The Federal Columbia River Power System (FCRPS) is managed to provide safe and effective passage for adults returning to their home streams to spawn. These passage actions primarily support protection and recovery efforts for the seven salmon and steelhead populations in the Interior Columbia and Snake Rivers listed under the Endangered Species Act.
This diagram provides an overview of the primary ways we measure adult survival.
Adult Conversion rate: Measures the minimum survival of known-origin adult salmonids that have passed Bonneville Dam to the last dam they passed before spawning. This number is adjusted by an estimate of in-river harvest rates and natural straying rates.
Smolt-to-adult returns: Measures the ratio of juvenile salmonids traveling out to the ocean to the number of adults counted at the last dam they passed before spawning. This number is influenced by survival in the estuary and the ocean.