Kluane's Kokanee Salmon
© Parks Canada/Sarah Davidson
Kluane National Park & Reserve is Canada's only national park with a naturally occurring population of kokanee salmon, known as samäy ghra in the Southern Tutchone language. Kluane's kokanee probably evolved from sockeye salmon that once migrated from the Gulf of Alaska up the Alsek River into the Kathleen Lake system. The kokanee may have become land-locked when Lowell Glacier surged and blocked their return to the ocean. The kokanee now complete their entire life cycle in the fresh waters of the Kathleen Lake ecosystem.
|© Parks Canada / Alida Allison / 2006|
At about four years, kokanee salmon mature and undergo dramatic changes in preparation for spawning. The male turns bright red and develops a slightly humped back and elongated jaw. Females turn a darker shade of red.
When spawners arrive at Sockeye Creek, females use their tails to dig nests in the gravel. They then release as many as 1000 eggs for the males to fertilize. The female again uses her tail to cover the eggs with gravel. Once all the eggs are laid, the adults die.
Kokanee eggs remain in the gravel of the spawning stream, hatching out in January or February as "alevins" nourished by egg sacs attached to their bodies, but still remaining in the gravel. In a few months alevins develop into kokanee "fry" which emerge from the gravel and ride the currents downstream to begin the cycle again.
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Mouth of Sockeye Lake© Parks Canada / R. Markel
For nearly 30 years the park has monitored kokanee salmon as they return to spawn in Sockeye Creek. Spawning runs have averaged about 2800 fish, but recently these numbers have dropped dramatically. Only 730 were counted in 2002, 160 in 2003, 53 in 2004, 66 in 2005, 94 in 2006 and 88 in 2007.
To protect the remaining population, the park closed sport fishing of kokanee salmon in 2004. The area around the spawning grounds is designated a Zone 1, Special Preservation Area. The park is now doing extensive research to try to find the possible of the decline.
As research is completed, more pieces of the kokanee salmon puzzle will emerge. Results will be compared to earlier data in hopes of discovering why the kokanee population appears to be declining.
Monitoring the spawning stream© Parks Canada / R. Markel
- Have the kokanee been over-fished?
- Is climate change disrupting its life cycle? Kokanee fry may be emerging before food is available.
- Is water chemistry in the spawning stream changing? Needles from beetle-killed spruce may be increasing water acidity.
- Are water temperatures increasing? Temperatures above 15 degrees Celsius on the spawning beds may kill kokanee eggs.
- Are warmer lake temperatures forcing kokanee deeper, where there are more predators?
- Is there more competition for food between kokanee and other fish species?
- Are the kokanee spawning in another part of the Kathleen Lake system?
- Has a new disease or parasite been introduced?
- Is this a natural cycle that will eventually recover on its own?
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Checking Water Quality in Kathleen Lake © Parks Canada
To try to find answers to these questions the park is:
- Measuring changes in stream flow, temperature and water chemistry in the spawning stream.
- Collecting weather and climate data.
- Examining the contents of predators’ stomachs.
- Measuring the abundance of plankton, the main food of kokanee fry.
- Comparing creel surveys to analyze fish harvests.
- Conducting hydro-acoustic surveys to learn more about kokanee population dynamics in the Kathleen Lake ecosystem.
- Reviewing studies of declines in kokanee populations elsewhere in North America.
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Spawning kokanee salmon in Sockeye Creek© YTG Fisheries
The number of kokanee salmon returning to their spawning grounds remains very low, 489 in 2012. A 2005 hydro-acoustic survey found no kokanee elsewhere in the Kathleen Lake system. Results from a 2006 veterinarian's study show no evidence of disease or parasites in the fish. Investigations into the kokanee's food supply, and links between warmer water temperatures and low spawning numbers, are ongoing.
It remains unclear why the numbers of kokanee salmon are so low, but we are slowly learning more about the lake system as a whole. As our understanding grows, we may move closer to solving the puzzle of the kokanee's decline.