Salmonid Life Cycle Models for Dynamic Hatchery and Harvest Management

The All-H Analyzer (AHA) model, which was developed as part of the Columbia Basin Hatchery Scientific Review Group (HSRG) review, predicts population outcomes in terms of natural production and harvest for management policies implemented over a long period of time.  We developed a new salmonid life cycle model (LCM) with several novel features:

1. The model predicts annual outcomes for natural and hatchery populations in terms of abundance and fitness. It predicts annual catch and escapement, and results are sensitive to the initial population status.
2. It allows for implementation of dynamic harvest and hatchery policies based on annual abundance.
3. It presents annual outcomes as a range, rather than as a point estimate, placing more emphasis on uncertainty and variability.  It accounts for variability in freshwater and marine survival and management imprecision.
4. It incorporates multiple populations and accounts for population interactions.

When hatchery reforms are first implemented, fitness benefits may not be immediately observable. In fact, abundance may decrease initially before fitness improvements increase survival and abundance. The new LCM paints a more realistic picture of what may happen under different management scenarios.  We use models developed for the Willapa Bay Chinook populations as a case study.