Analysis of Multiple Objectives in Oregon Coho Salmon Policy

Abstract

Our objective was to determine whether formal decision analysis could assist fishery managers in Oregon to evaluate alternative strategies with respect to allocation and production of wild and hatchery coho salmon. The method chosen given multiple objectives and uncertainty is multiattribute utility analysis. The analytical model consists of two main components: (1) a computer model that simulates the life cycle of hatchery and stream spawning coho salmon given environmental variation, different hatchery juvenile release levels, and harvest rates and (2) an objective function that evaluates the aggregate levels of catch and escapement resulting from alternative release levels and harvest rates. The approach was used to rank the expected outcomes from 12 proposed policies. We concluded that (1) the most effective policy is achieved with a relatively low harvest rate and high smolt release level, (2) selection of a particular harvest rate is the most important decision variable, and (3) a large smolt release level can be maintained unless such releases adversely decrease the ocean survival of stream spawning coho. If the agency is to be significantly helped, the analysis must be expanded to involve a larger number of decision makers, incorporate additional objectives such as catch variability, and include a finer level of detail in the simulation model.