A study by UC Santa Cruz and NOAA Fisheries has found that the aging pattern of Chinook salmon in the Sacramento River is changing, with more young fish spawning and fewer older ones, which could make the population less resilient to climate change. The research suggests that hatchery practices and fishery management need to be adjusted to increase the diversity in age groups and make the population more stable. The scientists believe that delaying maturity and reducing mortality could improve the population's resilience, and call for a shift in hatchery practices to prioritize older, larger fish. The research highlights the need for more diverse age structures in fish populations to better handle the effects of climate change.