The Influence of Behavior, Predation, and Water Project Operations on Fates of Central Valley Chinook Salmon Smolts: An Agent-Based Modeling Approach

The Central Valley Chinook Life Cycle Model (CVCLCM), under development by the National Marine Fisheries Service and collaborators, is a stage-structured model encompassing the complete life cycle of these ESA-listed salmonids, including the outmigration of smolts through the Sacramento-San Joaquin Delta. A variety of statistical approaches have been employed to identify and quantify the effects of environmental and management covariates on smolt survival during this critical transition. While these statistical studies have provided much insight into the influence of various factors on smolt survival, the nature and complexity of the Delta, particularly its complex channel network and tidally-driven, reversing flows that vary on hourly time scales, may limit our ability to extrapolate these relationships to novel conditions. A model that incorporates more mechanistic understandings of fish behavior and predation would complement these statistical models and enhance efforts to predict the consequences of anthropogenic and natural alterations of the Delta. With this goal in mind, in the present work we describe the development of an agent-based modeling and parameter inference framework for simulating the migration and survival of smolts, and present results that demonstrate the potential utility of this model as a research and management tool.