MOSCOW, Idaho — A University of Idaho study provides evidence that the practice by anglers of holding a fish out of water before releasing it has no impact on the fish’s survival or its ability to produce offspring, according to a U of I news release.
In the study, published this month in the North American Journal of Fisheries Management, researchers from U of I and the Idaho Department of Fish and Game caught more than 2,200 Yellowstone cutthroat trout over two years in a tributary of the South Fork of the Snake River in Idaho, a world-renowned fishery.
The researchers tagged the fish in the spring with tracking devices, took genetic samples, simulated angling and left some fish in the river while holding others out of the water for 30 and 60 seconds. The fish were then tracked to monitor their survival rates. The researchers returned to the same area in autumn to trap their offspring and determine the parentage of each fish through genetic analysis.
“We found that air exposure had no effect on short- or long-term survival, and no effect on reproductive success,” said Michael Quist, one of the study’s authors and an associate professor of fisheries management in U of I’s College of Natural Resources.
Curtis Roth, lead author of the study and a recent U of I master’s graduate, said the time intervals were chosen because they were consistent with how long anglers keep fish out of the water. An earlier study by the U of I researchers published in January 2018 in the journal Fisheries Research found more than 99 percent of anglers keep fish out of water for less than 60 seconds. The average was less than 20 seconds. Roth said researchers also focused on trout, a member of the salmonid family, because of its sensitivity.
“We chose salmonids for this study because they have lower tolerance of hypoxia — of being without oxygen. In theory, they would be the most likely to show an effect,” said Roth, who is now a fisheries biologist with the Idaho Department of Fish and Game in Salmon.
Salmonids include salmon, trout and steelhead, whose response to air exposure during catch-and-release fishing has been source of concern.