Salmon, lake trout in crosshairs of debate
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It was an ordinary day on Blue Mesa Reservoir when Travis Snyder’s fish finder was suddenly monopolized by a school of trophy lake trout swimming in the depths of the water. Snyder — an experienced angler and owner of High Mountain Drifters guide service — became enthralled in the pursuit of these fish.

By the end of the day, he and another local guide had caught six lake trout, totaling 106 pounds in cumulative weight — two of which were caught simultaneously.

“It’s not like throwing a worm out and hoping a fish bites it. It’s very intense,” said Snyder. “It’s something that I would like every angler to experience.”

Yet, on that day, no other anglers were in sight.

“Everyone else was salmon fishing,” Snyder explained.

In recent years, the popularity of trophy lake trout fishing at Blue Mesa Reservoir has decreased substantially due to an ongoing removal effort targeting small lake trout which began in 2009. The aim of the management project is to balance kokanee salmon and the lake trout fishery in the reservoir.

Kokanee — a main food source for lake trout — decreased dramatically during the mid-2000s. Early in the decade, the kokanee population was thriving at an estimated one million. Yet by 2009, the population size was reduced to 110,000.

According to various studies conducted by both Colorado Parks and Wildlife (CPW) and Colorado State University, predation was the primary reason for the decline. Using age structured kokanee and lake trout population models, linked with a bioenergetic model of lake trout predation, it was concluded that lake trout removal was needed to prevent the decline — and local extinction — of kokanee salmon.

Thus, CPW began physically removing lake trout larger than 18 inches using 1.75-inch gill nets. Using the nets, CPW maintains an overall mortality rate of 11 percent. Any fish longer than 27 inches were released back into the reservoir in order to sustain the trophy lake trout fishery.

“We certainly want to be releasing large lake trout to maintain trophy opportunity,” said CPW aquatic biologist Dan Brauch.

The removed lake trout are filleted, frozen and donated to the public during an annual giveaway day.

 

Trophy potential not what it was

Since its inception, CPW’s management plan has been shrouded in controversy. Trophy lake trout fishing was once a major attraction in the Gunnison Valley. In fact, the state record fish — weighing in at 53.35 lbs — was caught at Blue Mesa by Don Walker in 2007.

“I don’t know whether another state record fish is accomplishable,” Snyder said in regard to the reservoir. “The opportunity for these fish has decreased dramatically.”

For Andy Cochran co-owner of Gunnison Sports Outfitter and chairman of the Gunnison Wildlife Association — clients pursuing trophy lake trout once made up about 25 percent of his business. Today, it comprises less than 10 percent. In general, Cochran said that since 2010, requests for trophy lake trout trips have gone down due to the declining quality of the fishery.

“Overall, the population of trophy lake trout is not at a level where you can have continued successful guide trips,” he explained.

Cochran and the Gunnison Wildlife Association are concerned that the management project has spurred an unexpected consequence. They believe that increased numbers of yellow perch — due to lack of predation from lake trout — have resulted in the decline of brown trout in Blue Mesa.

Cochran cites competition for food between yellow perch and brown trout as the reason for the decline. While research conducted by CPW concludes that yellow perch populations frequently fluctuate based on the success of natural reproduction, Gunnison Wildlife Association is working on a management plan of their own — the first step of which is to corroborate their theories through research.

“We’re working on a management plan to prove with numbers what we are seeing on the water,” Cochran said.

 

Removal efforts necessary?

Gunnison Wildlife Association’s theory about yellow perch is just an added factor in an already complicated problem. Neither kokanee nor lake trout are native to Colorado, and they did not evolve together — making the management of these two species all the more difficult. Furthermore, kokanee spawned at the Roaring Judy Fish Hatchery are a primary source for salmon statewide — allowing for stocking of up to 25 other waters in Colorado.

“When we are looking to balance the lake trout and kokanee, one of the factors is to what degree kokanee have rebounded,” Brauch explained. “Particularly last year, we only removed a little over 400 lake trout.”

By way of comparison, since 2009 CPW has removed an average of 1,200 lake trout per year. Yet, as the kokanee populations begin to rise again, Brauch is hopeful that the removal efforts can be downsized. Based on this year’s study of both fisheries, CPW is currently considering moving to an alternating schedule for lake trout removal. If put in place, lake trout would be removed every other year.

Yet, Snyder believes lake trout should not be removed in the first place.

“I don’t think they should be removing them at all,” he said. “They could have achieved their goal — and even had better success — working with the fishermen instead of putting nets in the lake.”

However, according to Brauch, working with anglers is a primary objective of the management plan. CPW encourages anglers to harvest smaller lake trout as they comprise the biggest population of predators to kokanee.

“It’s really important to have anglers be a part of the process,” Brauch said. “Anglers harvest many more trout than we remove.”

(Julia Jacobson, special to the Times). 

 

 

 

SCIENCE IN SUPPORT OF THE PLAN

Simultaneously managing lake trout and kokanee salmon in the West is no easy feat. To that end, however, Colorado Parks and Wildlife has looked to research to inform their management plan. The following reports and links detail some of that research.

Title: “Managing for Coexistence of Kokanee and Trophy Lake Trout in Montane Reservoir”

Primary author: William M. Pate

Where found: https://www.tandfonline.com/doi/abs/10.1080/02755947.2014.923072#.VNBIsi...

Title: “Tracking Lake Trout Diet and Trophic Interactions in Blue Mesa Reservoir Using Stomach Contents and Stable Isotopes”

Authors: William M. Pate and Dr. Brett Johnson

Where found: http://files.cfc.umt.edu/cesu/NPS/CSU/2010/10Johnson_CURE_lake%20trout%2...