Foodscapes for Salmon and Other Mobile Consumers in River Networks

Abstract

Mobile consumers track fluctuating resources across heterogeneous landscapes to grow and survive. In river networks, the abundance and accessibility of food and the costs of foraging vary between habitats and through time, providing a shifting mosaic of growth opportunities for mobile consumers. However, a framework integrating the spatiotemporal dynamics of growth potential within riverscapes has been lacking. Here we present the concept of "foodscapes" to depict the dynamic changes in food abundance, food accessibility, and foraging costs that contribute to spatial and temporal variation of fish growth in rivers. Drawing on case studies of salmonid fishes from Alaska to California, we illustrate that "healthy" foodscapes provide a plethora of foraging opportunities--promoting diverse life history strategies that potentially enhance population stability. We identify knowledge gaps in understanding foodscapes, and approaches for management that focus on restoring trophic pathways which support diverse foraging and growth opportunities for fish in river networks.