Performance Standards Modeling for Alosines in the Northeast U.S

Passage failure and delay at dams can affect spatial and demographic structuring of spawning adults and downstream migrants. Species-specific recovery goals have been established for many alosine stocks following declines, often based on habitat. Objectives commonly involve increasing passage and reducing delay at regulated hydropower dams during upstream and downstream migration. However, a quantitative basis for dam passage performance standards that incorporates uncertainty in life-history parameters and migration characteristics is absent. We describe the development of a stochastic life history-based simulation model for alosines that can be used to estimate effects of dam passage and migratory delay on vital rates of migrants, spatial distribution of spawning adults, and demographic structuring. Using an individual-based approach to model migration dynamics, we relate fish passage performance and delay to metrics that can be used to evaluate impediments to recovery objectives. We use biological data from empirical studies of American Shad as a case study to examine model sensitivity with respect to uncertainty in those data. We characterize how sensitivity and uncertainty might affect decisions associated with stock recovery. As a result, the model provides a useful decision-making tool for informing quantitative-supported fish passage performance standards at hydroelectric dams in the Northeast U.S.