Habitat Modeling Field Validation for Various Salmonid Life Stages in Middle Fork John Day River, Oregon
* Can existing habitat modeling results using the Physical Habitat Simulation System be validated with site-specific observations of salmonids at key life stages in the Middle Fork John Day River?
The recommended tool to characterize flow conditions for federally listed fish species is the Physical Habitat Simulation System (PHABSIM). Reclamation's Technical Service Center (TSC) has the resources and capabilities to conduct PHABSIM studies. PHABSIM is a habitat simulation model that predicts habitat at various flows. However, it does not have a field validation component. A field validation study to observe actual habitat use by juvenile, adult, and spawning fish would improve our ability to accurately predict the effects of flow on fish habitat and strengthen modeling results while continuing to deliver water with as little impact to threatened and endangered fish species as possible.
Need and Benefit
Reclamation has the capability to use the PHABSIM model to predict habitat quantity and quality at various stream flows. Reclamation uses it to model juvenile habitat for a project in the Middle Fork John Day River in central Oregon. However, there was disagreement among Reclamation biologists on whether the habitat modeling results accurately reflected microhabitat use by juvenile fish. Without actual fish observations at specific flows in areas where the model predicts fish would occur, we cannot be certain that the model is producing accurate results. The model needs to be validated.
Validation of the model by specific fish observations at several life stages would provide evidence that the PHABSIM model predictions are correct for positive fish habitat at various and calculated simulated flows in project areas. If not, guidance for further enhancement for the model towards improved and enhanced predictions of fish habitat in study areas. Validation of this model will prove effective to provide beneficial fish habitat while continuing to deliver water and not detrimentally impact fish species.
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