A Decision Analysis Framework for Comparing Experimental Designs of Projects to Enhance Pacific Salmon

Abstract

Fisheries management agencies are involved in many activities to enhance Pacific salmon Oncorhynchus spp. Monitoring the performance of pilot projects before deciding whether or not to apply a particular method of enhancement on a wide scale will result in better investment decisions. However, the costs of such monitoring can be substantial. We developed a quantitative framework based on decision analysis to determine whether the expected value of the information obtained through monitoring exceeds the costs of obtaining it. We applied this framework to a hypothetical problem in which managers have a fixed budget for constructing groundwater-fed side channels for chum salmon O. keta and must choose how much, if any, of that budget to allocate to monitoring. We used this example to identify the conditions under which monitoring can generate positive net economic returns and the characteristics of experimental designs for monitoring that yield the greatest net value. The choice between monitoring and not monitoring depended critically on the probabilities placed on the alternative effects of enhancement. In addition, economically optimal experimental designs for monitoring programs generally had low statistical power, partly as a result of the high cost of monitoring. Thus, in cases such as ours, improvements in management performance from adopting statistically powerful experimental designs may not outweigh the potentially high cost of measuring the effects of enhancement on Pacific salmon.