Monday February 27, 2023

UC Santa Cruz

By returning to spawn in the Sacramento River at different ages, Chinook salmon lessen the potential impact of a bad year and increase the stability of their population in the face of climate variability, according to a new study by scientists at UC Santa Cruz and NOAA Fisheries.

Unfortunately, spawning Chinook salmon are increasingly younger and concentrated within fewer age groups, with the oldest age classes of spawners rarely seen in recent years. The new study, published February 27 in the Canadian Journal of Fisheries and Aquatic Sciences, suggests changes in hatchery practices and fishery management could help restore the age structure of the salmon population and make it more resilient to climate change.

The researchers focused on Sacramento River fall-run Chinook salmon, which contribute heavily to the salmon fisheries of California and southern Oregon. This population is particularly susceptible to the effects of increasingly severe drought conditions driven by climate change.

“As we get more variable climate conditions, with greater extremes of rainfall and drought, we are going to see more ‘boom-and-bust’ population dynamics unless we start to restore the age structure of the population, which can spread out the effects of good and bad years across time,” said senior author Eric Palkovacs, professor of ecology and evolutionary biology and director of the Fisheries Collaborative Program at UC Santa Cruz.

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