Blue Mesa Reservoir, Colorado. The largest reservoir in Colorado had a blue-ribbon kokanee fishery with over a million fish and an annual catch of more than 150,000. The fishery was estimated to have a value to Colorado of $8 million. Blue Mesa was also the primary source for kokanee eggs to stock 26 other reservoirs around the state. The total value of the kokanee population of Blue Mesa was thought to be around $29 million. Today, you would be hard pressed to catch a kokanee in Blue Mesa. What happened? The Colorado Department of Wildlife decided to plant lake trout in 1968. The biologists didn’t believe that lake trout would naturally reproduce in the reservoir and could provide a good trophy fishery. Be careful what you wish for.
Lake trout are prodigious predators. “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.” Biologists believe that the kokanee population is “in near complete collapse“. The annual catch rate for rainbow trout has dropped from about 70,000 to 10,000 fish. The Department has begun a program to re-balance the fishery in Blue Mesa Reservoir. From October to November, 2009 they removed 900 lake trout less than 30 inches and will plant over 3 million kokanee fry and about 120,000 10-12-inch rainbows. The project is not without controversy,
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.
Compared to Flathead Lake, Blue Mesa is a puny project. Blue Mesa has a surface area of 9,000 acres, Flathead Lake has a surface area of more than 120,000 acres. There are less than 10,000 lake trout in Blue Mesa and the estimated population of catchable lake trout in Flathead Lake is more than 400,000. The problem is both lakes is the same. Without a concerted effort on the part of fishery managers, lake trout will eat themselves out of house and home. As the population begins to approach carrying capacity, food disappears, fish become smaller, thinner and begin to mature and spawn later. In both cases, popular recreational fisheries have been lost due to the insatiable appetite of lake trout. In Flathead Lake, we are in danger of loosing native fish populations that have called the drainage home since the last ice age.
Flathead Lake is not alone in facing the lake trout dilemma. This is a problem across the western states. It is a predicament of our own creation and it is a problem that we can and must address. No one expects to eradicate lake trout in either Blue Mesa or Flathead Lake. They are here to stay, but we can and must suppress the overgrown population for the good of the lake trout themselves and most importantly, so we do not forever loose native bull trout and cutthroat trout populations.