02-18-2011, 12:10 PM
GUNNISON, Colo. -- The Colorado Division of Wildlife's effort to restore the kokanee salmon population at Blue Mesa Reservoir continued during 2010 with the targeted removal of the kokanee's main predator, the lake trout.
Predation by lake trout has decimated kokanee salmon during the last decade and rebalancing the fishery is a top priority for the DOW. To reduce kokanee predation, biologists targeted primarily the segment of the lake trout population that is most numerous -- fish less than 30 inches.
Some 1,733 lake trout were removed from the reservoir in 2010, roughly double the number removed in the previous year. Ninety-five percent were less than 30 inches in size. Only 77 fish greater than 30 inches were removed. A total of 11 fish over 38 inches were netted, but all were released safely back to the water. DOW biologists collaborated with Colorado State University aquatic researchers to set removal objectives.
The fish that were removed were filleted, frozen and distributed to licensed anglers in the Gunnison area.
"Restoring the kokanee is a long-term project, and we're beginning to make good progress toward rebalancing the fishery in Blue Mesa Reservoir," said Dan Brauch, aquatic biologist for the DOW in Gunnison.
The kokanee population, once estimated at more than 1 million, has declined by nearly 75 percent since 2000. With the population now estimated to be only 270,000, anglers caught an all-time low of 23,000 kokanee in 2010, just 18 percent of the landings in 2000.
Besides providing recreational fishing opportunity to anglers, kokanee at Blue Mesa Reservoir play a critical role in supplying eggs for 26 reservoirs that stock salmon throughout Colorado. The fall spawning run of kokanee from Blue Mesa Reservoir to the Roaring Judy Hatchery provides half of the eggs for all Colorado waters. It is estimated that the state's kokanee fishery resource injects $29 million annually into Colorado's economy.
The population of lake trout has grown significantly in Blue Mesa during the last decade, which has precipitated the decline in kokanee. Based on monitoring results completed last spring, biologists estimate that since the early 2000s the number of lake trout less than 20 inches has increased by 570 percent. During the same period, the number of lake trout more than 30 inches caught during sampling surveys has increased by 70 percent.
Paring back the burgeoning population of smaller lake trout is also necessary to maintain enough forage to sustain trophy-sized lake trout at Blue Mesa, Brauch explained.
"Without sufficient numbers of kokanee, the reservoir's potential for producing trophy lake trout will continue to decline," Brauch explained. "In the past decade, lake trout weights have plummeted by 25 percent. By harvesting more small lake trout, the remaining fish will have the food they need to grow to trophy size."
In recent years, the DOW has attempted to increase the harvest of lake trout by increasing bag and possession limits, and by encouraging fishermen to take more fish home. But anglers are not harvesting enough fish to keep up with population growth; some are also releasing lake trout back to the reservoir.
The DOW continues to encourage anglers to harvest the lake trout they catch. Bag and possession are now unlimited for lake trout under 38 inches; anglers can keep one lake trout more than 38 inches.
Native to Canada and the upper Midwest, introduced lake trout are also causing serious problems in other lakes and reservoirs throughout the West. Stocked illegally into Yellowstone Lake in Yellowstone National Park, lake trout are decimating native Yellowstone cutthroat trout, which provide a critical food source for the park's grizzlies. In Montana's Flathead Lake, lake trout are punishing the population of native bull trout, a threatened species, and have nearly wiped out the stocked kokanee salmon population. Lake trout are also harming sport fisheries in Washington, California, Idaho and Wyoming.
At Blue Mesa Reservoir, the DOW's research and management efforts will continue during 2011.
"This is a complex fishery in which we are managing non-native species," Brauch said. "All of our management decisions are designed for the long term and to provide recreational opportunity to a variety of anglers. The top priority is kokanee salmon, but through science- and research-based management, the fishery can also accommodate other species."
For a complete report on 2010 fisheries management work at Blue Mesa Reservoir, go to: http://wildlife.state.co.us/Fishing/Mana...gement.htm.
For more news about Division of Wildlife go to: http://wildlife.state.co.us/news/index.asp?DivisionID=3
For more information about Division of Wildlife go to: http://wildlife.state.co.us.
Media Contact
Joe Lewandowski, southwest region PIO<br />
Contact Phone: (970)375-6708
Predation by lake trout has decimated kokanee salmon during the last decade and rebalancing the fishery is a top priority for the DOW. To reduce kokanee predation, biologists targeted primarily the segment of the lake trout population that is most numerous -- fish less than 30 inches.
Some 1,733 lake trout were removed from the reservoir in 2010, roughly double the number removed in the previous year. Ninety-five percent were less than 30 inches in size. Only 77 fish greater than 30 inches were removed. A total of 11 fish over 38 inches were netted, but all were released safely back to the water. DOW biologists collaborated with Colorado State University aquatic researchers to set removal objectives.
The fish that were removed were filleted, frozen and distributed to licensed anglers in the Gunnison area.
"Restoring the kokanee is a long-term project, and we're beginning to make good progress toward rebalancing the fishery in Blue Mesa Reservoir," said Dan Brauch, aquatic biologist for the DOW in Gunnison.
The kokanee population, once estimated at more than 1 million, has declined by nearly 75 percent since 2000. With the population now estimated to be only 270,000, anglers caught an all-time low of 23,000 kokanee in 2010, just 18 percent of the landings in 2000.
Besides providing recreational fishing opportunity to anglers, kokanee at Blue Mesa Reservoir play a critical role in supplying eggs for 26 reservoirs that stock salmon throughout Colorado. The fall spawning run of kokanee from Blue Mesa Reservoir to the Roaring Judy Hatchery provides half of the eggs for all Colorado waters. It is estimated that the state's kokanee fishery resource injects $29 million annually into Colorado's economy.
The population of lake trout has grown significantly in Blue Mesa during the last decade, which has precipitated the decline in kokanee. Based on monitoring results completed last spring, biologists estimate that since the early 2000s the number of lake trout less than 20 inches has increased by 570 percent. During the same period, the number of lake trout more than 30 inches caught during sampling surveys has increased by 70 percent.
Paring back the burgeoning population of smaller lake trout is also necessary to maintain enough forage to sustain trophy-sized lake trout at Blue Mesa, Brauch explained.
"Without sufficient numbers of kokanee, the reservoir's potential for producing trophy lake trout will continue to decline," Brauch explained. "In the past decade, lake trout weights have plummeted by 25 percent. By harvesting more small lake trout, the remaining fish will have the food they need to grow to trophy size."
In recent years, the DOW has attempted to increase the harvest of lake trout by increasing bag and possession limits, and by encouraging fishermen to take more fish home. But anglers are not harvesting enough fish to keep up with population growth; some are also releasing lake trout back to the reservoir.
The DOW continues to encourage anglers to harvest the lake trout they catch. Bag and possession are now unlimited for lake trout under 38 inches; anglers can keep one lake trout more than 38 inches.
Native to Canada and the upper Midwest, introduced lake trout are also causing serious problems in other lakes and reservoirs throughout the West. Stocked illegally into Yellowstone Lake in Yellowstone National Park, lake trout are decimating native Yellowstone cutthroat trout, which provide a critical food source for the park's grizzlies. In Montana's Flathead Lake, lake trout are punishing the population of native bull trout, a threatened species, and have nearly wiped out the stocked kokanee salmon population. Lake trout are also harming sport fisheries in Washington, California, Idaho and Wyoming.
At Blue Mesa Reservoir, the DOW's research and management efforts will continue during 2011.
"This is a complex fishery in which we are managing non-native species," Brauch said. "All of our management decisions are designed for the long term and to provide recreational opportunity to a variety of anglers. The top priority is kokanee salmon, but through science- and research-based management, the fishery can also accommodate other species."
For a complete report on 2010 fisheries management work at Blue Mesa Reservoir, go to: http://wildlife.state.co.us/Fishing/Mana...gement.htm.
For more news about Division of Wildlife go to: http://wildlife.state.co.us/news/index.asp?DivisionID=3
For more information about Division of Wildlife go to: http://wildlife.state.co.us.
Media Contact
Joe Lewandowski, southwest region PIO<br />
Contact Phone: (970)375-6708