Experimental management for Snake River spring–summer chinook (Oncorhynchus tshawytscha): trade-offs between conservation and learning for a threatened species

Charles M. Paulsen and Richard A. Hinrichsen
Can. J. Fish. Aquat. Sci./J. Can. Sci. Halieut. Aquat. 59(4): 717-725 (2002)

Abstract: Using Snake River spring–summer chinook (Oncorhynchus tshawytscha) as an example, we explore trade-offs between conservation (restoring population abundance to self-sustaining levels) and learning (reliably estimating how management strategies affect productivity). The population has been studied extensively, especially since 1992, when the evolutionarily significant unit (ESU) was listed under the U.S. Endangered Species Act. Understanding both the conservation and learning dimensions is crucial in evaluating management actions. Using a Bayesian simulation model calibrated with 40+ years of spawner–recruit estimates, we performed population viability analyses to examine the biological risks of an array of management strategies. We also performed power analyses to estimate the precision of estimates of the actions' effects. The results suggest that if one can take actions that increase productivity and manage those actions as experiments, one can simultaneously increase fish numbers and reduce the uncertainty about the effects of those actions. However, because more powerful experiments will utilize controls where no action is taken, an experimental approach may increase risks to the ESU when compared to a strategy that tries to maximize productivity as soon as possible.