Hatchery salmon raised in noisy environments show lower return rates for spawning

On July 8, 2026, a study from Washington State University reveals that hatchery-raised Tule Fall Chinook salmon raised in noisy environments are less likely to return to spawn. This research highlights the impact of environmental factors on the survival rates of these fish, which are listed as threatened under the Endangered Species Act.

Impact of Noise on Salmon Return Rates

The study conducted by Rikeem Sholes and his team indicates that hatchery fish raised in quiet, noise-protected settings had better survival rates compared to those raised in ambient noise and continuous white noise conditions. The research was published in the North American Journal of Fisheries Management.

Sholes emphasized the importance of hatcheries, stating, "We spend millions upon millions of dollars raising these fish for various reasons, so we want to make sure that we're sending them out with all their systems working so they have the best chance of making it back." The findings suggest that sound-dampening techniques could significantly improve the return rates of hatchery-raised fish.

Research Methodology and Findings

The researchers evaluated salmon fry from the Spring Creek National Fish Hatchery near the lower Columbia River, known for its high ambient noise levels due to nearby train tracks and highways. They categorized the fish into three groups based on their rearing environments: one with noise dampening, one exposed to white noise, and one in normal hatchery noise.

While initial assessments showed no significant differences in sensory development or swimming behavior, the return rates of adult salmon indicated otherwise. Fish raised in quieter conditions returned at higher rates over two years. Specifically, those in noise-protected environments were twice as likely to return compared to those raised in continuous white noise.

Future Directions for Hatchery Practices

The implications of this research are critical for the management of hatchery operations across the nation. With the National Fish Hatchery System releasing approximately 125 million fish annually, improving return rates through environmental modifications could enhance the effectiveness of these programs.

Researchers advocate for further studies to understand the mechanisms behind these findings and tailor solutions for individual hatcheries. Implementing sound-dampening techniques, such as padding tanks, may provide a pathway to improve the success of hatchery-raised salmon.