Integrating human and ecological dimensions of recreational fisheries

Recreational fisheries are complex adaptive systems (CAS) that possess emergent properties and the potential to surprise us. In this dissertation, I investigate the social and ecological components of recreational fisheries, plus their interactions, to understand how these components might affect the sustainability of fishery systems as a whole. I start by exploring the motivations and preferences of participants in an unusual fishery, the Mongolian trophy fly-fishery for taimen (Hucho taimen), the largest salmonid in the world (Chapter 1). These anglers pay thousands of dollars and travel thousands of miles to catch-and-release a fish known for exceptionally low catch rates, making them an extreme example of the non-economic motives of recreational anglers. I find that taimen anglers are motivated almost as much by travel-related factors as by the expectation of catching fish and are mostly “bucket list” anglers who rarely return to the same destination twice. This means that fishing pressure for taimen depends far more how anglers choose among an international landscape of similarly remote trophy fisheries than they do on the population status of taimen themselves. In Chapter 2, I build on this knowledge about the social dimensions about recreational fisheries in Mongolia to ask how climate change might alter the way salmonids interact with fishing gear in this system. I find that hydrological changes caused by thunderstorms, which are increasing in Mongolia because of climate change, reduce the catchability of the Mongolian salmonids lenok (Brachymystax lenok) and Arctic grayling (Thymallus arcticus arcticus). These impacts depend on species feeding ecology and gear type in ways that suggest that international fly fishermen may maintain higher catch rates under climate change conditions than the Mongolian hobbyists who primarily fish with spinning gear, creating “winners” and “losers” under climate change. In Chapter 3, I ask whether factors that are theoretically thought to erode recreational fisheries’ stability actually do so when present at the levels that are observed in real-world systems. I synthesize data on four well-studied mechanisms: 1) depensatory population dynamics, 2) environmentally-driven variability in recruitment, 3) density-dependent catchability, and 4) anglers’ responsiveness to changing catch rates. Incorporating these mechanisms at empirically-relevant levels into mathematical simulations of a generic recreational fishery reveals that interactions involving the two social mechanisms (#3-4) have the greatest implications for system stability. In particular, anglers’ degree of responsiveness to catch determines whether other factors have the potential to collapse the recreational fishery CAS. Together, these chapters highlight the complexity of recreational fisheries and the importance of interdisciplinary research in understanding and managing this complexity.Ph.D.Includes bibliographical reference