Blue Mesa kokanee salmon numbers cause for concern
Colorado Division of Wildlife biologists this year are continuing a project aimed at protecting kokanee salmon by reducing the number of lake trout in Blue Mesa Reservoir.
The project includes netting and removing lake trout up to the 30-inch range, since those, according to the division, account for most of the predation on kokanee salmon.
Last fall, 900 lake trout were removed from the reservoir, located between Montrose and Gunnison on U.S. Highway 50. The fish were given to local residents.
Killing lake trout is extremely unpopular among lake trout fans, who in comments sent to the division, accuse the DOW of “ignoring” and “showing no respect” for lake trout, particularly trophy-sized lakers.
However, creel surveys from the DOW indicate most anglers at Blue Mesa prefer to catch kokanee salmon and rainbow trout.
Thanks to some astute management, Blue Mesa has the reputation as Colorado’s finest kokanee fishery.
But these are troubled waters.
As recently as 2002, anglers were catching up to 125,000 kokanee per year.
In 2008, that number had plummeted by nearly 100,000, even though the DOW continues to stock upward of 3 million kokanee fingerlings each spring.
Research indicates that as lake trout numbers increase, kokanee salmon catch decreases.
Rainbow trout return-to-creel numbers also are down, according to angler surveys.
DOW biologists assume many of the 8,000 or so lake trout in Blue Mesa are in the 20- to 30-inch range, and say a fish that size eats about 13 pounds of fish each year.
Last year, DOW aquatic biologist Dan Brauch said the kokanee population in Blue Mesa Reservoir was “in near complete collapse.”
“We are very concerned,” he said. “We need to be active to maintain the fishery.”
The whole project is complicated, long term and certainly controversial.
“The intent of this work is to assess predation on kokanee,” said Brauch. “The more we can learn about the extent of all predation the better we can manage the reservoir for multiple species.”
Lake trout first were stocked in Blue Mesa in 1968 to take advantage of a plentiful prey base of kokanee salmon and rainbow trout.
Because it was thought that lake trout wouldn’t reproduce in the reservoir, occasional plantings occurred up to the early 1990s.
It took a couple of decades for lake trout to get large enough to catch anglers’ attention, but several flirtations with the 40-pound mark raised interest levels considerably.
More attention was gained a few years ago after a flurry of short-lived, record-setting catches.
Now, anglers are searching for a laker hefty enough to beat Donald Walker’s state-record 50-pound laker caught out of Blue Mesa in 2007.
The kokanee-saving project also includes sampling stomach contents from brown and rainbow trout in the Gunnison River shortly after the spring release of salmon fry to gauge predation in the river.
Those fry surviving the run to Blue Mesa face threats from brown and rainbow trout, yellow perch and lake trout.
As those salmon grow, lake trout become their main predators.
Creel surveys show that in 2008, anglers caught 8,600 lake trout, thanks to a generous bag limit, part of a DOW tactic encouraging anglers to take more lake trout.
However, more than half of those lakers were released back into the reservoir.
A DOW report said 100 fish longer than 30 inches were netted, measured and released last year. Fourteen other large lake trout died after being netted.
Part of the DOW plan includes stocking larger rainbow trout, 10–12 inches long and less-susceptible to lake trout, raised at the Hotchkiss National Fish Hatchery.
A 2004 economic-impact report shows kokanee salmon anglers generated an estimated $6.4 million to the local economy.
More information about the Blue Mesa project is available at wildlife.state.co.us. Click on “Fishing” and then “Blue Mesa Reservoir management.”