12-20-2007, 09:10 PM
The Colorado Division of Wildlife has confirmed that a small parasitic crustacean known as gill lice (Salmincola spp.) caused a sizeable all age die-off of kokanee salmon at Elevenmile Reservoir over the past year.
Initial visual observations of affected kokanee in the late summer of 2006 indicated that only larger fish were succumbing to the parasite. However, a sonar survey conducted this fall revealed that all ages of kokanee that were present in the lake in late summer of 2006 were affected, causing the overall population to be reduced.
Kokanee in otherwise good health can tolerate a small number of adult Salmincola spp. parasites without serious debilitation. However, there is a breaking point for a fish in any condition at which the damage caused by gill lice weakens, disables or even kills. Warmer than usual water temperatures in the summer of 2006 combined with the parasite resulted in this event.
Gill lice, like most other aquatic parasites, are not harmful to humans as long as the fish is prepared properly (145°F or until the flesh is opaque and separates easily with a fork).
"Rainbows, browns, and Snake River cutthroat trout have a higher resistance to the parasite-- no loss of these species has been detected at Elevenmile Reservoir and their populations are healthy and populations are strong," said Jeff Spohn, Aquatic Biologist for the DOW. "Despite this die-off, the DOW will continue to manage Elevenmile as a kokanee brood water. Barring any unforeseen circumstances, we expect our age-1 kokanee to grow to catchable size by the winter of 2008/2009."
Kokanee salmon fishing enthusiasts can continue to pursue their catch in the interim at the following waters: Blue Mesa Reservoir, Carter Lake, Dillon Reservoir, Lake Granby, Green Mountain Reservoir and Taylor Reservoir.
The Colorado Division of Wildlife is the state agency responsible for managing wildlife and its habitat, as well as providing wildlife related recreation. The Division is funded through hunting and fishing license fees, federal grants and Colorado Lottery proceeds through Great Outdoors Colorado.
Initial visual observations of affected kokanee in the late summer of 2006 indicated that only larger fish were succumbing to the parasite. However, a sonar survey conducted this fall revealed that all ages of kokanee that were present in the lake in late summer of 2006 were affected, causing the overall population to be reduced.
Kokanee in otherwise good health can tolerate a small number of adult Salmincola spp. parasites without serious debilitation. However, there is a breaking point for a fish in any condition at which the damage caused by gill lice weakens, disables or even kills. Warmer than usual water temperatures in the summer of 2006 combined with the parasite resulted in this event.
Gill lice, like most other aquatic parasites, are not harmful to humans as long as the fish is prepared properly (145°F or until the flesh is opaque and separates easily with a fork).
"Rainbows, browns, and Snake River cutthroat trout have a higher resistance to the parasite-- no loss of these species has been detected at Elevenmile Reservoir and their populations are healthy and populations are strong," said Jeff Spohn, Aquatic Biologist for the DOW. "Despite this die-off, the DOW will continue to manage Elevenmile as a kokanee brood water. Barring any unforeseen circumstances, we expect our age-1 kokanee to grow to catchable size by the winter of 2008/2009."
Kokanee salmon fishing enthusiasts can continue to pursue their catch in the interim at the following waters: Blue Mesa Reservoir, Carter Lake, Dillon Reservoir, Lake Granby, Green Mountain Reservoir and Taylor Reservoir.
The Colorado Division of Wildlife is the state agency responsible for managing wildlife and its habitat, as well as providing wildlife related recreation. The Division is funded through hunting and fishing license fees, federal grants and Colorado Lottery proceeds through Great Outdoors Colorado.