BY ANDY WALGAMOTT, NORTHWEST SPORTSMAN MAGAZINE
A steady hum in the background at night? Good for helping people get a good rest, but apparently not so great if you’re a hatchery salmon.
Washington State University-Vancouver researchers found that tule Chinook reared in a noise-dampened environment were “nearly twice as likely” to return from the ocean as those constantly exposed to white noise, suggesting that quieting the facility could boost adult runs.
“The hatchery system is really critical for the nation, ecologically and economically,” said Rikeem Sholes, lead researcher and U.S. Fish and Wildlife fisheries biologist, in a WSU press release out today. “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 experiments were performed at Spring Creek National Fish Hatchery in the Columbia Gorge and recently published in the North American Journal of Fisheries Management.
Researchers raised Chinook in three different environs: “one where the noise was dampened with padding and other methods; one where white noise was played continuously; and one with the normal ambient noise of the hatchery” – think the roar of busy Highway 14, rumbling of trains down the BNSF tracks and normal hatchery operations at Spring Creek.
Prior to the young salmon being released, the scientists didn’t find any real differences in how the fish swam or in the development of their senses, but report that they did see “moderate differences” in length.
But the biggest surprise was in return rates.
“We found that fry exposed to continuous white noise were significantly less likely to return to the hatchery, whereas fish in the quiet and ambient noise treatments had higher return rates,” Sholes et al wrote in their paper.
“That surprised me the most — when they started coming back, we saw differences in the return rates when we had seen very few differences as they were heading out to sea,” said coauthor Allison Coffin in the WSU press release.
The researchers allow that more study is needed to figure out why that is, but it’s suggested that padding rearing tanks might help with returns.
