The Upper Snake River Tribes (USRT) Foundation asked that the ISAB review the scientific elements of a loss assessment of spring/summer Chinook salmon in the Upper Snake River Basin. To address the USRT’s specific review questions, the ISAB provides ideas of how to improve the presentation of results and specific comments about the analysis performed. In general, the ISAB agrees that USRT’s use of an intrinsic potential model to assess loss of spring/summer Chinook salmon in the upper Snake River was a good first step that yielded valuable information under a constrained budget. However, the ISAB has concerns about the accuracy and uncertainty of the results, and concerns about how the model was used in the large leap from assessing habitat suitability and availability to quantifying and distributing the historical numbers of spring/summer Chinook salmon in stream reaches above the Hells Canyon Complex.
The ISAB offers five suggestions for next steps to produce a more complete analysis with increased certainty:
- Explore more fully the current intrinsic potential model used in Parametrix (2023) to better understand the effect of assumptions made and scalars used.
- Experiment with alternative intrinsic potential models that consider other biologically relevant covariates, e.g., temperature, precipitation, and discharge.
- Explore the effects of landscape alterations from human disturbances and the expected effect of climate change.
- Explore other modeling methods for cross-model comparisons, to increase accuracy and to reduce uncertainty.
- Incorporate Indigenous knowledge to inform the analysis.
The ISAB hopes that this review will help USRT with plans for assessments of loss and current habitat capacity for spring/summer Chinook salmon and other fish stocks and species. Although the suggested next steps will require additional effort, they will be critical for informing future actions to reintroduce anadromous fish above the Hells Canyon Complex.
