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Columbia Basin Outmigrant Survival Simulator

screencapture: outmigrant survival simulator

Screen capture of the outmigrant survival simulator, applied to a reach of the Snake River. Swarm provides a process control panel (top left) and a probe display (not shown in this picture). The probe display allows the user to see and change all simulation parameters before and during execution. The animation window shows the predators, and the migrants as they disperse downstream. The dots in regular rows are nodes imported from a finite-difference hydrodynamic model; the river velocity is known in two dimensions at each node. The graphs update continuously. The line graph shows how many migrants are currently moving, have arrived at the downstream end, and have been eaten by predators. The histogram shows how predators are distributed by river depth.

This application is being built in collaboration with Dr. Jim Anderson, Columbia Basin Research, School of Fisheries, University of Washington. Its objective is to provide simulations that estimate how the survival probability of downstream migrating salmon and steelhead varies with river flow, predator densities, and predator behavior. These estimates are being used as parameters for other models that can be used to predict outmigrant survival under alternative reservoir management methods. [See: Zabel, R.W., J.J. Anderson & P.A. Shaw. 1998. A multiple-reach model describing the migratory behavior of Snake River yearling chinook salmon (Oncorhynchus tschawytscha). Canadian Journal of Fisheries and Aquatic Sciences 55: 658-667.]

We developed a complete formulation report and working computer code for this model, which has been improved and is now in use at Columbia Basin Research. The model has the following characteristics.