviewer provided helpful comments on an earlier version of this paper. Research was sponsored by the Electric Power Research Institute under contract WO9117-01 (DOE number ERD-95-1332) and with the United States Department of Energy, under contract DE-AC05-96OR22464 with Lockheed Martin Energy Research Corporation. This is publication 4695 of the Environmental Sciences Division, Oak Ridge National Laboratory.
- Brownlee Reservoir
- Micropterus dolomieu
- Predictive model