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Individual Based Modelling of Cold Water Refuge Use in the Columbia River.
Citation:
Snyder, M., N. Schumaker, Joe Ebersole, R. Comeleo, J. Dunham, M. Keefer, A. Brookes, S. Heppell, D. Keenan, AND J. Palmer. Individual Based Modelling of Cold Water Refuge Use in the Columbia River. Cold water refuge workshop, Portland, OR, November 08, 2017.
Impact/Purpose:
Many rivers and streams in the Pacific Northwest are currently listed as impaired under the Clean Water Act as a result of high summer water temperatures. Much effort is being expended to improve conditions for salmon and steelhead, with increasing emphasis on preparing for future climate change. One climate change adaptation strategy that is gaining increased attention is the potential for thermal refuges to help mitigate the effects of increasing temperatures. Research at WED is looking at ways to model these cold water patches, or refugia, and looking at the costs and benefits of spatially distributed refugia. Marcia Snyder will be presenting “Individual Based Modelling Approach to Thermal Refuge Use by Migrating Adult Salmon and Steelhead.”. This work contributes to ACE-CIVA 2.8: Climate Refugia for Salmon and Other Cold-water Aquatic Taxa.
Description:
Anadromous fish populations in the Pacific Northwest face challenges along their migratory routes from declining habitat quality, harvest, and barriers to longitudinal connectivity. Changes in river temperature regimes are producing an additional challenge for upstream migrating adult salmon and steelhead, species that are sensitive to absolute and cumulative thermal exposure. Adult salmon populations have been shown to utilize cold water patches along migration routes when mainstem river temperatures exceed thermal optimums. We are employing an individual based model (IBM) to explore the advantages and disadvantages of spatially-distributed cold water refugia for adult migrating salmon and steelhead in the Columbia River. Our model, developed in the HexSim platform, is built around a mechanistic behavioral decision tree that drives individual interactions with their spatially explicit simulated environment. Population-scale responses to dynamic thermal regimes, coupled with other stressors such as disease and harvest, become emergent properties of the spatial IBM. Other model outputs include arrival times, species-specific survival rates, body energetic content, and reproductive fitness levels. Here, we discuss model development and the challenges associated with parameterizing an individual based model of salmon and steelhead in a section of the Columbia River.