---

Blue Mesa Reservoir is renowned as one of the best kokanee salmon fisheries in the United States. Since fish stocking began at the reservoir in 1965, developing and maintaining the kokanee fishery has been the major priority for Colorado Parks and Wildlife. Kokanee continue to provide great fishing opportunities at the reservoir, but maintaining overall kokanee numbers has become more difficult due to increased predation of kokanee by lake trout.

A decade ago the kokanee population at Blue Mesa numbered more than 1 million. But the most recent surveys by Colorado Parks and Wildlife biologists show that the current population is 290,000, about the same as last year. While there is evidence that the recent overall trend of the population is positive, it is still short of numbers needed to maximize angler opportunities for kokanee and trophy potential for lake trout at Blue Mesa.

Colorado Parks and Wildlife is working aggressively to rebuild the kokanee population by stocking 3.5 million kokanee annually and by continuing work to reduce lake trout predation on kokanee. We're also calling on anglers to help by harvesting the lake trout they catch.

Kokanee egg-take operations from the Blue Mesa kokanee run were very successful again in 2013 with a record 13 million kokanee eggs collected. That amount ensures that Blue Mesa and 25 other reservoirs in Colorado will be adequately stocked with kokanee this year.

Although kokanee population trends have seen improvement, continued reduction in the lake trout population is necessary to ensure that kokanee numbers continue to improve and do not backtrack. The lake trout population can be maintained at a reasonable level through a combination of angler harvest and lake trout removal work. If the population goes unchecked, it is believed that lake trout will eventually overwhelm kokanee.

---

Reduction and eventual maintenance of lake trout population size at desired levels will be best achieved through a combination of lake trout harvest by anglers and removal by Colorado Parks and Wildlife staff. Fish populations will be monitored over time to assess whether harvest and removal are being effective; but it is expected that removal work will continue indefinitely.

Anglers do catch a significant number of lake trout and Colorado Parks and Wildlife continues to encourage anglers to harvest this species. Since 2009, anglers have harvested about 17,000 lake trout, three times the number Parks and Wildlife staff have removed. The main reason is that anglers are on the water in much greater numbers throughout the year: about 60,000 anglers fish at Blue Mesa annually.

Angler harvest of lake trout will make the largest impact on kokanee recovery efforts. Lake trout under 26 inches in length are most abundant and therefore consume the most kokanee. There are no bag or possession limits for lake trout measuring less than 38 inches.

Smaller lake trout are often caught by anglers pursuing other fish species. In fact, 84 percent of the lake trout caught are under 22 inches. Lake trout make excellent eating and are very nutritious. Anglers can, literally, fill their freezers with this delicious fish.

By reducing the lake trout population, overall kokanee catch rates for Blue Mesa anglers will improve. But there's also something in this for lake trout anglers – as smaller fish are removed a greater number of lake trout will grow to trophy size.

During the last four years, biologists have removed about 4,800 lake trout from the reservoir. About 800 lake trout were removed in 2012. Biologists hope to remove up to 2,000 lake trout this year.

Although removal efforts have always targeted primarily small lake trout, Parks and Wildlife made a management change during 2012 regarding the maximum size of lake trout to be removed. Biologists only removed lake trout that were 32 inches or less in length. In 2010 and 2011 a limited number of fish up to 38 inches were removed. The change was made because lake trout in the smaller category comprise the largest population segment and therefore consume the most kokanee.

For anglers, fish more than 32 inches are often considered trophy size. So this change will allow more of the big lake trout to remain in the reservoir.

Also new in 2012 was an effort by Colorado Parks and Wildlife to transplant some of the captured fish to other waters. Last fall 70 lake trout were moved from Blue Mesa to Twin Lakes. Biologists hope to move more fish next year to provide more opportunity to anglers.

---

Every year during fall, kokanee swim 20 miles up the Gunnison and East rivers to the Roaring Judy hatchery where they are spawned. Colorado Parks and Wildlife have taken steps to ensure that most of the spawning kokanee swim into the hatchery canal where the eggs are harvested. Those efforts have resulted in two consecutive years of record egg take.

Biologists also work to protect the fish in the spring when young kokanee, about 2 inches in size, are released from the hatchery. On the day the fish are released, local landowners and Colorado Parks and Wildlife work cooperatively to close or screen irrigation ditches along the East and Gunnison rivers to prevent the tiny fish from leaving the main channel, thus assuring that more young fish make it to the reservoir.

Parks and Wildlife has also bolstered the population of kokanee in the reservoir by releasing more fish in the spring. During each of the last four years, the agency has increased the number of fingerlings released into the reservoir by about 500,000, bringing the total number stocked annually to about 3.5 million.

Stocking more and more fingerlings, however, is not a long-term solution. Fish production space is limited and egg takes can vary considerably from year to year, and will likely decline in some years.  

A critical factor in understanding the Blue Mesa fishery is that the reservoir is a human-made impoundment. The biology of a reservoir is far different than a natural lake. Managing a fishery in this type of environment is complex and challenging. Neither kokanee nor lake trout are native to Colorado and the species did not evolve together. Consequently, the predator-prey relationship is not natural.
 
Kokanee, however, are the key species for maintaining a variety of angling opportunities in the reservoir. Trophy lake trout are dependent on a healthy kokanee population. While biologists believe that population trends for kokanee are improving, the fishery is still out of balance. There are no quick fixes; balancing the fishery at Blue Mesa is a long-term project.

---

All types of fishing at Blue Mesa Reservoir are important to the economy of Gunnison County. Based on years of surveys, kokanee anglers are the most active at the reservoir.  In 2004, a study estimated that fishing at Blue Mesa generated an economic impact of about $8 million per year. Of that amount, 80 percent of the spending -- about $6.4 million -- came from kokanee anglers. People throughout Colorado and the United States travel to Blue Mesa to fish for this freshwater salmon species.

Beyond the immediate impacts in Gunnison County, kokanee production at the reservoir is critical to sport fishing throughout Colorado. Blue Mesa provides an average of 60 percent of the eggs needed to stock fingerlings into lakes and reservoirs throughout the state. The overall annual economic impact of kokanee salmon fishing in Colorado is estimated to be at least $29 million.

---

Lake trout predation on kokanee is also a problem in other western states. Wildlife agencies in Wyoming, Idaho, Montana, California, Utah and Washington are also working to maintain their kokanee populations.
 
You can learn about how this issue is affecting all of these western states by reading Introduced Species: Western Lake Trout Woes , published in "Fisheries," a journal of the American Fisheries Society.

---

• The latest overall fish survey summary and management information  at Blue Mesa Reservoir explains stocking, management strategies and fish survey data.
• Colorado State University researchers are also studying lake trout at Blue Mesa Reservoir. Read the latest information from CSU.
• Read about CSU fisheries research at cold-water reservoirs.

For frequently asked questions regarding Blue Mesa Reservoir, see FAQs .