May 29, 2014
In theory, it only makes sense that a more aggressive fish would be more apt to wind up on an angler’s hook.The more aggressive fish would seem more likely to assertively protect its spawning nest or pursue food items, not to mention a fisherman’s bait.
Fisheries officials and biologists in Oregon are taking a proactive approach toward improving fishing in the state, and are beginning work toward breeding hatchery steelhead trout and Chinook salmon whose bite can match that of the wild members of species. The process has just begun and will be lengthy, but if it works, the same process could be applied to other species.
“It’s an exciting day for us,” David Noakes, a professor of fisheries at Oregon State University and senior scientist at the Oregon Hatchery Research Center, told the Associated Press. “Depending on what the answer is, we might be changing a lot of things about raising hatchery fish and stocking hatchery fish.”
Along the Alsea River in northwestern Oregon, anglers have long maintained that wild fish in the area are more aggressive and, as a result, easier to catch. Results of recent studies back up that hypothesis.
Since 1990, the adipose fin, a fleshy knob at the base of the tail, has been clipped on hatchery fish to distinguish them from the wild ones, which generally must be released unharmed. Salmon and steelhead born in the hatcheries make up the vast majority of those returning to the rivers in the area, but rarely the largest number of those being caught.
Surveys of anglers on the Deschutes River in central Oregon since 1977 consistently have shown that wild fish account for the bulk of the fish caught, even as their numbers have dwindled. In 2013, nearly six wild fish were caught for every hatchery fish, even as hatchery fish outnumbered the wild ones nearly 3 to 1.
The Alsea hatchery releases 120,000 steelhead smolts every year. Hatcheries have been used to supplement salmon and steelhead numbers in the West for more than 120 years, helping increase numbers depleted by overfishing and habitat lost to dams, logging, mining and development.
Evidence has grown to show that hatchery fish are less likely to survive in the wild and also can add to decline in the wild fish population. With eyes toward improving the gene pool, many hatcheries have been mixing wild fish into their breeding.
Now the first year of a three-year creel survey on the Alsea River has shown that hatchery fish bred from wild parents were caught by fishermen three times more often than those bred from hatchery stock.
The largest of species of the Pacific salmon, the Chinook salmon is native to the north Pacific Ocean and river systems throughout western North America, from California to Alaska. Steelhead trout are rainbow trout that migrate to the ocean to grow up.
In 2009, a 30-year study was published in Transactions of the American Fisheries Society on the effects fishing had on black bass in an Illinois lake. It showed that removing the aggressive fish that bite while defending their spawning areas produces a population that is less likely to bite.
In short, according to Dr. David Philipp, the study’s lead author, the tendency to bite aggressively can be inherited.
“As you fish a population, you tend to catch the most aggressive ones,” Philipp, a conservation geneticist for the Illinois Natural History Survey at the University of Illinois, told the AP. “Often times, they are removed from the population. As a result, the population becomes less vulnerable to angling because it is less and less aggressive.”
Complete results of the Alsea River study will not be known for at least four years. A small number of steelhead returned to the Alsea this year, so volunteer anglers did not turn in the 30 wild fish needed to start the experiment, according to Ryan Couture, the director of the Oregon Hatchery Research Center. They will try again next year, but then it takes a year for the fish to be old enough for release and another two years for them to return as adults.