Project Title

Biotic and abiotic features of salmon habitat: Implications for juvenile Chinook and steelhead growth and survival in the Salmon River Basin, Idaho

Description

The main and interactive effects of biotic (e.g., prey abundance) and abiotic factors (e.g., habitat complexity) regulate natural communities. For the most part, studies investigating factors that regulate fish communities emphasize abiotic factors, such as wood abundance or temperature. However, fish growth is also dependent on foraging opportunities, with more productive ecosystems generally providing more food. Understanding the importance of both biotic and abiotic factors in regulating fish populations is critical for the conservation of threatened species. For example, what are the relationships among primary and secondary productivity, physical habitat structure and fish growth and survival?

Salmon carcasses once provided large subsidies of nutrients and organic matter to Pacific Northwest watersheds, which were available to the next generation of salmon and a host of other plants and animals. Now these subsidies have been reduced to 90% of their historical levels, and this reduction has likely contributed to declines in anadromous and resident fish. In collaboration with the Shoshone-Bannock Tribe, Washington Department of Fish and Wildlife and Weyerhaeuser Company, this project examines the importance of marine derived nutrients (i.e., salmon carcasses) on stream productivity and growth and survival of wild juvenile Chinook and steelhead salmon in the Salmon River basin of Idaho. We have been monitoring stream food webs as well as a suite of physical and chemical conditions in roughly 20 streams since 2002. Our study is unique because we are examining reach-scale functional relationships between abiotic and biotic factors in sites where fish survival has been and continues to be measured (Steve Achord, Fish Ecology Division). By measuring nutrient concentrations, biomass, isotopic signatures and production of algae and macroinvertebrates (i.e., fish food), and density, growth and survival of juvenile salmon among streams, we can estimate whether streams with more productive food webs provide better conditions for juvenile salmon and steelhead. The large-scale nature of this project and the multiple years of data (2002 � 2006), will allow us to evaluate thoroughly how the biotic and abiotic conditions of salmonid habitats affect juvenile fish growth and survival. These data and relationships will demonstrate how stream food web monitoring can provide valuable insights into conditions for Chinook and steelhead, and will be useful to managers as they decide how best to allocate resources for restoration and recovery.

Investigators

Beth Sanderson, Kate Macneale, and Peter Kiffney

Collaborators

Chau Tran (Frank Orth), Holly Coe (Frank Orth), Bill Reichert, Steve Achord, Rich Zabel, Mark Scheuerell, numerous interns, Shoshone-Bannock tribe, Washington Department of Fish and Wildlife, Weyerhaeuser Company

Support

Bonneville Power Administration, NOAA Fisheries

Project Status

Monitoring data collected 2001-2005; Analysis and writing in progress

Researchers monitoring effects of marine-derived nutrients in the Salmon River Basin, Idaho.