PARENT SESSION
Symposium #11: Using Ecology to Build Sustainable Ecosystems: Approaches, Pitfalls and Successes.
Organized by: L Jackson, M Barber, and CM Pringle
Tuesday, August 6. 8:00 AM to 11:30 AM. Leo Rich Theatre.
Caught between the food web and the gill net: can ecologists facilitate sustainable fisheries management?
Harvey, Chris*,1, Cox, Sean2, Kitchell, James2, 1 Northwest Fisheries Science Center, Seattle, WA2 Center for Limnology, Madison, WI
ABSTRACT- Fisheries management traditionally follows single-species models, but increasing evidence indicates that multispecies interactions also influence dynamics of exploited stocks. Given this dichotomy, ecosystem-level management may be essential for sustainable fisheries. We have studied this issue in Lake Superior, where fish populations are recovering from overfishing and exotic species introductions. Fish community objectives (FCOs) emphasize rehabilitating native species and associated fisheries; maintaining desirable exotics; and controlling nuisance exotics. Our approach was to address ecological, relevant hypotheses embedded within the FCOs. We first examined food web structure through stable isotope analysis and bioenergetics modeling. These analyses revealed little trophic overlap among major piscivores, but raised questions regarding the availability of prey stocks relative to demands of predators and fisheries. We then synthesized information into ecosystem-level food web models. Our model suggested that some rehabilitation targets in the original FCOs were unattainable, because of indirect food web interactions, and further implied that sustainable fisheries would be compromised by dreissenid mussel invasions. Collaborations with fishermen and managers have enabled us to demonstrate that sea lamprey apparently prey on many hosts, including non-target fishes; and to refine our models to better identify sources of uncertainty in fish population dynamics. Another outcome has been the adaptability of the FCOs to reflect experience, research, and social interests. Thus, collaboration between interest groups and evolving research and management goals have promoted the opportunity to achieve sustainable fisheries management.
KEY WORDS: sustainable fisheries management, Lake Superior, models