East Lake has long been a destination for anglers looking to catch a variety of fish.

The natural lake in the Newberry National Volcanic Monument east of La Pine is home to stocked rainbow trout, brown trout, Atlantic salmon and kokanee.

Catching all four species in one day is sometimes referred to as the “East Lake Slam.”

But rarely does an angler accomplish that feat without hooking several tui chub. The invasive species — which has harmed the rainbow trout fishery by competing with young trout for food sources — has been a problem in the lake for some 70 years, according to Brett Hodgson, a Bend-based fisheries biologist for the Oregon Department of Fish and Wildlife.

Now, the ODFW is doing something about it.

Biologists from the ODFW and volunteers have been trapping tui chub in East Lake for the last two weeks as part of a five-year plan to restore the rainbow trout fishery.

According to ODFW fish biologist Jen Luke, the biologists and volunteers are targeting the tui chub for three weeks in June and July, when the fish concentrate in shallow waters near shore to spawn.

“Our plan is to trap and remove as many tui chub as we can over the next three spawning seasons,” Luke said this week.

Once the chub have been reduced, the ODFW will attempt to keep the remaining population of the species in check by stocking in East Lake a more aggressive strain of rainbow trout that will eat the chub.

Since the project started on June 28, biologists have been trapping an average of 600 pounds of tui chub a day, according to the ODFW.

“Our goal is not the complete elimination of the tui chub — which is likely impossible using traps,” Luke said. “Instead, we want to try to keep the chub population at a low enough level that rainbow trout can still thrive.”

For decades, Luke noted, East Lake was well known for producing trophy-sized rainbow trout. In recent years, however, the quality of the rainbow trout fishing in East Lake has declined as the tui chub population has increased.

“They dominate the zooplankton supply in the lake,” Hodgson said of the tui chub. “Zooplankton are the bottom link of the food chain for trout. Without them, the entire food web collapses.”

Hodgson added that, without intervention, the chub will continue to multiply and become a more severe problem.

“We’ve had repeated contacts with angling groups over the last several years, voicing their dissatisfaction and asking what we’re going to do,” he said.

Biologists and volunteers are using three large box nets made of nylon to capture the chub, mostly on the lake’s south and east shorelines. The fish swim into the lead lines of the net and are funneled into a trap compartment, Hodgson explained.

The chub are then removed each morning and discarded at a gravel pit on U.S. Forest Service land about 10 miles away, according to Hodgson. Any trout that are captured are removed from the net and released back into the lake.

(Hodgson noted that the ODFW would consider using the chub as fish fertilizer or for human consumption, but the dangerous mercury levels in East Lake preclude the agency from doing so.)

Hodgson said the ODFW plans to continue the trap operation through this weekend, then return next summer for more trapping.

Trout populations at many other Oregon lakes have been decimated by tui chub, including Diamond Lake in southwest Oregon. In 2005, the ODFW killed all the fish in Diamond Lake with the plant-derived pesticide rotenone, then restocked the lake with rainbow trout.

As a result of the treatment, the Diamond Lake rainbow trout fishery is once again flourishing.

A total kill with rotenone is not an option on East Lake, Hodgson explained, because it would be too costly, and it would be difficult to kill all the fish.

“The depth and water volume (in East Lake) would make it hugely expensive, and all the inflow of underwater springs would make it difficult to get a 100 percent kill,” Hodgson said. “Our objective is to hit the population hard with the traps for three years during the spawning period. This is not a long-term strategy — it’s very labor-intensive. We can’t commit to it with our limited staff.”

Hodgson said it will likely be a couple of years before anglers notice an upturn in the rainbow trout fishing at East Lake.

“I think you could see an improvement next year,” he said. “By the end of the three-year removal period, I think we’ll see significant improvement. We’ll stock with rainbow trout that will utilize the chub as food, perhaps next year.”

Resort owners at two other popular Central Oregon trout lakes — Paulina Lake, located just west of East Lake, and Lava Lake, southwest of Bend off Cascade Lakes Highway — trap chub with nets on their own.

“They’ve controlled the chub populations and it’s resulted in great improvements to the trout fishery at Lava (Lake),” Hodgson said.

The biologist said that East Lake has the most significant chub problem of any lake in Central Oregon. The grayish-bronze-colored fish average 6 to 8 inches in length, but Hodgson said they grow to 12 inches in East Lake.

The lake is naturally devoid of fish and was first stocked with rainbow trout in 1912, according to the ODFW. By the 1920s, East Lake was gaining a reputation as a premiere trout fishery due to abundant food sources that allowed trout to grow to trophy sizes. Tui chub are not native to Central Oregon and were most likely introduced to East Lake by anglers using them as live bait, according to the ODFW.

David Jones, owner of East Lake Resort, said he is pleased that the ODFW is taking action to reduce the number of tui chub in the lake.

“Anything they can do to improve the fishery is a good thing, both short term and long term,” Jones said. “We’re very excited.”

He added that fishing for kokanee has been outstanding this season.

“The fishing has been excellent,” Jones said. “I can’t imagine what it will be like without the chub.”