Developing models, indicators, and visualizations for ecosystem assessments in Alaska

The ecology and modeling of marine food webs has been an area of active research in Alaska, particularly with respect to the fisheries management. Food web analyses have played a role in managing walleye pollock fisheries, in estimating overall yields that may be sustainably extracted from ecosystems, and more recently in modeling and predicting future ecosystem responses to climate. Here, I review current progress in advancing the science behind the ecosystem assessments used in Alaska. Our ultimate goal is to develop appropriate multispecies and ecosystem criteria for fishery management analogous to those used in single-species stock assessments. Work to date has three themes: fitting dynamic ecosystem models to time series of biomass, diet, and recruitment data; formally incorporating uncertainty in analyses and outputs; and presenting results for aggregated trophic guilds (e.g., apex predators, pelagic foragers) as well as for key individual species. The current ecosystem assessment uses diverse data streams to reconstruct historical production and mortality at multiple levels of organization, and can also incorporate single species assessment results. Tracking the surplus production of trophic guilds over time may lead to a particularly promising new multispecies indicator for management. I present this and other indices and visualizations in development.