Friday February 17, 2023
NOAA Fisheries —
New research examines how Chinook salmon from West Coast rivers travel through the ocean. It shows that endangered Southern Resident killer whales do not have access to as many salmon prey as previously thought. That does not mean the number dropped, but that it has always been lower than estimated.
Calculating the number as accurately as possible is important because it determines whether to shut down West Coast salmon fisheries. These limits are imposed at certain places and times when the number of salmon falls to a certain level, or what fisheries managers call a “threshold.” The Chinook salmon threshold is a measure of where the endangered whales have a markedly harder time finding prey.
The Pacific Fishery Management Council recently asked NOAA Fisheries to update the threshold to incorporate new science showing fewer salmon in parts of the ocean accessible to the whales. The new science illustrates the way technology is revealing the Pacific salmon life cycle and its intersection with other species in ever-greater detail.
The numerical threshold for fishing limits was first established under Amendment 21 of the Pacific Coast Fishery Management Plan. The plan drew thousands of supportive comments in 2021. The threshold was determined as the average of 7 years of low salmon abundance that included years when the Southern Residents were in varied health. It considered the prey needs of pregnant and nursing whales.