Confronting Uncertainty in Wildlife Management: Performance of Grizzly Bear Management

Scientific management of wildlife requires confronting the complexities of natural and social systems. Uncertainty poses a central problem. Whereas the importance of considering uncertainty has been widely discussed, studies of the effects of unaddressed uncertainty on real management systems have been rare. We examined the effects of outcome uncertainty and components of biological uncertainty on hunt management performance, illustrated with grizzly bears (Ursus arctos horribilis) in British Columbia, Canada. We found that both forms of uncertainty can have serious impacts on management performance. Outcome uncertainty alone – discrepancy between expected and realized mortality levels – led to excess mortality in 19% of cases (population-years) examined. Accounting for uncertainty around estimated biological parameters (i.e., biological uncertainty) revealed that excess mortality might have occurred in up to 70% of cases. We offer a general method for identifying targets for exploited species that incorporates uncertainty and maintains the probability of exceeding mortality limits below specified thresholds. Setting targets in our focal system using this method at thresholds of 25% and 5% probability of overmortality would require average target mortality reductions of 47% and 81%, respectively. Application of our transparent and generalizable framework to this or other systems could improve management performance in the presence of uncertainty. &nbsp

A fibre optic microsensor for measurement of temperature dynamics in gas turbine systems

The use of computational fluid dynamics (CFD) to model the temperature and pressure distributions which drive complex thermodynamic processes in gas turbine systems contributes to more cost efficient turbine design and development. However, experimental measurements are still required for validation of full-field CFD models, particularly in regions of highly unsteady flow where model stability is most severely tested. THis work concerns the development of fiber optic temperature and pressure microsensors for measurements combining high spatial resolution and high bandwidth in unsteady gas flows. The objective of the work presented in this paper was to measure gas total temperature in a large- scale turbomachinery test-rig at DERA Pyestock, known as the Isentropic Light Piston Facility. We have accordingly designed a dual sensor system, in which one of the elements is heated, so that gas total temperature can be measured independently of the convective heat transfer coefficient. While such dual element probes based on thin-film resistance gauges have been developed previously for aerodynamic studies, this is the first report of their development using optical sensors. ©2003 Copyright SPIE - The International Society for Optical Engineering