Development of a Climate-to-Fish-to-Fishers Model: Implementation in the Eastern Pacific Sardine and Anchovy System

An ecosystem approach to understanding large-scale patterns in exploited systems caused by both climate change and human activity increasingly relies on the use of numerical models.  In the past, physical, lower and higher trophic level models were developed, tested, and implemented independently of each other. Recently, the advances in physics and biology have created the needed pieces for a comprehensive (end-to-end) ecosystem model, including humans as a dynamical component. The challenge is to integrate all the components, and examples of  fully-coupled end-to-end models are relatively rare. This is partly due to the perception that blending separate yet complex sub-models is impractical because of demanding computational requirements and partly due to the respective communities working independently. In this presentation, we present our progress to date on the development of an end-to-end model  modeling framework within the widely-used ROMS (Regional Ocean Modeling System) circulation model. The NEMURO Nutrient-Phytoplankton-Zooplankton (NPZ) submodel provides the lower trophic level dynamics, and a multi-species individual-based submodel simulates fish population and community dynamics, including  fishing fleets as one of the predator species.   All of these models exist in various forms, but the individual sub-models have never been harmonized together into one integrated analysis tool useful for synthesis, integration, and prediction. This model framework was designed to investigate the effects of climate and fishing on marine ecosystems within one model that includes dynamical feedbacks among the different systems.  We will present results of a test-bed application developed to study the low-frequency fluctuations of sardine and anchovy.