Using Life-Cycle Models to Identify Steelhead Recovery Goals and Actions in Puget Sound

In Puget Sound, steelhead were listed as threatened under the U.S. Endangered Species Act in 2007.  In order to establish recovery goals and evaluate potential recovery actions, we are developing a life cycle model for the three major population groups (MPGs) and 32 demographically independent populations (DIPs) within Puget Sound.  The goal of the project is to predict plausible abundance trajectories under a range of biological and management scenarios based on observed patterns of adult abundance, juvenile abundance, and life history diversity.  The model uses stage specific survival rates to simulate successive, linked generations of spawning and recruitment over long term time frames.  In its simplest form, the model will be composed of two stages, freshwater production (smolts per spawner) and marine survival.  Marine survival will vary across Puget Sound in accordance to recent work showing depressed marine survival for southern Puget Sound populations.  A series of scenarios will examine the impacts of changes in life-stage specific survival rates on DIP or MPG status across a range of management scenarios.  Overall, the model will use existing empirical population data to provide realistic bounds for population abundance, productivity, and diversity goals.