Cooperative Fish and Wildlife Research Units Program: Wyoming
Education, Research and Technical Assistance for Managing Our Natural Resources

A basic goal of ecosystem-based management (EBM) is to account for species interactions and the potential for harvest levels on target species to have indirect effects on others. An implicit assumption of most EBM strategies is that harvested species can be modeled as homogenous entities with interactions governed by their numerical abundance or biomass. However, recent research on species interactions suggests this assumption is flawed. Rather than occurring as homogeneous entities, many prey resources exhibit functional diversity in terms of where and when they are available to consumers. For example, genetically differentiated prey populations often exhibit differential timing in the life-cycle events that make them available to consumers. Consumers benefit from phenological diversity in prey resources because it spreads foraging opportunities across space and time, enabling individuals to track a shifting mosaic of food rather than get swamped by a single pulse. Recent studies suggest many wide-ranging consumers depend not only on phenological diversity in prey resources, but also on habitat connectivity, which enables them to track shifting prey phenologies across heterogeneous landscapes. The goal of this proposal is to explore whether these recent discoveries in ecology have substantial implications for how we manage ecosystems. As we experience rapid losses to population diversity and widespread habitat fragmentation, a key uncertainty is in understanding how much trophic diversity and habitat connectivity is necessary to support consumers at the top of the food chain. This question is especially important in coastal ecosystems of North America, where recent research shows that phenological diversity in commercially harvested salmon may provide benefits to wide-ranging consumers including grizzly bears, rainbow trout, and eagles. Habitat loss and homogenization, hatchery supplementation, and climate change have the potential to alter salmon phenologies and the mobility of consumers. I propose to address these issues by generating consumerresource models that consider trophic resources not as a homogenous entity, but instead as an aggregate of stocks analogous to a financial portfolio.