In order to understand the ebb and flow of the fish populations that are harvested by Oregon's commercial or recreational fisheries, it is important to have a reasonable idea of changes in those populations and how they are influenced by fishing. Since you can’t easily "see" a fish stock, stock assessment and bioeconomic models are used to help deduce the information needed to most effectively manage fisheries. David Sampson’s Commercial Fisheries Dynamics research works directly with the Oregon Department of Fish and Wildlife (ODFW) to provide stock assessments for economically valuable finfish species in Oregon. David’s most recent research has involved developing models for "fishing selectivity", which occurs when fishing operations catch relatively more of some age- and size-classes of fish (e.g., relatively more large fish rather than small fish). Models for selectivity are an important feature of stock assessments. When combined with other types of research, the information generated through David’s stock assessment and bioeconomic models is used to inform fishery management decisions, commercial fishing quotas, and to measure the relative health of specific fisheries of importance to Oregon’s commercial fishing industry.