Peterson Et Al – a Rational Route to Collapse Uncertainty and the Management of Multi-state Ecosystems: an Apparently Rational Route to Collapse Running Head: Rational Route to Collapse

We use a simple model of ecosystem management to demonstrate that apparently rational management approaches can lead to ecological collapse. Our model of the ecosystem management of lake eutrophication integrates lake dynamics, management decision-making, and learning in a framework that is deliberately simplified to highlight the role of model uncertainty. The simulated lake can switch between alternate eutrophic and oligotrophic states. Managers consider two management models of the lake, one for an oligotrophic lake and the other for a eutrophic lake. As managers observe the lake varying from year to year, they estimate how well each of the two management models is supported by the observed data. Management policies maximize the expected net present value of the lake. Even under optimistic assumptions about environmental variation, learning ability, and management control, conventional decision theory and optimal control approaches fail to stabilize ecological dynamics. Rather, these methods drive ecosystems into cycles of collapse and recovery. We suggest how scientists could help prevent ecosystem management from driving ecosystems towards collapse. Ecosystem management has a long and diverse history. It has sometimes been successful (Berkes and Folke 1998), and sometimes not. For example, historical societies, such as the Maya (Hodell et al. 2001), and modern scientifically managed resource extraction systems, such as the Northern cod (Walters and Maguire 1996), have appeared to succeed at ecosystem management until an abrupt and surprising collapse. Researchers have tried to explain these collapses. Some researchers attribute ecological collapse to ignorance of gradual ecological change (Martin 1973, Alroy 2001), rational overexploitation (Clark 1973), or the difficulties of creating effective institutions to manage common pool resources (Hardin 1968). Others focus on