Kokanee Salmon
Kokanee salmon were first stocked in Blue Mesa Reservoir in 1965. Even before the reservoir was built, aquatic biologists recognized that it would be an ideal environment for the fresh-water salmon. The water is very clean and it produces an abundance of phytoplankton and zooplankton which are the primary food sources for kokanee. Kokanee do not compete with native fish, they cannot cross-breed with other species, they are whirling-disease resistant and they can be released as fingerlings. They live in open water, so the large size of the reservoir provides excellent habitat. Kokanee also grow to an ideal size for anglers, 15-18 inches, and provide very tasty meat.
The location of the reservoir also allowed the DOW to build a highly-efficient and cost-effective kokanee rearing facility at the Roaring Judy hatchery. Eggs hatch in the facility in December, and the young are raised to a length of 2 inches in the hatchery building. In April, they are released directly into a one-half mile long canal which flows into the East River/Gunnison River system. The fingerlings move down the river 21 miles until they arrive at Blue Mesa Reservoir.
After three to four years of living in the reservoir, 
the fish respond to their natural instincts and make their way back up river seeking the place where they were born. They swim into the fish raceways just below the hatchery where their spawn is collected. Every year the DOW is able to develop a new year-class of fish.
Rainbow trout
Rainbow trout are the most popular game fish in Colorado. For many years, the U.S. Fish and Wildlife Service has stocked 850,000 5-inch rainbows in Blue Mesa. The trout are raised at the federal hatchery in Hotchkiss. These small fish, however, are vulnerable to predation by lake trout. Starting in 2010, the service will stock 10-inch rainbows which are, generally, large enough to avoid predation by small- to medium-sized lake trout. Rainbow trout reproduce naturally in several Blue Mesa tributaries but not in large enough numbers needed to sustain a sport fishery in the reservoir.
Brown trout
Brown trout reproduce naturally in the Gunnison River, the Lake Fork of the Gunnison River and Cebolla Creek. The fish then move into the reservoir as they get older. In 2008, anglers caught about 12,000 brown trout that average 14 inches in length. 
Brown trout prefer water near the banks of the reservoir and water depths no greater than 65 feet. They are predators and do eat small kokanee; but their predation effect is insignificant compared with lake trout.
Lake trout
Lake trout - also known as Mackinaw - are natives of northern North America. This predator species is the largest trout in North America and can routinely grow to 25 pounds or more if they have a reliable source of other fish to eat. The largest lake trout taken at Blue Mesa weighed 50 pounds and was caught in 2007. They were first introduced in Blue Mesa in 1968. Biologists knew that the presence of kokanee and rainbows would provide a prey base for the lake trout. Subsequent stocking occurred in the early 1970s, 1980s and 1990s. Lake trout spend most time in open water, the same area favored by kokanee.
At the time the lake trout were introduced it was believed that they would not naturally reproduce in the reservoir. In the early1990s, water management at Blue Mesa was changed which reduced water level fluctuation in the fall and appear to have made conditions more favorable for lake trout reproduction.
Since then the species has reproduced naturally, the population has grown significantly and lake trout have become the major predator fish in the reservoir.
Economic Impact of Kokanee at Blue Mesa Reservoir
All types of fishing at Blue Mesa Reservoir are important to the economy of Gunnison County. But 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. Kokanee fishing is popular and people from throughout Colorado and the United States travel to Blue Mesa to fish for them. But in the last few years, the number of kokanee anglers has declined substantially.
According to surveys with anglers, from 1997-2007, an average of 60 percent of anglers stated that they were satisfied with the number of fish that they caught at Blue Mesa.
However, their perception changed radically in 2008: only 18 percent of anglers interviewed said they were satisfied. Dissatisfaction with angler catch continues into 2010 with only 25 percent of anglers satisfied with their catch. Angler dissatisfaction is attributed primarily to the decline in the number of kokanee salmon and rainbow trout caught.
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 in 26 other lakes and reservoirs in the state. The overall annual economic impact of kokanee salmon fishing in Colorado is estimated to be at least $29 million.
Surveying Fish Populations at Blue Mesa
Determining the exact number of fish in any body of water, especially in a reservoir the size of Blue Mesa, is difficult. However, using a variety of methods, aquatic biologists can learn a lot about the status of the populations of various species. These methods have been tested, refined and accepted by the scientific fisheries management community across the United States over the years.
Methods include: sonar technology to count open water fish; angler surveys -- also known as creel surveys -- to estimate catch, harvest and fishing pressure; live fish surveys using electro-fishing or net sampling to study body condition, growth, diet and abundance; and by tracking how many fish are stocked in a body of water each year.
These methods have revealed that the kokanee population has dropped significantly during the last 10 years. In 2000, the DOW estimated the Blue Mesa kokanee population at about 1 million. Now, the population is estimated to be only about 270,000 -- despite the stocking of more fish whenever possible. That represents a decline of more than 70 percent.
While the catch of kokanee has dropped substantially, angler surveys show that the catch of lake trout has increased significantly -- an indication that the population is growing fast. In the late 1990s, summer creel surveys showed that anglers caught about 1,700 lake trout per year. In 2010, lake trout catch was estimated at 5,800. Anglers caught 8,600 fish in 2008. In 2010, anglers released about one-third of the lake trout that they caught.
The estimated kokanee catch in 2000 was 130,000. In 2010 the estimated catch was just 23,300, an all-time low.
Creel surveys also show that lake trout predation is taking a large toll on rainbow trout. In 2005, anglers caught about 40,000 rainbows. In 2010, the estimated catch was only 11,700.
Perch, which were introduced illegally to Blue Mesa years ago, are also a prime target for lake trout. In 2005, anglers caught about 8,000 perch. In 2010, catch totaled just 938. Surveys and creel counts have found that perch are abundant; however, most are of very small size -- most six inches or less.
The fishery can be restored to a balance at Blue Mesa Reservoir through sound management practices. Anglers can also assist by keeping the lake trout that they catch. The more fish anglers keep the fewer fish the DOW must remove. The bag limit for lake trout smaller than 38 inches is unlimited. Anglers can keep one lake trout larger than 38 inches. By removing fish, anglers can help to slow the rate of population growth of lake trout and preserve trophy opportunities. Lake trout are tasty and provide healthy and nutritious food.